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Автор: Sanchis-Alfonso V.
Теги: medicine physiology practical medicine human physiology
ISBN: 978-3-031-09766-9
Год: 2023
Текст
Anterior Knee Pain and Patellar Instability
Vicente Sanchis-Alfonso Editor Anterior Knee Pain and Patellar Instability Third Edition 123
Editor Vicente Sanchis-Alfonso Department of Orthopedic Surgery Hospital Arnau de Vilanova Valencia, Spain ISBN 978-3-031-09766-9 ISBN 978-3-031-09767-6 https://doi.org/10.1007/978-3-031-09767-6 (eBook) 1st edition: © Springer-Verlag London Limited 2006 2nd edition: © Springer-Verlag London Limited 2011 3rd edition: © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland
To my mother, my maternal aunt and my little sister with all my love In memoriam (†) It is very difficult to accept that my little sister is no longer by my side and that I will never see her again, at least in this life. My mother used to say that one only dies when we no longer think of them. If that is true, I can say that my sister is more alive than ever for me. I think about her all the hours of the day. I have very vivid and intense memories, and anecdotes of our times together during the 11 years that her disease lasted. Some memories are painful, but others make me smile without realizing it. She was a great sister, an amazing person, brave and determined. She was even generous when dying as she gave us
time to prepare ourselves and say goodbye. The time that she gave us has made her loss more bearable. I cannot even imagine how I would be right now if she had died suddenly being healthy. Mari Carmen, I carry you deeply within me and time will never erase you from my memory. You will be forever in my heart; having you close has been the greatest gift I have ever been bestowed.
Foreword to the Third Edition It has been a great pleasure to witness the development of this book over these past few years. This book is much improved over previous editions as Vicente has incorporated many new ideas and concepts. Moreover, as in previous editions, he has been able to gather a group of extremely talented experts to help him write this book. This edition will establish him as the unchallenged leader in understanding the workings of the Patellofemoral Joint, why it fails, how it fails, and what we now think are the best approaches to treatment. I call him a leader. But what constitutes a leader? For Warren Bennis, an American academic who focused his entire life on the study of leadership, it is clear. Returning from World War II to enter university eventually with a Ph.D. from the Massachusetts Institute of Technology, he studied leadership in all its facets. He wrote 30 books and left behind a legacy of an almost 17-meter-long shelf of published and working papers in the archives of the University of Southern California. Once when asked in an interview to say what it takes to be a great leader, he replied “That’s easy! A great leader has a vision for accomplishment and a particular passion for a profession and for persisting in pursuit of his vision in spite of failures. Integrity is imperative and a leader never lies…about anything. Equally necessary he is curious and daring. A true leader wonders about everything, wants to learn as much as he can, experiments and takes risks” (The New York Times, Warren G. Bennis Obituary, August 1, 2014). Leaders possessing these attributes are indeed uncommon. Communicating with Vicente, it is clear he possesses vision, passion, integrity, curiosity, and daring. A vision to understand the Patellofemoral Joint and the passion to follow that dream and deliver perfection for his patients. Integrity and curiosity, he listens intensely to his patients, examines them carefully. Moreover, he questions his poor results. Although he may be quiet, he is daring and courageous to enter uncharted areas performing seemingly foolish complex surgeries. However, only after intense vii
viii Foreword to the Third Edition and deep study has he rejected standard approaches and revealed that the indications are not so foolish as our conventional treatments. With these attributes, he is indeed a leader, and this brilliant book should lead us all forward. Robert A. Teitge, M.D. Professor Emeritus of Orthopedic Surgery Wayne State University Detroit, Michigan, USA
Foreword to the Second Edition I am particularly pleased to write the introduction to this fine compendium of ideas, as Dr. Sanchis Alfonso has been a leader in the understanding of patellofemoral pain origins. This topic has fascinated me my entire career in orthopedic surgery, and has been a focus of most of my research and teaching. In 1985, I published our findings of nerve injury in the peripatellar retinaculum of patients with patellar imbalance and anterior knee pain, helping to establish the link between pain and patellofemoral malalignment. Dr. Sanchis Alfonso has not only added substance and scientific evidence to the link between musculoskeletal stress and neural changes causing pain, he has now brought together many good thinkers and scientists to present interesting and sometimes divergent points of view in this current volume. The great philosopher Hegel stated “it is through the tension of opposites that we come to a higher truth”. Through computer simulated knee mechanical function noted in this book, Elias and Cosgarea demonstrate how articular loads can be tracked accurately and that even small aberrations of mechanical function can cause considerable alterations of stress transmitted through articular surfaces. Similarly, retinacular restraints around the patellofemoral joint will experience profound changes of loading when alignment is off, overuse is extreme, surgical balancing is not precise, and at extremes of laxity or tightness. Such is the nature of patellar and peripatellar stress and the relative anoxia caused by abnormal loading of peripatellar structure leading to cytokine elaboration and resulting pain. Thank you Dr. Sanchis Alfonso. I believe this book is a wonderful compendium of current patellofemoral thought, not designed as a cookbook with easy answers, because there are many complex problems around the anterior knee and few easy answers. Rather, Dr. Sanchis-Alfonso’s text contains many independent thinkers and scientists with a variety of approaches and concepts, some validated, some not, but all important in our search of the patellofemoral “holy grail”. I encourage the reader to think, along with the authors of this textbook, synthesizing ideas and considering carefully how each concept presented here applies to the individual patient, always emphasizing non-operative and simple measures whenever possible, but recognizing the importance of appropriate surgery when necessary for the relief of pain and suffering in the challenging patients with recalcitrant patellofemoral pain and instability. ix
x Foreword to the Second Edition In closing, I want to summarize my 32 years of experience with patellofemoral patients by saying that I believe a critical underlying concept for treating many patients with patellofemoral dysfunction is to recognize that the structural imbalance we see in patients with patellofemoral malalignment is at the root of much patellofemoral pain and instability. Therefore, our challenge is to restore balance and reduce excessive patellofemoral stress in these patients, using non-operative measures including rest when possible, but designing necessary surgery to absolutely minimize both articular and periarticular damages while restoring patellofemoral balance as precisely as possible. John P. Fulkerson, M.D. Clinical Professor of Orthopaedic Surgery University of Connecticut School of Medicine Farmington, Connecticut, USA
Foreword to the First Edition Anterior knee pain is one of the really big problems in my specialty, sports orthopedic surgery, but also in all other types of orthopedic surgery. Many years ago Sakkari Orava in Finland showed that among some 1311 Finnish runners, anterior knee pain was the second most common complaint. In young school girls around 15 years of age, anterior knee pain is a common complaint. In ballet classes of the same age as much as 60–70% of the students complain of anterior knee pain. It is therefore an excellent idea of Dr. Sanchis-Alfonso to publish a book about anterior knee pain and patellofemoral instability in the active young. He has been able to gather a group of extremely talented experts to help him write this book. I am particularly happy that he has devoted so much space to the non-operative treatment of anterior knee pain. During my active years as a knee surgeon, one of my worst problems was young girls referred to me for surgery of anterior knee pain. Girls that already had had 8–12 surgeries for their knee problem–surgeries that had rendered them more and more incapacitated after each operation. They now came to me for another operation. In all these cases, I referred them to our pain clinic for careful analysis, pain treatment followed by physical therapy. All recovered but had been the victims of lots of unnecessary knee surgery before they came to me. I am also happy that Suzanne Werner in her chapter refers to our study on the personality of these anterior knee pain patients. She found that the patients differ from a normal control group of the same age. I think this is very important to keep in mind when you treat young patients with anterior knee pain. In my mind physical therapy should always be the first choice of treatment. Not until this treatment has completely failed and a pain clinic recommends surgery, do I think surgery should be considered. In patellofemoral instability the situation is different. When young patients suffer from frank dislocations of the patella, surgery should be considered. From my many years of treating this type of patients, I recommend that the patients undergo an arthroscopy before any attempts to treat the instability begins. The reason is that I have seen so many cases with normal X-rays that have 10–15 loose bodies in their knees. If these pieces consist of just cartilage, they cannot be seen on X-ray. When a dislocated patella jumps back, it often hits the lateral femoral condyle with considerable force. Small cartilage pieces are blasted away as well from femur as from the patella. If they are overlooked they will eventually lead to blockings of the knee in the future. xi
xii Foreword to the First Edition The role of the medial patellofemoral ligament can also not be overstressed. When I was taught to operate on these cases, this ligament was not even known. I also feel that when patellar instability is going to be operated on, it is extremely important that the surgeon carefully controls in what direction the instability takes place. All instability is not in lateral direction. Some patellae have medial instability. If someone performs a routine lateral release in a case of medial instability, he will end up having to repair the lateral retinaculum in order to treat the medial dislocation that eventually occurs. Hughston and also Teitge have warned against this in the past. It is a pleasure for me to recommend this excellent textbook by Dr. Vicente Sanchis-Alfonso. Ejnar Eriksson, M.D., Ph.D. Professor Emeritus of Sports Medicine Karolinska Institute Stockholm, Sweden
Preface Take good care of your patients and they will take good care of you —Freddie Fu Medicine is meant to help people! It is OK to make some money but it´s not the key —Peter Lauterbur Santiago Ramón y Cajal, Spanish Nobel Laureate in Medicine, in his book, “The Tonics of the Will”, he said: “What a great tonic it would be for the young researcher that his mentor, instead of astonishing him and discouraging him with the sublimity of great completed projects, would explain the genesis of each scientific creation along with the mistakes and doubts that preceded them”. This is why I think it is interesting for you to know how the book you are holding in your hands came to be. This book is not only the fruit of my effort and perseverance and, clearly, the generosity of all my colleagues but also of chance. Many years ago, my good friend Donald Fithian from San Diego told me that to stand out in something I had to focus on a topic not well known and that many did not like. In those years, patellofemoral disorders fulfilled both. Paraphrasing a great American poet Robert Frost in his poem “The Road Not Taken”, I took the least traveled road 24 years ago, that is, I focused on the patella. As in this poem, it made all the difference. Without a doubt, I do not regret having chosen this road. The patella has led to very satisfactory experiences with my patients and other colleagues. In 2003, I wrote a book in Spanish with the “Editorial Médica Panamericana”, one of the most prestigious publishing houses in the Spanish language. It was entitled “Dolor Anterior de Rodilla e Inestabilidad Rotuliana en el Paciente Joven” (Anterior Knee Pain and Patellar Instability in the Young Patient). Frankly, I never thought it would be very successful. That attitude was not due to its quality, of which I was convinced, but due to its subject matter. This book was the germ for the one I am now referring to. In 2004, I had the fortune of meeting Prof. Ejnar Eriksson, from the Karolinska Institute of Stockholm, at an international meeting in Sardinia, Italy. My good friend, Roland Biedert from Switzerland, had invited me to participate in a panel session about patellofemoral pain. During the coffee break, Prof. Eriksson approached me and encouraged me to translate this book into English. I was quite delighted by his suggestion. So, as soon as I returned to Spain, I prepared a project and presented it to Springer. I was lucky that this renowned publishing house accepted the challenge of xiii
xiv publishing, in English, an extension of the Spanish edition. It was quite successful both with regard to sales and the book critics. They even said it was a model for what a book for specialists should be. That first English edition was published in December 2005. However, getting there is only half the battle, as it must be kept up to date. Therefore, in 2011, a second edition of the book was published in English. I donated my author’s royalties to the research foundation of the Hospital Clínico Universitario in Valencia, Spain. It was specifically given for the line of research in breast cancer, which made my sister very happy. Sadly, she recently died from breast cancer. For this reason, I proposed doing this third and last edition to Springer, as a tribute to my sister. This book is, in fact, the third edition in English. Notwithstanding, we are really before a fourth edition of this book since the first edition was the one that was published in Spanish. This monograph reflects my deep interest in the pathology of the knee, particularly that of the extensor mechanism, and emphasizes the great importance I give to the concept of subspecialization. This is the only way to confront the deterioration and the mediocrity of our specialty, Orthopedic Surgery, and to give our patients better care. In line with the concept of subspecialization, this book clearly required the participation of various authors. They are of different nationalities as well as from different schools of thought. Moreover, the participation of diverse specialists, from a multidisciplinary perspective, affords us a wider vision of this pathology. With this book, we draw upon the most common pathology of the knee even though it is the most neglected, the least known, the most problematic and controversial topic (The Black Hole of Orthopedics). Our knowledge of its etiopathogenesis is limited. Therefore, its treatment is one of the most complex among the different pathologies of the knee. On the other hand, we also face the problem of frequent and serious diagnostic errors that may lead to unnecessary operations. This book is organized into four parts. Unlike other publications, it gives great importance to etiopathogenesis. Albeit in an eminently clinical and practical manner, the latest theories are presented regarding the pathogenesis of anterior knee pain and patellar instability (Part I “Etiopathogenic Bases, Prevention and Therapeutic Implications”). In agreement with John Hunter, I think that to know the effects of an illness is to know very little. To know the cause of the effects is what is important. In Part II (“Surgical techniques-Why, When and How I Do It”), the surgical techniques that are in use today for the patellofemoral joint are described in detail. They are described by the surgeons who have designed the technique and who are recognized by their colleagues as “masters” in their specialty. The third part of this monograph is given over to the discussion of complex clinical cases. I believe we learn far more from our own mistakes (“To Err is Human”, Marcus Tullius Cicero), and those of other specialists than from our own success (“Learn from the mistakes of others-you can never live long enough to make them all yourself”, John Luther). The diagnoses reached and how the cases were resolved are explained in detail (“Good results come from experience, experience from bad results”, Prof. Erwin Morscher). Finally, in Preface
Preface xv Part IV, new frontiers in anterior knee pain, patellar instability, and patellofemoral osteoarthritis evaluation and treatment are analyzed. The first objective I have laid out in this book is to highlight the soaring incidence of this pathology and its impact on young people, athletes, workers, and the economy. The second goal is to improve prevention and diagnosis to reduce the economic and social costs of this condition. The final objective is to improve health care for these patients. “Anterior Knee Pain and Patellar Instability” is addressed to orthopedic surgeons (both general and those specialized in knee surgery), specialists in sports medicine, rehabilitation specialist MDs, and physiotherapists. Thus, we feel that this monograph will fill an important gap in the literature about the pathology of the extensor mechanism of the knee with this approach. However, we do not intend to substitute any books on patellofemoral pathology but rather to complement them (“All in all, you’re just another brick in the wall”, Pink Floyd, The Wall). Although the information contained herein will evidently require future revision, it serves as an authoritative reference on one of the most problematic entities in the pathology of the knee at this time. We hope this book will be a reference in the future from our youngest to our oldest colleagues. We trust that the reader will find this book useful and, consequently, be indirectly valuable for patients. Valencia, Spain April 2022 Vicente Sanchis-Alfonso, M.D., Ph.D.
Acknowledgments At times our own light goes out and is rekindled by a spark from another person. Each of us has cause to think with deep gratitude of those who have lighted the flame within us —Albert Schweitzer (Nobel Peace Prize) I wish to express my sincere gratitude to my good friends and colleagues Don Fithian, John Fulkerson, and Bob Teitge. My journey in knee surgery began in 1992 in San Diego, California, USA. When I got to San Diego, pure serendipity put Donald Fithian in my path. Quoting William Shakespeare, destiny is the one that shuffles the cards, but we are the ones who play them. But someone has to give us a chance to play. Donald gave me this opportunity. He shuffled the cards. He introduced me in the International Patellofemoral Study Group. I was his guest at the meeting in Lyon, France, in 1998. I will be forever grateful for his invaluable help and friendship. The next year, in 1999, I was selected to become a member of this organization and where else but in St. Helena, in Napa County. California again. Belonging to this group has motivated me to study every day and to stay updated, in order to keep up with the rest of my colleagues. I have had a deep respect and admiration for John Fulkerson ever since I read the second edition of his book ``Disorders of the Patellofemoral Joint'' when I was a resident in Orthopedic Surgery. For me this book was a real page-turner, a kind of Harry Potter for today´s teenagers. Reading this book was a breakthrough. John Fulkerson made the patellofemoral joint my professional passion. Despite being the most important and recognized surgeon in this field, he turned out to be the most modest and closest to me. He gave me a lot of support and guidance. Bob Teitge got me into thinking outside of the box. He gave me the gift of his friendship and all the necessary tools for my complete professional development. With his incredible generosity, he shared all his knowledge without expecting anything in return. He also showed me techniques I had not heard of before that made it possible for me to help many patients who were considered lost-causes by others. Bob, thank you for always being there, for helping me improve day by day and for teaching me to row against the tide. I am extremely lucky to be surrounded by incredible people who support me unconditionally. They have provided me with the means and thus the opportunities to fully develop in my professional life. I would like to acknowledge Julio Domenech-Fernandez, Erik Montesinos-Berry, Cristina Ramírez-Fuentes, and Maria Jose Sanguesa-Nebot for their friendship and invaluable help. Thank you, Julio, you are the best boss that one can have. Thank you for your understanding. You are truly a motivating and inspiring xvii
xviii person. Thank you, Maria Jose, for being the way you are, marvelous, keep it up. I also want to commend my colleague at the Knee Unit of my hospital, Alejandro Roselló-Añón. Undoubtedly, he has a bright future ahead of him. All of you are, in part, responsible for this book. My gratitude also goes out to my friends Jack Andrish, Roland Biedert, Antonio Darder-Prats, David Dejour, Scott F. Dye, João Espregueira-Mendes, Jack Farr, Christian Fink, Ronald Grelsamer, Laura López-Company, Luis Martí-Bonmatí, Al Merchant, Joan Carles Monllau, James Selfe and to all the members of the International Patellofemoral Study Group for their constant encouragement and inspiration. Furthermore, I have had the privilege and honor to count on the participation of outstanding specialists who have lent prestige to this monograph. I thank all of them for their time, effort, dedication, kindness, as well as for the excellent quality of their contributing chapters. They all have demonstrated generosity in sharing their great clinical experience in a clear and concise way. I am in debt to you all. Personally, and on behalf of those patients who will undoubtedly benefit from this work, thank you. My sincere gratitude to Eric L. Goode and Justyna Mazurek for their inestimable collaboration. Last but not least, I am extremely grateful to both Springer London and to the production team for the confidence shown in this project and for completing this project with excellence from the time the cover is opened until the final chapter is presented. Spring 1993, photograph at the Albufera Natural Park (Valencia, Spain). Donald Fithian (right), his wife M.E. (left), and the editor of this book, Vicente Sanchis-Alfonso (in the middle) Acknowledgments
Acknowledgments xix Mount Sinai Medical Center, New York City, NY, USA, 2009. Vicente Sanchis-Alfonso (right), Ronald Grelsamer (left), and John Fulkerson (in the middle) Vicente Sanchis-Alfonso, M.D., Ph.D.
Contents Etiopathogenic Bases, Prevention and Therapeutic Implications Patellofemoral Pain: An Overview . . . . . . . . . . . . . . . . . . . . . . . . . . Vicente Sanchis-Alfonso and Ronald P. Grelsamer 3 Pathophysiology of Anterior Knee Pain . . . . . . . . . . . . . . . . . . . . . . Vicente Sanchis-Alfonso, Esther Roselló-Sastre, Scott F. Dye, and Robert A. Teitge 19 Femoral and Tibial Rotational Abnormalities Are the Most Ignored Factors in the Diagnosis and Treatment of Anterior Knee Pain Patients. A Critical Analysis Review . . . . . . . . . . . . . . . Vicente Sanchis-Alfonso and Robert A. Teitge Why is Torsion Important in the Genesis of Anterior Knee Pain? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Robert A. Teitge Clinical and Radiological Assessment of the Anterior Knee Pain Patient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vicente Sanchis-Alfonso, Cristina Ramírez-Fuentes, Laura López-Company, and Pablo Sopena-Novales 41 53 59 Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat These Patients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vicente Sanchis-Alfonso, Julio Doménech-Fernández, Benjamin E. Smith, and James Selfe 81 Management of Anterior Knee Pain from the Physical Therapist’s Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jenny McConnell 99 Targeted Treatment in Anterior Knee Pain Patients According to Subgroups Versus Multimodal Treatment . . . . . . . . . . . . . . . . . 119 James Selfe Surgical Treatment of Anterior Knee Pain. When is Surgery Needed? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Vicente Sanchis-Alfonso and Robert A. Teitge xxi
xxii The Failed Patella. What Can We Do? . . . . . . . . . . . . . . . . . . . . . . 151 Vicente Sanchis-Alfonso, Julio Domenech-Fernandez, and Robert A. Teitge Risk Factors for Patellofemoral Pain: Prevention Programs . . . . . 175 Michelle C. Boling and Neal R. Glaviano Anterior Knee Pain After Arthroscopic Meniscectomy: Risk Factors, Prevention and Treatment . . . . . . . . . . . . . . . . . . . . . . . . . 187 Jorge Amestoy, Daniel Pérez-Prieto, and Joan Carles Monllau Anterior Knee Pain Prevalence After Anterior Cruciate Ligament Reconstruction: Risk Factors and Prevention. . . . . . . . . 197 Antonio Darder-Sanchez, Antonio Darder-Prats, and Vicente Sanchis-Alfonso Patellar Tendinopathy: Risk Factors, Prevention, and Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 Rochelle Kennedy and Jill Cook Pathophysiology of Patellar Instability . . . . . . . . . . . . . . . . . . . . . . 225 William R. Post Evaluation of the Patient with Patellar Instability: Clinical and Radiological Assessment . . . . . . . . . . . . . . . . . . . . . . . 235 Andrew E. Jimenez, Lee Pace, and Donald C. Fithian Evolving Management of Acute Dislocations of the Patella . . . . . . 251 Vicente Sanchis-Alfonso, Erik Montesinos-Berry, and Marc Tompkins How to Deal with Chronic Patellar Instability . . . . . . . . . . . . . . . . 259 Vicente Sanchis-Alfonso and Erik Montesinos-Berry Limitations of Patellofemoral Surgery in Children . . . . . . . . . . . . . 277 Mahad Hassan and Marc Tompkins The Failed Medial Patellofemoral Ligament Reconstruction. What Can We Do? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 Vicente Sanchis-Alfonso and Cristina Ramírez-Fuentes Surgical Treatment of Recurrent Patellar Instability: History and Current Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305 Christopher A. Schneble, David A. Molho, and John P. Fulkerson Chondral and Osteochondral Lesions in the Patellofemoral Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315 Kevin Credille, Dhanur Damodar, Zachary Wang, Andrew Gudeman, and Adam Yanke Patellofemoral Arthritis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329 Christopher S. Frey, Augustine W. Kang, Kenneth Lin, Doug W. Bartels, Jack Farr, and Seth L. Sherman Contents
Contents xxiii Fresh Osteochondral Allografts in Patellofemoral Surgery . . . . . . 349 Suhas P. Dasari, Enzo S. Mameri, Bhargavi Maheshwer, Safa Gursoy, Jorge Chahla, and William Bugbee Extensor Mechanism Complications After Total Knee Arthroplasty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375 Jobe Shatrov, Cécile Batailler, Gaspard Fournier, Elvire Servien, and Sebastien Lustig Surgical Techniques: Why, When and How I Do It Sonosurgery Ultrasound-Guided Arthroscopic Shaving for the Treatment of Patellar Tendinopathy When Conservative Treatment Fails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403 Ferran Abat and Håkan Alfredson Medial Patellofemoral Ligament Reconstruction: Anatomical Versus Quasi-anatomical Femoral Fixation . . . . . . . . . . . . . . . . . . . 415 Vicente Sanchis-Alfonso, Maximiliano Ibañez, Cristina Ramirez-Fuentes, and Joan Carles Monllau Minimal Invasive MPFL Reconstruction Using Quadriceps Tendon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431 Christian Fink Combined Medial Patellofemoral Ligament and Medial Patellotibial Ligament Reconstruction . . . . . . . . . . . . . . . . . . . . . . . 445 Robert S. Dean, Betina B. Hinckel, and Elizabeth A. Arendt Warning: Lateral Retinacular Release Can Cause Medial Patellar Dislocation—Lateral Patellofemoral Ligament Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461 Robert A. Teitge Reconstruction of the Lateral Patellofemoral Ligament . . . . . . . . . 469 David S. Zhu and Lutul D. Farrow Patellar Tendon Imbrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 477 Ronak M. Patel, Sneh Patel, and Jack Andrish Quadricepsplasty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483 Jason Koh Sulcus Deepening Trochleoplasty . . . . . . . . . . . . . . . . . . . . . . . . . . . 491 Edoardo Giovannetti de Sanctis and David H. Dejour Arthroscopic Deepening Trochleoplasty. . . . . . . . . . . . . . . . . . . . . . 503 Lars Blønd Lengthening Trochleoplasty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 521 Roland M. Biedert Tibial Tubercle Osteotomy in Patients with Patella Supera or Infera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533 Joan Carles Monllau and Enrique Sanchez-Muñoz
xxiv Tibial Tubercle Anteromedialization Osteotomy (Fulkerson Osteotomy) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 543 Andrew Gudeman and Jack Farr Rotational Osteotomy. Principles, Surgical Technique, Outcomes and Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555 Vicente Sanchis-Alfonso, Alejandro Roselló-Añón, Cristina Ramírez-Fuentes, and Robert A. Teitge Bipolar Fresh Osteochondral Allograft Transplantation of the Patellofemoral Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 585 Vicente Sanchis-Alfonso and Joan Carles Monllau Patellofemoral Arthroplasty. Pearls and Pitfalls . . . . . . . . . . . . . . . 593 Pedro Hinarejos Clinical Cases—Primary and Revision Patellofemoral Surgery Patellofemoral Joint Preservation Surgery A Case-Based Approach Case # 1: Disabling Anterior Knee Pain After Failed MPFL Reconstruction in a Patient with Patellar Chondropathy, Femoral Anteversion and External Tibial Torsion . . . . . . . . . . . . . 615 Vicente Sanchis-Alfonso and Alejandro Roselló-Añón Case # 2: Disabling Anterior Knee Pain Recalcitrant to Conservative Treatment in a Patient with Patellofemoral Osteoarthritis and Structural Femoral Retrotorsion and Genu Varum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623 Vicente Sanchis-Alfonso and Alejandro Roselló-Añón Case # 3: Severe Anterior Knee Pain Recalcitrant to Conservative Treatment in a Patient with Functional Femoral Retrotorsion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629 Vicente Sanchis-Alfonso, Marc Tey-Pons, and Joan Carles Monllau Case # 4: Disabling Anterior Knee Pain in a Multi-operated Young Patient with Severe Patellofemoral Osteoarthritis and Medial Patellar Instability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635 Vicente Sanchis-Alfonso Case # 5: Multidirectional Patellar Instability After Over-Medialization of the Tibial Tubercle in a Patient with Severe Trochlear Dysplasia and Patella Alta . . . . . . . . . . . . . 639 Vicente Sanchis-Alfonso Case # 6: Failed MPFL Reconstruction in a Patient with Severe Trochlear Dysplasia and Malpositioning of the Femoral Attachment Point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 645 Vicente Sanchis-Alfonso Contents
Contents xxv Case # 7: Lateral Patellar Instability in a Multi-operated Young Patient with Severe Patellofemoral Osteoarthritis and Severe Trochlear Dysplasia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 651 Vicente Sanchis-Alfonso and Joan Carles Monllau Case # 8: Extensor Mechanism Reconstruction After Resection of a Soft Tissue Sarcoma that Infiltrates the Patellar Tendon . . . . 657 Vicente Sanchis-Alfonso, Alejandro Roselló-Añón, Eloisa Villaverde-Doménech, Onofre Sanmartin, and Juan Pablo Aracil-Kessler Case # 9: Severe Patellofemoral Chondropathy in an Active 47-Year-Old Patient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 663 Erik Montesinos-Berry Case # 10: Dislocated Patella After Revision Total Knee Arthroplasty. Case # 11: Patella Baja and Valgus Limb 56 Years After Tibial Tubercle Transfer . . . . . . . . . . . . . . . . . . . . . 667 Robert A. Teitge New Frontiers in Anterior Knee Pain, Patellar Instability and Patellofemoral Osteoarthritis Evaluation and Treatment Kinetic and Kinematic Analysis in Evaluating Anterior Knee Pain Patients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 675 Vicente Sanchis-Alfonso and Jose María Baydal-Bertomeu Patellofemoral Instrumented Stress Testing . . . . . . . . . . . . . . . . . . 689 Ana Leal, Renato Andrade, Cristina Valente, André Gismonti, Rogério Pereira, and João Espregueira-Mendes Anterior Knee Pain and Functional Femoral Maltorsion in Patients with Cam Femoroacetabular Impingement . . . . . . . . . . 699 Marc Tey-Pons, Vicente Sanchis-Alfonso, and Joan Carles Monllau Finite Element Technology in Evaluating Medial Patellofemoral Ligament Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 705 Vicente Sanchis-Alfonso, Diego Alastruey-López, Cristina Ramirez-Fuentes, Erik Montesinos-Berry, Gerard Ginovart, Joan Carles Monllau, and María Angeles Perez Biomechanical Analysis of the Influence of Trochlear Dysplasia on Patellar Tracking and Pressure Applied to Cartilage . . . . . . . . 721 John J. Elias Brain Network Functional Connectivity Clinical Relevance and Predictive Diagnostic Models in Anterior Knee Pain Patients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731 María Beser-Robles, Vicente Sanchis-Alfonso, and Luis Martí-Bonmatí
xxvi Robotic-Assisted Patellofemoral Arthroplasty . . . . . . . . . . . . . . . . . 745 Joseph C. Brinkman, Christian Rosenow, Matthew Anastasi, Don Dulle, and Anikar Chhabra Modern Patellofemoral Inlay Arthroplasty—A Silver Lining in the Treatment of Isolated Patellofemoral Arthritis . . . . . . . . . . . 757 Marco-Christopher Rupp, Jonas Pogorzelski, and Andreas B. Imhoff Virtual Orthopaedic Examination in Patellofemoral Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 765 Casey L. Wright and Miho J. Tanaka Epilogue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 781 Contents
Contributors Ferran Abat ReSport Clinic Barcelona. Blanquerna-Ramon Llull University School of Health Science. Rosselló, Barcelona, Spain Diego Alastruey-López Instituto de Investigación en Ingeniería de Aragón (I3A), Instituto de Investigación Sanitaria Aragón (IIS Aragón), Multiscale in Mechanical and Biological Engineering, University of Zaragoza, Zaragoza, Spain Håkan Alfredson Department of Community Medicine and Rehabilitation, Sports Medicine, Umeå University, Umeå, Sweden Jorge Amestoy Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain; Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain; Universitat Autònoma de Barcelona (UAB), Barcelona, Spain Matthew Anastasi Department of Orthopaedic Surgery, Mayo Clinic, Phoenix, AZ, USA; Department of Sports Medicine, Mayo Clinic, Tempe, Phoenix, AZ, USA; Alix School of Medicine, Mayo Clinic, Phoenix, AZ, USA Renato Andrade Dom Henrique Research Centre, Porto, Portugal; Clínica Espregueira - FIFA Medical Centre of Excellence, Porto, Portugal; Porto Biomechanics Laboratory (LABIOMEP), Faculty of Sports, University of Porto, Porto, Portugal Jack Andrish The Cleveland Clinic Foundation, Cleveland, OH, USA Juan Pablo Aracil-Kessler Plastic and Reconstructive Surgery Department, Hospital Provincial de Castellón, Castellón, Spain Elizabeth A. Arendt University of Minnesota, Minneapolis, MN, USA Doug W. Bartels Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA Cécile Batailler Albert Trillat Center, Lyon North University Hospital, Lyon, France Jose María Baydal-Bertomeu Instituto de Biomecánica de Valencia (IBV), Valencia, Spain xxvii
xxviii María Beser-Robles Biomedical Imaging Research Group at Health Research Institute, Valencia, Spain Roland M. Biedert Sportsclinic 1, Wankdorf Center, Bern, Switzerland Lars Blønd Department of Orthopaedic Surgery, The Zealand University Hospital, Koege, Denmark; Department of Orthopaedic Surgery, Aleris-Hamlet, Copenhagen, Denmark Michelle C. Boling Clinical and Applied Movement Sciences, Brooks College of Health, University of North Florida, Jacksonville, USA Joseph C. Brinkman Department of Orthopaedic Surgery, Mayo Clinic, Phoenix, AZ, USA; Department of Sports Medicine, Mayo Clinic, Tempe, Phoenix, AZ, USA; Alix School of Medicine, Mayo Clinic, Phoenix, AZ, USA William Bugbee Department of Orthopaedic Surgery, Scripps Clinic, La Jolla, CA, USA Jorge Chahla Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA Anikar Chhabra Department of Orthopaedic Surgery, Mayo Clinic, Phoenix, AZ, USA; Department of Sports Medicine, Mayo Clinic, Tempe, Phoenix, AZ, USA; Alix School of Medicine, Mayo Clinic, Phoenix, AZ, USA Jill Cook La Trobe University, Melbourne, Australia Kevin Credille Midwest Orthopedics at Rush University Medical Center, Chicago, IL, USA Dhanur Damodar Midwest Orthopedics at Rush University Medical Center, Chicago, IL, USA Antonio Darder-Prats Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain Antonio Darder-Sanchez Department of Orthopaedic Surgery, Hospital Clínico Universitario, Valencia, Spain Suhas P. Dasari Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA Robert S. Dean Beaumont Health, Royal Oak, MI, USA David H. Dejour Lyon-Ortho-Clinic: Clinique de La Sauvegarde, Lyon, France Julio Doménech-Fernández Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain Contributors
Contributors xxix Don Dulle Department of Orthopaedic Surgery, Mayo Clinic, Phoenix, AZ, USA; Department of Sports Medicine, Mayo Clinic, Tempe, Phoenix, AZ, USA; Alix School of Medicine, Mayo Clinic, Phoenix, AZ, USA Scott F. Dye University of California San Francisco, San Francisco, CA, USA John J. Elias Department of Health Sciences, Cleveland Clinic Akron General, Akron, OH, USA João Espregueira-Mendes Dom Henrique Research Centre, Porto, Portugal; Clínica Espregueira - FIFA Medical Centre of Excellence, Porto, Portugal; 3B’s Research Group–Biomaterials, Biodegradables and Biomimetics, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, Parque de Ciência e Tecnologia, Zona Industrial da Gandra, University of Minho, Barco, Guimarães, Portugal; ICVS/3B’s–PT Government Associate Laboratory, Braga/Guimarães, Portugal; School of Medicine, University of Minho, Braga, Portugal Jack Farr Knee Preservation and Cartilage Restoration Center, OrthoIndy, Indianapolis, IN, USA Lutul D. Farrow Cleveland Clinic Orthopaedic and Rheumatologic Institute, Cleveland, OH, USA; Cleveland Clinic Lerner College of Medicine, Cleveland Clinic Sports Health Center, Ohio, USA Christian Fink Gelenkpunkt Sport and Joint Surgery, Innsbruck, Austria; Research Unit for Orthopedic Sports Medicine and Injury Prevention, UMIT Hall, Tirol, Austria Donald C. Fithian Senta Clinic, San Diego, CA, USA Gaspard Fournier Albert Trillat Center, Lyon North University Hospital, Lyon, France Christopher S. Frey Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA John P. Fulkerson Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT, USA Gerard Ginovart Department of Orthopaedic Surgery, Hospital Terres de l’Ebre, Tortosa, Spain Edoardo Giovannetti de Sanctis Lyon-Ortho-Clinic: Clinique de La Sauvegarde, Lyon, France André Gismonti Clínica Espregueira - FIFA Medical Centre of Excellence, Porto, Portugal
xxx Contributors Neal R. Glaviano Department of Kinesiology, College of Agriculture, Health and Natural Resources, University of Connecticut, Mansfield, USA Ronald P. Grelsamer The Icahn School of Medicine at the Mount Sinai Medical Center, New York, NY, USA Andrew Gudeman Indiana University School of Medicine, Indianapolis, IN, USA Safa Gursoy Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA Mahad Hassan University of Minnesota, Minneapolis, MN, USA Pedro Hinarejos Consorci Parc de Salut Mar. Barcelona Universitat Pompeu Fabra, Barcelona, Spain Betina B. Hinckel Beaumont Health, Royal Oak, MI, USA Maximiliano Ibañez ICATME, Hospital Universitari Dexeus, UAB, Barcelona, Spain Andreas B. Imhoff Department of Orthopaedic Sports Medicine, Hospital Rechts der Isar, Technical University of Munich, Munich, Germany Andrew E. Jimenez Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT, USA Augustine W. Kang Stanford School of Medicine, Stanford, CA, USA Rochelle Kennedy La Trobe University, Melbourne, Australia Jason Koh Department of Orthopaedic Surgery, NorthShore University HealthSystem, Skokie, IL, USA Ana Leal CMEMS—Center for MicroElectroMechanical University of Minho, Guimarães, Portugal Systems, Kenneth Lin Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA Laura López-Company Department of Rehabilitation and Physical Therapy, Hospital Arnau de Vilanova, Valencia, Spain Sebastien Lustig Albert Trillat Center, Lyon North University Hospital, Lyon, France Bhargavi Maheshwer Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA Enzo S. Mameri Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA Luis Martí-Bonmatí Medical Imaging Department and Biomedical Imaging Research Group at Hospital, Universitario y Politecnico La Fe and Health Research Institute, Valencia, Spain Jenny McConnell Private Practice, Sydney, NSW, Australia
Contributors xxxi David A. Molho Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT, USA Joan Carles Monllau Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain; Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain; Universitat Autònoma de Barcelona (UAB), Barcelona, Spain Erik Montesinos-Berry ArthroCentre–Agoriaz, Riaz and Clinique CIC Riviera, Montreux, Switzerland Lee Pace Children’s Health Andrews Institute, Plano, TX, USA Ronak M. Patel Illinois Center for Orthopaedic Research and Education, Hinsdale, IL, USA Sneh Patel University of Illinois College of Medicine at Chicago, Chicago, IL, USA Rogério Pereira Dom Henrique Research Centre, Porto, Portugal; Clínica Espregueira - FIFA Medical Centre of Excellence, Porto, Portugal; Faculty of Sports, University of Porto, Porto, Portugal; Health Science Faculty, University Fernando Pessoa, Porto, Portugal María Angeles Perez Instituto de Investigación en Ingeniería de Aragón (I3A), Instituto de Investigación Sanitaria Aragón (IIS Aragón), Multiscale in Mechanical and Biological Engineering, University of Zaragoza, Zaragoza, Spain Daniel Pérez-Prieto Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain; Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain; Universitat Autònoma de Barcelona (UAB), Barcelona, Spain Jonas Pogorzelski Department of Orthopaedic Sports Medicine, Hospital Rechts der Isar, Technical University of Munich, Munich, Germany William R. Post Mountaineer Orthopedic Specialists, LLC, Morgantown, WV, USA Cristina Ramírez-Fuentes Medical Imaging Department, Universitario y Politecnico La Fe, Valencia, Spain Hospital Alejandro Roselló-Añón Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain Esther Roselló-Sastre Department of Pathology, Hospital General de Castellón, Castellón, Spain
xxxii Christian Rosenow Department of Orthopaedic Surgery, Mayo Clinic, Phoenix, AZ, USA; Department of Sports Medicine, Mayo Clinic, Tempe, Phoenix, AZ, USA; Alix School of Medicine, Mayo Clinic, Phoenix, AZ, USA Marco-Christopher Rupp Department of Orthopaedic Sports Medicine, Hospital Rechts der Isar, Technical University of Munich, Munich, Germany Enrique Sanchez-Muñoz Knee Unit, Department of Trauma and Orthopaedic Surgery, Toledo University Hospital, Toledo, Spain Vicente Sanchis-Alfonso Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain Onofre Sanmartin IVO’s Dermatology Department, Instituto Valenciano de Oncología (IVO), Valencia, Spain Christopher A. Schneble Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT, USA James Selfe Faculty of Health and Education, Department of Health Professions, Manchester Metropolitan University, Manchester, UK; Visiting Academic in Physiotherapy Studies, Satakunta University of Applied Sciences, Pori, Finland Elvire Servien Albert Trillat Center, Lyon North University Hospital, Lyon, France Jobe Shatrov Albert Trillat Center, Lyon North University Hospital, Lyon, France; Sydney Orthopedic Research Institute, St. Leonard’s, Sydney, NSW, Australia Seth L. Sherman Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA Benjamin E. Smith Physiotherapy Outpatients, University Hospitals of Derby and Burton NHS Foundation Trust, Derby, UK Pablo Sopena-Novales Department of Nuclear Medicine, Hospital Vithas 9 Octubre, Valencia, Spain Miho J. Tanaka Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA Robert A. Teitge Department of Orthopaedic Surgery, Wayne State University, Detroit, MI, USA Marc Tey-Pons Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain; Department of Orthopaedic Surgery, iMove orthopaedics, Hospital Mi Tres Torres, Barcelona, Spain Marc Tompkins University of Minnesota, TRIA Orthopedic Center, Minneapolis, MN, USA Contributors
Contributors xxxiii Cristina Valente Dom Henrique Research Centre, Porto, Portugal; Clínica Espregueira - FIFA Medical Centre of Excellence, Porto, Portugal Eloisa Villaverde-Doménech Plastic and Reconstructive Surgery Department, Hospital Provincial de Castellón, Castellón, Spain Zachary Wang Midwest Orthopedics at Rush University Medical Center, Chicago, IL, USA Casey L. Wright Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA Adam Yanke Midwest Orthopedics at Rush University Medical Center, Chicago, IL, USA David S. Zhu Cleveland Clinic Orthopaedic and Rheumatologic Institute, Cleveland, OH, USA
Etiopathogenic Bases, Prevention and Therapeutic Implications
Patellofemoral Pain: An Overview Vicente Sanchis-Alfonso and Ronald P. Grelsamer That those who know her, know her less, the nearer her they get. Emily Elizabeth Dickinson 1 Anterior Knee Pain—So Common a Symptom, so Misunderstood Patellofemoral pain (PFP) or anterior knee pain (AKP) is defined as “pain around or behind the patella, which is aggravated by at least one activity that loads the patellofemoral joint (PFJ) during weight-bearing on a flexed knee (e.g., squatting, stair ambulation, jogging/running, hopping/jumping)” [1]. The best available test is “anterior knee pain elicited during a squatting manoeuvre: PFP is evident in 80% of people who are positive on this test” [1]. According to the International patellofemoral pain research retreat “people with a history of dislocation, or who report perceptions of subluxation, should not be included in studies of PFP, unless the study is specifically evaluating these subgroups” [1]. Although it typically occurs in physically active people lesser than 40 years, it also affects people of all activity levels and ages [2]. In a systematic review with meta-analysis, Smith and colleagues [3] have recently found high incidence and prevalence levels for AKP. Subjects were excluded “if the study V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com R. P. Grelsamer The Icahn School of Medicine at the Mount Sinai Medical Center, New York, NY, USA population was selected from a specific disease area (e.g. diabetes, rheumatoid arthritis, osteoarthritis); if the study population comprised of participants with other knee pathology (e.g. knee ligamentous instability, history of patella dislocations, true knee locking or giving way, patella or iliotibial tract tendinopathy, osteoarthritis)”. The results of that systematic review confirmed that AKP is a common pathology among adolescents and adults. That is the case in both the general population as well as those who practice sports or perform physically demanding activities such as those performed by the military. The prevalence in the general population is reported to stand at 23%, in professional cyclists at 35.7% and in the general adolescent population at 30% [3]. Moreover, a woman is twice as likely to develop AKP than a man [3]. The mean prevalence of low-back pain in the general population is 18% and goes up to 20% among runners [4]. Overall, the prevalence of knee osteoarthritis (OA) has been found to be 16% [5]. Although the prevalence of these three pathological entities is very similar, the interest they arouse in researchers is very different: There have been more than 14,000 articles on knee OA indexed on MEDLINE in the last 20 years. Compare that to only 1,500 indexed articles on AKP [3]. It seems clear that PFP or AKP is of less interest than other conditions of the musculoskeletal system. Despite its high incidence and prevalence, AKP is the most neglected, the least understood, and the most problematic pathological knee condition. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_1 3
4 2 V. Sanchis-Alfonso and R. P. Grelsamer The Problem. Anterior Knee Pain—A Paradigm of Aversion Towards a Diagnosis Implicated factors in AKP include the loss of homeostasis as well as functional, mechanical and structural alterations (see chapters “Pathophysiology of Anterior Knee Pain”, “Femoral and Tibial Rotational Abnormalities are the Most Ignored Factors in the Diagnosis and Treatment of Anterior Knee Pain Patients. A Critical Analysis Review” and “Why is Torsion Important in the Genesis of Anterior Knee Pain?”). The etiology of AKP is multifactorial with not only local (e.g., knee) factors but also proximal (e.g., hip and trunk) and distal ones (e.g., foot and ankle). In fact, the primary cause of AKP in many patients does not lie within the PFJ. There are several subgroups within the AKP population. Therefore, the optimum treatment must be tailored to the individual patient (see chapter “Targeted Treatment in Anterior Knee Pain Patients According to Subgroups Versus Multimodal Treatment”). Among all the subsets of patients with AKP, the most challenging type of AKP, from a therapeutic point of view, is neuropathic. Rathleff and colleagues [6] have shown that young female adults with long-standing AKP demonstrated impaired conditioned pain modulation, meaning that AKP might have important central components that need to be further studied. Another challenge we face is patellar nomenclature. The study of the PFJ is complicated by the use of terms that have different meanings depending on who reads them (The Tower of Babel) [7]. There are terms that must be clarified such as the terms patellar malalignment and skeletal malalignment of the lower limb. There are other terms that should be abandoned, such as “chondromalacia patellae” and “patellofemoral pain syndrome.” AKP is a nemesis to both the patient and the treating physician, creating chronic disability, limited participation in sports, diminished quality of life, psychological impairment, and the basis for sick leave. Collins and colleagues [8] showed that 40% of AKP patients had a less-thanfavorable recovery at 12 months from the time of diagnosis. AKP negatively influences the quality of life of the patient in the same way as knee OA, another affection that is considered more serious. However, since AKP affects younger populations, it can have a greater impact on their lives than knee OA [9]. The World Health Organization (WHO) defines disability as “a limitation of function that compromises an individual’s ability to perform an activity within the range considered normal”. Because AKP frequently occurs in young working adults, it has an important societal impact due to absenteeism from work and lowered productivity as well as the economic expense of treating these patients [10]. Moreover, people including friends and family might consider AKP patients to be malingering, which only makes things worse. Furthermore, making this worse, we must point out that it is a source of iatrogenic pathology (e.g., medial patellar instability) [11]. We must be very cautious when recommending surgical treatment for AKP patients (see chapter “The Failed Patella. What Can We Do?”). This caution is particularly directed to those “wellmeaning trigger-happy orthopedic surgeons” (a term coined by Scott F. Dye, MD) educated in a purely structural/biomechanical view of this pathology. These surgeons base their surgical decisions solely on Computed tomography (CT) or Magnetic resonance imaging (MRI) findings. This approach is misguided. The patient who began with just mild, intermittent symptoms may get even worse. We must note that the vast majority of AKP patients only need non-operative treatment. The current best evidence-based non-surgical treatment for AKP is multimodal therapy. The core components of this approach include a diverse mix of exercise therapies (e.g., strengthening, stretching), patellar taping or bracing and foot orthoses depending on the sub-group that the patient falls into. There is limited evidence supporting the long-term outcomes of any single approach. Over the years, there have been many attempts to define subgroups within the AKP population. Despite these
Patellofemoral Pain: An Overview efforts, there is currently no consensus on what the optimal treatments are for the various subgroups. Nonetheless, there is emerging evidence that tailoring treatments to each subgroup can improve the treatment outcomes when compared to currently common multimodal approaches (see chapter “Targeted Treatment in Anterior Knee Pain Patients According to Subgroups Versus Multimodal Treatment”). Finally, we are convinced that the so-called biopsychosocial model currently used in chronic lumbar pain will soon be applied to AKP patients. According to this model, anatomic, biological and biomechanical factors as well as psychological and social factors must be considered (see chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat These Patients”). Among all the psychological factors that have been analyzed in the AKP patient, the most relevant one is catastrophizing (exaggerated worrying), which relates to pain and disability (see chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients”). Consequently, cognitive behavioral interventions that have brought on a reduction of catastrophizing pain in patients with arthritis or lumbar pain may also be helpful in patients suffering from AKP (see chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients”). Therefore, treatments for this should be incorporated into conventional approaches. Of course, catastrophizing can come from repeated doctors’ failures to diagnose and treat (see chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients”). Unfortunately, the criteria for proper treatment of the AKP patient have largely been anecdotal. More studies with a high level of evidence are needed. These patients bring to the office “a bag full of MRIs or CTs” in which the radiologist reports a patellar subluxation or a patellar tilt. As a last resort, they have been advised to undergo surgery to correct a supposed “lateral displacement of the patella” or the “lateral tilt” diagnosed 5 with the MRI or CT alone. This can be problematic when no adequate physical examination has been performed. The malalignment theory, which is strongly supported by many orthopedic surgeons, has enormously damaged many AKP patients and has given this pathology a bad reputation. Of course, a structural anomaly can be responsible for AKP. For example, a rotational osteotomy ought to be considered for that AKP patient with a significant torsional deformity (transverse plane) of the limb (see chapters “Femoral and Tibial Rotational Abnormalities are the Most Ignored Factors in the Diagnosis and Treatment of Anterior Knee Pain Patients. A Critical Analysis Review”, “Why is Torsion Important in the Genesis of Anterior Knee Pain?”, “Surgical Treatment of Anterior Knee Pain. When is Surgery Needed?” and “Rotational Osteotomy. Principles, Surgical Technique, Outcomes and Complications”). We must note that this biomechanical approach is compatible with the biological perspective (“Tissue Homeostasis Theory”) (see chapter “Pathophysiology of Anterior Knee Pain”). We should not be distracted by structural findings manifested on an MRI—but neither should we ignore them. Van der Heijden and colleagues [12] have shown that the structural abnormalities of the PFJ seen on MRIs are not automatically associated with AKP. Thus, AKP patients often undergo treatments with little scientific basis. A number of patients receive intra-articular injections of platelet-rich-plasma (PRP). A plethora of treatment options with different levels of agreement have been described. The great number of variables associated with AKP, most of which lack valid measurement tools, can explain this confusion. All of this makes this pathology an urgent research priority. Moreover, this all explains why many orthopedic surgeons have an aversion to treating AKP patients. Doctors do not want to spend the time evaluating these patients—it’s just not cost-effective. They order an MRI and read the report. Moreover, in some parts of the world, radiologists do not appreciate patellar pathology unless it is extreme; therefore, orthopedists relying completely on the MRI report also miss
6 V. Sanchis-Alfonso and R. P. Grelsamer structural issues. Not uncommonly, AKP patients are quickly shunted off to orthopedic surgeons with a particular interest in the topic. 3 Patellofemoral Pain—A Pathologic Condition with Many Clichés and False Beliefs There are many myths surrounding this condition, false collective beliefs that are transmitted from generation to generation. One of these myths is that the AKP patient is a person with peculiar psychological traits that are responsible for the genesis of pain. This belief is reinforced by the fact that many patients have very disabling pain but insignificant radiological findings and unremarkable physical signs. The psychological explanation as the cause of pain could not be further from the truth. Psychological factors in AKP patients are only modulators of pain and disability and should be addressed in combination with the search for structural causes (see chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients”). Another misconception is that AKP is always a self-limiting and benign condition, which is why some physicians believe that an active treatment is unnecessary. It is frequently said to that AKP is related to growth. Therefore, symptoms will disappear once the patient reaches adulthood. For this reason, some physicians recommend “expectation”. That approach is a great mistake. Collins and colleagues [8] have shown that success in treating the AKP patient depends on how early the treatment starts. Patients with pain of less than 2 months duration have a better prognosis than those who have had pain for more than 2 months. Rathleff and colleagues [13] have shown that AKP is not a self-limiting knee condition. Those authors observed that adolescents with PFP were more likely to reduce or stop participation in sports compared to adolescents with other types of knee pain. They also found that a majority of their AKP patients had been symptomatic for more than two years, suggesting that it is not a self-limited condition. In other words, early detection and treatment are advisable. In addition, when possible it is essential to implement prevention measures during adolescence. This will help us prevent years of pain and functional impairment as well as considerable health care expenditures. Given the importance we attach to prevention, we dedicate four chapters in the first section of this book to this topic (chapters “Risk Factors for Patellofemoral Pain. Prevention Programs”, “Anterior Knee Pain After Arthroscopic Meniscectomy. Risk Factors, Prevention and Treatment”, “Anterior Knee Pain Prevalence After Anterior Cruciate Ligament Reconstruction. Risk Factors and Prevention” and “Patellar Tendinopathy. Risk Factors, Prevention, and Treatment”). Furthermore, AKP in an adolescent has a high potential for becoming chronic. Between 70 and 90% of individuals with AKP have recurrent or chronic pain [14]. Conchie and colleagues [15] brought into question the traditional belief that AKP in adolescence is a benign pathology by showing that it is associated with patellofemoral osteoarthritis (PFOA) in adulthood. An individual is 7.5 times more likely to develop PFOA if they have suffered from adolescent AKP. The results of this study are perhaps debatable, as it was a retrospective study rather than a longitudinal one. Moreover, the follow-up time for a longitudinal study of this type should be 50 years and this is impossible. Furthermore, the diagnosis of AKP was based on mailed questionnaires with all their limitations. The paper by Conchie and colleagues [15] nevertheless questions the traditional belief that adolescent AKP is a benign pathology. Thus, AKP and PFOA may form a continuum of disease. Sadly, many orthopedic surgeons do not focus enough attention on this pathology, which reflects their limited understanding. A very common symptom of great concern to AKP patients is patellofemoral crepitation (a.k.a. crepitus). Johnson and colleagues [16] published a paper in Arthroscopy in 1998 on the assessment of asymptomatic knees. Indeed, patellofemoral crepitation has a high incidence rate in asymptomatic women (94% in females vs. 45% in males). Patellofemoral crepitation has been
Patellofemoral Pain: An Overview associated with the lateral subluxation of the patella. However, Johnson and colleagues [16] have observed that lateral subluxation of the patella (radiographic finding) in asymptomatic people is more common in males than in females (35% and 19%, respectively). It leads some to think that crepitus is not of major importance. We currently know that this is not the case. Crepitus is an important symptom: Women with AKP and pain-free controls with knee crepitus had lower functional performance compared to pain-free controls without knee crepitus. This is an indication that both pain and crepitus may negatively influence function [17]. Crepitus is a poorly understood sign and symptom that creates negative emotions (no one likes a noisy joint), inaccurate etiological theories, and ultimately leads to fear-avoidance behaviors (see chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients”) [18]. 4 Chondromalacia Patellae. A Symbol of Our Helplessness in Regards to a Diagnosis and Our Ignorance on AKP Proof that AKP is not well understood is that an obsolete diagnosis like chondromalacia is still used by many doctors and physical therapists today for any pain in the anterior aspect of the knee. More than a century (116 years) has passed since the term chondromalacia was coined, and this term is still used by clinicians, by the staff in charge of codifying the different pathologies for our hospital databases, as well as on private health insurers’ lists of covered services. The term “Chondromalacia Patellae” continues in use in the “International Statistical Classification of Diseases and Related Health Problems (ICD-10, Version 2019)”, its code being M22.4 (Table 1) [19]. AKP has historically been associated with the terms “internal derangement of the knee” and “chondromalacia patellae”. Surprisingly, the term “internal derangement of the knee” also continues in use in the “International Statistical 7 Classification of Diseases and Related Health Problems (ICD-10, Version 2019)”, its code M23.9 [19]. The expression “internal derangement of the knee” was coined in 1784 by the British surgeon from Leeds, William Hey [20]. This term was later discredited by the German school surgeon Konrad Büdinger, Dr Billroth’s assistant in Vienna. It was he who described fissuring and degeneration of the patellar articular cartilage of spontaneous origin in 1906 and similar lesions of traumatic origin in another paper in 1908 [21, 22]. Büdinger considered that the expression “internal derangement of the knee” was a “wastebasket” term. He was right since the expression lacks any etiological, therapeutic or prognostic significance. Until the end of the 1960s, AKP was attributed to chondromalacia patellae. However, not all the patients with AKP suffer from “chondromalacia patellae”, and at the same time many patients with “chondromalacia patellae” do not have AKP. In 1978, Leslie and Bentley [23] reported that only 51% of patients with a clinical diagnosis of “chondromalacia” had changes on the patellar surface when examined by means of arthroscopy. In 1991, Royle and colleagues [24] published a study in Arthroscopy, with special reference made to the PFJ, in which they analysed 500 arthroscopies performed over a 2- period. In those patients with pain thought to have its origin in this joint, 63% had “chondromalacia patellae” compared with a 45% incidence in those with meniscal pathological findings at arthroscopy. They concluded that AKP patients do not always have patellar articular changes, and patellar pathology is often asymptomatic. Consistent with this, Scott F. Dye did not feel any pain during arthroscopic palpation of his extensive lesion of the patellar cartilage without intraarticular anesthesia [25]. In this regard, it should be remembered that the articular cartilage is devoid of nerve fibres and, therefore, cannot cause pain. Van der Heijden and colleagues [26] have not detected any differences in the composition of the patellofemoral cartilage between AKP patients and healthy controls. Moreover, even patients with severe patellofemoral chondropathy may not suffer from AKP (Fig. 1).
8 V. Sanchis-Alfonso and R. P. Grelsamer Table 1 Codification of patellofemoral disorders by the International Statistical Classification of Diseases and Related Health Problems in 2019 [19] M22 Disorders of patella Excl.: Dislocation of patella (S83.0) M22.0 Recurrent dislocation of patella M22.1 Recurrent subluxation of patella M22.2 Patellofemoral disorders M22.3 Other derangements of patella M22.4 Chondromalacia patellae M22.8 Other disorders of patella M22.9 Disorder of patella, unspecified A B Fig. 1 The intensity of preoperative pain is not related to the severity or the extension of the chondral lesion found during surgery. The most serious cases of chondromalacia arise in patients with a recurrent patellar dislocation who feel little or no pain between their dislocation episodes (A). Chondral lesion of the patella with fragmentation and fissuring of the cartilage in a patient with AKP (B). (Reprinted by permission from Springer Nature, Anterior Knee Pain and Patellar Instability by Vicente SanchisAlfonso, 2011) Consequently, the International Patellofemoral Study Group (IPSG) advises against using chondromalacia as a diagnosis and suggests the term “anterior knee pain” as it is only descriptive without implying a specific diagnosis. Chondromalacia should not be used to describe a clinical condition. It is merely a descriptive term for morphological softening of the patellar articular cartilage. The term “chondromalacia” comes from the Greek “chondros” and “malakia” and means “softened articular cartilage”. In conclusion, this is a finding that can be made only upon palpation with open surgery or by arthroscopic means, and it is irrelevant. In short, chondromalacia patellae is not synonymous with PFP or AKP. Although traditions die hard, the term “chondromalacia patellae” should be excluded from the clinical terminology for the reasons we have stated. The following unfavorable 1908 comment of Büdinger about “internal derangement of the knee”, might be applied to “chondromalacia patellae”: “[It] will simply not disappear from the surgical literature. It is the symbol of our helplessness in regard to a diagnosis and our ignorance of the pathology” [27]. The term chondromalacia is a twentieth century mistake. Unfortunately, we always make the same mistakes, as evidenced by the expression “patellofemoral pain syndrome” having replaced “chondromalacia patellae.” Thus, one nonsense has been replaced by another.
Patellofemoral Pain: An Overview 5 Patellar Malalignment Versus Skeletal Lower Limb Malalignment 9 In the 1970s, AKP was correlated with the presence of patellar malalignment (PM). PM “is the abnormal positioning of the patella in any plane” (Fig. 2) [28]. The most common type of patellar malalignment is patellar tilt [27]. Moreover, a lateralized tibial tuberosity is included in the patellar malalignment category because it leads to a lateral force vector on the patella that might be responsible for pain and/or lateral displacement of the patella. In 1968, Jack C. Hughston (Fig. 3) published an article on subluxation of the patella that represented a major turning point in the recognition and treatment of patellofemoral disorders [29]. In 1974, Al Merchant (Fig. 4), in an attempt to better understand patellofemoral biomechanics, introduced his version of the patellofemoral axial radiograph [30]. The same author suggested, also in 1974, the open lateral retinacular release as a way of treating recurrent patellar subluxation [31]. In 1975, the French orthopedist Paul Ficat popularized the concept of patellar tilt, always associated with increased tightness of the lateral retinaculum, which causes excessive pressure on the lateral facet of the patella leading to the “lateral patellar compression syndrome” (“Syndrome d’Hyperpression Externe de la Rotule”) [32]. In fact, the excessive lateral pressure syndrome represents a type of PM. According to Ficat, the lateral patellar compression syndrome causes hyperpressure in the lateral patellofemoral compartment and hypopressure in the medial patellofemoral compartment. Hypopressure and the disuse of the medial patellar facet cause malnutrition and early degenerative cartilage changes. This may explain the early cartilage degeneration found in the medial patellar facet. Hyperpression also leads to cartilage degeneration, thus the degeneration of the lateral cartilage. In 1977, Ficat and Hungerford published “Disorders of the Patellofemoral Joint.” It is a classic of knee extensor mechanism surgery and the first book in English devoted exclusively to the extensor mechanism of the knee [27]. In the preface of the book, these authors refer to the PFJ as “the forgotten compartment of the knee” reflecting the situation through the 1970s. In fact, only two diagnoses were used relating to AKP or patellar instability before the 1970s: chondromalacia patellae and recurrent dislocation of the patella. What’s more, the initial designs for knee arthroplasties ignored the PFJ. In Fig. 5, you can see the logo of the International Knee Society in the late 1980s. There is no patella. In 1995, in Hong Kong, the International Society of the Fig. 2 CT at 0º of a patient with AKP and functional patellofemoral instability in the right knee. However, the left knee was completely asymptomatic. The PM was symmetric in both knees. (Reprinted by permission from Springer Nature, Anterior Knee Pain and Patellar Instability by Vicente Sanchis-Alfonso, 2011)
10 Fig. 3 Jack C. Hughston, MD (1917–2004). One of the founding fathers of Sports Medicine (The Hughston Foundation, Inc. © 2022) V. Sanchis-Alfonso and R. P. Grelsamer Knee (ISK) and the International Arthroscopy Association (IAA) merged to found ISAKOS. Curiously, the ISAKOS logo, which is relatively modern, does not show the patella either. The same goes for the logos of ESSKA and of the Asia–Pacific Knee Arthroscopy Sports Medicine Society. This reflects the little importance knee surgeons have placed on the PFJ. In 1979, John Insall published a paper on the “patellar malalignment syndrome” and his proximal patellar realignment technique used to treat this “syndrome” [33, 34]. According to Insall, lateral loading of the patella is increased in the malalignment syndrome. In some cases, this causes “chondromalacia patellae” but this does not correlate with the presence/absence of pain. Accordingly, Insall and colleagues [35] reported in 1983 that AKP correlates better with malalignment rather than with the severity of cartilage changes found at surgery. Fulkerson and colleagues have also emphasized the importance of PM and an excessively tight lateral Fig. 4 John Fulkerson (left) and Alan C Merchant (right), IPSG Meeting, Boston, MA, USA, 2006
Patellofemoral Pain: An Overview Fig. 5 Logo of the International Knee Society. 6th Congress of the International Society of the Knee, Rome, 8th-12th May 1989—Cavalieri Hilton Hotel retinaculum as a source of AKP [36, 37]. Moreover, John Fulkerson (Fig. 4) popularized the anteromedialization (AMZ) of the tibial tuberosity in 1983 to address pain from patellofemoral chondropathy with patellofemoral tilt and/or chronic patellar subluxation [38]. This technique is indicated when restoring normal patellar tracking. This widely appreciated procedure is not only used for isolated PFOA but for chronic lateral patellar instability. For many years, PM has been widely accepted as an explanation for the genesis of AKP in the young patient. Moreover, this theory had a great influence on orthopedic surgeons who developed several surgical procedures to “correct the malalignment.” Unfortunately, PM has too often been treated surgically. Many surgical treatments have been described yielding extremely variable results. Consequently, the PM concept is currently questioned, and is not universally accepted as a source of AKP. In fact, the number of realignment surgeries performed has dropped dramatically in recent years, at least in Spain, due to a reassessment of this paradigm. To think of AKP as somehow being necessarily tied to PM is an oversimplification that has stultified progress toward better diagnosis and treatment. Overreliance on PM as a diagnosis leads to misguided surgical procedures that can aggravate a patient’s condition. At the end of 1970s, skeletal malalignment of the lower limb was suggested as one of the causes of AKP in some young patients [39]. It must be acknowledged that skeletal malalignment is not an abnormal Q-angle or an increased 11 TT-TG distance [40]. It is also not the position of the patella in the trochlea. Neither is it its increased shift (subluxation) or increased tilt [40]. Skeletal malalignment is malalignment of the limb measured on the transverse, coronal, and sagittal planes [40]. For example, the presence of femoral torsion, excessive external tibial torsion, or increased varus or valgus abnormalities have a great impact on PFJ biomechanics. Rotational abnormalities are particularly important [40–42]. In 1979, Stan James presented a comprehensive review of AKP in which the condition of “miserable malalignment” was described, being increased femoral anteversion and increased external tibial torsion [39]. In 1995, he reported on seven patients with “miserable malalignment” who had been treated with internal tibial rotational osteotomy over an 18-year period [43]. Several years earlier, in 1990, Cooke and colleagues described internal proximal tibial rotational osteotomy in seven patients presenting with AKP and drew attention to the inwardly pointing knee (“squinting patella”) as an unrecognized cause of AKP [44]. However, the concept of skeletal malalignment was almost unnoticed and has had extremely little influence on orthopedic surgeons even until a few years ago. In fact, very few publications refer to skeletal malalignment as a cause of AKP. From 1990 to June of 2021, only 22 published papers in English in which the association between patellofemoral disorders in young patients and in which torsional abnormalities of the femur and/or tibia are analyzed from a clinical point of view could be found [45]. One of the world's greatest exponents of the skeletal malalignment theory in the genesis of patellofemoral pain is Robert A. Teitge, MD (Fig. 6), one of the prominent members of the International Patellofemoral Study Group (IPSG). In short, structural abnormalities predispose to pain but are not automatically the source of pain in any given patient. If you have flat feet and foot pain, your foot pain does not necessarily relate to your flat feet. Structural abnormalities are only a predisposing factor just as hypertension predisposes to strokes—even though not everyone with hypertension suffers from a stroke.
12 V. Sanchis-Alfonso and R. P. Grelsamer Fig. 6 Vicente SanchisAlfonso (left) and Robert A. Teitge (right), IPSG Meeting, Banff, Canada, 2019 (Courtesy of Ronald P. Grelsamer, MD) 6 Tissue Homeostasis Theory. An Alternative to the Structural/Biomechanic Paradigm In the 1990s, Scott F. Dye (Fig. 7), of the University of California, San Francisco, and his research group came up with the tissue homeostasis theory [46, 47]. The initial observation that led to the development of the tissue homeostasis theory of patellofemoral pain was made by Dye when a patient with complaints of AKP without evidence of chondromalacia or malalignment underwent a technetium 99 m methylene diphosphonate bone scan evaluation of the knees. It was an attempt to assess the possible presence of covert osseous pathology; and indeed, the bone scan of that individual manifested an intense diffuse patellar uptake despite normal radiographic images. The tissue homeostasis theory states that joints are more than mechanical structures; they are living metabolically active systems. This theory attributes pain to a physiopathological mosaic of causes such as increased osseous remodelling, increased intraosseous pressure, or peripatellar synovitis that leads to a decrease in what he called the “Envelope of Function” (or “Envelope of Load Acceptance”). The “Envelope of Function” describes a range of loading and energy absorption that is compatible with tissue homeostasis of an entire joint system; that is, with the mechanisms of healing and maintenance Fig. 7 Scott F. Dye, IPSG Meeting, San Diego, CA, USA, 2011 (Courtesy of Ronald P. Grelsamer, MD) of normal tissues. Obviously, the Envelope of Function for a young athlete will be greater than that of sedentary elderly individual. Within the Envelope of Function is the region termed Zone of Homeostasis. Loads that exceed the Envelope of Function but are insufficient to cause a macrostructural failure are termed the Zone of Supraphysiologic Overload. If sufficiently great forces are put on the patellofemoral system, macrostructural failure can occur. For Dye [46], the following four factors determine the Envelope of Function or Zone of Homeostasis: (1) anatomic factors (the morphology, structural integrity and biomechanical characteristics of tissue); (2) kinematic factors (dynamic control of the joint involving proprioceptive sensory output, cerebral and cerebellar
Patellofemoral Pain: An Overview sequencing of motor units, spinal reflex mechanisms, and muscle strength and motor control); (3) physiological factors (the genetically determined mechanisms of molecular and cellular homeostasis that determine the quality and rate of repair of damaged tissues); and (4) treatment factors (type of rehabilitation or surgery received). According to Dye, the loss of both osseous and soft tissue homeostasis is more important in the genesis of AKP than structural characteristics. To him, it matters little which specific structural factors may be present (i.e., patellar cartilage lesions, PM, etc.) if the joint is being loaded within its Envelope of Function and is therefore asymptomatic. He suggests that patients with AKP are often symptomatic due to supraphysiological loading of anatomically normal knee components [47]. In fact, AKP patients often lack an easily identifiable structural abnormality to account for the symptoms. The Envelope of Function frequently diminishes after an episode of injury to the point where previously well-tolerated activities of daily living (e.g., stair climbing, sitting down in and arising out of chairs, pushing the clutch of a car) become supraphysiological loads for that patient, leading to ineffective tissue healing and continued symptoms. Bringing loads down within the newly diminished Envelope of Function allows for the normal tissue healing processes to go forward. 7 Creation of Study Groups: An Inflection Point in the Knowledge of Patellofemoral Pain We are therefore faced with a very prevalent symptom with multiple possible etiologies. This is fertile ground for a study group. In 1994, Jean Yves Dupont from France, travelled to Farmington, Connecticut in the USA to visit John Fulkerson. They decided to gather “a group of friends” from different countries with a proven interest in the academic study of patellofemoral problems. They would meet 13 informally to take stock of their patellofemoral opinions. Dr. Fulkerson served as the first secretary and organizer of the study group and set up an initial meeting in Orlando, Florida on February 17, 1995. Thus was born the International Patellofemoral Study Group (IPSG). The second meeting of the IPSG was held near Dupont’s home in beautiful Benodet in Brittany (France) in the fall of 1995 (Fig. 8). Each participant was encouraged to speak on a patellofemoral topic of his choice, and the group was encouraged to discuss, debate, and critique. Around this time, Joan and Al Merchant designed the logo for the IPSG. Patellofemoral pain is of such complexity that even within this group there are opposing approaches and theories with surgeons, therapists and engineers often holding dogmatic positions. Perhaps less dogmatic over time. Moreover, in 2003, John Fulkerson created with the help of Eric Dahlinger, Dr. Peter Jokl, and tennis legend Ivan Lendl, the Patellofemoral Foundation (www.patellofemoral.org). to stimulate research efforts, education, and fundraising. The Patellofemoral Foundation sponsors the “Patellofemoral Research Excellence Award” to encourage outstanding PF research. Moreover, this foundation sponsors the “Patellofemoral Traveling Fellowship” to stimulate global patellofemoral communication. Finally, the Patellofemoral Foundation awards the “Patellofemoral Lifetime Achievement Award” every year in recognition of those surgeons who have dedicated their career to the understanding and treatment of patients with patellofemoral disorders along with organizing the “Comprehensive Patellofemoral Online Education Course.” In 2009, the International Patellofemoral Research Network (iPFRN), a group of researchers and clinicians with a specific interest in patellofemoral pain, was founded. The iPFRN was established by five global leaders in patellofemoral pain research. They are Irene Davis, Chris Powers, Kay Crossley, Jenny McConnell and Erik Witvrouw. This group has published 7 consensus statements in high impact journals since 2009 [1, 14, 48–52].
14 V. Sanchis-Alfonso and R. P. Grelsamer Fig. 8 IPSG Meeting, Benodet, France, Fall 1995. (Courtesy of Ronald P. Grelsamer, MD) 8 The “Proximal Control” Concept—A Turning Point Historically, the patella has been considered a mobile structure that sits on a fixed structure that is the femur. That thinking is based on kinematic studies done without weight-bearing or in studies in which the femur has been considered a fixed structure. In the 2000s, Chris Powers, of the University of Southern California, Los Angeles, and his working group conducted studies of the PFJ with weight-bearing and suggested that the main factor contributing to patella tilt and lateral displacement during weight-bearing is the internal rotation of the femur. Powers and colleagues [53] published a study in 2003 in which the objective was to compare PFJ kinematics during non-weight-bearing and weight-bearing knee extension in people with AKP and lateral patellar subluxation. They demonstrated that lateral patellar displacement was more pronounced during non-weight-bearing (open chain) compared to weight-bearing (closed chain) knee extension. However, PFJ kinematics during nonweight-bearing was characterized by the rotation of the patella on the femur, while it was characterized by the femur rotating underneath the patella during weight-bearing. In 2010, Chris Powers and colleagues published another study comparing PFJ kinematics, femoral rotation, and patella rotation between females with AKP and pain-free controls using weight-bearing kinematic MRI [54]. The results of that study suggest that the control of femur rotation may be important to restoring normal PFJ kinematics. That is, the problem of PM is not in the patella but in the femur. In other words, the primary contributor to lateral patellar subluxation and patellar tilt is the internal rotation of the femur underneath the patella. Therefore, control of the rotation of the femur is fundamental to guaranteeing normal patellofemoral kinematics. This theory supposes a change in mentality relative to the concept of PM. It is a true turning point. These findings suggest that control of the rotation of the femur is essential to restoring the normal
Patellofemoral Pain: An Overview kinematics of the PFJ. In addition, normalizing femoral rotation can affect the tension of peripatellar soft structures, including the lateral retinaculum, and can also affect patellofemoral pressures. Lee and colleagues [55] have demonstrated that femoral rotation results in an increase in PFJ contact pressures on the contralateral facet of the patella (i.e., lateral PFJ during internal rotation of the femur and vice versa). Using a finite element model, Liao and colleagues [56] have demonstrated that internal rotation of the femur provokes an increment in PFJ stress. We are thus facing a paradigm shift. It has been shown that excessive internal rotation of the femur can cause (1) a decrease in the patellofemoral contact area and therefore an increase in patellofemoral pressure and (2) tightness of the lateral retinaculum. Thus, a new concept was born: the “proximal control” concept that is currently fundamental to understanding the physiotherapeutic treatment of an important subgroup of AKP patients. Therefore, a treatment that addresses the control of femoral motion may play a crucial role in the treatment of some AKP patients. This way of thinking is diametrically opposed to the one that had been maintained until this moment, which was to consider patella tracking as the relative motion of the patella on a fixed femur. 9 Take Home Message To summarize, the high incidence and prevalence of AKP along with its high associated disability, its high potential for becoming chronic, and its association with PFOA in adulthood makes PFP an urgent research priority. References 1. Crossley KM, Stefanik JJ, Selfe J, et al. Patellofemoral pain consensus statement from the 4th International Patellofemoral Pain Research Retreat, Manchester. Part 1: Terminology, definitions, clinical examination, natural history, patellofemoral osteoarthritis and patient-reported outcome m. Br J Sports Med 2016;50:839–843. 15 2. Crossley KM, Callaghan MJ, van Linschoten R. Patellofemoral pain. Br J Sports Med. 2016;50 (4):247–50. 3. Smith BE, Selfe J, Thacker D, et al. Incidence and prevalence of patellofemoral pain: a systematic review and meta-analysis. PLoS ONE. 2018;13(1): e0190892. https://doi.org/10.1371/journal.pone. 0190892. 4. Maselli F, Storari L, Barbari V, et al. Prevalence and incidence of low back pain among runners: a systematic review. BMC Musculoskelet Disord. 2020;21(1):343. 5. Wallace IJ, Worthington S, Felson DT, et al. Knee osteoarthritis has doubled in prevalence since the mid-20th century. Proc Natl Acad Sci USA. 2017;114(35):9332–6. 6. Rathleff MS, Petersen KK, Arendt-Nielsen L, et al. Impaired conditioned pain modulation in young female adults with long-standing patellofemoral pain: a single blinded cross-sectional study. Pain Med. 2016;17(5):980–8. 7. Grelsamer RP. Patellar nomenclature. The tower of babel revisited. Clin Orthop. 2005;436:60–65. 8. Collins NJ, Bierma-Zeinstra SM, Crossley KM, et al. Prognostic factors for patellofemoral pain: a multicentre observational analysis. Br J Sports Med. 2013;47(4):227–33. 9. Reijnders L, van de Groes SA. The quality of life of patients with patellofemoral pain—a systematic review. Acta Orthop Belg. 2020;86(4):678–87. 10. Tan SS, van Linschoten RL, van Middelkoop M, et al. Cost-utility of exercise therapy in adolescents and young adults suffering from the patellofemoral pain syndrome. Scand J Med Sci Sports. 2010;20:568–79. 11. Sanchis-Alfonso V, Merchant AC. Iatrogenic medial patellar instability: an avoidable injury. Arthroscopy. 2015;31(8):1628–32. 12. van der Heijden RA, de Kanter JL, Bierma-Zeinstra SM, et al. Structural abnormalities on magnetic resonance imaging in patients with patellofemoral pain: A cross-sectional case-control study. Am J Sports Med. 2016. pii: 0363546516646107. 13. Rathleff MS, Rathleff CR, Olesen JL, et al. Is knee pain during adolescence a self-limiting condition? Prognosis of patellofemoral pain and other types of knee pain. Am J Sports Med. 2016;44(5):1165–71. 14. Powers CM, Bolgla LA, Callaghan MJ, et al. Patellofemoral pain: proximal, distal, and local factors, 2nd International Research Retreat. J Orthop Sports Phys Ther. 2012;42:A1-54. 15. Conchie H, Clark D, Metcalfe A, et al. Adolescent knee pain and patellar dislocations are associated with patellofemoral osteoarthritis in adulthood: A case control study. Knee. 2016. https://doi.org/10. 1016/j.knee.2016.04.009. 16. Johnson, LL. van Dyk E, Green JR et al. Clinical assessment of asymptomatic knees: comparison of men and women. Arthroscopy. 1998;14:347–359.
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Pathophysiology of Anterior Knee Pain Vicente Sanchis-Alfonso, Esther Roselló-Sastre, Scott F. Dye, and Robert A. Teitge 1 Introduction Anterior knee pain (AKP) is the most common reason for adolescents, adults, and physically active people to consult with an orthopedic surgeon who specializes in the knee. Despite the high incidence and prevalence of AKP and an abundance of clinical and basic science research, the etiology of this condition is not well-known. This chapter synthesizes a review of the literature and our research and clinical experience on pathophysiology of AKP in the young patient. 2 Theories on the Genesis of AKP Until the end of the 1960s, AKP was attributed to chondromalacia patellae, a concept from the early twentieth century [1] that has no clinical V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com E. Roselló-Sastre Department of Pathology, Hospital General de Castellón, Castellón, Spain S. F. Dye University of California San Francisco, San Francisco, CA, USA R. A. Teitge Wayne State University, Detroit, MI, USA value because it offers no specific diagnostic, therapeutic, or prognostic implications. In fact, many authors have failed to find a clear connection between AKP and chondromalacia patellae [2, 3]. In the 1970s AKP was related to the presence of patellar malalignment (PM) [4–8]. For many years, PM has been widely accepted as an explanation for the genesis of AKP in the young patient. Currently, the PM concept is questioned and is not universally accepted as an underlying factor in AKP. An obvious problem with the PM concept is that not all patellar malalignments, even those of significant proportions, are symptomatic (Fig. 1). A person with PM may not experience pain if the joint is never stressed to the extent that the tissues are irritated. Such individuals probably learn early that “my knee hurts when I do sports” and therefore stop being active. Further, only one knee may be symptomatic, even though the underlying patellar malalignment is entirely symmetrical in both knees (Fig. 1). In addition, patients with normal patellar alignment on computed tomography (CT) can also experience AKP. Therefore, although the patellar malalignment theory is biomechanically appealing, it has failed to explain the presence of AKP in many patients. We must also remember that significant differences have been demonstrated between subchondral bone morphology and the geometry of the articular cartilage surface of the patellofemoral joint (PFJ), in both the axial and sagittal © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_2 19
20 V. Sanchis-Alfonso et al. Fig. 1 Disabling AKP and patellar instability of the left knee. The right knee was asymptomatic in spite of the fact that PM was symmetric in both knees. A Preop CT at 0°, B Postop CT at 6 months of proximal realignment surgery, C CT of the right knee, D CT of the left knee at 13 years of follow-up—the patient is completely asymptomatic in spite of the presence of a visible PM. (A-Reused with permission from Thieme. From: SanchisAlfonso V. American Journal of Knee Surgery. Volume 7, Issue 2. Usefulness of computed tomography in evaluating the patellofemoral joint before and after Insall’s realignment. Thieme: New York. 1994, www. thieme.com) planes [9]. Therefore, a radiographical PM may not be real, and realignment surgery to correct the nonexistent problem could lead to a worsening of preoperative symptoms. At the end of 1970s, skeletal malalignment of the limb was suggested as the genesis of AKP in some cases [10]. Skeletal malalignment, which is not the same as PM, is the malalignment of the limb measured in the transverse, coronal, and sagittal planes. The presence of excessive femoral anteversion, excessive external tibial torsion, or increased varus or valgus abnormalities has a definite effect on the PFJ [11]. James in 1979 presented a comprehensive review of AKP in which he described the condition of “miserable malalignment”, that is, increased femoral anteversion and increased external tibial torsion [10]. In 1995 he reported on seven patients with miserable malalignment who had been treated with internal rotational tibial osteotomy during an 18-year period [12]. Several years earlier, Cooke and colleagues [13] described internal rotational proximal tibial osteotomy in seven patients presenting with AKP and drew attention to the inwardly pointing knee as an unrecognized cause of AKP. Unlike the concept of PM, however, the concept of skeletal malalignment was almost unnoticed and has had very low influence on orthopedic surgeons. In fact, very few publications refer to skeletal malalignment as a cause of AKP. In the 1990s, Scott F. Dye and his research group at the University of California, San Francisco, proposed the tissue homeostasis theory [14, 15]. According to this theory, joints are not simply mechanical structures; they are systems that are alive and metabolically active [14]. Pain arises from a physiopathological mosaic of causes, including increased osseous remodeling, increased intraosseous pressure, or peripatellar synovitis leading to a reduced “envelope of function” (or “envelope of load acceptance”) (Fig. 2) [2, 14, 15]. This envelope of function is defined by the range of loading and energy absorption that coexists with normal tissue healing and maintenance (i.e., tissue homeostasis). According to Dye, in the vast majority of AKP cases, the loss of homeostasis of both osseous (Fig. 3) and soft tissue in the peripatellar region is more important than biomechanical/ structural issues in the genesis of AKP. He suggests that AKP patients are often symptomatic because of supraphysiologic loading of anatomically normal knee components [2, 14, 15]. In fact, patients with AKP often lack an easily identifiable structural abnormality to account for their symptoms. According to Dye’s theory of envelope of load acceptance, overuse or cyclical overload of soft tissue or bone areas may explain AKP in many patients. However, it should be noted that this biological perspective is compatible with the biomechanical approach. The
Pathophysiology of Anterior Knee Pain 21 Fig. 2 The envelope of function theory. (Reused with permission from SAGE. From Sanchis-Alfonso V, Dye SF. “How to Deal with Anterior Knee Pain in the Active Young Patient” Sports Health. 2017; 9(4):346–351) Fig. 3 SPECT-CT in a patient with disabling left AKP due to excessive external tibial torsion showing the loss of osseous homeostasis rotation of the femur [16, 17]. That is to say, the primary contributor to lateral patellar subluxation and patellar tilt is the internal rotation of the femur below the patella. Therefore, control of the rotation of the femur is fundamental to guaranteeing normal patellofemoral kinematics. Thus, a new concept was born. It is the “proximal control” that is currently considered fundamental to understanding the physiotherapeutic treatment of an important subgroup of AKP patients. Lee and colleagues [18] have demonstrated that femoral rotation results in an increase in PFJ contact pressures on the contralateral facet of the patella (i.e., lateral PFJ during internal rotation of the femur and vice versa). 3 diagnostic challenge is to find the cause of the loading which is “in excess of the envelope of function or load acceptance”. Finally, in the 2000s, Chris Powers and his working group conducted weight-bearing studies of the PFJ and suggested that the main factor contributing to patella tilt and lateral displacement during weight-bearing is the internal A Critical Analysis of Realignment Surgery for PM After wide usage of certain surgical techniques, surgeons may come to question the basic tenets justifying the procedures and devise clinical research to test the underlying hypotheses. Realignment surgery for treating PM is no exception. In 2005, Sanchis-Alfonso and
22 colleagues [19] retrospectively evaluated 40 Insall’s proximal realignments (IPRs) performed on 29 patients, with an average postsurgical follow-up of 8 years (range: 5–13 years). One of the objectives of this study was to analyze whether a relationship existed between the presence of PM and that of AKP. In this study, IPR was found to provide a satisfactory centralization of the patella into the femoral trochlea in the short-term follow-up and the surgery was associated with resolution of AKP [19, 20]. This outcome appears to support the PM theory; however, the success of realignment surgery may have been due to factors independent of the relative patellofemoral position, such as denervation of the patella, extensive postoperative rest (unload), and postoperative physical therapy. Unfortunately, the satisfactory centralization of the patella observed at the short-term follow-up was lost by the long-term follow-up in almost 57% of the cases, based on CT scans [19]. That is, IPR did not provide a permanent correction of patellofemoral congruence in all cases. Nonetheless, this loss of centralization did not correlate with a worsening of clinical results. In short, a relation between the result (satisfactory versus non-satisfactory) and the presence or absence of postoperative PM was not found in the long term [19]. Out of 29 patients in the study, 12 presented with unilateral symptoms. In nine of these patients, the contralateral asymptomatic knee presented a PM, and there was a satisfactory centralization of the patella into the femoral trochlea in only three cases [19]. If the presence of PM is crucial in the genesis of AKP, how can we account for unilateral symptoms in patients with similar morphologic characteristics between both patellofemoral joints? With regard to unilateral pain in the presence of bilateral PM, patients are known to preferentially load one limb more than the other (usually the dominant limb) in highly demanding activities, such as sports. This loading difference could be enough to cause V. Sanchis-Alfonso et al. unilateral pain, but we did not find a relationship between the lateral dominance and the affected side in cases with unilateral pain [21]. Further, in six patients with bilateral symptoms who received surgery on the knee with the most severe symptoms, the contralateral knee was pain-free at follow-up. Therefore, if the presence of PM is crucial in the genesis of AKP, why do symptoms disappear without any change in the patellofemoral alignment? Loss of both tissue and bone homeostasis may be more important than structural characteristics in the genesis of AKP. Viewing AKP as being necessarily tied to PM is an oversimplification that has impeded progress toward better diagnosis and treatment. The great danger in using PM as a diagnosis is that the unsophisticated or unwary orthopedic surgeon may think that he or she can correct it with surgical procedures. Pursuing this misguided path very often makes the patients’ pain worse. The worst cases of AKP, at least in my series (V. S-A), occur in patients that have had multiple PM-oriented operative procedures for symptoms that initially were only mild and intermittent. We have observed that not all patellofemoral malaligned knees show symptoms, which is not surprising, because asymptomatic anatomic variations are not uncommon. Moreover, we have demonstrated that PM is not a sufficient condition for the onset of symptoms, given that many patients with AKP do not have PM. We can conclude that the pain does not arise from the PM. That is, pain does not arise from the malposition of the patella on the trochlea. Thus, no imaging study should give us an indication for surgery. PM diagnosed with plain x-ray, CT or MRI is only an instant in time and does not describe the dynamics of motion. Moreover, we do not have adequate proof of the definition of normal alignment. History, physical exam, and differential injection must point towards surgery, with imaging only being used to confirm clinical impression.
Pathophysiology of Anterior Knee Pain 4 The Key Question: Is There a Mechanical Overload of the PFJ Behind AKP and What is the Role of Patellofemoral Imbalance in the Genesis of AKP? Multiple approaches have been taken to determine the genesis of AKP, from the more traditional structural/biomechanical view to the newer tissue homeostasis perspective. Despite their differences, all potential explanations include joint loading as an important factor. This commonality is not surprising because the PFJ is very sensitive to stress. Certain activities that highly load the PFJ, such as going down stairs or inclines or experiencing prolonged flexion while a person is sitting, kneeling, or squatting, are strongly associated with the genesis and persistence of AKP. In addition, a direct blow to the patella in a fall to the ground or with dashboard contact in an automobile accident can also cause pain that may persist for an extended time, even without an overt radiographically identifiable fracture. How can pain be explained in such cases by the tissue homeostasis perspective? The PFJ is one of the most highly loaded joints in the human body [22] as well as one of the most difficult musculoskeletal systems in terms of restoration of functionality after an injury and the subsequent loss of tissue homeostasis [23]. Joint reaction forces that are created within the PFJ with certain activities can be many times the body weight [24]. These high loads have been estimated to be 3.3 times the body weight with activities such as climbing up or down stairs, 7.6 times the body weight with squatting, and in excess of 20 times the body weight with jumping activities [25, 26]. In addition to the load applied to the joint, the actual stresses generated within the PFJ also depend on the surface areas of the patella and femur that may be in contact at any given moment [19]. Such high forces can easily result in loads that may exceed the safe load acceptance capacity of musculoskeletal tissues, leading to symptomatic damage and inducing a mosaic of pathophysiologic processes causing AKP [2, 15]. 23 Further, patellofemoral overload could be secondary to inappropriate physiotherapy in some cases of AKP. Attempting to strengthen the quadriceps through open kinetic chain exercises will unacceptably overload the PFJ if the exercises are performed between 0 and 45 degrees of flexion [27]. Likewise, closed kinetic chain exercises performed between 45 and 90 degrees of flexion will also overload the PFJ [27]. Although there may be no obvious structural alteration, the PFJ can be overloaded and AKP can be triggered. In some cases, PFJ overloading is secondary to structural anomalies, such as trochlear dysplasia [28]. Patients with AKP are more likely to have trochlear dysplasia compared to pain-free individuals [29]. Moreover, in patients with a trochlear bump (severe trochlear dysplasia) and AKP, both hydrostatic pressure and water content increase in the patella [30]. Such increases potentially provoke episodes of tissular ischemia and mechanical stimulation of nociceptors, which are both associated with pain [31]. Along these lines, Barton and colleagues [32] have demonstrated that the patella contains an intraosseous nerve network that is the densest in the medial and central portions of the patella and significantly sparser laterally. Moreover, growing evidence shows that in the subgroup of patients with patellofemoral chondral lesions, some of their pain is related to such lesions due to the overload of the richly innervated subchondral bone interface [31]. Such subchondral bone overload is secondary to damaged cartilage and the loss of its capacity as a shock absorber. However, of all the structural factors that can cause an overload of the PFJ, the most powerful is the skeletal malalignment of the lower limb (limb alignment in the three planes), specifically torsional alterations (femoral anteversion and/or external tibial torsion) [33, 34]. With regard to malalignment, Albert van Kampen [35] has demonstrated that patellar tracking is highly susceptible to tibial rotations. Therefore, patellar tracking biomechanical studies must take tibial rotation into account. However, the classic PM theory does not take tibial and femoral torsion
24 into consideration, which represents another weak point in the PM theory. Limb alignment appears to very strongly influence the quadriceps vector [33, 34]. An abnormal quadriceps vector is an important contributor to AKP, and abnormal limb alignment is the underlying cause of the incorrect quadriceps vector [33, 34]. The direction of the quadriceps vector is likely more important than its magnitude [33, 34]. It should be noted that skeletal malalignment is not an abnormal Qangle or an increased TT-TG distance, nor is it an increased tilt or increased shift of the patella. It instead involves the alignment of the limb in all three spatial planes—coronal, sagittal, and transverse. During a normal gait, the knee joint axis moves straight forward with minimal amounts of internal or external rotation, and the quadriceps force is directed posteriorly, compressing the patella into the trochlea. With abnormal limb torsion, the knee joint axis often moves forward in a manner that is oblique to the direction of motion. Such movement generates abnormal shear forces between the patella and the femur that will eventually cause tissue failure. If the force is not perfectly aligned, it can lead to an unbalanced distortion of the soft tissues surrounding the patella. It is very likely that one of the sources of AKP is in the peripatellar soft tissues due to the stress that the soft tissues undergo. However, we do not know the strain levels that must be reached to trigger the pain. Some patients with torsional deformities have unilateral AKP, despite the deformity being symmetric. Why one side is symptomatic and the other is not remains an enigma. It is probable that most people limit their activity to avoid overuse or injury to the PFJ and thus AKP. Many of these patients are symptomatic only when they attempt an activity that causes increased loading; therefore, many select their activities based on what is comfortable. Once an injury (soft tissue lesion) or overuse (soft tissue strain) develops, quick recovery does not occur because of the underlying mechanical inefficiency. This situation may explain why disabling pain may occur on one side, while the opposite side remains V. Sanchis-Alfonso et al. asymptomatic. Moreover, the lack of symptoms on one side may be relative. In some cases, patients have asked for surgery on the asymptomatic side after the symptomatic side has been corrected because “they never knew what it was like to feel normal”. In short, according to Robert A. Teitge, it is the excess of force in the PFJ that exceeds tissue homeostasis which is responsible for AKP. However, the problem is not a question of leaving the load acceptance envelope, but rather knowing what the envelope size limits are and why the excess force is excessive. If this is true, then the problem in diagnosing AKP is determining the source of the excess force. Robert A. Teitge puts forward a simile to understand the etiopathogenesis of AKP. To build a bridge, one must be knowledgeable of several factors. They include: (a) the required load limit, meaning the envelope; (b) the design of the bridge parts, which is the skeletal alignment; and (c) what materials the bridge is made of, connoting the response of those materials to the load. In the following sections, we will look at the biological response to a mechanical stimulus. The question we must ask ourselves is whether it is possible that all the neuroanatomical factors that we are going to discuss below are secondary to an excess of force. In other words, is the excess force the precipitating event? We do not have an answer to these questions. 5 Neuroanatomical Bases for AKP in the Young Patient: Neural Model Sanchis-Alfonso and colleagues have developed the neural model as an explanation for the genesis of AKP in young patients [36]. The origin of AKP can be in the lateral retinaculum (LR), medial retinaculum, infrapatellar fat pad, synovium, or subchondral bone [37–39]. Studies by Sanchis-Alfonso and colleagues on AKP pathophysiology have mainly focused on the LR retrieved during patellofemoral realignment surgery in patients with a diagnosis of PM [40–43].
Pathophysiology of Anterior Knee Pain 5.1 Morphologic Neural Changes in the Lateral Retinaculum Some studies have implicated neural damage in the LR as a possible source of AKP in the young patient. In 1985, Fulkerson and colleagues described for the first time, nerve damage (demyelination and fibrosis) in the LR of patients with intractable patellofemoral pain requiring lateral retinacular release or realignment of the PFJ [44]. The changes in the retinacular nerves observed by these authors resembled the histopathologic picture of Morton's interdigital neuroma. Later, in 1991, Mori and colleagues found degenerative neuropathy in the LR in AKP patients [45]. Sanchis-Alfonso and colleagues have also observed nonspecific, chronic degenerative changes in nerve fibers, including myxoid degeneration of the endoneurium, retraction of the axonal component, and perineural fibrosis, in the LR in many cases (Fig. 4A) [42, 43]. Moreover, Sanchis-Alfonso and colleagues have found that a smaller group of specimens presented nerve fibers mimicking amputation neuromas seen elsewhere in the body (Fig. 4B) [42, 43]. A clear relationship has been demonstrated between the presence of neuromas and AKP; however, a similar relationship between neural Fig. 4 A Myxoid degeneration in the nerve fibers. No inflammatory cells are seen, B Microneuroma next to a rich vascular area (HE). (B-Reused with permission from SAGE. From: “Quantitative analysis of nerve changes in 25 myxoid degeneration and pain has not been found [43]. Nerve damage occurs diffusely in the affected LR, and one must therefore consider the possibility of multiple neurologic sequelae in the peripatellar region. A possible consequence of such damage could be an altered proprioceptive innervation [43]. For example, Baker and colleagues observed an abnormal sense of the knee joint position (proprioception) in subjects with AKP [46]. Current research shows the importance of proprioceptive information from joint mechanoreceptors for proper knee function. Connective tissues, in addition to their mechanical function, play an important role in transmitting specific somatosensory afferent signals to the spinal and cerebral regulatory systems. Thus, the giving-way in AKP patients can be explained, at least in part, by the alteration or loss of joint afferent information with regard to proprioception due to nerve damage in the ascendant proprioception pathway or a decrease of healthy nerve fibers capable of transmitting proprioceptory stimuli. It seems likely that, to a certain degree, the instability of the PFJ in patients with AKP arises not only from mechanical factors but also neural factors [47, 48]. Such factors center on a proprioceptive deficit both in the sense of position and in the slowing or diminution of the lateral retinaculum in patients with isolated symptomatic patellofemoral malalignment” Am J Sports Med. 1998; 26:703–709)
26 stabilizing and protective reflexes. In addition, Jensen and colleagues reported abnormal sensory function in the painful and nonpainful knee in some subjects with long-term unilateral AKP [49]. 5.2 Hyperinnervation into the Lateral Retinaculum and AKP Several studies have implicated hyperinnervation of the LR as a possible source of AKP in the young patient, with higher innervation in those with severe pain compared with those with moderate or mild pain [43]. Moreover, the LR of patients with pain as the predominant symptom has been shown to have a higher innervation pattern than the medial retinaculum or the LR of patients with patellar instability [43]. This nerve ingrowth consisted of myelinated and Fig. 5 A Free nerve endings immersed in the connective tissue, B Hot spot of free nerve endings forming a microneuroma, C Nerve endings entering the arterial wall. (Neurofilament NF). (Reused with permission from SAGE. From: “Immunohistochemical analysis for neural markers of the lateral retinaculum in patients with isolated symptomatic patellofemoral malalignment” Am J Sports Med. 2000; 28: 725–731) V. Sanchis-Alfonso et al. unmyelinated nerve fibers with a predominant nociceptive component (Fig. 5) [40]. The nociceptive properties of at least some of these nerves were shown by their substance P (SP) immunoreactivity (Fig. 6) [40]. SP, which is found in primary sensory neurons and C fibers (slow-chronic pain pathway), is involved in the neurotransmission pathways of nociceptive signals [50–62]. SP was detected in the axons of big nerve fibers, in free nerve endings, and in the vessel walls in some patients with pain as the predominant symptom [40]. Nociceptive fibers (i.e., neural fibers with intraaxonal SP) were fewer in number than NF fibers, indicating that not all the tiny perivascular or interstitial nerves were nociceptive [40]. Interestingly, the finding that SP fibers are more abundant in the LR than in its medial counterpart reinforces the role of the LR as the main source of pain in some AKP patients. Moreover, the number of these
Pathophysiology of Anterior Knee Pain Fig. 6 A Substance P, a marker of sensory fibers, is expressed in the nerve fibers in a granular pattern, B Neuromas are rich in nociceptive axons, as can be demonstrated studying substance P. (Reused with permission from SAGE. From: “Immunohistochemical analysis for neural markers of the lateral retinaculum in patients with isolated symptomatic patellofemoral malalignment” Am J Sports Med. 2000; 28: 725–731) nociceptive fibers has been observed to be higher in patients experiencing pain as the main symptom relative to those with instability as the predominant symptom (with little or no pain between instability episodes) [40]. Nerve ingrowth, is mostly located within and around blood vessels (Fig. 7) [40, 43]. Thus, within the LR of AKP patients, S-100 positive fibers in the adventitia and within the muscular layer of medium and small arteries resemble a necklace. S-100 protein is a good marker of nerves because it permits identification of the Schwann cells in the myelinated parts of axons. Myelinated fibers typically lose their myelin sheath before they enter the muscular arterial wall, but this was found to not be the case in AKP patients. In a study of myelinated fibers by S-100 immunostaining, we were surprised by the identification of S-100positive fibers within the muscular layer of medium and small arteries given that the myelin sheath 27 was expected to be lost before the nerve entered the muscular arterial wall [43]. Vascular innervation has been demonstrated to be more prominent (94%) in patients with severe pain, whereas this type of hyperinnervation has been found in only 30% of the patients with light or moderate pain [42]. These findings are in agreement with the statement of Byers, who postulated in 1968 that pain in an osteoid osteoma could be generated and transmitted by vascular pressure-sensitive autonomic nerves [63]. In reviewing the literature, we have seen that hyperinnervation is also a factor implicated in the pathophysiology of pain in other orthopedic abnormalities, such as chronic back pain and jumper’s knee [54, 55, 64, 65]. On the other hand, pain has also been related with vascular innervation in some pathologies, as is the case in osteoid osteoma, in which an increase in perivascular innervations has been found in all the cases, leading the authors to postulate that pain was more closely related to this innervation than to the release of prostaglandin E2 [66]. Grönblad and colleagues have reported similar findings in the lumbar pain of facet syndrome [67]. Finally, Alfredson and colleagues related pain in Achilles tendinosis with vasculo-neural ingrowth [64]. Hyperinnervation has been demonstrated to be associated with the release of neural growth factor (NGF), a polypeptide that stimulates axonogenesis [41]. NGF has two biologically active precursors: a long form with a molecular weight of approximately 34 kD and a short form of 27 kD [68]. The 34 kD precursor has been found in the LR of AKP patients [41]. Since some of the nerve fibers of the LR express NGF, these nerve fibers must still be in a proliferative phase. As expected, NGF expression is higher in PM patients with pain that in those with instability as the main symptom (Fig. 8) [41]. Gigante and colleagues [69] have also found NGF and TrkA (the NGF receptor) expression in the LR of patients with PM, but not in patients with jumper’s knee or meniscal tears. Interestingly, NGF is related not only to neural proliferation in vessels and perivascular tissue but also to the release of neuroceptive transmitters, such as SP [70].
28 Fig. 7 Lateral retinaculum vessels are richly innervated in some of our patients. The myelinated innervation enters the muscular wall from the adventitial tissue, forming a necklace. (S-100). (Reused with permission from SAGE. V. Sanchis-Alfonso et al. From: “Quantitative analysis of nerve changes in the lateral retinaculum in patients with isolated symptomatic patellofemoral malalignment” Am J Sports Med. 1998; 26:703–709) Fig. 8 Immunoblotting detection of NGF showing a thicker band in cases with AKP (4,5,6,7) compared with cases of instability without pain (1,2,3) In short, in symptomatic PM patients with pain as the main symptom, there are detectable levels of NGF that cause hyperinnervation and stimulate SP release, whereas in patients with instability as the predominant symptom, there are lower levels of local NGF release, less neural proliferation, and less nociceptive stimulus [41]. Consequently, there must be some factors acting on a PM that make the patient has pain or instability as the main symptom. PM may in fact not have anything to do with the presence of pain. In other words, symptoms appear to be related to multiple factors with variable clinical expression, and our imperfect understanding of
Pathophysiology of Anterior Knee Pain these factors may explain the all-too-frequent failure to achieve adequate symptom relief with the use of realignment procedures. The question is, what are the mechanisms that stimulate NGF release in these patients? We hypothesize that periodic short episodes of ischemia could be the primary mechanism of NGF release and hyperinnervation, and therefore could be implicated in pain, at least in a subgroup of AKP patients. 5.3 Role of Ischemia in the Genesis of AKP: Loss of Vascular Homeostasis Despite numerous publications on AKP, the mechanism underlying the pain is controversial. The loss of vascular homeostasis has been proposed as an intrinsic pain mechanism in a subgroup of AKP patients. 5.3.1 Basic Science According to some authors, ischemia can induce NGF synthesis [70–72]. Moreover, NGF has been shown to stimulate neural sprouting and hasten neural proliferation in blood vessel walls [73, 74], which is the same pattern of hyperinnervation that is seen in the LR of some AKP patients [40, 42, 43]. Similar changes have been studied in animal models and are present in the coronary innervation of patients with myocardial infarcts and brain ischemia [71, 72, 74]. Thus, short episodes of tissular ischemia due to vascular torsion or vascular bending have been hypothesized as the main problem in painful patellofemoral imbalance [40, 42]. Vascular bending could be induced mechanically by medial traction over the retracted LR with knee flexion [38]. Sanchis-Alfonso and colleagues have demonstrated histologic retinacular changes associated with hypoxia in painful PM [42]. They have found lesions that can lead to tissular anoxia, such as arterial vessels with obliterated lumina and thick muscular walls, and other lesions that can arise from ischemia, such as infarcted foci of the connective tissue, myxoid stromal degeneration, and ultrastructural findings 29 related with anoxia (degenerated fibroblasts with autophagic intracytoplasmic vacuoles, endothelial cells with reduplication of the basal lamina, young vessels with endothelial cells containing active nuclei and conspicuous nucleoli, and neural sprouting) (Fig. 9) [75]. Another phenomenon related to ischemia is angiogenesis. Chronic ischemia leads to release of vascular endothelial growth factor (VEGF), a potent hypoxia-inducible angiogenic factor that causes hypervascularization [76]. This hypervascularization creates blood vessels to supply the nutrient needs of the tissue. Sanchis-Alfonso and colleagues have performed a quantitative analysis of vascularization in the LR excised during surgical patellofemoral realignments, using a pan-vascular marker, anti-Factor VIIIrelated antigen [42]. They have found an increase in the number of blood vessels in the LR of patients with painful PM, with the severe pain group having greater numbers compared with those of moderate or mild pain group [42]. Moreover, as expected, they found a positive linear correlation between the number of blood vessels and number of nerves [42]. Tissular ischemia induces VEGF release by fibroblasts, synovial cells, mast cells, or even endothelial cells [77–80]. Based on these principles, Sanchis-Alfonso and colleagues performed a study of VEGF expression in the LR of patients with PM, using immunohistochemistry and immunoblot analysis [42]. VEGF release begins 8 h after hypoxia, and the peptide disappears in 24 h if the ischemic crisis has ended [42]. Therefore, VEGF positivity reflects the presence of an ischemic process, or better said, 8–24 h has elapsed since the onset of the transitory ischemic episode. However, given that the average duration of VEGF is very short, its absence has no significance regarding whether a transitory ischemic process is occurring. Although this process has been well documented in joints affected by rheumatoid arthritis and osteoarthritis [79–81], it has never been documented in AKP until the study by Sanchis-Alfonso and colleagues [42]. They have shown VEGF production in stromal fibroblasts, vessel walls, certain endothelial cells, and even nerve fibers, including
30 V. Sanchis-Alfonso et al. A B C E D F G Fig. 9 A Arterial vessel in the retinacular tissue can show a prominent and irregular endothelium and thick muscular walls or even an irregular reduction of the vascular lumen. (Hematoxylin–Eosin stain). B Infarcted foci in the connective tissue showing a degenerative pattern of the collagen fibers, with loss of the fibrillar component and accumulation of myxoid material in the interstitium, (Masson’s Trichrome stain). C Myxoid stromal degeneration in the middle of the fibrous retinacular tissue (Hematoxylin–Eosin stain). D Degenerative changes in fibroblasts (increased autophagic vacuoles— asterisk–) secondary to hypoxia (TEM). E Young vessels with endothelial cells containing active nuclei and conspicuous nucleoli. F Neural sprouting is detected ultrastructurally as a bunch of tiny axons immersed in the Schwann cell cytoplasm. G Neural sprouting detail similar levels in axons as in perineurium (Fig. 10) [42]. Their immunohistochemical findings were confirmed by immunoblot analysis. VEGF levels were higher in patients with severe pain than in those with mild to moderate pain; the protein was barely detectable in two cases with mild pain (Fig. 11) [42]. VEGF expression is absent in normal joints, although inflammatory
Pathophysiology of Anterior Knee Pain 31 Fig. 10 A VEGF, the factor promoting vascular proliferation, is present in smalls vessels (wall and endothelium) and in perivascular fibroblasts. B Some cases have VEGF expression in the perineural shift and inside the axons (VEGF) Fig. 11 Immunoblotting detection of VEGF showing a thicker band in cases with severe AKP (2,3,10) compared with cases with moderate pain (1,5,8) or light pain (4,6,7,9) processes can stimulate its release [81, 82]. In such cases, synovial hypoxia secondary to articular inflammation is assumed to trigger VEGF production [82]. However, inflammatory changes have not been observed in the LR of AKP patients [42, 43]. Furthermore, peripheral nervous system hypoxia has been reported to be able to simultaneously trigger VEGF and NGF synthesis via neurons [83], or inflammatory or stromal cells [71, 72]. VEGF induces hypervascularization, and NGF induces hyperinnervation. Both occurrences have been observed in AKP patients [42, 43]. In conclusion, ischemia could be the main trigger for pain in at least a subgroup of AKP patients. 5.3.2 Clinical Studies The role of vascular insufficiency in AKP has not been studied extensively from a clinical point of view. In fact, only a few clinical papers have alluded to the possibility of hypoxia as a factor in the pathogenesis of AKP. Sandow and Goodfellow [84] investigated the natural history of AKP in adolescents. In a study sample of 54 adolescent girls, the researchers observed that 9 out of 54 (16.7%) had pain that was aggravated by cold weather. According to Selfe and colleagues [85] the proximal part of the rete patellae is very superficial and is therefore vulnerable to thermal environmental stress, resulting in greater hypoxia during cold weather. More recently, Selfe and colleagues [86] studied clinical outcomes in a sample of AKP patients categorized as hypoxic, that is to say, with “cold knees” (his or her legs felt cold even in warm surroundings). Fourteen out of 77 (18.2%) of the patients were categorized as “cold sufferers,” a percentage very similar to that reported by Sandow and Goodfellow [84]. Selfe and colleagues [86] studied local hypothermia by means of infrared thermography and concluded that patients categorized as hypoxic reported greater pain levels and had poorer response to an exercise-based treatment than non-hypoxic patients. Gelfer and colleagues [87], using single photon emission computed tomography (SPECT), also found a relationship between transient patellar ischemia after total knee replacement and the clinical symptoms of AKP. Similarly, using photoplethysmography, which is a reliable technique for estimating blood flow in bone tissue, Naslund also observed that an ischemic mechanism (decreased
32 V. Sanchis-Alfonso et al. blood flow in the patellar bone) is involved in the pathogenesis of AKP [88]. Moreover, in half of the AKP studied patients, Naslund observed accelerated bone remodeling in bony compartments of the knee joint, which may have been due to a dysfunctioning sympathetic nervous system and caused intermittent ischemia and pain. Selfe and colleagues [85] classified AKP patients into three groups: hypoxic, inflammatory, and mechanical. However, ischemia may be the painprovoking factor in all three groups, given that inflammatory changes can develop not only after ischemia but also after mechanical damage to the vascular system. Ischemia could be caused by higher intraosseous pressure, redundant axial loading, or decreased arterial blood flow. 6 The Role of the Peripheral and/or Central Nervous System in the Pathophysiology of AKP—“Central Sensitization”—“The Neuromatrix Model” AKP is a paradigm of chronic pain. Chronic pain is a multidimensional phenomenon composed of sensitive, cognitive-evaluative and affectivemotivational domains. The central nervous system, both the brain and spinal cord, is where pain is produced and modulated. Several brain and spinal cord areas work together (the pain neuromatrix) in response to corporal stimuli to create the multidimensional experience of pain. Interestingly, Damasio and colleagues [89] observed an overlap between the cerebral activity areas related to chronic pain and those related to cognition and emotions. This finding suggests that chronic pain, cognition, and emotions are interrelated. Moreover, it has been shown that AKP is not only related to structural anomalies but also to altered central neural processes along with alterations in central nociceptive processing [90, 91]. Slutsky-Ganesh and colleagues [92] indicate that the posterior cerebellum could be a key modulator in cognitive assessment of pain in patellofemoral pain across the cortico-cerebellar loops, possibly leading to consequences on motor function downstream. As we will see in chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients”, AKP patients have a high incidence of anxiety, depression, kinesiophobia (the belief that movement will create additional injury or re-injury and pain) and catastrophizing (the belief that pain will worsen, and one is helpless to deal with it) [93–95]. Psychological factors play an important role as pain modulators. Even in cases with clear structural findings that justify pain, psychological factors influence and modify pain sensation as well as subsequent impairment. Therefore, they can be barriers to recovery after the appropriate surgical treatment. Catastrophizing is not only responsible for the chronification of pain due to a psychological mechanism but may also influence the neurophysiology of pain modulation. In a functional MRI study of patients with chronic pain, Gracely and colleagues [96] showed that catastrophizing ideas were associated with a higher degree of brain activity not only in the pain regions but also in the cortical regions associated with attention, anticipation of pain and emotional aspects of pain. Catastrophizing may play a role as a facilitator of the pain perception process. It also has been suggested that pain catastrophizing interfere with descending paininhibitory systems and may facilitate neuroplastic changes in the spinal cord during repeated painful stimulation, thereby promoting sensitization in the central nervous system. Impaired “conditioned pain modulation,” defined as the endogenous pain inhibition ability of a subject, has been demonstrated in young women with long-standing AKP [97]. Central sensitization (CS) has been defined by the International Association for the Study of Pain (IASP) as “increased responsiveness of nociceptive neurons in the central nervous system to their normal or subthreshold input” [98]. In other words, there is ineffective pain modulationinhibition in the central nervous system. That is to say, there is a process of amplification of the afferent signal that arrives from the periphery. For all that, the malfunctioning of the descending pain-inhibiting mechanisms is another of the
Pathophysiology of Anterior Knee Pain mechanisms involved in CS. From a clinical standpoint, we can suspect that there is CS when the patient presents with allodynia or hyperalgesia. A significant number AKP patients present more signs of CS when compared to healthy pain-free individuals. Interestingly, it has been demonstrated that pain sensitization may be amenable to treatment through exercises, pharmacological therapy, and surgery [99]. In AKP patients, there is “central sensitization,” meaning an increased responsiveness of the central nervous system to a variety of stimuli [100–102]. Rathleff and colleagues [101] suggested that adolescent females with AKP have both localized and distal hyperalgesia (a reduced pressure pain threshold), which can be determined through pressure algometry. This hyperalgesia may signal altered central processing of nociceptive information. Jensen and colleagues [49] have shown that some patients with unilateral AKP have neuropathic pain, which suggests damage in the peripheral and/or central nervous system that causes pain signals without a specific cause. In this way, many AKP patients have alterations in the central nervous system that might play an important role both in the magnitude and persistence of pain after suitable conservative or surgical treatment. Lefaucheur and colleagues [103] found a link between chronic neuropathic pain and motor cortex disinhibition. The current data suggest that repetitive transcranial magnetic stimulation of the motor cortex corresponding to the patient’s site of pain may be a complementary treatment modality for patients with chronic neuropathic AKP [104]. Motor cortex stimulation may produce analgesic effects by restoring missing or impaired intracortical inhibitory processes [103]. As we can see in chapter “Brain Network Functional Connectivity Clinical Relevance and Predictive Diagnostic Models in Anterior Knee Pain Patients”, AKP patients have brain functional connectivity changes compared to healthy controls. That is especially the case between the brain areas involved in cognitive stimulus processing and the regions involved in pain 33 modulation. This widespread impact on overall brain function could play an important role in explaining the magnitude, experience and persistence of pain after suitable conservative or surgical treatment. 7 Authors’ Proposed AKP Pathophysiology A subgroup of patients with AKP have a skeletal malalignment of the limb, especially in the transverse plane (femoral and/or tibial rotational malalignment) [33, 34]. This malalignment of the lower limb could provoke pain due to the abnormal stress on tissue which is not of sufficient magnitude or direction to result in instability. It is likely that nerve changes or ischemia may be due to chronic repetitive stretch of soft tissue (retinaculum). Moreover, skeletal malalignment could provoke patellofemoral instability due to a failure of the ligaments that stabilize the PFJ, and it will also lead to the development of patellofemoral cartilage lesions due to the increased patellofemoral compression forces (Fig. 12). However, in most cases, the abnormal femoral rotation is functional due to a deficit of the proximal control [105]. This situation will lead to a patellofemoral imbalance as it occurs in the structural skeletal malalignment of the lower limb. We hypothesize that short and repetitive episodes of tissular ischemia, potentially due vascular torsion or vascular bending induced by a patellofemoral imbalance, could trigger release of NGF and VEGF in the peripatellar soft tissues. Once NGF is present in the tissues, it induces hyperinnervation, attracts mastocytes, and triggers substance P release by free nerve endings (Fig. 13) [70]. In addition, VEGF induces hypervascularization and plays a role in increasing neural proliferation. Free nerve endings, slowly adapting receptors that mediate nociception, are activated in response to deformation of tissues. In the knee, such deformation results from abnormal tensile and compressive forces generated during flexo-
34 V. Sanchis-Alfonso et al. Fig. 12 Pathways to pain in patients with torsional abnormalities. Force out of balance is the culprit, and force out of the balance is due to the limb out of alignment Fig. 13 Pathophysiology of AKP extension of the joint or in response to chemical agents such as histamine, bradykinin, prostaglandins, and leukotrienes [57, 106, 107]. Therefore, SP is released from peripheral endings of nociceptive afferents as a result of noxious chemical or mechanical stimulation. The nociceptive information relayed by these free nerve endings is responsible, at least in part, for the pain. Once SP is liberated in the connective tissue, it induces the release of prostaglandin E2, one of the biochemical agents known to stimulate nociceptors (Fig. 13) [50]. The activation of nociceptive pathways by prostaglandins could be one of the many mechanisms involved in the transmission of pain in AKP patients. Moreover, SP stimulates mast cells, facilitating a degranulation process that can liberate histamine, another non-neurogenic pain mediator (Fig. 14) [56]. Numerous mast cells have been identified in the LR of AKP patients [19]. Mast cells are also associated with the release of NGF [40, 108], contributing to the hyperinnervation and indirectly provoking more pain. Furthermore, SP has been shown to induce the release of collagenase, interleukin-1, and tumor necrosis factor-alpha (TNF-a) from synoviocytes, fibroblasts, and macrophages [50, 52]. These factors could contribute to the genesis of patellar instability through degradation of soft tissues. SP, NGF and mast cells have also recently been implicated in bone resorption in both in vitro and in vivo experiments, which could explain, at least in part, the osteoporosis found in many cases of AKP
Pathophysiology of Anterior Knee Pain 35 A B Fig. 14 Mast cells are abundant in the stroma (arrow), mainly in a perivascular disposition. Some of them show a degranulation process (activated mast cells) (A), (Giemsa stain). Ultrastructural image of a mast cell of the lateral retinaculum with its cytoplasm full of chemotactic granules, (TEM) (B). (A)-(Reused with permission from SAGE. From: “Immunohistochemical analysis for neural markers of the lateral retinaculum in patients with isolated symptomatic patellofemoral malalignment” Am J Sports Med. 2000; 28: 725–731) [109]. Finally, SP and VEGF stimulate endothelial cell proliferation and migration [53], which are essential to the development of a new vascular network that may promote tissue repair, but indirectly maintain a vicious cycle. Woolf [110] described four types of pain from a clinical point of view: (1) nociceptive pain, which is transient pain in response to noxious stimulus; (2) homeostatic pain, which is pain that promotes the healing of injured tissue (i.e., the cascade of events toward re-establishing homeostasis); (3) neuropathic pain, which is spontaneous pain and hypersensitivity to stimulus in association with damage to the nervous system; and (4) functional pain, which is pain resulting from abnormal central processing of normal input. All these mechanisms appear to be involved in the pathophysiology of pain in AKP patients. orthopedic pathologies from a clinical point of view. AKP obliges us to “think out of the box”, to look deeper into the anatomy, biomechanics, biology, anatomic pathology, physiopathology, and psychology. AKP is a great stimulus for orthopedic intellectual development. Chondromalacia patellae is not synonymous with AKP. It is not the underlying problem. Very often, patellofemoral malalignment (patellar tilt/lateral patellar subluxation) is not the problem. In a subgroup of AKP patients, skeletal malalignment of the limb is responsible for disabling AKP due to both patellofemoral overload and patellofemoral imbalance. Understanding the biomechanics is crucial— orthopedic surgery is very much a mechanical engineering discipline. At this time, from the biomechanical viewpoint, the most powerful treatment effect in treating AKP comes from limb re-alignment. In the vast majority of AKP cases, the loss of both soft tissue (peripatellar synovitis and others soft tissue impingements such as synovial hypertrophy around the inferior pole of 8 – – – – Take Home Messagess – Currently, much remains to be learned about the cause of AKP. Our understanding is limited. AKP is one of the most intriguing –
36 – – – – 9 V. Sanchis-Alfonso et al. the patella) and osseous (intraosseous edema, osseous hypertension) homeostasis is more important in the genesis of AKP than local structural anomalies (patellar till, lateral patellar displacement, and patellofemoral chondropathy). However, we do not know how often is AKP present in a structurally perfect limb, except for overtraining. It is likely that the loss of homeostasis can be mechanical with an as yet unrecognized structural anomaly. There is a neuroanatomical basis for AKP in the young patient. A dysfunction of the peripheral and/or the central nervous system may cause neuropathic pain in some individuals with AKP. Periodic short episodes of ischemia, secondary to a mechanical stimulus, could be implicated in the pathogenesis of AKP by triggering neural proliferation of nociceptive axons (SP-positive nerves), mainly in a perivascular location. These findings are in line with the homeostasis perspective. Loss of vascular homeostasis in the knee region (e.g., hypervascularity, ischemia, osseous hypertension) may be associated with AKP. It is possible that all of the neuroanatomical factors involved in the genesis of AKP and the loss of vascular homeostasis are due to an excess of force that would be the precipitating event. Chronic pain is a multidimensional phenomenon composed by sensitive, cognitiveevaluative and affective-motivational domains. The neuromatrix model can explain the multidimensional pain experience in AKP patients. Key Message – We hypothesize that it is the force (magnitude or direction) which determines whether one is in or out of Dye’s envelope. In short, the diagnostic challenge is determining the source of excess force which overcomes tissue homeostasis. We are a long way from determining why excess force is excess. References 1. Büdinger K. Üeber ablösung von gelenkteilen und verwandte prozesse. Dtsch Z Chir. 1906;84:311–65. 2. Dye SF. The pathophysiology of patellofemoral pain: a tissue homeostasis perspective. Clin Orthop Relat Res. 2005;436:100–10. 3. Royle SG, Noble J, Davies DR, et al. The significance of chondromalacic changes on the patella. Arthroscopy. 1991;7:158–60. 4. Ficat P, Ficat C, Bailleux A. Syndrome d’hyperpression externe de la rotule (S.H.P.E). Rev Chir Orthop. 1975;61:39–59. 5. Ficat P, Hungerford DS. Disorders of the PatelloFemoral Joint. Baltimore: Williams & Wilkins; 1977. 6. Hughston JC. Subluxation of the patella. J Bone Joint Surg. 1968;50–A:1003–1026. 7. Insall J. “Chondromalacia Patellae”: Patellar malalignment syndrome. Orthop Clin North Am. 1979;10:117–27. 8. Merchant AC, Mercer RL. Lateral release of the patella: a preliminary report. Clin Orthop Relat Res. 1974;103:40. 9. Staeubli HU, Bosshard C, Porcellini P, et al. Magnetic resonance imaging for articular cartilage: cartilage-bone mismatch. Clin Sports Med. 2002;21:417–33. 10. James SL. Chondromalacia of the Patella in the adolescent. In: Kennedy JC. editor. The injured adolescent knee. Baltimore: The Williams & Wilkins Company, 1979. 11. Orthopaedic Knowledge Update 3 Home Study Syllabus Published by American Academy of Orthopaedic Surgeons, Park Ridge, Illinois, January 1990, pp 563–567. 12. Meister K, James SL. Proximal tibial derotation osteotomy for anterior knee pain in the miserably malaligned extremity. Am J Orthop (Belle Mead NJ). 1995;24:149–55. 13. Cooke TD, Price N, Fisher B, et al. The inwardly pointing knee. An unrecognized problem of external rotational malalignment. Clin Orthop Relat Res. 1990;56–60. 14. Dye SF. The knee as a biologic transmission with an envelope of function: a theory. Clin Orthop Relat Res. 1996;325:10–8. 15. Dye SF, Staubli HU, Biedert RM, et al. The mosaic of pathophysiology causing patellofemoral pain: therapeutic implications. Oper Techni Sports Med. 1999;7:46–54. 16. Powers CM, Ward SR, Fredericson M, et al. Patellofemoral kinematics during weightbearing and non-weightbearing knee extension in persons with patellar subluxation: a preliminary study. J Orthop Sports Phys Ther. 2003;33:677–85. 17. Souza RB, Draper CE, Fredericson M, et al. Femur rotation and patellofemoral joint kinematics: a
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Femoral and Tibial Rotational Abnormalities Are the Most Ignored Factors in the Diagnosis and Treatment of Anterior Knee Pain Patients. A Critical Analysis Review Vicente Sanchis-Alfonso and Robert A. Teitge 1 Introduction At the end of 1970s, skeletal malalignment of the limb was suggested as one of the causes of anterior knee pain (AKP) in some young patients [1]. It must be acknowledged that skeletal malalignment is not an abnormal Q-angle or an increased TT-TG distance. Skeletal malalignment is also not the position of the patella on the trochlea. Neither is it its increased shift (subluxation) or increased tilt. Skeletal malalignment is malalignment of the limb measured on the transverse, coronal, and sagittal planes. The presence of excessive femoral anteversion, excessive external tibial torsion, or increased varus or valgus abnormalities has a great impact on the patellofemoral joint (PFJ) biomechanics. In particular, rotational abnormalities are important [2, 3]. In 1979, Stan James presented a comprehensive review of AKP in which the Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/978-3-031-09767-6_3. V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com R. A. Teitge Wayne State University, Detroit, MI, USA condition of “miserable malalignment” was described, being increased femoral anteversion and increased external tibial torsion [1]. In 1995, he reported on seven patients with “miserable malalignment” who had been treated with internal tibial rotational osteotomy over an 18-year period [4]. Several years earlier, Cooke and colleagues [5] described internal proximal tibial rotational osteotomy in seven patients presenting with AKP and drew attention to the inwardly pointing knee as an unrecognized cause of AKP. However, the concept of skeletal malalignment was almost unnoticed and has had extremely little influence on orthopedic surgeons even until today. In fact, very few publications refer to skeletal malalignment as a cause of AKP. From 1990 to June of 2021, only 22 published papers in English in which the association between patellofemoral disorders in young patients and in which torsional abnormalities of the femur and/or tibia are analyzed from a clinical point of view could be found [6]. This scarcity of published papers may be indicative that symptomatic torsional abnormalities are a rare condition. However, in our daily clinical practice, surgery to correct torsional abnormalities in young AKP patients is frequent. Obviously, this elevated incidence in our clinical practice may be biased by the fact that numerous patients are referred to both of us for many patellofemoral disorders. The aim of this chapter is to analyze why so little importance is given to © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_3 41
42 V. Sanchis-Alfonso and R. A. Teitge this problem in the specialized medical literature. Why do we ignore torsional abnormalities in the diagnosis and especially in the treatment of the AKP patient? It is a fundamental question to delve into. We will attempt to answer it. 2 There is no Agreement on How to Measure Torsion We fully understand the scarce interest knee surgeons have in rotational osteotomies. The main reason is the diagnostic uncertainty. Limb alignment on the transverse plane is hard to see and difficult to measure. Currently, there is no consensus on how to measure torsion [7–9]. Obviously, accurate measurement of torsion is essential to diagnosing, correct surgical decisionmaking and the preoperative planning of a rotational osteotomy (i.e., the amount of correction needed). The first problem that is faced when we see a patient with a torsional abnormality is to objectify and quantify the magnitude of the torsion and therefore determine whether it is pathological or not. Many times, the values the radiologist provides do not match with the clinical findings. This mismatch generates doubt and uncertainty Fig. 1 Evaluation in prone position in a patient with excessive left femoral anteversion in the orthopedic surgeon who is going to treat those patients. This is especially true when it comes to femoral anteversion or femoral torsion. Currently, there are 28 methods to measure femoral neck anteversion [7]. Figure 1 shows the case of a patient with a pathological left femoral anteversion in which the CT study using the Jeanmart's method [10] (classic method), which is the most widespread, reveals a value of 20° that can be considered as normal. Therefore, there is a contradiction between the physical examination and the image in this case. How is it possible that the imaging shows a normal value? Without a doubt, something does not work here. This something is the fact that the radiological method used to evaluate femoral anteversion is not adequate. Murphy and colleagues have shown that the traditional methods may underestimate the actual femoral anteversion by a mean 13° and as much as 18° [11]. In the same way, Kaiser and colleagues have shown a significant difference in measurement techniques of even up to 11° [12]. Unfortunately, the current tendency is to trust the images more and more and devalue or mistrust the physical examination. It is a big mistake. The CT method that we use to evaluate femoral anteversion is the one described by
Femoral and Tibial Rotational Abnormalities … A C 43 B D Fig. 2 A, B Measurement of femoral anteversion using the Jeanmart's method (classic method). C, D Measurement of femoral anteversion according to the technique described by Murphy. Draw a circle on the femoral head (red circle) and another circle centered in the femoral shaft below the lesser trochanter (green circle). Then, draw a line connecting the center of these two circles. This line defines the femoral neck axis on the transverse plane. Next, draw a line tangent to the posterior aspect of the femoral condyles (posterior condylar line). The angle between these two lines represents the femoral anteversion. The line that is used as the axis of the femoral neck in the method described by Jeanmart is not the true axis of the femoral neck Murphy in 1987 (Fig. 2) [11]. Murphy’s method comes closest to defining the reality as it started with the physical measurement of anatomic specimens. His method of anteversion measurement correlates well with the physical examination. In the patient in Fig. 1, the measurement of femoral anteversion with Murphy’s method reveals a value of 39°, which is clearly pathological and coincides with what the physical examination reveals. Interestingly, Schmaranzer and colleagues [13] have observed that the differences between the classic and Murphy’s method become more evident in patients with a clinical diagnosis of femoral torsional abnormality. It has been shown that the difference in femoral torsion between the classic method and Murphy’s method increased from 3° in a patient with normal femoral torsion to 17° in a patient with excessive femoral torsion upon physical examination [14]. Furthermore,
44 the more significant the increase in femoral torsion, the greater the differences between the two methods was also observed [14]. In other words, the differences between the two methods increase progressively with the increase in femoral torsion, the relationship between the two methods being trigonometric and not linear [14]. This must be considered especially when planning a rotational osteotomy in patients with severe femoral torsional abnormalities to avoid mistakes in preoperative planning. Once it is known that there is a pathological torsional abnormality that must be corrected, the next step is to determine at what level the correction must be made. It may be at the proximal, mid-diaphysis or distal level. In theory, the ideal would be to perform the osteotomy at the site where the deformity originates. If we do it at another level, we can create a new deformity on the coronal or sagittal plane even though the total angle is going to be corrected adequately [15]. Some authors [16–18] have used conventional imaging studies in an attempt to define where the torsion occurs along the length of the femur. Femoral anteversion is defined by the angle formed by the intersection of 2 reference lines: one proximal that represents the axis of the femoral neck, and one distal that is tangential to the posterior aspect of the femoral condyles and approximates the knee joint axis. Since this angle of torsion is defined between these 2 lines, it is not possible to specify the level of this torsional alteration. Defining the location of a torsional abnormality between these 2 primary lines will require creation of an additional 3 or 4 references lines. Herzberg and colleagues [19] measured the anteversion angle of the femoral neck and the “retrotorsion” angle of the lesser trochanter in 52 female and 34 male femora taken from 46 human cadavers (age at death 80.3 ± 8.67 years). These authors showed that the lesser trochanter is a well-defined landmark between the proximal and distal femur, and its location follows a linear correlation with femoral anteversion. Therefore, the lesser trochanter is a landmark for separating proximal version and distal femoral torsion. Archibald and colleagues [15] evaluated 1210 paired adult femora from a well-preserved V. Sanchis-Alfonso and R. A. Teitge osteological collection. They have shown that both the femoral neck and femoral shaft substantially contribute to femoral version. Kim and colleagues [16] showed that femoral torsion could occur in the supratrochanteric, infratrochanteric region, or in both sites. Seitlinger and colleagues [17] have demonstrated that the neck, mid and distal femur contribute to the total femoral torsion. Sanchis-Alfonso and colleagues [20] have shown that pathological FAV in the AKP patient depends on both the neck and the shaft. However, Waisbrod and colleagues [18] have proposed that femoral torsion is a subtrochanteric deformity. Ferràs-Tarragó and colleagues [21, 22] have used three-dimensional (3D) technology and advanced techniques to assess similarities between volumetric structures in order to evaluate the site where the deformity originates. It might be a good method for planning rotational femoral osteotomy in patients with unilateral torsional femur abnormalities (Fig. 3) (See Videos 1 and 2). In short, there is no universally accepted method that allows us to determine the origin of the deformity. Therefore, it is difficult to decide at what level to perform the rotational osteotomy. In summary, the fact that there is no consensus as to how to measure torsion leaves the orthopedic surgeon in doubt about the confirmation of the diagnosis and, more importantly, in doubt about the surgical planning. The easiest thing to do in this situation is not to recommend surgical treatment. If we do not correct the torsion enough, the pain will persist and the pain will persist if we correct more than necessary. It has been shown that a difference of 10° during rotational osteotomy causes a considerable increase in PFJ pressure (Fig. 4) [23]. In the same way, Karaman and colleagues [24] showed that both external and internal rotational malalignment greater than or equal to 10° after closed intramedullary nailing of femoral shaft fractures provoked AKP while climbing stairs. Finally, Yildirim and colleagues [25] observed that an external rotation deformity of the femur greater than 10° could cause a deterioration in the patellofemoral scores and provoke AKP. Considering the possible iatrogenesis that we can
Femoral and Tibial Rotational Abnormalities … Fig. 3 3D technology and advanced techniques to assess similarities between volumetric structures in order to evaluate the site where the deformity originates. In this case, the right femur (yellow femur) has an excessive femoral anteversion (39°). However, the left femur (blue femur) has a normal femoral anteversion. In this patient, there is severe right hip pain and disabling right AKP. However, the lower left limb is completely asymptomatic. The left femur is reverted as it was a mirror vision. Then we place the blue femur over the yellow femur to see 45 the degree of similarity between them. That is, we overlap both femurs. The differences between both femurs are represented in a color code. The intensity of the blue and red colors represents the magnitude of the positive and negative differences between both femurs. The green color represents the absence of differences. In this case, there is a high similarity in all the femur except in the proximal part. Thus, we can conclude that the torsional deformity in this particular case originates in the proximal part of the femur Fig. 4 Finite elements analysis in the preop and after intertrochanteric external rotational femoral osteotomy of 5° and 15° (From reference 23). (Courtesy of M.A. Perez, PhD)
46 V. Sanchis-Alfonso and R. A. Teitge cause in a young patient if we make a hypercorrection of the torsion along with the scarce literature that supports this technique, it is understandable why it is not a common technique among orthopedic surgeons. 3 Not All Torsional Abnormalities are Symptomatic Another reason for the scarce interest knee surgeons have shown in rotational osteotomies would be the fact that there are patients with clear torsional anomalies that are completely asymptomatic. There are patients with bilateral torsional abnormalities who are completely asymptomatic (Fig. 5). The only explanation is that their level of activity is low enough not to apply sufficient stress to bone and or peripatellar soft tissues. In other cases, the maltorsion is symmetrical but only one side is symptomatic and the other one is completely asymptomatic. This fact increases uncertainty and discourages the surgeons from recommending a rotational osteotomy. We must take note that an abnormal anatomy is only a risk factor for developing AKP [26]. However, the length of time and magnitude of stress on bone and/or soft tissues that are necessary to initialize the physio-pathological mechanisms that lead to pain and makes for a patient are not known. In AKP patients with torsional abnormalities, knee pain and disability are highly variable. Furthermore, the incidence of psychological affectation is high in AKP patients, and the AKP patient with a torsional abnormality is not an exception. The prevalence of anxiety and depression in AKP patients is higher than those found in the general population [27, 28]. The fact that there are patients with a lot of pain and others with less as well as patients with a lot of pain and little disability with the same magnitude of pathological torsion, makes the importance of the torsional anomaly doubtful with regard to the symptoms. It is understandable that many orthopedic surgeons may think that the main problem is psychological. According to Robert A. Teitge, the main player in patellofemoral disease is the force which traumatizes the PFJ tissues. That force may act on the cartilage and bone, being responsible for cartilage breakdown and pain. It may also place excess tension in the patellar ligaments, being responsible for instability and pain. Of all the structural factors causing overload of the PFJ, the most powerful is the skeletal Fig. 5 Asymptomatic bilateral torsional abnormality (Courtesy of R. Teitge, MD)
Femoral and Tibial Rotational Abnormalities … malalignment, especially the torsional [3]. When the skeleton is not normal, the quadriceps force acting on the PFJ is not normal either. A change in the quadriceps lateral vector may result from an increase in femoral anteversion or an increase in limb valgus. Additionally, it may just as well be due to an increase in the external rotation of the tibia on the femur or an actual lateral placement of the tibial tuberosity (TT) on the proximal tibia that will provoke an increment of the TTTG distance. Of all the factors influencing the lateral vector, the most important is femoral anteversion. For example, the lateral vector increases more than 112% if a person has an internal torsion of the femur of 30° above the normal value. Maltorsion may cause a maldistribution of force on the PFJ which probably acts on both the subchondral bone and all surrounding ligaments. Bone overload is detectable using SPECT-CT. In some patients with torsional abnormalities, the SPECT-CT study reveals an uptake increment in the lateral aspect of the PFJ that allows us to justify the pain in these patients. Therefore, SPECT-CT helps to make a correct surgical indication. But in other cases, the SPECT-CT is negative in spite of the presence of a symptomatic torsional abnormality. This raises uncertainty when it comes to blaming torsional abnormality for the pain. This fact discourages the surgeons from putting forward a rotational osteotomy. 4 Lack of Agreement Regarding Surgical Technique. Fear of Internal Fixation Failure and Other Complications Another reason for the scarce interest knee surgeons have shown in rotational osteotomies is the lack of agreement when it comes to the choice of surgical technique. This means that if five different surgeons were asked about the best way to proceed, it is highly probable each of them would come up with a totally different solution (osteotomy level, open vs percutaneous osteotomy, type of osteotomy fixation, combined procedures: release of the peroneal nerve vs. non- 47 release, fibular osteotomy vs non-osteotomy). This would leave an inexperienced surgeon rather confused. There are a few unanswered questions in osteotomy surgery. One is about knowing how much to correct. From a practical point of view, we always prefer undercorrecting to overcorrecting when performing rotational osteotomy. Another debatable issue is the level of osteotomy. For example, our proposal in rotational tibial osteotomy is an osteotomy distal to the TT. However, other orthopedic surgeons suggest a supra-tuberosity osteotomy. Then again, there are others who are inclined toward a mid-shaft or distal (supramalleolar) osteotomy. Recently, Winkler and colleagues [29] have shown that increased external tibial torsion is an infratuberositary deformity and is not correlated with a lateralized position of the tibial tuberosity. Regarding the surgical technique, take note that it is difficult to achieve a highly precise osteotomy and keep it perfectly in place during healing. With a fracture or an osteotomy, the stress of moving the limb does not reach the bone ends but it does concentrate at the fracture/osteotomy site as strain (displacement) [30]. Relative to a fracture, the more comminuted it is, the less strain is concentrated at the fracture line. This is because it is divided between the number of fracture segments and the length of the fracture. On the contrary, a straight transverse osteotomy causes the greatest strain concentration. Thus, the internal fixation must be more rigid to share the stress and reduce strain to an acceptable level. Greater stability results from the increased compression of fragments. If there is no motion at the osteotomy site and the gap between fragments is less than 0.5 mm, then bone cutting cones pass across the gap and new osteons are produced without the need for a callus. If the gap is 0.5 mm and there is motion, the motion of the bone ends up crushes the cutting cones and primary bone healing will not occur. It is well known that if you see a callus developing after internal fixation, you know the fixation is unstable. IM nails do not normally provide sufficient rigid fixation. Therefore, they are classified as “internal splints”. Inadequate
48 stabilization by means of internal fixation results in failure when the strain is too great: plates break, screws bend or pull out or delayed healing. Without a doubt, the fear of internal fixation failure might be another reason for the scarce interest knee surgeons have shown in rotational osteotomies. A more widespread surgical technique for treating AKP patients is the TT osteotomy, which has undoubtedly overshadowed the rotational osteotomy. We do not intend to deny the validity of this technique, but rather to broaden our horizon in order to treat AKP patients. At this point, it would be interesting to make some observations on the surgery of the TT in the patient with torsional abnormality. Mani and colleagues [31] have demonstrated that TT medialization increases tibial external rotation. Therefore, greater AKP could triggered if we perform a medialization of the TT in a patient with excessive external tibial torsion. Moreover, Tensho and colleagues [32] have shown that TTTG distance is affected more by knee rotation than by tubercle malposition. For that reason, the measurement of the TT-TG distance in patients with torsional abnormalities is not reliable. Franciozi and colleagues [33] have seen diminished results from TT osteotomies in patients with increased femoral anteversion. In the same way, Zhang and colleagues [34] evaluated 144 consecutive patients with recurrent patellar instability. Patients were assigned into three groups: group A (femoral anteversion <20°), group B (femoral anteversion 20°–30°) and group C (femoral anteversion >30°). They have demonstrated that patients with an increased femoral anteversion angle (>30°) had inferior postoperative clinical outcomes and a higher rate of residual J-sign after medial patellofemoral ligament reconstruction combined with TT osteotomy. That is, the TT osteotomy does not prevent the negative effect of femoral anteversion on PFJ. Therefore, the best available evidence supports not performing TT osteotomy in patients with torsional abnormalities. On the other hand, the frequency and types of complications seen in rotational osteotomy surgery are similar to those of the TT osteotomy. We have V. Sanchis-Alfonso and R. A. Teitge followed the same definition as Payne and colleagues [35] to compare the total percentage of major complications in rotational osteotomy surgery and TT osteotomy surgery. Major complications were defined as non-union, fracture, infections and wound complications requiring return to the operating room, and DVT or PE. Payne and colleagues [35], in a systematic review, found an overall risk of major complications after TT osteotomy of 3.0%. In our systematic review, the overall risk of major complications after rotational osteotomy was of 3.3% [6]. 5 “Orthopedics is All About Anatomy … Plus A Little Bit of Common Sense” We believe that a logical approach to surgical treatment should be based on restoring native anatomy and repairing what is damaged. This was clearly reflected by Jack Hughston in his well-known sentence: “Orthopedics is all about anatomy … plus a little bit of common sense”. Therefore, it would be logical to correct them surgically if we observe an obvious pathological torsional alteration in the femur or tibia. You should strive to restore normal anatomy, because that will create a better biomechanical environment for the tissue. If you repair a failed tissue that can be bone, ligament or cartilage and ignore the mechanics that caused the tissue failure, you will usually have a failed result. In cases of combined femoral anteversion and excessive external tibial torsion, there is a question. What is more important in the genesis of AKP, femoral anteversion or external tibial torsion? From an anatomical standpoint, the best option to treat a patient with combined excessive femoral internal torsion and excessive external tibial torsion would be a combination of a rotational femoral and a tibial osteotomy. Another option would be to operate on the bone with the greatest variance from normal, the femoral anteversion in the case of Fig. 6. In the case of Fig. 6, we performed a 25° proximal femoral external rotational osteotomy with a good result
Femoral and Tibial Rotational Abnormalities … Fig. 6 Intra-operative x-Rays. Preoperative (left). The patella is well centered on the distal femur after an external rotational femoral osteotomy of 25°. Mechanical axis (MA) but there was a recurrence of the symptoms at 9 months. For that reason, a rotational tibial osteotomy was performed that gave a good clinical result. This case highlights the importance of restoring completely the normal anatomy. In short, we must understand biomechanics because orthopedic surgery is a mechanical engineering discipline. A complete physical examination attempts to uncover all of the anatomic abnormalities, of which there are often many. When you uncover any abnormal anatomy you must then answer the question: how does this change the normal biomechanics? This is the key question. 6 The Keys to Increasing Adherence to Rotational Osteotomy by a Knee Surgeon. Future Studies The first step in attracting orthopedic surgeons to the field of rotational osteotomy is to give them the means to arrive at diagnostic certainty. In this aspect, the SPECT-CT to objectify the origin of pain can help. The SPECT-CT reveals the 49 metabolic and geographic pattern of bone homeostasis (Fig. 7). It can evidence overloaded osseous areas. However, the most important contribution to rotational osteotomy being definitively incorporated into daily clinical practice by the knee surgeon is the implementation of a methodology that simplifies preoperative surgical planning and allows for the pre-visualization of the results of surgical interventions on our computers. For this, the working group of the first author of this chapter (V.S-A) uses 3D technology (see Video Case # 1). The imaging dataset used for surgical planning is based on a CT of the patient. Our 3D method, is open Access, that is, it is accessible to any orthopedic surgeon at no economic cost. Furthermore, it not only allows for the quantification of the femoral torsion (Fig. 8) but also carrying out virtual surgical planning. Interestingly, with 3D technology, we have shown that the magnitude of the intertrochanteric rotational femoral osteotomy does not present a 1:1 relationship with the effect on the correction of the deformity (see Video Case # 1). Moreover, rotational osteotomy surgery using 3D printed surgical guides might improve surgical accuracy. In the long run, surgeons will perform rotational osteotomies if they obtain good results. To that end, the selection of the appropriate patient is essential. To obtain a satisfactory result, it is important to analyze patient expectations with regard to the results of the surgery. Moreover, whether it is really feasible to achieve a “Minimal Clinically Important Difference” (MCID) after surgery should be considered. Despite a statistically significant improvement in functional scores after rotational osteotomy in a torsional abnormality, not all patients perceive a MCID in every functional domain of the score. Defining a MCID value for Patient-Reported Outcome Measures (PROMs) is crucial to determining the effectiveness of a surgical procedure and therefore the indication for surgery. It would be interesting to determine the best scores to evaluate patients with torsional abnormalities and ascertain the MCID for this pathology.
50 V. Sanchis-Alfonso and R. A. Teitge Fig. 7 SPECT/CT in an AKP patient with right external tibial torsion. The scintigraphic uptake is markedly high in the right patella. Disabling right AKP. The left knee was asymptomatic in spite of the fact that external tibial torsion was symmetric in both knees Fig. 8 Femoral anteversion measurement. Left: Transparency has been added to the proximal femur to identify landmarks for the center of the femoral head and the base of the femoral neck. The junction of the center of the ball of the femoral head and the center of the circumference at the base of the neck define the plane of inclination of the neck (red). The plane tangent to the posterior condyles and posterior region of the greater trochanter is the femoral bearing plane (purple). Right: Femoral anteversion measurement based on Murphy’s method, between the neck inclination plane (red) and the femoral support plane (purple) 7 Take Home Messages – Skeletal torsional abnormalities, especially abnormal femoral torsion, are the most ignored factors not only in the diagnosis but even more so in the treatment of AKP patients. – The “collective consciousness”, that is the beliefs shared by the majority of orthopedic surgeons, conveys the idea that rotational osteotomy is a complex procedure with a high
Femoral and Tibial Rotational Abnormalities … risk of severe complications. It seems overly aggressive to cut the femur or the tibia of a young “healthy” person that only “complains of pain”. Nothing could be further from the truth. Rotational osteotomy is a very welltolerated surgery with a low complication rate and, in many cases, the results are immediate relative to eliminating pain. – Changing the limb alignment by means of osteotomy is the single most powerful and underutilized treatment available. The quadriceps is responsible for the force acting on the patella. Osteotomy changes the quadriceps direction and therefore the force acting on the patella. If one operates on the traumatized tissue (bone, ligament or cartilage) without changing the force which produced the trauma, one should expect a failed result. References 1. James SL. Chondromalacia of the Patella in the Adolescent. In: Kennedy JC. editor. The Injured Adolescent Knee. Baltimore: The Williams & Wilkins Company, 1979. 2. Teitge RA. Does lower limb torsion matter? Tech Knee Surg. 2012;11:137–46. 3. Teitge RA. The power of transverse plane limb malalignment in the genesis of anterior knee pain— clinical relevance. Ann Joint. 2018;3:70. 4. Meister K, James SL. Proximal tibial derotation osteotomy for anterior knee pain in the miserably malaligned extremity. Am J Orthop (Belle Mead NJ). 1995;24:149–55. 5. Cooke TD, Price N, Fisher B. The inwardly pointing knee. An unrecognized problem of external rotational malalignment. Clin Orthop 1990;56–60. 6. Sanchis-Alfonso V, Domenech-Fernández J, FerrasTarrago J, et al. The incidence of complications after derotational femoral and/or tibial osteotomies in patellofemoral disorders in adolescents and active adult patients. A Systematic Review with MetaAnalysis. (In press). 7. Scorcelletti M, Reeves ND, Rittweger J, et al. Femoral anteversion: significance and measurement. J Anat. 2020;237(5):811–26. https://doi.org/10.1111/ joa.13249. 8. Stephen JM, Teitge RA, Williams A, et al. A validated, automated, 3-Dimensional method to reliably measure tibial torsion. Am J Sports Med. 2021;49 (3):747–56. 51 9. Snow M. Tibial torsion and patellofemoral pain and instability in the adult population: current concept review. Curr Rev Musculoskelet Med. 2021;14 (1):67–75. 10. Jeanmart L, Baert AL, Wackenheim A. Computer tomography of neck, chest, spine and limbs. Atlas of pathologic computer tomography, vol 3. Springer, Berlin Heidelberg New York, 1983; pp 171–177. 11. Murphy SB, Simon SR, Kijewski PK, et al. Femoral anteversion. J Bone Joint Surg Am. 1987;69 (8):1169–76. 12. Kaiser P, Attal R, Kammerer M, et al. Significant differences in femoral torsion values depending on the CT measurement technique. Arch Orthop Trauma Surg. 2016;136(9):1259–64. 13. Schmaranzer F, Lerch TD, Siebenrock KA. Differences in femoral torsion among various measurement methods increase in hips with excessive femoral torsion. Clin Orthop Relat Res. 2019;477(5): 1073–83. 14. Ferràs-Tarragó J. Planificación quirúrgica tridimensional de las osteotomías femorales en el dolor anterior de rodilla. Doctoral Thesis. University of Valencia, 2021. 15. Archibald HD, Petro KF, Liu RW. An anatomic study on whether femoral version originates in the neck or the shaft. J Pediatr Orthop. 2019;39:e50–3. 16. Kim HY, Lee SK, Lee NK, et al. An anatomical measurement of medial femoral torsion. J Pediatr Orthop B. 2012;21(6):552–7. 17. Seitlinger G, Moroder P, Scheurecker G, et al. The contribution of different femur segments to overall femoral torsion. Am J Sports Med. 2016;44(7):1796– 800. 18. Waisbrod G, Schiebel F, Beck M. Abnormal femoral antetorsion—a subtrochanteric deformity. J Hip Preserv Surg. 2017;4(2):153–8. 19. Herzberg W, Meitz R, Halata Z. Antetorsion of the femur neck. A variable of the trochanter minor? Unfallchirurg 1991;94:168–171. 20. Sanchis-Alfonso V, Domenech-Fernández J, BeserRobles M, et al. Pathological femoral anteversion in the anterior knee pain patient depends on both the neck and the shaft (Submitted). 21. Ferràs-Tarragó J, Sanchis-Alfonso V, RamírezFuentes C, et al. A 3D-CT analysis of femoral symmetry—surgical implications. J Clin Med. 2020;9:3546. 22. Ferràs-Tarragó J, Sanchis-Alfonso V, RamírezFuentes C, et al. Locating the origin of femoral maltorsion using 3D volumetric technology—the hockey stick theory. J Clin Med. 2020;9:3835. 23. Gracia-Costa C. Análisis por elementos finitos de las presiones femoropatelares previas y posteriores a osteotomía desrrotadora. Trabajo de Fin de Grado. Escuela de Ingeniería y Arquitectura: University of Zaragoza; 2019. 24. Karaman O, Ayhan E, Kesmezacar H, et al. Rotational malalignment after closed intramedullary
52 25. 26. 27. 28. 29. V. Sanchis-Alfonso and R. A. Teitge nailing of femoral shaft fractures and its influence on daily life. Eur J Orthop Surg Traumatol. 2013;24 (7):1243–7. Yildirim AO, Aksahin E, Sakman B. The effect of rotational deformity on patellofemoral parameters following the treatment of femoral shaft fracture. Arch Orthop Trauma Surg. 2013;133(5):641–8. Erkocak OF, Altan E, Altintas M, et al. Lower extremity rotational deformities and patellofemoral alignment parameters in patients with anterior knee pain. Knee Surg Sports Traumatol Arthrosc. 2016;24 (9):3011–20. Wride J, Bannigan K. Investigating the prevalence of anxiety and depression in people living with patellofemoral pain in the UK: the Dep-Pf Study. Scand J Pain. 2019;19(2):375–82. Domenech J, Sanchis-Alfonso V, Lopez L, et al. Influence of kinesiophobia and catastrophizing on pain and disability in anterior knee pain patients. Knee Surg Sports Traumatol Arthrosc. 2013;21 (7):1562–8. Winkler PhW, Lutz PM, Rupp MC, et al. Increased external tibial torsion is an infratuberositary deformity and is not correlated with a lateralized position of the tibial tuberosity. Knee Surg, Sports Traumatol, Arthroscopy. 2021;29:1678–85. 30. Muller ME, Allgower M, Schneider R, et al. Manual of internal fixation. Third Edition. Springer. 1991. 31. Mani S, Kirkpatrick MS, Saranathan A, et al. Tibial tuberosity osteotomy for patellofemoral realignment alters tibiofemoral kinematics. Am J Sports Med. 2011;39(5):1024–31. 32. Tensho K, Akaoka Y, Shimodaira H, et al. What components comprise the measurement of the tibial tuberosity-trochlear groove distance in a patellar dislocation population? J Bone Joint Surg Am. 2015;97(17):1441–8. 33. Franciozi CE, Ambra LF, Albertoni LJ, et al. Increased femoral anteversion influence over surgically treated recurrent patellar instability patients. Arthroscopy. 2017;33(3):633–40. 34. Zhang ZZ, Zhang H, Song GY, et al. Increased femoral anteversion is associated with inferior clinical outcomes after MPFL reconstruction and combined tibial tubercle osteotomy for the treatment of recurrent patellar instability. Knee Surg Sports Traumatol Arthrosc. 2020;28(7):2261–9. 35. Payne J, Rimmke N, Schmitt LC, et al. The incidence of complications of tibial tubercle osteotomy: a systematic review. Arthroscopy. 2015;31(9):1819–25.
Why is Torsion Important in the Genesis of Anterior Knee Pain? Robert A. Teitge Femoral Anteversion and Tibial Torsion are listed in many of the patellofemoral publications over the past 60–80 years as risk factors or associated factors for anterior knee pain, but discussion stops after making the list and is almost never to be reconsidered. Why? I believe this is because we don’t know why torsion should matter, we don’t know why it there, we don’t know how to measure it, we don’t know how to fix it and even those intrepid surgeons who are willing to operate to alter it, have really no guide as where they are starting and where they are going. It is a daunting challenge to know nothing. I wish here to present how interest in these questions grew and propose a rationale for why it matters to anterior knee pain. A challenge to me came from Robert Kerlan MD in 1976 who said to me “Bob, no one has studied foot problems in professional athletes, why don’t you see what you can learn.” The podiatrists were known to be providing “orthotics” but that was almost the limit of studies. I stumbled across The Running Foot Doctor [1] by Steven Subotnick D.P.M. and in it I discovered a drawing of a limb with Chondromalacia of the Knee which was said to result from a pronated foot which was increasing the Q-Angle from 15° R. A. Teitge (&) Department of Orthopaedic Surgery, Wayne State University, Detroit, MI, USA e-mail: rteitge@med.wayne.edu to 30° and creating an abnormal quadriceps pull. I left Dr. Kerlan and moved to Seattle where Sigvard (Ted) Hansen, Jr. M.D. said “Bob, You have to get to know Stan Newell, D.P.M.” Stan Newell was the artist who had produced all of the drawings for The Running Foot Doctor. Stan was making all the orthotics for the professional athletes in Seattle skirting around the orthopaedic community. Stan told me “Bob, I can cure more than 50% of all athletic knee pain with orthotics, even though I have no idea why.” An interesting thought. The recreational running craze was just beginning, Nike was just starting and Stan Newell and Stan James, M.D. in Eugene, Oregon became the consultants to Nike Shoes as the orthopaedic world became interested in running and anterior knee pain. Stan James was working with many world-class runners in Eugene and being asked to lecture on “Runner’s Knee” at various professional society meetings. In 1979 he contributed a chapter “Chondromalacia of the Patella in the Adolescent” to Jack Kennedy’s book The Injured Adolescent Knee [2]. This chapter almost summarizes what we know today and contains the brilliant description of Miserable Malalignment. So, beginning in 1980 and using what I learned from the two Stans, I have examined every knee patient with both the standard knee examination and the runner’s exam and concluded torsion is important. The correlation of physical examination with clinical assessment of femoral or tibial torsion is modest to poor. Consequently, awareness of © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_4 53
54 R. A. Teitge torsional excess is often overlooked. Special imaging is mandatory. To understand lower extremity kinematics requires knowing where the axis of motion is for all the joints in the chain including hip, knee, ankle and subtalar joint. Variations in joint geometry will change the axis of a particular joint, which will change the kinematics of that limb. Correlating anatomic landmarks with imaging is not standardized and despite modern imaging there is still controversy in locating with precision the axes of these 4 joints. It may not be possible to define an axis of joint motion by studying a single bone. Two points near the ends of the bones are selected and lines between the two points are used to define the axis. Different investigators have selected different points, thus different lines are proposed to reflect the same axes. It is common that axes from different investigators may vary by 100% for the hip, knee, ankle and subtalar joint. Kaiser et al. [3] found the difference between the mean of 2 commonly used measurement techniques was 97% and in one single specimen the difference was 140%. These variations in measurement technique makes comparing studies difficult Fig. 1 A The maximum quadriceps efficiency is with knee joint facing forward in the direction the body is moving (Joint axes are red lines). 1 B With normal femoral anteversion the greater trochanter is posterior when the knee faces straight forward A and even these selected lines may have nothing to do with joint motion. The action of a muscle in moving a joint is most efficient when it’s line of action is perpendicular to the joint axis. The quadriceps controls knee flexion. It is most efficient when working in the sagittal plane with the knee axis ⊥ to the sagittal plane and with the knee joint moving straight forward in the direction the body mass is moving. Levens et al. [4] as long ago as 1948, reported the knee joint axis normally moves directly forward during gait in line of the body motion with only a minimal amount of rotation in the transverse plane (Fig. 1). Anterior knee pain is usually the result of an abnormal force. A knee joint in which no force is acting is seldom painful. The abnormal force may be an excessive force or a mal-directed force. A reduction in force generally results in reduction of pain, but usually with some associated loss of function. Most of the quadriceps muscle force is exerted as a vector in the sagittal plane pushing the patella against the trochlea to maintain of control knee flexion–extension. (Fig. 2). B
Why is Torsion Important in the Genesis … Fig. 2 A The resultant of the quadriceps force vector and the patellar tendon force vector creates the patellofemoral joint reaction force. It is this force which keeps the knee from collapsing and controls its position of flexion–extension. B This force is maximum when it is perpendicular to the knee joint axis and is in the sagittal plane with the knee axis in the coronal plane 55 B A But the knee joint is unusual because it must have a tibio-femoral valgus. The tibio-femoral valgus is needed to move the knee joint closer to the midline under the center of mass. Placing the knee joint closer to the center of body mass reduces bending forces in the femur and tibia and allows us to balance on one foot, a requirement for bipedal gait. The tibiofemoral angle, however, means the quadriceps does not act perpendicular to the knee joint axis, but is deviated in the lateral direction, thus in addition to the major posterior vector component, there is a lateral component (Fig. 3). It is assumed that the lateral vector is counterbalanced by the lateral trochlear inclination. As the knee internally rotates during flexion the tibial tuberosity moves medially so the direction of the quadriceps force is more medial and the lateral vector of this quadriceps force decreases. The femur and tibia are both normally twisted. The biomechanical purpose of the twist is unclear. It is an assumption that “normal” twist is optimal for “normal” function such as walking. Femoral twist is measured as the angle in the transverse plane between the axis of the hip and knee. If there is an abnormal inward twist in femur so the knee joint points medially, the knee joint can be placed facing forward only by external rotation of the hip joint. The acetabulum may limit the degree of external rotation needed to place the knee axis forward, or it may place the external rotators of the hip in such a shortened position they cannot provide stability. It is common in such cases, that fatigue of the hip rotators allows the femur to rotate inward so the knee joint axis faces medially. If the patella is pointing medially the quadriceps force will be more in the lateral direction and the lateral
56 Fig. 3 The valgus tibiofemoral angle acts to move the knee joint closer to the center of mass of the body. This tibiofemoral angle deviates the quadriceps insertion laterally which produces a lateral quadriceps vector in addition to the major posterior vector quadriceps vector increases at the expense of the posterior vector which decreases (Fig. 4). To maintain knee flexion stability, the total force must increase to prevent knee collapse. One cause of anterior knee pain is thought to be this excess lateral quadriceps vector. As the knee joint rotates out of the sagittal plane the posterior vector becomes less effective so the total quadriceps force must increase to maintain stability. As the posterior vector decreases the lateral vector increases so articular shear is increased which shifts the center of force in the PFJ as well as altering tension in the retinacular ligaments. Altering the direction of the quadriceps vector may also alter the tibiofemoral rotation orientation. This is probably best measured today with weight-bearing CT scanning for transverse plane alignment. R. A. Teitge If there is an abnormal outward twist of the femur, femoral retroversion, the opposite effect occurs, the quadriceps medial vector will increase obviously shifting the center of force medially in the PFJ (Fig. 5). If there is an increase in external tibial torsion and the knee joint is facing forward the foot will face more laterally. The body weight vector will push on the side of the outward pointing foot resulting in excess pronation, stretch of the medial arch, bunions, posterior tibial tendon strain, shortening of the Achilles tendon and lateral ankle impingement. Landing from a jump requires the ankle joint axis to be perpendicular to the direction of landing so dorsiflexion can absorb excess energy. Since gait on an outward facing foot can be uncomfortable or fatiguing the limb is often internally rotated placing the foot its optimal functional position but causing the knee joint axis to face medially which again increases the lateral quadriceps vector and requiring more total quadriceps force required to stabilizing knee flexion. An increase in internal tibial torsion has the opposite effect with the primary complaint being of increased tripping, lateral ankle sprains and increased loading of the medial plafond. The normal angular relationship of the hip joint, knee joint, ankle joint and subtalar joint axes when viewed in the transverse plane allows for normal kinematics and with normal distribution of forces transferring the body weight to the ground. Precise location of these axes is necessary for limb kinematic and gait studies. Torsional abnormalities in the femur or tibia obviously can only be corrected by transverse plane osteotomy. A simple coronal plane vector diagram of the Q angle including its lateral component vector in a normal aligned limb suggests a 5 mm medial transfer of the tibial tuberosity may reduce the lateral quadriceps vector by 27%, but a reduction
Why is Torsion Important in the Genesis … A 57 B Fig. 4 The Quadriceps direction is changed with a change in limb torsion. The quadriceps force is generally in line with the femur. A with normal anteversion the knee joint faces forward and the majority of the quadriceps is posterior which produces the PF Joint reaction force. B If the knee points inward, the quadriceps pulls more laterally so the lateral vector is increased while the posterior vector is decreased. The reduction in posterior force means the total quadriceps force must increase to control knee stability. The black arrows represent the quadriceps force and its posterior and lateral vectors. The quadriceps force is normally in line with the femur, the posterior force vector is indicated on the left and the lateral force vector is indicated on the right. A medial pointing knee may occur if there is increased femoral anteversion, if there is more internal rotation of the hip joint or if there is more external tibial torsion and the foot is then placed facing forward of 30° excess femoral anteversion may reduce the lateral quadriceps vector by 112%. Precise biomechanical studies investigating the effect of changing skeletal geometry on force transmission are needed to estimate when pathologic values are reached. These studies must include the changing of force provided by altered skeletal geometry, contracting muscles, body weight, limb length, hip, and foot and ankle positions. Until then we can only assume that the population normal is a reasonable goal for torsion correction.
58 R. A. Teitge References 1. The Running Foot Doctor by Steven I. Subotnick, D. P.M, World Publications, Mt View, California © 1977. 2. James SL. Chondromalacia of the Patella in the Adolescent, p205–251 in The Injured Adolescent Knee Ed. J.C. Kennedy, Williams & Wilkins Co. Baltimore, © 1979. 3. Kaiser P, et al. Significant differences in femoral torsion values depending on the CT measurement technique. Arch Orthop Trauma Surg. 2016;136 (9):1259–64. 4. Levens AS, et al. Transverse rotation of the segments of the lower extremity in locomotion. J Bone Joint Surg. 1948;30(4):859–72. Fig. 5 Computer simulation of the skeleton in a patient landing from a jump. Both knees are equally flexed. She has 50° of femoral anteversion on the right and has had an external rotation proximal femoral osteotomy of 35° on the left. The right knee is pointed inward so the quadriceps is not acting in the sagittal plane. She does not have a valgus alignment, the apparent valgus is due to the combination of knee flexion and an inward pointing knee. This produces a very large lateral component to the quadriceps force. On the left, the knee is flexing in the sagittal plane, the patella is facing forward and because the tibia internally rotates in flexioin there is no lateral vector to the left quadriceps
Clinical and Radiological Assessment of the Anterior Knee Pain Patient Vicente Sanchis-Alfonso, Cristina Ramírez-Fuentes, Laura López-Company, and Pablo Sopena-Novales 1 Introduction Anterior knee pain (AKP), which is pain behind or around the patella, is one of the most common reasons for consultation with an orthopedic surgeon specializing in the knee among teenagers and young adults. Although it typically occurs in physically active people less than 40 years of age, it does indeed affect people of all activity levels and ages [1]. A careful clinical history and physical examination along with imaging studies are crucial to obtaining an accurate diagnosis. They will be the cornerstone for a correct treatment. The objective of this chapter is to come to an understanding of how AKP patients should be evaluated during consultation to obtain a whole picture for each patient. Doing so will aid in V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com C. Ramírez-Fuentes Medical Imaging Department, Hospital Universitario y Politecnico La Fe, Valencia, Spain L. López-Company Department of Rehabilitation and Physical Therapy, Hospital Arnau de Vilanova, Valencia, Spain P. Sopena-Novales Department of Nuclear Medicine, Hospital Vithas 9 Octubre, Valencia, Spain identifying potentially modifiable factors to personalize treatment and achieve better outcomes. We want to emphasize that the physical examination must not be limited to the knee. The entire limb must be evaluated. Moreover, we must always assess the psychological status and central sensitization of all patients with AKP, including those with severe structural anomalies that may justify the pain. 2 Clinical History—“Listen to the Patient” Talking with the patient is fundamental but is too often neglected. We must listen very carefully to our patients as they will usually tell us, in their own words, what is wrong. It is our mistake if we fail to truly understand them and assume we know better. The first diagnostic step is a thorough clinical history. This is where we uncover the main clue for an exact diagnosis. For instance, the absence of a traumatic episode or presence of bilateral symptoms should lead towards a patellofemoral pathology and away from a meniscal pathology in the young patient. It is common to have symptoms in both knees that may change from one knee to the other over time. This is a tip-off for a patellofemoral problem. On the contrary, the presence of effusion, more than patellofemoral pain, suggests an intra-articular pathology (e.g., meniscal rupture, pathologic plicae, © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_5 59
60 osteochondral or chondral lesions or synovial pathology). Nevertheless, a small effusion may be present in AKP patients. However, polyarthralgia is not a part of the pathology we are now dealing with. Generally, the onset of symptoms is insidious. It reflects an overuse condition or an underlying malalignment. Overuse can be the result of a new activity or of the increase in the time, frequency or intensity of a previous work or sports activity. In these cases, getting the history should be oriented to determining which supraphysiologic loading activity or activities are of importance in the origin of AKP. The identification and rigorous control of the activities associated with the initiation and persistence of symptoms is crucial for treatment success. For example, patients with left AKP should avoid driving a car with a clutch for prolonged periods of time because it aggravates the symptoms. In these cases, patient education is crucial to preventing recurrence. In other cases, the symptoms can be secondary to a direct knee trauma (e.g., automobile accident in which the anterior knee strikes the dashboard [“dashboard knee”]) or an indirect knee trauma. One must not forget the possibility of AKP secondary to a posterior cruciate ligament (PCL) deficiency when there has been a knee trauma. This is a well-known cause for AKP given that PCL tears increase patellofemoral joint (PFJ) reaction force through posterior displacement of the tibial tuberosity [2]. It is also important to examine the integrity of the anterior cruciate ligament (ACL) as AKP is present in 20–27% of patients with a chronic ACL insufficiency [2]. The main symptom AKP patients experience is pain. That pain can be retropatellar or peripatellar. The pain is often described as dull with occasional sudden episodes of sharp pain. When asked to locate the pain, it is often difficult for the patient to pinpoint the area of pain while placing his or her hand over the anterior aspect of the knee. However, the pain can also be medial, lateral or popliteal. Generally, patients have multiple painful sites with different degrees of pain intensity. Pain related to the extensor mechanism is typically aggravated by activities V. Sanchis-Alfonso et al. like climbing and descending stairs, squatting, using the clutch when driving a vehicle with manual transmission (left AKP), wearing highheeled shoes. It is also worsened after prolonged sitting with knee flexion, for instance during a long trip by car or prolonged sitting in a cinema (“movie sign” or “theater sign”). It improves by extending the knee. A constant and severe pain way out of proportion to physical findings that has a sudden onset after a knee injury or surgery should make us think of psychological issues or Reflex sympathetic dystrophy (RSD) or Complex regional pain syndrome (CRPS). This is true even when the classic vasomotor findings are absent. It is classified as neuropathic pain. Finally, constant burning pain indicates a neuromatous origin. To quantify the pain, we use the Visual analogue scale (VAS). It is a sensitive outcome measure for AKP, with a difference of 2 cm being considered clinically relevant [3]. To screen for neuropathic pain, we advocate for the use of the Douleur Neuropathique 4 scale (DN4) [4]. The sensitivity and specificity of the DN4 stands at around 95% and 97% [4]. Other symptoms of AKP are a giving-way sensation and crepitus. Determining whether the patient’s pain is associated with a lateral patellar instability is very important because both the treatment and the prognosis are very different in patients with AKP secondary to patellar instability when compared to those without patellar instability. “Giving-way” episodes due to ACL deficiency are brought on by rotational activities. On the other hand, “giving-way” episodes related to patellofemoral problems are associated with activities that do not imply rotational strains. It is a consequence of a sudden reflex inhibition and/or atrophy of the quadriceps muscle. Patients sometimes report locking of the knee, which is usually only a catching sensation. However, they can actively unlock the knee. Therefore, this type of locking should not be confused with the one experienced by patients with meniscal lesions. Finally, another symptom is crepitus. It should not be mistaken for the snapping sensation more consistent with a pathological plica. Crepitus is common but is clinically irrelevant in most cases. However, crepitus creates negative emotions,
Clinical and Radiological Assessment … inaccurate etiological beliefs and finally leads to fear-avoidance behavior and lower functional performance [5]. Apart from pain, AKP patients present disability to a great or lesser degree. The World Health Organization defines disability as “a limitation of function that compromises an individual’s ability to perform an activity within the range considered normal”. Regardless of how intense the pain is, AKP patients show different degrees of disability in their everyday life. A way to objectify and quantifying disability is by means of self-administered scales like the International Knee Documentation Committee evaluation (IKDC) and the Kujala score. It is also important to know the patient’s activity level prior to the treatment and what he or she wants to achieve through treatment to be able to offer realistic goals. Patients with AKP have a high incidence of anxiety, depression, kinesiophobia (the fear that physical activity will cause more injury or a reinjury and subsequent pain) and catastrophizing (the belief that pain will worsen and cannot be relieved) [6]. Over half of people living with AKP experience anxiety and/or depressive symptoms. The levels of anxiety and depressive symptoms in AKP patients are much higher than those found in the general population (anxiety symptoms: 49.5% vs. 5.9–7.8%, respectively; depressive symptoms: 20.8 vs. 3.3–7.8%, respectively) [7, 8]. Therefore, recognizing and quantifying the presence of these psychological factors are important to getting a whole picture of the patient and to planning the best treatment. Self-administered screening tests for anxiety and depression (Hospital Anxiety and Depression Scale), catastrophizing (Pain Catastrophizing Scale), and kinesiophobia (Tampa Scale for Kinesiophobia) should be incorporated into the clinical history in all the cases [6]. Moreover, signs of central sensitization are present in AKP patients in a high percentage of cases [9]. Therefore, it would be very interesting to recognize and quantify it using a self-administered Central sensitization score. Finally, we must ask about previous knee surgeries. For example, one of the causes of 61 disabling AKP after surgery is iatrogenic medial patellar instability (IMPI) secondary to an “extensive” lateral retinacular release. Inappropriate physiotherapy could also be responsible for iatrogenic AKP. Therefore, it is essential that the patient describe exercises that are being or have been done with the physiotherapist or in the gym. 3 Physical Examination The second diagnostic step is a thorough and careful physical examination. It is essential. Its primary goal is to locate the painful zone and to reproduce the symptoms. The location of the pain can indicate which structure is injured. This is extremely helpful to making the diagnosis and to planning the treatment. The most important diagnostic tool is the “finger”. 3.1 Tests to Locate the Painful Zone and Reproduce the Pain The lateral retinaculum should be felt and assessed carefully. Tenderness anywhere over the lateral retinaculum, especially where the retinaculum inserts into the patella, is a very frequent finding (90%) in AKP patients [10]. We perform the patellar glide test to evaluate lateral retinacular tightness. This test is performed with the knee flexed at 30º and the quadriceps relaxed. The patella is divided into four longitudinal quadrants and is displaced medially (Fig. 1). A medial translation of one quadrant or less is suggestive of excessive lateral tightness [2]. With this test, pain is elicited over the lateral retinaculum. The patellar tilt test can also detect a tight lateral retinaculum. It should always be done. In a normal knee, the patella can be lifted from its lateral edge farther than the transepicondylar axis, with a fully extended knee. On the contrary, a patellar tilt of 0º or less indicates a tight lateral retinaculum. Lateral retinacular tightness is very common in AKP patients. Furthermore, it is the hallmark of the excessive lateral pressure syndrome described by Ficat [11]. In those cases with AKP after ACL reconstruction, we
62 Fig. 1 Patellar glide test. The patellofemoral joint is mentally divided into quadrants and patellar mobility is assessed in both directions passively “tilt” the inferior pole of the patella away from the anterior tibial cortex to rule out pretibial patellar tendon adhesions. The axial compression test of the patella (or patellar grind test) should be part of the systematic examination as it elicits AKP originating in the patellofemoral articular surfaces (patellar and/or trochlear subchondral bone). To perform the axial compression test, we compress the patella against the trochlea with the palm of the hand at various angles of knee flexion (Fig. 2). In addition, this test makes for determining the location of the lesion in the patellar articular cartilage. With knee flexion, the patellofemoral contact zone is displaced proximally in the V. Sanchis-Alfonso et al. patella and distally in the femur. Thus, proximal lesions will yield pain and crepitation at approximately 90º of knee flexion. On the contrary, distal lesions are tender in the early degrees of knee flexion. We also perform the sustained knee flexion test. When it is positive (the appearance of pain), it means that the patella is the origin of the pain. It is caused by an increase in intraosseous pressure [12]. For the sustained knee flexion test, the patient lies supine on an examination table with his or her knee extended and relaxed. The knee is then flexed fully and kept firmly in a sustained flexion for up to 45s. The test is positive if the patient complains of increasing pain after a pain-free interlude of 15 to 30s. Allen and colleagues [13] found a significant association between proximal patellar tendinosis and abnormal patellar tracking in AKP patients. Therefore, palpation of the inferior pole of the patella ought to be carried out in all cases to rule-out patellar tendinopathy. To perform this test, press downward on the proximal patella. In this way, the inferior pole of the patella tilts anteriorly. This maneuver permits palpation of the proximal patellar tendon attachment (Fig. 3). However, there is quite often mild tenderness at the attachment of the patellar tendon at the inferior pole of the patella in individuals who play sports. Thus, only moderate and severe pain should be considered pathological. Moreover, Hoffa’s fat pad should always be felt as it can be a source of pain as well (Hoffa’s test) (Fig. 4). Finally, existing scars should be palpated and Tinel’s sign performed to detect neuromas. Pain improvement after an infiltration of the painful area with local anesthesia or after unloading the area with functional taping provides evidence for the origin of pain. 3.2 Pressure Algometry Fig. 2 Axial compression patellar test The clinical examination is crucial to identifying the neuropathic AKP subgroup. This is important to know the prognosis of the patient that is to undergo treatment. A patient with CRPS presents with skin changes like erythema and edema with
Clinical and Radiological Assessment … 63 Fig. 3 Palpation on the distal pole of the patella and the proximal patellar tendon 3.3 Range of Motion and Muscle Length Testing Fig. 4 In patients with impingement of the Hoffa fat pad, pain is dramatically exacerbated by quadriceps contraction or passive knee extension while applying pressure of the fat pad with the fingers. This happens because this movement causes a small posterior tilt of the inferior pole of the patella, which impinges on an inflamed and sensitized infrapatellar fat pad an allodynic or a hyperalgesic pain response to palpation on the anterior aspect of the knee and restriction in the mobility of the patella. Hyperalgesia can be demonstrated with pressure algometry [14]. In these cases, we found reduced pain thresholds. However, pressure algometry should be used to quantify the pain at baseline and to monitor an improvement in terms of hyperalgesia with the treatment rather than as a diagnostic method as there is no specific value that serves as a threshold value for hyperalgesia. The range-of-motion of the knee as well as hip and ankle should be evaluated. Both legs should be examined. Exploring knee extension in both knees is mandatory because even small degrees of extension loss can cause AKP. To evaluate knee extension, the patient lies prone on the examining table with the lower extremity supported by the thighs. The difference in heel height is measured [15]. The conversion of heel height difference to degrees of extension loss is presented in the table of Fig. 5. Limited ankle dorsiflexion range of motion has been related to AKP. Therefore, it should be evaluated in all AKP patients [16]. It is very important to assess the flexibility of anterior hip structures (iliopsoas) (Fig. 6), the quadriceps, hamstring, soleus, gastrocnemius muscles and the iliotibial band as the pathology under scrutiny is often associated with a decreased flexibility of these structures [17, 18]. Tightness of these structures indicates the need for specific stretching exercises and possible training modification. However, only a shortened quadriceps muscle has been shown to predict AKP development [19]. Flexibility tests can be measured with different reproducible tools like the standard or digital goniometer.
64 V. Sanchis-Alfonso et al. Fig. 5 Evaluation of knee extension. (Table from Dale Daniel et al. Raven Press, 1990) [15] A B C Fig. 6 Evaluation of the flexibility of anterior hip structures. A, B Normal subject. C Shortening of the iliopsoas
Clinical and Radiological Assessment … To test quadriceps flexibility, the patient lies prone, and the knee is passively flexed with one hand while stabilizing the pelvis with the other hand to prevent compensatory hip flexion (Fig. 7). We can measure quadriceps tightness as degrees of prone knee flexion. Suggestions for quadriceps retraction are: (1) asymmetry, a different flexion of one knee compared to the other, (2) the feeling of tightness in the anterior aspect of the thigh, and (3) elevation of the pelvis due to flexion of the hip. It is important to assess quadriceps contracture as this can increase the contact pressure between patella and femur in a direct way. To test hamstring flexibility, the patient lies supine with the hip at 90º of flexion. The patient is then asked to straighten his or her knee (Fig. 8). If complete extension is not possible, there is a hamstring contracture, and its amount is measured by the popliteal angle. Most young athletic individuals have popliteal angles between 160º and 180º [2]. Hamstring tightness implies an increase in the quadriceps force necessary to extend the knee, which augments the PFJ reaction force. Gastrocnemius and soleus flexibility is evaluated by measuring the amount of active ankle dorsiflexion while the physical therapist stabilizes the subtalar joint. Gastrocnemius flexibility is evaluated with the knee extended and we evaluate soleus flexibility with the knee flexed at 90º (Fig. 9). Tightness of the 65 gastrocnemius, in the same way as hamstrings tightness, increases the PFJ reaction force, keeping the knee in a flexed position. Moreover, limited ankle dorsiflexion results in increased subtalar joint pronation. It causes an increment of tibial internal rotation with deleterious effects on PFJ biomechanics [2]. The iliotibial band (ITB) is often tight in AKP patients. This causes lateral patellar displacement and tilt as well as weakness of the medial patellar retinaculum. We use Ober’s test to assess ITB flexibility. To perform this test, the patient lies on the side opposite the affected leg with the hip and knee of the bottom leg fully flexed to eliminate the lumbar lordosis. Then, the examiner flexes the affected knee and hip at 90º. After that, he/she passively abducts the affected hip as far as possible and extends the thigh so that it is in line with the rest of the body (neutral position), which places the ITB on maximal stretch. Palpation of the ITB just proximal to the lateral femoral condyle during maximal stretch will cause severe pain in patients who have excessive ITB tightness. At this position, the patient is told to relax, and then the thigh is adducted passively. If the thigh remains suspended off the table, the test is positive (shortened ITB). If the thigh drops into an adducted position, the test is negative (normal ITB). Finally, Thomas’s test (Figs. 10 and 11) is a good method to evaluate both the iliopsoas and iliotibial band tightness. The patient holds the non-test limb with the hip at 90° of flexion while the physician stabilizes the pelvis of the test limb from the anterior superior iliac spine. The free leg is allowed to fall in the extension direction to the point where the pelvis begins to move. 3.4 Assessment of Muscle Strength Fig. 7 Evaluation of quadriceps flexibility It has been demonstrated that hip abductors and external rotation weakness are associated with AKP [20, 21]. Therefore, it is crucial to evaluate the strength of these muscles in AKP patients to address muscle imbalances. Traditional manual muscle testing or a handheld dynamometer could be used depending on availability (Fig. 12).
66 Fig. 8 Evaluation of hamstrings flexibility. (Republished with permission of AME Publishing Company. From Sanchis-Alfonso V, et al. Evaluation of anterior knee pain A V. Sanchis-Alfonso et al. patient: clinical and radiological assessment including psychological factors. Ann Joint, 3:26, 2018; permission conveyed through Copyright Clearance Center, Inc.) B Fig. 9 Evaluation of grastrocnemius (A) and soleus (B) flexibility. (Republished with permission of AME Publishing Company. From Sanchis-Alfonso V, et al. Evaluation of anterior knee pain patient: clinical and radiological assessment including psychological factors. Ann Joint, 3:26, 2018; permission conveyed through Copyright Clearance Center, Inc.) 3.5 It is Mandatory to Look Beyond the Patellofemoral Joint between torsional abnormalities [excessive external tibial torsion (Fig. 13) and femoral anteversion (Fig. 14)] and AKP. It is very important to evaluate skeletal malalignment, the malalignment of the limb on the transverse, coronal, and sagittal planes. With the patient standing, barefoot, with their feet together, we assess (Fig. 13): (1) the alignment Many orthopedic surgeons focus only on the knee when evaluating an AKP patient. This approach is a great mistake because there are other causes of AKP that are at a distance from the knee. For example, a clear relation exists
Clinical and Radiological Assessment … 67 Fig. 10 Thomas’s test in a normal subject A B C Fig. 11 Thomas’s test in a pathological case. A Shortening of the iliotibial band. Hip abduction occurs when the hip goes in extension. B Shortening of the iliopsoas. C Shortening of the rectus femoris
68 Fig. 12 A Hip abductor strength measurement. B Hip external rotator strength measurement. (Republished with permission of AME Publishing Company. From SanchisAlfonso V, et al. Evaluation of anterior knee pain patient: V. Sanchis-Alfonso et al. clinical and radiological assessment including psychological factors. Ann Joint, 3:26, 2018; permission conveyed through Copyright Clearance Center, Inc.) Fig. 13 External tibial torsion (right limb). Pseudo-varus (right limb). Squinting patella (right knee)
Clinical and Radiological Assessment … 69 Fig. 14 Femoral anteversion on the coronal plane (valgus/varus), (2) patella orientation (neutral, squinting patella), and (3) the morphology of the forefeet (pronatus, hallux valgus). From the back, we evaluate: (1) the varus or valgus alignment of the knee and (2) a varus or valgus alignment of the calcaneus. Finally, we evaluate genu recurvatum or flexum of the knees from the side. When the patient stands with the feet parallel, the patella should be facing forward. In patients with excessive external tibial torsion, a squinting patella and a genu varum can be seen. The varus in patients with external tibial rotation may be real, or it may be a reflection of the tibial torsion (thus pseudovarus). The combination of increased femoral anteversion and increased external tibial torsion has been termed miserable malalignment syndrome that includes the squinting patella, genu varum, genu recurvatum and the pronated foot. In the prone position, the proportion of internal to external rotation of the hips in extension must be measured. If internal rotation exceeds external rotation by more than 30º, there is increased femoral anteversion (Fig. 14). In cases with isolated excessive external tibial torsion, internal and external rotation are similar. In a previous study, we observed that there is an association between Cam femoroacetabular impingement (FAI) and AKP [22]. Therefore, an evaluation of Cam FAI should be performed during the physical examination of AKP patients, especially in patients with normal knee imaging studies when the pain continues after appropriate conservative treatment. In this case, AKP is secondary to functional femoral external rotation as a defense mechanism to avoid hip pain. Finally, examination of the feet is essential as pronated feet play an important role in the origin of AKP. A functional hallux limitus may be a predisposing factor for AKP [23]. Functional hallux limitus consists of a loss of dorsal flexion of the first metatarsophalangeal joint with the ankle in dorsal flexion. Limited ankle dorsiflexion range-of-motion has been linked with AKP and has also been related to altered kinematics of the knee. The implication is that this may be involved in the pathogenesis of AKP. Therefore, ankle dorsiflexion should be evaluated in all AKP patients (Fig. 15) [24]. 3.6 Functional Tests The current trend in evaluating AKP patients is using functional tests to detect inapt body movement patterns that might be responsible for
70 V. Sanchis-Alfonso et al. Fig. 15 Measurement of ankle joint dorsiflexion range. (Republished with permission of AME Publishing Company. From Sanchis-Alfonso V, et al. Evaluation of anterior knee pain patient: clinical and radiological assessment including psychological factors. Ann Joint, 3:26, 2018; permission conveyed through Copyright Clearance Center, Inc.) the pain symptomatology. The final objective would be to retrain these inapt movements and thereby reduce the pain. Fig. 16 Single-leg squat test. A Correct neuromuscular control. B Poor neuromuscular control A The most frequently used functional tests are: (1) the single-leg squat (Fig. 16); (2) the stepdown test (Fig. 17) and (3) the hop down test (Fig. 18). The three tests explore the same thing but with different levels of demand. Therefore, we will use the most appropriate for each patient, which depends on the disability that the patient has. During these tests, many AKP patients have excessive functional knee valgus. This functional knee valgus is mainly secondary to femoral adduction. Some AKP patients show lower limb abnormalities secondary to muscle weakness with the subsequent lack of dynamic control of the lower extremity. It may have an influence on the normal patellofemoral tracking and bring on patellofemoral imbalance. This has important implications for patient rehabilitation. The malalignment of the patella is secondary to functional knee valgus and abnormal movements of the femur. Such abnormalities are (1) femoral adduction (secondary to weakness of hip abductors—gluteus medius, upper fibers of gluteus maximus and tensor fascia latae), (2) internal rotation of the femur secondary to weakness of B
Clinical and Radiological Assessment … A 71 B Fig. 17 Step-down test. During this test, the limb going down only brushes the floor with the heel and then goes back to full knee extension. A Correct neuromuscular control. B Poor neuromuscular control the hip external rotators, (3) internal rotation of the tibia, and (4) tibial abduction secondary to (5) excessive pronation of the foot. We must note that a lack of dynamic control of the lower limb does not depend on the degree of physical activity of the patient [25]. That is, most physically active adolescents do not necessarily have better lower limb control [25]. other knee conditions that could simulate patellofemoral pathology. There are three categories of imaging studies in patellofemoral pathology: (1) structural imaging (radiographs, computed tomography [CT], magnetic resonance imaging [MRI]), (2) metabolic imaging (technetium scintigraphy), and (3) a combination of both. 4 4.1 Standard Radiography Imaging Studies Imaging studies are the second diagnostic step and cannot replace the first step. Overlooking this rule can lead to diagnostic errors that is followed by failed treatment and iatrogenic morbidity. A surgical indication should never be based solely on imaging techniques since the correlation between clinical and image data is not good. The history and physical examination are the fundamental elements in the evaluation of the AKP patient. Nothing can replace the history and clinical examination. The aim of the imaging studies is to quantify the pathology and rule out The majority of patients with patellofemoral pain will only require standard radiography (standing anteroposterior view, a true lateral view, and the low flexion angle axial view [Merchant]). Generally, imaging studies beyond standard radiography are not indicated. The weight-bearing whole-limb anteroposterior view radiograph allow us to evaluate limb alignment on the coronal plane (varus, valgus), and joint space narrowing (Fig. 19). The lateral view allows one to evaluate the recurvatum and flexion contracture. It also aids in evaluating the
72 A V. Sanchis-Alfonso et al. B C Fig. 18 A, B, C Hop down test. B Correct neuromuscular control. C Poor neuromuscular control. Excessive knee valgus when landing from a drop. Femoral adduction and tibial abduction are contributing to this knee position. Knee valgus increases lateral compressive forces in the PFJ Fig. 19 Weightbearing whole-limb anteroposterior view radiograph in a patient with external tibial torsion. Bilateral varus alignment and squinting patella patellar height. Is there a high-riding patella or patella alta or a low-riding patella or patella baja? Moreover, a true lateral X-ray (overlapping of the posterior borders of the femoral condyles) allows one to assess trochlear dysplasia (defined by the crossing sign and quantitatively expressed by the trochlear bump and the trochlear depth), and patellar tilt (Fig. 20). Axial views can demonstrate patellofemoral maltracking (i.e., tilt, shift, or both) when this happens beyond 30º of knee flexion, the sulcus angle, loss of joint space, subchondral sclerosis, and the shape of the patella. In addition to this, an axial view can detect secondary clues of earlier dislocation episodes. For example, medial retinacular calcification is sometimes observed in axial views and may occur in association with recurrent subluxation. Finally, a standard X-ray allows one to rule out associated and potentially serious bony conditions like tumors or infections. In cases in
Clinical and Radiological Assessment … Fig. 20 Lateral X-ray. Patellar tilt which medial patellar instability is suspected, the stress axial radiography is essential to identifying and quantifying medial patellar instability [26]. When the patient response to conservative treatment is not adequate, other imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI) and singlephoton emission computed tomography (SPECT)-CT are indicated. 4.2 Computed Tomography The CT allows for the measurement of knee parameters like the tibial tubercle-trochlear groove (TT-TG) distance, which is widely used to indicate and plan distal realignment surgeries. However, it must be noted that the value of the TT-TG distance is a controversial issue [16]. The TT-TG distance is influenced by multiple factors like tibial torsion, knee joint rotation, the slices selected, and the landmarks of the distal femur and tibial tuberosity established by the radiologist. However, no pathological distance or index should be interpreted in isolation. Clinical correlation is requisite in all cases. Moreover, the CT allows for the evaluation of torsional abnormalities (Fig. 21). In our clinical practice, we use the technique described by Murphy and colleagues in 1987 to measure femoral torsion [27]. This is the most anatomic, accurate and reproducible method for evaluating 73 femoral anteversion (high intra- [ICC: 0.95–0.98] and inter-observer agreement [ICC: 0.93]) [28]. Murphy and colleagues reported that the common method of running a line along the femoral neck on a CT image underestimated the actual anteversion by a mean 13º [27]. Moreover, the line that is used in the most common method, like the axis of the femoral neck, is not the true axis of the femoral neck. External tibial torsion is measured as the angle between the posterior aspect of the tibial metaphysis and the ankle joint line. Our normal reference values are femoral anterversion of 13° for both sexes and external tibial torsion of 21° in males and 27° in females [29, 30]. 4.3 Magnetic Resonance Imaging MRI is useful for evaluating intraosseous edema (Fig. 22), soft tissue impingement (Figs. 23 and 24), Hoffa fat pad edema (Fig. 25), and patellar cartilage damage even though this structural damage may not necessarily be the cause of AKP. In addition, it also detects possible concomitant lesions. Moreover, MRI often shows low-grade effusions associated with symptomatic peripatellar synovitis, which is an underdiagnosed pathological condition of the knee. 4.4 Technetium Scintigraphy and Single-Photon Emission Computed Tomography (SPECT)—CT Bone scintigraphy using 99mTc hydroxyl ethylene diphosphonate (99mTc-HDP) may be useful in selected cases. The bone scintigraphy in the three-dimensional and the conventional CT can be fused in a single (SPECT/CT) hybrid imaging procedure which overcomes the limitations of the CT and SPECT as separate techniques (Fig. 26). The intensity and distribution of the tracer uptake correlate with the etiological mechanism and has been accepted as an effective diagnostic tool in the orthopedic field [31–34]. If the patella is hot, this suggests that it is the source of pain, but it does not provide a diagnosis
74 Fig. 21 CT evaluation of femoral anteversion (A, B, C, D) and external tibial torsion (E). Measurement of femoral anteversion. Technique described by Murphy (A, B, C). Draw a circle on the femoral head (B) and another circle centered in the femoral shaft below the lesser trochanter (C). Then, draw a line connecting the center of these two circles (A). This line defines the femoral neck axis on the transverse plane. Next, draw a line tangent to the posterior Fig. 22 Intraosseous edema in a patient with AKP V. Sanchis-Alfonso et al. aspect of the femoral condyles (posterior condylar line) (A). The angle between these two lines represents the femoral anteversion. (D) Commonly used method described by Jeanmart (classic method). The line that is used as the axis of the femoral neck (yellow line) is not the true axis of the femoral neck connection to the femoral shaft
Clinical and Radiological Assessment … A B Fig. 23 A Peripatellar synovitis in a patient with AKP (white arrow). B Quadriceps fat pad impingement syndrome in a patient with AKP (white arrow). (“Republished with permission of Springer Nature BV, from A 75 B Holistic approach to understanding anterior knee pain, Sanchis-Alfonso V, Knee Surg Sports Traumatol Arthrosc, 22, 2275–2285, 2014; permission conveyed through Copyright Clearance Center, Inc.”) C Fig. 24 A, B 25-year-old woman with AKP. Morphologic changes of the fat pad observed frequently in patients with Hoffa’s fat pad impingement: edema localized in the superior and posterior part of the fat pad, deep infrapatellar bursitis (directly posterior to the distal part of the patellar tendon, just proximal to its insertion on the tibial tubercle) and non-visualization of intrahoffatic clefts. Moreover, we can see a patellar intraosseous edema. C Normal knee. (“Republished with permission of Springer Nature BV, from Holistic approach to understanding anterior knee pain, Sanchis-Alfonso V, Knee Surg Sports Traumatol Arthrosc, 22, 2275–2285, 2014; permission conveyed through Copyright Clearance Center, Inc.”) (Figs. 26, 27 and 28). Dye and Boll [35] observed that about one-half of their patients with AKP presented increased patellar uptake in comparison with 4% of the control group. Biopsy demonstrated that this increased patellar uptake was secondary to the increased remodelling activity of the bone. Bone scintigraphy can detect loss of osseous homeostasis, and often correlates well with the presence of patellar pain and its resolution. According to Dye and Boll [35] the bone scan commonly reverted to normal at an average time of 6.2 months (range, 3– 14 months), which is interpreted as restoration of osseous homeostasis. Naslund and colleagues [36] showed that nearly 50% of AKP patients show diffuse bone uptake in one or more compartments of the knee (Fig. 28). Not only has a relationship between hyper-uptake and pain been demonstrated, but also between pain intensity and greater uptake (Fig. 28) [37, 38]. Ro and
76 V. Sanchis-Alfonso et al. and colleagues [40], SPECT bone scintigraphy is highly sensitive in the diagnosis of patellofemoral abnormalities. For those authors, SPECT significantly improves the detection of maltracking of the patella and the ensuing increased lateral patellar compression syndrome. They conclude that this information could be used to treat patellofemoral problems more effectively. SPECT bone scans may be overlaid onto an MRI or CT (fusion) to correlate bone activity with the specifics of anatomy (Figs. 26, 27 and 28). It reveals the metabolic and geographic pattern of bone homeostasis, which is the normal osseous metabolic status of the joint. 5 Fig. 25 Post-traumatic Hoffa fat pad edema. (“Republished with permission of Springer Nature BV, from Holistic approach to understanding anterior knee pain, Sanchis-Alfonso V, Knee Surg Sports Traumatol Arthrosc, 22, 2275–2285, 2014; permission conveyed through Copyright Clearance Center, Inc.”) colleagues [39] have seen a higher degree of uptake in the patella in cases with a poorer response to conservative management. Scintigraphy may be especially useful in cases of difficult diagnosis (Fig. 29) and in patients with injuries related to workers’ compensation cases in which the physician wishes to establish objective findings. According to Lorberboym Take Home Messages – There is no substitute for a thorough history and a complete and careful physical examination. The history and physical examination remain the first step, more than any diagnostic imaging technique, to come to an accurate diagnosis of AKP. – Most orthopedic surgeons only focus on the knee when they explore a patient with AKP. This approach is a great mistake because other important etiological factors that are at a distance from the knee may be responsible for the pain. We should examine the entire lower extremity. – Imaging studies are a second step and can never replace the former. Fig. 26 SPECT-CT overcomes the limitations of the CT and SPECT as separate techniques. It reveals the metabolic and geographic pattern of bone homeostasis. That is, it correlates bone activity with the specifics of anatomy
Clinical and Radiological Assessment … A B 77 C Fig. 27 SPECT/CT in an AKP patient with right femoral anteversion and external tibial torsion. A Fused SPECT/CT MIP, B, C fused axials. The scintigraphic uptake is markedly high in the patella’s articular face Fig. 28 SPECT-CT in a symptomatic patient with bilateral AKP with much more pain in the left knee. (Republished with permission of AME Publishing Company. From Sanchis-Alfonso V, et al. Evaluation of anterior knee pain patient: clinical and radiological assessment including psychological factors. Ann Joint, 3:26, 2018; permission conveyed through Copyright Clearance Center, Inc.)
78 V. Sanchis-Alfonso et al. Fig. 29 Value of SPECT-CT in the differential diagnosis of knee pain. This patient came to our office with severe AKP. In this case, the patient presented a type I epiphysiolysis of the distal femoral physis that was responsible for pain (Courtesy of A. Darder, MD). (Republished with permission of AME Publishing Company. From Sanchis-Alfonso V, et al. Evaluation of anterior knee pain patient: clinical and radiological assessment including psychological factors. Ann Joint, 3:26, 2018; permission conveyed through Copyright Clearance Center, Inc.) – Surgical indications should not be based only on methods of image diagnosis as there is a poor correlation between the clinical and imaging data. patellofemoral pain: which are reliable and valid? Arch Phys Med Rehabil. 2004;85:815–22. Bouhassira D, Attal N, Alchaar H, et al. Comparison of pain syndromes associated with nervous or somatic lesions and development of a new neuropathic pain diagnostic questionnaire (DN4). Pain. 2005;114(1–2):29–36. Robertson CJ, Hurley M, Jones F. People’s beliefs about the meaning of crepitus in patellofemoral pain and the impact of these beliefs on their behaviour: a qualitative study. Musculoskelet Sci Pract. 2017;28:59–64. Domenech J, Sanchis-Alfonso V, Lopez L, et al. Influence of kinesiophobia and catastrophizing on pain and disability in anterior knee pain patients. Knee Surg Sports Traumatol Arthrosc. 2013;21 (7):1562–8. Wride J, Bannigan K. Investigating the prevalence of anxiety and depression in people living with patellofemoral pain in the UK: the Dep-Pf study. Scand J Pain. 2019;24;19(2):375–382. 4. 5. References 1. Crossley KM, Callaghan MJ, van Linschoten R. Patellofemoral pain. Br J Sports Med. 2016;50 (4):247–50. 2. Post WR. History and physical examination. In: Fulkerson JP (ed) Disorders of the patellofemoral joint. 4th edition. Lippincott Williams & Wilkins Philadelphia, 2004; pp 43–75. 3. Crossley KM, Bennell KL, Cowan SM, et al. Analysis of outcome measures for persons with 6. 7.
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Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat These Patients Vicente Sanchis-Alfonso, Julio Doménech-Fernández, Benjamin E. Smith, and James Selfe 1 Introduction Anterior knee pain (AKP) is one of the most common reasons why physically active people consult an orthopedic surgeon specializing in the knee. It can be challenging to manage. Despite its high prevalence and the abundance of research the etiopathogenesis of AKP is not well known. Therefore, there are many myths surrounding this condition, false collective beliefs that are transmitted from generation to generation. One of these myths is that the AKP patient is a person with peculiar psychological traits that are responsible for the genesis of pain. It could not be further from the truth. Many AKP patients have insignificant clinical and radiological findings. However, they have severe pain and an important disability. Moreover, some AKP patients have allodynia (pain in V. Sanchis-Alfonso (&) J. Doménech-Fernández Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com B. E. Smith Physiotherapy Outpatients, University Hospitals of Derby and Burton NHS Foundation Trust, Derby, UK J. Selfe Department of Health Professions, Faculty of Health and Education, Manchester Metropolitan University, Manchester, UK the presence of a non-noxious stimulus), primary hyperalgesia, (pain hypersensitivity in the knee) or secondary hyperalgesia (pain hypersensitivity in uninjured tissues beyond the affected area). We can thus understand that many orthopedic surgeons, who do not know this condition well, may think that the main problem is psychological. Furthermore, the absence of structural pathology leads to cataloging these patients as somatizers in many cases even though there is no evidence to justify this. It is important to note that acute pain does not have anything to do with chronic pain. Chronic pain can have significant psychological effects on the sufferers, and we must note that AKP is a paradigm of chronic pain. Chronic pain is a multidimensional experience with sensitive, cognitive and affective domains [1]. Functional Magnetic Resonance Imaging (MRI) has identified many pain centres in the brain that work together as a network. This pain neuromatrix can account for the multidimensional experience of pain [2]. Interestingly, Damasio and colleagues [3] observed an overlap between the cerebral activity areas related to chronic pain and those related to cognition and emotion. This finding suggests that chronic pain, cognition, and emotion are interrelated [3]. Patients with AKP have a high incidence of anxiety, depression, kinesiophobia (the fear that physical activity will cause more injury or a re-injury and subsequent pain) and catastrophizing (the belief that pain © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_6 81
82 V. Sanchis-Alfonso et al. will worsen and cannot be relieved) [4]. However, ascribing AKP only to psychological problems is a crude excuse to hide our ignorance as to the cause of pain in these patients. What it is true is that psychological disorders are the result of the pain severity but not the cause of the pain and disability. We have all seen AKP patients that have been operated on several times with completely inappropriate surgical indications and that were obviously quite affected with painrelated fear. AKP is usually considered a biomechanical paradigm hence the literature is dominated by biomechanical studies that overlook social and psychological factors. Until recently, the role of psychological factors involved in AKP have received little attention. Even so, psychological factors are increasingly recognized for their role in chronic pain conditions. Most of the papers in which AKP is analyzed from a psychological perspective (the human side of the patellofemoral pain) have been published in the last 5 years. The objective of this chapter in to analyze the psychological factors affecting AKP patients in depth. Moreover, we are going to review the experience of living with AKP. This chapter is about expanding our horizons, that is, the options for treating AKP patients. What this chapter is not about is negating any other existing paradigm (the homeostasis paradigm and structural/ anatomic/biomechanical paradigm). From a biopsychosocial perspective, psychological factors are not an isolated cause of pain, but rather interact with biological and structural factors. The key message of this chapter is that psychological factors are modulators of pain and disability. Throughout this chapter, we will work to justify this statement. a direct and sequential relation between tissue damage and pain, and between pain and disability. Therefore, the doctor’s task would be to repair the damaged tissue and eradicate the pain, making the functional impairment and disability disappear. This model has worked well for some conditions (e.g., meniscal tears). However, for some conditions that develop with chronic pain such as AKP, which is a paradigm of chronic pain, this classic biomedical model is not enough to understand the pathophysiology of the pain and determine adequate treatment. Regardless of how intense the pain is, patients with AKP show different degrees of disability in their everyday life. Furthermore, no significant correlation between structural alterations of the patellofemoral joint and disability have been observed. In fact, some cases with important anatomic alterations (patellar subluxation, patellar tilt, pathologic external tibial torsion, and severe patellar and/or trochlear chondropathy) are painless [5– 8]. Therefore, not only must we consider anatomic, biological and biomechanical factors to understand AKP, but also the psychological and social ones. This approach was proposed by the American pathologist and psychiatrist George Engel. In 1977, the Journal “Science” published his paper “The need for a new medical model: A challenge for biomedicine”, introducing the term “Biopsychosocial Model” (Fig. 1) [9]. This model allows for the development of more adequate therapeutic strategies than the biomedical model. However, very few studies currently focus on the patient with AKP from a psychological and social perspective in comparison with other conditions such as low back pain (LBP), knee osteoarthritis, fibromyalgia or rheumatoid arthritis. 2 3 Biopsychosocial Model in Anterior Knee Pain—An Alternative to the Classic Biomedical Disease Model Currently, the biomedical disease model is the dominant one used by physicians in the diagnosis and treatment of diseases. This model establishes Fear-Avoidance Model in Anterior Knee Pain. Kinesiophobia To try to explain how and why some individuals with musculoskeletal pain develop chronic pain, Lethem and colleagues [11] introduced the socalled “fear-avoidance” model in 1983 (Fig. 2). The central concept of their model is fear of pain.
Evaluation of Psychological Factors … 83 Fig. 1 The Biopsychosocial model of chronic pain and disability. International Classification of Functioning Disability and Health, World Health Organization (Modified from Waddell [10]) “Confrontation” and “avoidance” are the two opposite responses to this fear. The former response leads to a reduction of fear over time with the patient being able to cope with it satisfactorily, continue their usual activities and achieve full recovery. On the other hand, patients who interpret pain in an exaggerated or catastrophic way, develop fear of pain and associated behaviors like hypervigilance and avoidance in search of security. Although these behaviors can be adaptive when coping with acute pain, they can worsen the patient’s condition if the pain is chronic, because they favor disuse, depression and increased disability. The fear-avoidance model is framed within the biopsychosocial disease model, the patient being trapped in a vicious circle of pain, disability and suffering (Fig. 2). Asmudson and colleagues [12] added the pain anxiety component to this model as an aggravating factor in the avoidance behavior generating circuit (Fig. 2). Avoidance behavior not only includes limiting one’s movements, but also avoiding social interactions and recreational activities, which increase the pain and suffering in these patients. Crombez and colleagues [13] have even stated that “the fear of pain is more disabling that pain itself”. In many studies, fear and avoidance behaviors have been strongly associated with the disability present in patients with low back pain (LBP) [15–18]. Also, in LBP longitudinal studies, changes in fear-avoidance beliefs were good predictors of disability [19–24]. The fear of pain and the catastrophic vision of pain also occur in pain free people. Therefore, these beliefs can play an important role in the development of new episodes of pain. In studies performed on subjects without LBP [25–28], it was observed that fear of pain increased the risk of suffering episodes of LBP, and so the risk of disability was increased. Picavet and colleagues [29], in 2002, studied whether pain catastrophizing and fear of movement/(re)injury (kinesiophobia) are important in the etiology of chronic LBP and the associated disability. For patients with LBP at baseline, a high level of catastrophizing predicted chronic LBP, in particular severe LBP and LBP with disability. Moreover, a high level of kinesiophobia showed similar associations. For those subjects without LBP at baseline, a high level of catastrophizing or kinesiophobia predicted LBP with disability during follow-up. They concluded that catastrophizing and kinesiophobia were good predictors for the chronification of pain and disability. In another study, Carragee and colleagues [19] performed a five-year follow-up study on a group of 100 subjects with mild LBP by means of MRI and a discography, measuring their fear-avoidance beliefs with a FABQ (FearAvoidance Beliefs Questionnaire). Surprisingly,
84 V. Sanchis-Alfonso et al. Fig. 2 The fear-avoidance model of chronic pain based on the fear-avoidance model of Vlaeyen and Linton [14] and the fear-anxiety-avoidance model of Asmudson and colleagues [12] the severe LBP cases and disabilities had no relation with structural anomalies found in the MRI or discography. It was the presence of fear and avoidance behaviors that turned out to be the strongest predictor in LBP and disability. AKP shares with non-specific LBP a low correlation between the symptoms and structural anomalies found in imaging studies. Moreover, both conditions tend to become chronic and cause disability. The World Health Organization defines disability as “a limitation of function that compromises an individual’s ability to perform an activity within the range considered normal”. AKP patients show different degrees of disability in their everyday life, regardless of how intense the pain is. In some cases, there is severe pain and little disability. In other cases, the pain is severe and the disability, too. Piva and colleagues [30] studied whether changes in fearavoidance behaviors (measured with the FABQ modified for the knee) influenced disability in a group of patients with AKP undergoing conventional physical therapy treatment. They found that those patients who lowered their levels of fear and avoidance of physical activity and work saw decreased levels of pain and disability at the end of the treatment. Jensen and colleagues [31] studied a group of AKP patients by measuring the degree of pain with the VAS scale and disability with the Cincinnati Knee Rating System (CKRS) questionnaire and found a weak correlation between the level of pain and disability, one that was not statistically significant. Therefore, we can reason that AKP causes pain on one hand and disability on the other, being both independent dimensions with a poor correlation. Domenech and colleagues [4] evaluated the ideas of fear and avoidance with the Tampa Kinesiophobia Scale (TSK) and have found a moderate statistically significant correlation with the patient’s referred disability measured with the Lysholm Score (Table 1) [4]. The greater the fear and avoidance beliefs, the greater the disability perceived by the patient. It is interesting to highlight that the correlation between kinesiophobia and disability was higher than the one between pain and disability (Table 1) [4]. Obviously, not all the AKP patients have
Evaluation of Psychological Factors … Table 1 Spearman correlation between pain, disability and the psychological variables. (“Republished with permission of Springer Nature BV, from Influence of kinesiophobia and catastrophizing on pain and disability in anterior knee pain patients, Domenech J et al., Knee Surg Sports Traumatol Arthrosc, 21, 1562–1568, 2013; permission conveyed through Copyright Clearance Center, Inc.”) 85 Pain (VAS) Pain (VAS) a Disability (Lysholm) 0.49** Coping Strategies (CSQ) 0.21 −0.01 Reinterpreting pain sensation 0.18 −0.16 Ignoring pain sensations 0.08 0.06 Coping self-statements 0.08 −0.01 Praying or hoping 0.35* −0.38** Catastrophizing 0.48** −0.59** Increasing activity level 0.01 Anxiety (HAD) 0.46** 0.57** Depression (HAD) 0.44** −0.61** Kinesiophobia (TSK) 0.26* −0.53** Catastrophizing (PCS) 0.43** −0.53** Diverting attention 0.15 Subscale PCS rumination 0.39** −0.49** Subscale PCS magnification 0.41** −0.47** Subscale PCS hopelessness 0.46** −0.56** VAS (Visual Analogue Scale), CSQ (Coping Strategies Questionnaire), HAD (Hospital Anxiety and Depression inventory), TSK (Tampa Scale for Kinesiophobia), and PCS (Pain Catastrophizing Scale) * p < 0.01; ** p < 0.001 a Correlation between pain and disability was performed after deleting the subscale pain of the Lysholm questionnaire to avoid colinearity kinesiophobia. However, its presence is very important because it has clinical relevance. If kinesiophobia is present, then the levels of the pain and the disability soar (Table 2). In many cases, AKP patients also exhibit catastrophizing. Domenech and colleagues [4] evaluated catastrophizing through the Catastrophizing Coping Scale Questionnaire (CSQ) and through the Pain Catastrophizing Scale (PCS) and found a moderate statistically significant correlation with the patient’s disability (Table 1). When the perception of pain is more catastrophic, the patients perceive greater disability. Moreover, pain and disability show a moderate but significant correlation even though it is lower than that observed with catastrophizing or kinesiophobia [4]. Therefore, there are other factors besides pain that contribute to disability. It has been shown that what is mainly responsible for disability is not the pain, but the associated psychological factors. Pain explains only 24% of the variance in disability whereas catastrophizing and depression account for 56% of the variance in disability [4]. There are other factors besides pain that contribute to disability. It seems plausible that psychological factors contribute to it. There are complex cultural beliefs about many aspects of health including the potential iatrogenic effect of healthcare itself. The pain experience is a good example where there is great cultural complexity for example the fearavoidance model of pain cautions against exercise and activity, which in an acute injury state may be helpful and common sense but in a chronic pain state has a negative impact on outcomes [32]. Crepitus is another example where painless noises from the knee can create negative emotions, inaccurate etiological beliefs and finally leads to fear-avoidance behavior and lower functional performance [33]. Maclachlan and colleagues [34] showed that there were no significant differences in TSK, PCS or HADS between less-severe pain patients and controls. However, more severe AKP
86 V. Sanchis-Alfonso et al. Table 2 T test comparison of mean values in pain and disability between patients with high or low levels of anxiety, depression, kinesiophobia and catastrophizing. (“Republished with permission of Springer Nature BV, from Influence of kinesiophobia and catastrophizing on pain and disability in anterior knee pain patients, Domenech J et al., Knee Surg Sports Traumatol Arthrosc, 21, 1562–1568, 2013; permission conveyed through Copyright Clearance Center, Inc.”) Pain Disability Anxiety High level ( 11) n = 29 8.2 (1.1) Low level (<11) n = 68 6.9 (1.7) P < 0.0001 30.3 (17.0) P < 0.0001 53.8 (18.5) Depression High level ( 11) n = 16 8.3 (1.4) Low level (<11) n = 81 6.8 (1.7) P = 0.009 23.0 (11.3) P < 0.0001 51.1 (19.4) Kinesiophobia High level ( 40) n = 80 7.2 (1.6) Low level (<40) n = 17 5.8 (2.2) P = 0.009 44.7 (20.0) P = 0.002 61.6 (16.6) Catastrophizing High level ( 24) n = 35 7.7 (1.5) Low level (<24) n = 62 6.5 (1.8) P = 0.001 patients had significantly higher HADS-D and PCS scores than the controls. Moreover, the more severe AKP group also had significantly worse scores for the TSK, HADS-D and PCS than the less severe AKP group [34]. Among all the factors, the greatest difference in prevalence was observed for kinesiophobia, which was 27% more prevalent in the more-severe AKP group [34]. This means kinesiophobia seems to be an important factor in the experience of AKP, because it was elevated in the AKP group, significantly differed between the AKP sub-groups (more-severe vs. less-severe) and contributed to explaining disability [34]. Curiously, Maclachlan and colleagues [35] emphasize that clinicians should not assume that kinesiophobia is always linked to avoidance behaviors and disability. Therefore, reported high levels of activity should not preclude the evaluation of kinesiophobia. Selhorst and colleagues [36] found a significant and negative association between psychological impairment in adolescents with AKP and the self-reported function, being the fearavoidance beliefs the most associated variable. Pain related fear and non pain catastrophizing were significantly associated with some aspects 35.1 (16.2) P < 0.0001 54.8 (19.1) of objective function such as quadriceps strength, hip abduction and single leg hop distance. 4 Relationship Between Cognitions and Anterior Knee Pain. Catastrophizing 4.1 Coping Strategies Understanding individual pain coping strategies is one of the most important aspects in comprehending the consequences of chronic pain on patient health. Patients see their pain as a source of stress for which they develop cognitive and behavioral strategies that are constantly changing to minimize the impact of pain and disability. On certain occasions, these coping strategies are positive, improving tolerance to reduce the perception of pain and disability. Then, on other occasions, these coping strategies are maladaptative and worsen the clinical course of the disease. The Coping Strategies Questionnaire (CSQ) [37] measures the frequency with which patients use different coping strategies. It is
Evaluation of Psychological Factors … comprised of seven subscales, six cognitive (distraction, reinterpreting pain sensation, ignoring pain sensation, coping self-assertion, prayer or hope, and catastrophizing), and a behavioral subscale (increase in the activity level and the behaviors that reduce the feeling of pain). Thomeé and colleagues [38] studied the coping strategies in a group of 50 Swedish patients with chronic AKP using the CSQ and found that the scores in the different coping subscales where in accordance with the results published in other patients with chronic pain. The most commonly used strategy was the coping self-statements and the least used was reinterpreting pain sensations [38]. Domenech and colleagues [4], found similar results relative to the frequency with which the different coping strategies are used, regardless of the cultural differences between people in different studies. The most used strategies were the increase in behavioral activities and the coping selfstatements [4]. The least used was reinterpreting pain sensations [4]. Domenech and colleagues [4] also analyzed the relationship between the pain coping subscales and pain and disability. Both subscales, the catastrophic vision and prayer-hope, showed significant correlation with the patient’s disability [4]. Additionally, all of the coping strategies except the prayer-hope one had a significant relationship with the hospital anxiety and depression (HAD) scale [4]. However, none of the coping strategies showed a significant relationship with the degree of pain [4]. 4.2 The Role of Catastrophizing Catastrophizing is the exaggerated interpretation of the negative consequences of pain. It is a multidimensional construct with elements of magnification (heightened perception of pain), rumination (excessive focus on pain), and helplessness (beliefs that the control of pain is beyond one’s ability). AKP patients have a high prevalence of catastrophizing. Obviously, not all AKP 87 patients catastrophize. However, its presence is very important because it has clinical relevance. If catastrophizing is present, then the levels of pain and disability increase dramatically [4]. Catastrophizing plays a key role in pain modulation. However, the exact mechanisms by which catastrophizing affects the experience of pain is not well known. Goodin and colleagues [39] have shown that the heightened pain reported by individuals that exhibit extreme pain catastrophizing may be related to a disruption in the endogenous pain-inhibitory modulation processes of pain. In a study using functional MRI in patients with chronic pain, it was seen that catastrophizing was not only associated with a greater degree of activity in the brain’s pain processing areas but also in the cortical areas related to attention, the anticipation of pain, and emotional aspects of pain [40]. In healthy subjects in whom pain was caused by heat, higher levels of catastrophizing were related to a greater degree of pain as well as a longer duration of the heat related pain [41]. This suggests that catastrophizing plays a facilitating role in the pain perception process. Catastrophizing in chronic pain and disability has been widely studied in musculoskeletal conditions such as rheumatoid arthritis, knee osteoarthritis, or LBP [42–47]. There is growing evidence that the catastrophic vision of pain is related not only to the pain patients report but also to other aspects that influence the course of the illness. Some studies show that patients with musculoskeletal pain with these ideas have a greater degree of disability [48], increased use of health resources [49] and medication [50, 51], and a worse recovery after knee arthroplasty surgery [52]. Many studies confirm a strong association between catastrophizing and the patient’s disability in several conditions with chronic pain, mainly in musculoskeletal pain [53–56]. Besides the association with disability, catastrophizing has been related to the degree of pain. Patients with significant catastrophizing
88 reported greater degrees of pain both in acute and chronic pain conditions [49, 54, 56, 57]. Thomeé and colleagues [58] studied pain coping strategies in a group of AKP patients. The catastrophizing subscale showed a very high score in the patients with AKP, more than double the score found in rheumatoid arthritis patients. Domenech and colleagues [4] studied the relationship between catastrophizing, measured on the catastrophizing subscale of the CSQ or by means of the PCS, and disability in a group of AKP patients. A statistically significant correlation was found between the disability, measured using the Lysholm scale score, and the score obtained from the PCS questionnaire [4]. However, there was a poorer correlation with the degree of pain [4]. Catastrophizing was also found to be a widely used coping strategy in chronic AKP patients [4]. There is controversy about whether catastrophizing is a stable construct, like a personality trait that predisposes a patient with AKP to the chronification of pain and disability, or whether it is a dynamic attribute that can be modified. If the first premise is correct, then catastrophizing could be an obstacle to recovery. We believe that the second premise is correct since we have observed that catastrophizing is reduced when patients feel a reduction in pain after a classic biomedical treatment (physical therapy) [59]. This finding is clinically important because it contradicts the common belief that AKP patients are patients with pre-existing psychological problems that are responsible for pain. Another relevant finding is that a change in catastrophizing is the strongest predictor of changes in both pain and disability after treatment (Table 3) [59]. A reduction in catastrophizing explains by itself the 48% of the variance of the changes in the degree of pain (Table 4) [59]. The reduction of catastrophizing and anxiety explains 56% of the variance in disability (Table 4) [59]. What is very important is that catastrophizing is a cognition and therefore it is a modifiable factor. Therefore, cognitive-behavioral therapy (CBT) focused on reducing fear-avoidance V. Sanchis-Alfonso et al. behaviors and the catastrophizing may influence the clinical state of AKP patients in a positive manner. 5 Psychological Involvement in AKP Patients. Depression and Anxiety As measured by HADS over half of people living with AKP experience anxiety and/or depressive symptoms. The levels of anxiety and depressive symptoms in AKP patients are much higher than those found in the general population (anxiety symptoms: 49.5% vs. 5.9–7.8%; depressive symptoms 20.8 vs. 3.3–7.8%) [60, 61]. Nevertheless, these figures must be viewed with caution due to the potential for the HADS to overestimate anxiety and depression [62]. High levels of anxiety and depression are found in several musculoskeletal conditions. In a systematic review, Stubbs and colleagues [63] found figures of around 20% for both anxiety and depression in osteoarthritis. Similar figures have also been reported in low back pain [64]. This suggests that the figures in AKP are realistic, despite concerns regarding the accuracy of the HADS as a measurement tool. We have found similar rates of anxiety (30%) and depression (16%) in people with AKP (n = 97) in a tertiary setting [4]. Obviously, not all AKP patients have painrelated fear. However, the presence of painrelated fear is very important because it has clinical relevance. For example, if depression is present, then the levels of the pain and disability soar [4]. The same goes for anxiety [4]. If there is psychological involvement, disability and pain are greater (Fig. 3) [4]. 5.1 Relationship Between Anxiety and Anterior Knee Pain Anxiety and stress are normal emotional reactions in certain situations. Both anxiety and stress in a mild or moderate form are healthy and even
p < 0.001 −0.59** −0.43** Disability posttreatment ** 0.54** 0.41** Pain posttreatment p < 0.05; −0.59** −0.49** Disability pretreatment * 0.30* 0.39** Depression Pain pretreatment Anxiety 0.24 −0.03 −0.04 −0.12 0.28 −0.25 0.44** −0.21 −0.02 0.12 Ignoring pain Reinterpreting pain 0.19 0.02 Diverting attention 0.02 0.15 0.25 −0.19 Coping selfstatements 0.08 0.01 −0.38** 0.40** Praying or hoping Pain Coping Strategies (CSQ) −0.50** 0.50** −0.62** 0.48** Catastrophizing 0.30* −0.26 0.33* −0.41** Increasing activity level −0.41** 0.35* −0.55** 0.35* Kinesiophobia −0.57** 0.59** −0.49** 0.47** Catastrophizing Table 3 Spearman correlation coefficients of pain intensity and disability level with the psychometric variables before and after treatment. (“Republished with permission of Springer Nature BV, from Changes in catastrophizing and kinesiophobia are predictive of changes in disability and pain after treatment in patients with anterior knee pain, Domenech J et al., Knee Surg Sports Traumatol Arthrosc, 22, 2295–2300, 2014; permission conveyed through Copyright Clearance Center, Inc.”) Evaluation of Psychological Factors … 89
90 V. Sanchis-Alfonso et al. Table 4 Hierarchical regression explaining pain and disability. (“Republished with permission of Springer Nature BV, from Changes in catastrophizing and kinesiophobia are predictive of changes in disability and pain after treatment in patients with anterior knee pain, Domenech J. et al., Knee Surg Sports Traumatol Arthrosc, 22, 2295–2300, 2014; permission conveyed through Copyright Clearance Center, Inc.”) Explanatory variables (Change scores) R2 Corrected R2 Model predicting pain intensity Catastrophizing (PCS) 0.49 0.48 0.13 (0.09, 0.17) 0.70 0.001 Model predicting disability Catastrophizing (PCS) Anxiety 0.58 0.56 –0.92 (–1.42, –0.41) –2.26 (–3.85, –0.67) –0.47 –0.37 0.001 0.006 B (95% IC) Beta P Fig. 3 If there is psychological involvement, disability and pain are greater beneficial because they motivate a person to prepare a response, either to remain vigilant or to serve as a warning when in danger. However, it occasionally becomes dysfunctional when anxiety levels are too high or it lasts too long, becoming pathological. Anxiety expresses itself differently in patients, sometimes in emotional and cognitive manners (tension, fear, edginess, discomfort, nervousness), behavioral or motor aspects (immobility, avoidance, restlessness). Anxiety is also accompanied by vegetative reactions such as perspiration, palpitations, dry mouth, shaking, dizziness or nausea on occasion. Patients with chronic pain perceive pain as a situation that generates prolonged stress. The presence of anxiety influences the symptoms in these patients bidirectionally. High degrees of pain can sometimes predict anxiety symptoms [65] and conversely, anxiety increases the painful experience [66]. One of the most studied mechanisms of the effects of maladaptative anxiety in chronic pain patients is a tendency towards hypervigilance and catastrophization [12]. These tendencies amplify the perception of pain and cause behaviors that lead to increased disability [67]. Clark and colleagues [68] performed a RCT to determine the efficacy of physiotherapy for AKP. The four treatment groups were: (1) exercise, taping and education; (2) taping and education; (3) exercise and education; and (4) education alone. They found that 27% of patients with AKP showed anxiety symptoms measured with the HAD questionnaire. After receiving treatment, those symptoms improved. Thomee and colleagues [58] also found high levels of anxiety in a group of patients with AKP using the STAI questionnaire (State Trait Anxiety Inventory), finding similar scores to those published for
Evaluation of Psychological Factors … rheumatoid arthritis. Carlsson and colleagues [69] measured distress/anxiety using the Rorschach test in patients with AKP and in a control group of mainly physical therapy students and found that patients had high anxiety levels but with no difference from the control group. That may have been because the students also have a high level of distress. Piva and colleagues [30] studied a group of AKP patients with at least 4 weeks pain and an average numeric pain rating scale score of 3.6. They found a correlation between disability and level of anxiety measured with the Beck questionnaire, suggesting that patients with more limitations in physical function had higher anxiety levels. Domenech and colleagues [4] have shown that if anxiety is present in chronic AKP patients with important symptoms, then levels of pain and disability increase (Table 2). 5.2 Relationship Between Depression and Anterior Knee Pain The importance of this association lies in the fact that both conditions, chronic pain and depression, can interact to intensify their effects. A meta-analysis of 83 studies has shown that the severity of depression is related not only to the presence of chronic pain, but also to its duration, the degree of pain and the number of painful areas [70]. Regarding its influence on disability, several studies show that depression reduces the functional capacity of patients with osteoarthritis and rheumatoid arthritis [71–73]. Furthermore, in patients with depression and chronic pain, the depression symptoms improve if the pain is reduced [70, 74, 75]. The relationship between depression and pain is reinforced by the fact that antidepressant drugs have an analgesic effect on musculoskeletal pain patients even without depression [76]. Although the relationship between chronic pain and depression has been widely studied in other musculoskeletal conditions, very few studies analyze this relationship in AKP patients. Carlsson and colleagues [69] used the Rorschach test on a group of patients with AKP while comparing it to a control group. Patients with 91 AKP were different to control patients in that they showed a higher depression index (DEPI > 4). Comparison with a group of psychiatric outpatients showed a higher depression rate in patients with AKP. However, Witonski [77], using the Beck Depression Inventory (BDI), found no differences between a group of 20 AKP patients with a mean age of 18 and a control group of similar age. It is possible that the difference in the results is because the last group was too young, a mean age of 18, or because of the different type of measurement tool. Clark and colleagues [68] performed a clinical trial with 81 AKP patients, assigning them randomly to four types of physical therapy treatments. Prior to this treatment, 15% of the patients had borderline depression symptoms or a well-established depression measured with the HAD questionnaire scale. Interestingly, the levels of depression, pain and disability improved after 3 months and after 12 months of treatment in the 4 groups. Domenech and colleagues [59] analyzed a sample of 54 patients with chronic AKP. They measured the presence of depressive symptoms with the HAD questionnaire. They demonstrated that if anxiety is present, then levels of pain and disability rise drastically (Table 2). In conclusion, in a chronic AKP patient it is important to identify the presence of depression for several reasons. The most important fact is that depression increases disability as well as the degree of pain. Therefore, it prolongs the condition. Another reason is that undiagnosed and untreated depression has been related to a poor response to physical therapy or surgery. It is essential to perform a special evaluation aimed at ruling out the coexistence of hidden depression in these patients. 6 The Experience of Living with Anterior Knee Pain As has been discussed so far in this chapter, psychological factors, such as fear and catastrophizing, can modulate the pain response in people with AKP. This in turn can act as a barrier to successful rehabilitation and further modulate the physiological responses to pain with the development
92 and maintenance of chronic persistent pain. However, the main stay of the research demonstrating this is quantitative. Advocates of qualitative research methods, however, suggest that qualitative research can disclose the experience of people with pain, and can therefore be used to better understand patients’ behaviors and perspectives. Qualitative research gives rich insights into the sociocultural context of pain. 6.1 Pain-Related Fear In 2017 (published 2018) the first known qualitative research study investigating the lived experience of AKP was conducted by Smith and colleagues [78]. A convenience sample of ten patients aged between 18 and 40 years with AKP were recruited prior to starting physiotherapy. The mean duration of symptoms was 78 months, and the mean age of the participants was 30.6 years old. These patient characteristics are comparable to those of other studies recruiting from the National Health Service (NHS) in the UK. Interviews were designed to cover the following topics of the lived experience of AKP: living with knee pain; past healthcare management; interpretation of causation of pain; beliefs, attitudes and behavior concerning pain; and expectations for the future. Participants offered a rich and detailed account of the impact and lived experience of AKP; the first theme that emerged from the data were labelled (1) impact on self. It described the participants’ sense of loss in relation to their self and self-identity. The loss of physical ability was profound and considerable. As one patient described it, “I struggle at work, bending down to get the bottom shelf and getting back up, I literally have to hold onto the table to pull myself up. I can’t do it off just my knees”. The further four themes described how participants dealt with this loss in a climate of uncertainty, what they understood and how they made decisions about their knee pain, these were labelled (2) uncertainty, confusion and sense making; (3) exercise and activity beliefs; (4) behavioral coping strategies and (5) expectations of the future. V. Sanchis-Alfonso et al. Participants expressed intense confusion around their pain and symptoms, resulting in specific beliefs regarding barriers to exercise and activity, with all the participants included describing fear-avoidant, or kinesiophobic, behaviors with strong ‘damage’ beliefs. “If something hurts it is because your body’s telling you if you do that, you’re going to cause more injury”. Also, low expectation for the future and low self-efficacy was demonstrated by most of the participants included, which could be conceptualized as ‘catastrophizing’. One participant described negative feelings about the future and their prognosis, “it does concern me that it’s going to be every day for the rest of my life I’m going to be struggling to walk upstairs. And then I think about getting old, and I think I’m going to end up with a stairlift and living downstairs”. The research also identified judgmental attitudes from colleagues, friends or family, and loss of meaningful activity, acting as moderators to low moods and feelings of loss of self-identity. For example, one participant described work colleagues as “saying that I’m a grandma. They say, ‘Yeah. If you were a horse, they’d put you down”, 26-year-old. 6.2 Distress from Joint Noises Audible joint noises, such as ‘grinding’, ‘creaking’, ‘clunking’ are common features of AKP and are often referred to as crepitus. Crepitus in AKP should be considered a normal rather than a pathological finding on assessment, although more common in females. For example, in a 1998 cohort study of 210 pain-free adults 94% of females (mean age 47), with no lifetime history of knee pain reported crepitus [6]. In comparison, in the same study they found only 45% of males (mean age 48) reported crepitus. Crepitus was found to be a source of distress and confusion by Smith and colleagues and this was corroborated in further qualitative research published by Robertson and colleagues [79]. Robertson aimed to understand people’s beliefs and understanding of joint crepitus and recruited
Evaluation of Psychological Factors … eleven participants with a history of AKP, conducting interviews focusing on the participants’ joint noises. Both Smith and colleagues and Robertson and colleagues identified that joint noises were often accompanied by negative emotions and inaccurate aetiological beliefs, such as a sign of premature ageing or damage beliefs. This often led to fear-avoidance of the activities the patients associated with the joint noises, such as running, squatting, stairs, sitting, and kneeling, with a negative cycle of fear of degenerative changes and subsequent reduced physical activity. A participant in Smith’s study described the emotional anxiety associated with the joint noises, “It was the noise that was concerning me more than the pain.” Although crepitus seems normal, time should be taken to explain this to patients carefully so that they can focus on their rehabilitation. 6.3 Responding to Treatment Following Smith’s initial qualitative study, the research team conducted a feasibility RCT with 60 participants investigating a biopsychosocial approach to physiotherapy (a holistic approach that attempts to include patients’ behaviors, thoughts and feelings into a comprehensive rehabilitation program) for AKP compared to usual physiotherapy, in a large UK based teaching hospital [80]. The experimental exercise program was a novel physiotherapy lead intervention based on pain education and exercise prescription, where a single exercise was designed to gradually expose the participant to the activities they had been avoiding, coupled with self-management strategies aiming to facilitate improvements in physical activity levels. Further to this, the study team conducted interviews with a subset of ten patients (five from both intervention arms) to understand potential barriers and facilitators to the implementation of the intervention [80]. The quantitative data collected with the feasibility RCT was not powered to detect any statistical significance in outcome data, and indeed there was no difference between the two groups 93 at 6-months follow in terms of the global rating of change (GROC), the visual analogue scale (VAS) for pain, the Tampa Scale for Kinesiophobia (TSK), the ‘Pain Catastrophizing Scale’ (PCS), the General Self Efficacy Scale (GSES), and the generic health outcome Euro-QOL (UK dataset) (EQ-5D-5 L). However, there was some difference when analyzing the qualitative data. Self-efficacy and locus of control was a theme discussed with all participants, however, patients in the experimental intervention group described narratives that were conceptualized as greater self-efficacy and greater internal locus of control, compared with patients in the usual physiotherapy group. Locus of control and self-efficacy are inter-related psychological constructs related to the power of thinking in achieving treatment outcomes and goals [81]; to put it another way, it’s how much an individual believes that have the capability to carry out a specific activity to achieve their goals [82]. Smith and colleagues suggested that improvements in pain and function may have been mediated, in some part, by greater self-efficacy and locus of control. In conclusion, quantitative methods dominate AKP research, and have focused on pain and biomechanics. Qualitative research can offer an insight into the experience of individuals living with AKP that cannot be measured with numbers. For example, this qualitative research suggest future intervention development and research is warranted into biopsychosocial targeted interventions that are aimed to address the pain-related fear identified. 7 Implications of Psychological Factors for Clinicians Who Are Treating AKP Patients People with severe AKP and psychological impairment may benefit from therapeutic strategies that target both the physical and nonphysical aspects of this pathological condition. Selhorst and colleagues [83] have shown that better functional results and better reduction of pain compared to a traditional approach in the short-term follow-up will occur if we address
94 V. Sanchis-Alfonso et al. psychosocial and physical impairments in the treatment algorithm of AKP patients. However, at six months follow-up, the majority of patients in both groups (sequential cognitive and physical approach group vs non-sequential physical impairment-based approach group) reported high levels of function, but 43% of patients still reported pain [83]. Moreover, we significantly reduce pain-related fear, pain catastrophizing, fear-avoidance beliefs, and improve function if we incorporate a brief one-time psychologically informed video into the standard physical therapy protocol [84, 85]. Priore and colleagues [86] have demonstrated that a knee brace is effective at reducing kinesiophobia. Therefore, the use of a knee brace could be a good strategy to improve exercise compliance by reducing kinesiophobia. De Oliveira Silva and colleagues [87] have shown that kinesiophobia may be a potential psychological mediator of pain and disability outcomes in AKP patients. The moderate relationship of kinesiophobia with self-reported pain and disability indicates that addressing kinesiophobia during treatment may be important to improve clinical outcomes. Kinesiophobia may play a more important role in the self-reported pain and disability than PFJ loading during stair ambulation. Future research should try to determine whether interventions targeting reductions in psychologic factors can effectively optimize rehabilitation and reduce the high rate of people with AKP reporting unfavorable outcomes in the long-term. – – – – 9 status of all patients with AKP, including those with severe structural anomalies. Our data shows that the presence of psychological factors is a limitation to recovery. That is, psychological factors are barriers to recovery. Patients with high levels of pain-related fear with pathology get back to normal or are at least much better mentally after effective treatment. Therefore, we should not ignore them. We need to look hard for pathology and help them, even if it takes more patience and tender loving care from the provider. Cognitive-behavioral therapy focused on reducing fear-avoidance behaviors and catastrophizing may influence the clinical state of AKP patients in a positive manner. Therefore, psychological therapies might be able to work together with physical therapy and surgical therapies in the treatment of AKP patients. The change in catastrophizing is the strongest predictor of changes in both pain and disability after treatment. Key Message – Psychological factors in AKP patients are modulators of pain and disability and should be addressed in combination with the search of structural causes. References 8 Take Home Messages – Chronic pain and disability in AKP patients are the result of a combination of biomechanical, anatomic and biological factors, as well as the social environment, psychological distress, and attitudes and beliefs, such as catastrophizing and kinesiophobia. – The clinical interest in addressing the whole picture is to identify the potentially modifiable factors to achieve better outcomes. Therefore, we must always evaluate the psychological 1. Melzack R, Casey KL. Sensory, motivational, and central control determinants of pain: a new conceptual model. In: Kenshalo D, editor. The skin senses. Springfield: CC Thomas; 1968. p. 423–39. 2. Moayedi M. All roads lead to the insula. Pain. 2014;155(10):1920–1. 3. Damasio AR, Grabowky TJ, Bechara A, et al. Subcortical and cortical brain activity during the feeling of self-generated emotions. Nat Neurosci. 2000;3:1049–56. 4. Domenech J, Sanchis-Alfonso V, Lopez L, et al. Influence of kinesiophobia and catastrophizing on pain and disability in anterior knee pain patients. Knee Surg Sports Traumatol Arthrosc. 2013;21:1562–8.
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Management of Anterior Knee Pain from the Physical Therapist’s Perspective Jenny McConnell Anterior knee pain is a complex and interesting disorder for clinicians to manage. Various soft tissue structures of the knee can generate neurosensory signals that result in conscious pain perception. It behooves the clinician to determine, where possible, the source of the symptoms and the underlying causative factors so the patient receives appropriate management for their anterior knee pain problem. Pain has biopsychosocial components, so the clinician is in an ideal position to determine how to effectively help the patient improve and manage their symptoms. As the patellofemoral joint is essentially a soft tissue joint, the clinician needs to examine the complex interaction of the dynamic loading and control of the lower limb, as well as the relative flexibility of various soft tissue structures to ascertain the appropriate management of the anterior knee pain symptoms. This requires a thorough understanding not only of the lower limb anatomy and mechanics, but also the neural innervation of the various soft tissue structures Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/978-3-031-09767-6_7. J. McConnell (&) Private Practice, Sydney, NSW, Australia e-mail: jenny@mcconnell-institute.com around the knee, and the effect of pain on muscle activation. This chapter will explore these issues to guide the clinician through an evidence based, clinical reasoned management approach to empower the patient to self-manage their symptoms. 1 Sources of Pain The tissue-based structures that can be a potential source of knee pain are the synovium, lateral retinaculum, subchondral bone, and the infrapatellar fat pad (IFP), with the articular cartilage because it is aneural, providing only an indirect source, perhaps either through synovial irritation or increasing bone stress [1–3]. As histologic changes in the synovium of patients with patellofemoral (PF) are only moderate, peripatellar synovitis is a possible but less likely source of knee pain symptoms. Histologic changes have also been found in some patients with PF pain in the lateral retinaculum with an increased number of myelinated and unmyelinated nerve fibres, neuroma formation and nerve fibrosis, providing evidence that in some individuals, a laterally tilted patella compromising the lateral retinacular structures, may be the source of the symptoms [2]. Additionally, increased intraosseous pressure of the patella has been found in patients with PF pain who complain of pain on prolonged sitting (movie goers’ knee), possibly secondary to a © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_7 99
100 J. McConnell transient venous outflow obstruction [3]. But the structure which possibly has the greatest impact on pain around the knee is the infrapatellar fat pad (Hoffa’s pad). Superolateral fat pad oedema is a frequent finding with patellar mal-tracking and may precede clinically significant chondrosis [1, 4, 5]. The IFP is a potent source of pain owing to its rich innervation and relationship with the highly innervated synovium [1, 5]. The IFP and the medial retinaculum of PF patients have a higher number of substance P fibers than the same structures of individuals without PF pain [5]. The IFP is a dynamic structure, displacing significantly during knee motion, which is, therefore, vulnerable to interference from trauma or repetitive overload [6]. The IFP stabilizes the patella in extremes of knee motion (that is less than 20° and greater than 100° of knee flexion), increases tibial external rotation and facilitates the distribution of synovial fluid [7]. Experimentally inducing knee pain by injecting hypotonic saline into the fat pad of asymptomatic individuals causes severe infrapatellar pain, as well as retro patellar pain, with some experiencing medial thigh and even groin pain [8]. 2 Effect of Pain The presence of pain will certainly decrease muscle activity, timing and endurance as well as alter movement patterns [9]. Experimental vastus medialis muscle pain has been found to reduce the EMG activity in the VM and VL muscles as well as attenuate the loading response phase peak knee extensor moments in gait [9, 10]. The observed changes persist when the pain disappears. So, muscle pain modulates the function of the quadriceps muscle, resulting in impaired knee joint control and joint instability during walking, which is a similar finding to patients with knee pain. This loss of joint control during and subsequent pain may leave the knee joint prone to injury and potentially participate in the chronicity of musculoskeletal problems [10]. Experimentally inducing pain in the IFP of asymptomatic individuals causes a decrease in both VMO and VL activity, but when a painful electric shock is randomly and intermittently applied to the knee, mimicking the fear of pain state experienced by PF pain patients, only VMO activity is decreased [9]. Thus, pain is a cortical experience, where extrinsic factors such as fear of pain, stress, anxiety, and depression can amplify the pain experience for the patient, so the contribution of these factors must be understood if we are to satisfactorily improve the rehabilitation of individuals with anterior knee pain. Depression typically affects 5% of the general population, but among patients with chronic pain, 30%–45% experience depression. Studies have shown that the relationship between depression and pain is bidirectional: depression is a positive predictor of the development of chronic pain, and chronic pain increases the risk of developing depression [11]. Neuroimaging suggests an anatomic overlap in the pathway of chronic pain and depression. Hence, positive psychological factors, such as hope, optimism, and pain acceptance may improve persistent and chronic pain [11]. In a study of 710 chronic low back pain sufferers, self-confidence to manage pain was the most commonly perceived selfmanagement barrier, with 40% of these individuals feeling they were not involved as equal partners in decision making and goal setting related to their care [12]. It is therefore essential for the clinician to develop a positive therapeutic relationship with the patient, so the pain chronicity and intensity may diminish with the patient’s improved understanding of how to manage their knee symptoms. In a recent study examining the psychological features of PF pain, no difference was found between PFP and painfree groups. However, when the PF groups were sub-grouped into severe and less severe, there were higher levels of psychological impairment in the more-severe PFP-related disability group compared with the less severe cases. Kinesiophobia was the most significant psychological factor followed by depression and catastrophizing [13]. To help unpack the complexity of patellofemoral pain and minimise the risk of established chronicity, an understanding of the knee joint
Management of Anterior Knee Pain from the Physical … anatomy and the inter-relationship of the dynamic lower limb mechanics is required, so an individually tailored treatment can be designed for the patient. 3 Anatomy and Biomechanics The patella articulates with the femoral trochlea during knee flexion and extension. The lateral aspect of the femoral trochlea extends further anteriorly than the medial aspect to provide inherent stability for the patella, once the patella is within the confines of the trochlea (from 2030o− knee flexion). Prior to this point, there is no bony support for the patella, and passive stability is provided by the medial and lateral retinaculum and the joint capsule [14]. The stability of the patella is also affected by the starting position of the femur [15]. Femoral anteversion changes the interrelationship of the patella and the femur. Passive stability for the patella in the first 20° of knee flexion is provided by the medial and lateral retinaculum and the joint capsule. The lateral side of the knee is made up of various fibrous layers from the iliotibial band and vastus lateralis to form the superficial and deep lateral retinaculum [14]. As most of the lateral retinaculum arises from the iliotibial band, tightness of the band, which has its greatest influence at 20° of knee flexion, will contribute to lateral tracking and tilt of the patella [15]. The retinacular support is stronger on the lateral side than it is on the medial side. Passive medial patellar stability is poor, so medial patellar stability needs to be achieved actively, which occurs through the muscular attachment of the medial quadriceps into the patella. The vastus medialis is commonly divided into the oblique portion, the VMO, and the more vertical component, the vastus medialis longus (VML) [16, 17] While there is often difficulty accurately distinguishing the VMO and VML as separate entities, most authors agree that they act as two distinct functional units due to their fibre orientation and attachments, and thus angle of force on the patella [18]. The VMO has significantly shorter mean fibre bundle length, greater 101 mean pennation angle, and smaller mean physiological cross-sectional area than VML. Sarcomere lengths of VMO and VML are comparable. The VMO, being more obliquely aligned (50 to 55° medially in the frontal plane) than the VML (15 to 18° medially in the frontal plane) [19], is more likely to contribute to medial patellar stabilization, whereas VML, with a larger relative excursion and force-generating capability, to the extension of the knee [19, 20]. It has been found on ultrasonography that athletic individuals have an even higher VMO fiber angle of 67.8°, providing a stronger medial stabilizing force on the patella, than sedentary individuals where it was 53.6° [21]. On the lateral side, the VL is oriented 12 to 15° laterally in the frontal plane with the obliquity of the distal fibres being greater. The VMO opposes the lateral vector force of the VL, allowing a more efficient extensor moment at the knee. Senavongse and Amis found in a cadaver study that relaxation of VMO caused a 30% reduction in lateral stability of the patella [14]. This is supported by the work Sheehan et al. [22], who found in asymptomatic individuals during a dynamic cine- phase contrast MRI that after motor branch block to the VMO, there was a lateral shift of the patella of up to 1.8 mm, a tibiofemoral lateral shift of up to 2.1 mm, and a tibiofemoral external rotation 3.7°; concluding that VMO weakness is a major factor in, but not the sole source of, altered PF kinematics in PF pain subjects. VMO is active throughout knee extension to keep the patella centred in the trochlea of the femur. Thus, the synergistic relationship between the medial and lateral vastii is important in maintaining the alignment of the patella within the femoral trochlea. Electromyographic (EMG) studies have demonstrated that the muscle activity of VMO and VL in the general asymptomatic population is relatively balanced in terms of activation, magnitude, and timing in a wide variety of static, dynamic, weightbearing and non-weightbearing activities [23, 24]. This synergistic relationship between the VMO and VL should maintain the alignment of the patella in the femoral trochlea in the first 30° of knee
102 flexion, before the patella is fully engaged in the trochlea. It has been proposed that this balanced activation of the VMO and VL is disrupted in patients with PFPS. The issue of whether the disruption could be a motor control dysfunction has been investigated by Mellor and Hodges [24, 25] who found that synchronization of motor unit action potentials, is reduced in PFP subjects (38%) compared with controls (90%). However, the evidence to support an imbalance in the activation of the vastii (either decreased activation of VMO or enhanced activation of VL) is contentious, as was examined in the systematic review by Smith et al. [26]. Differences in methodology (particularly with respect to the use of EMG) and the inherent heterogeneity in the PFPS population may account for some of the inconsistencies in study results. This prompted an impassioned plea by Grant el [27] to establish methodological uniformity in the PF field (albeit in this paper the concern was about measurement of maltracking), with specific standards for anatomic and outcome measures, as the large methodological variability across the literature not only hinders the generalization of results, but it mitigates understanding of the underlying mechanisms of PF pain. While there is inconclusive evidence to support or refute an imbalance in the magnitude of vastii activation in patients with PFPS, disrupted activation of the vastii may take the form of delayed activation of the VMO relative to the VL. It is hypothesized that the VMO, which has a smaller cross-sectional area than the VL, must receive a feedforward enhancement of its excitation level to track the patellar optimally. Many studies examining individuals with PFP have supported this hypothesis, by demonstrating that the EMG activity and reflex onset time of the VMO relative to the VL is delayed, when compared with asymptomatic individuals [23–25]. It seems that most PF sufferers have a delayed onset of VMO relative to VL on a stair stepping task (67% concentrically, 79% eccentrically), but it is apparent in some PFP patients there is no delay of VMO [23]. Additionally, in some asymptomatic individuals there is a delay in onset of VMO relative to VL (46% J. McConnell concentrically and 52% eccentrically) [23]. So, one could pose the hypothetical question, are these individuals at risk of developing PF pain in the future, if their activity level changes? Only a longitudinal study would determine the answer to this hypothetical question. What is apparent from the study by Cowan et al. [23] is the need for subgrouping of patients with PF pain and tailoring an individual program to their specific needs. If a delayed onset of VMO is detected, a treatment aim would be to facilitate a balance between medial and lateral structures, so the load through the joint could be distributed as evenly as possible. The control of the proximal segment by the pelvic muscles, particularly the gluteals, is critical for dynamically positioning the femur and hence the orientation of the trochlea. However, a recent systematic review to investigate the association between hip muscle strength and dynamic knee valgus found the relationship between hip muscle strength, including abductors, extensors, and external rotators and dynamic knee valgus conflicting [28]. Some studies have concluded that men with PFP show muscular weakness of the hip [29], whereas others have found no difference in hip strength in women between PFP sufferers and asymptomatic individuals [30]. Additionally, prospective studies indicate that hip weakness is not a risk for development of patellofemoral pain [31, 32]. In some clinical trials strength training of the gluteal muscles promotes improvement in symptoms in PF patients but does not alter the kinematics [33, 34]. These findings demonstrate that not all individuals suffering from PFP present with dynamic knee valgus and that perhaps only it is only a subgroup of patients that require strengthening of the hip musculature [33] or perhaps the problem is more an issue of control, timing, and endurance rather than just strength. There is also evidence that restricted ankle dorsiflexion range of motion may alter lowerextremity landing mechanics, whereby a smaller amount of ankle dorsiflexion displacement during landing is associated with less knee flexion displacement, greater ground reaction forces, and greater knee valgus displacement [35]. A meta-
Management of Anterior Knee Pain from the Physical … analysis by Lima et al. [36] confirms the relationship between reduced ankle dorsiflexion and increased dynamic knee valgus. These authors concluded that the assessment of dynamic ankle dorsiflexion in the clinical setting was important. It has been found during the step-down test, that individuals who have 17° or less of ankle dorsiflexion range of motion (ROM) display significantly greater hip adduction ROM than those with more than 17° of dorsiflexion [37]. When the heel is elevated in the step-down test, the same participants with limited dorsiflexion ROM showed a significant reduction in hip adduction ROM [37]. Thus, ankle dorsiflexion and midfoot mobility should be considered when assessing patients with aberrant frontal plane lower limb alignment. If ankle dorsiflexion is restricted then the subtalar and midfoot joints can compensate by pronating, provided the foot has sufficient mobility to allow this. The pronation allows further movement to occur at the foot and can cause an increase in dynamic knee valgus and hip adduction. A meta-analysis on the relationship between foot posture as a risk factor for overuse injuries showed very limited evidence that a pronated foot posture was a risk factor for patellofemoral pain development [38]. Kedroff and Amis [39] have recently found no relationship between foot posture and kinematics in PFP participants, thus questioning the use of orthoses to correct pronation. A recent study by Matthews et al. [40] confirmed there was no difference in success rates between foot orthoses versus hip exercises in those with high or low midfoot width mobility. These authors concluded that there was no association between midfoot width mobility and treatment outcome, and in their randomised controlled trial, there was no difference in success rate between foot orthoses and hip exercises in patients with PF pain [40]. However, some studies have indicated the benefit of using orthoses in the management of individuals with PF pain, particularly those who wear less supportive footwear, report lower levels of 103 pain, exhibit less ankle dorsiflexion range of motion, and report an immediate reduction in pain with foot orthoses [41, 42]. 4 Load and Frequency Forces in the PF joint are a function of the quadriceps and patellar tendon forces, which compress the patella against the femur. The PFJ Reaction Force (PFJRF) is equal and opposite to this resultant force and acts perpendicular to the articular surfaces and increases with increasing flexion, as the angle between the patellar tendon and the quadriceps becomes more acute. During normal daily activities the PFJ becomes exposed to force values between 0.5 (walking) to 9.7 (squatting and running) x body weight, whilst sporting activities create force values that approach up to 20 body weight [43]. It is apparent that not one factor is responsible for anterior knee pain symptoms (Table 1), but it is often the cumulative effect of too much load or too great a frequency of load, as has been well described by Dye in his seminal 1996 paper ‘The knee as a biologic transmission with an envelope of function: a theory’ [44], which hypothesizes that anterior knee pain is a consequence of an individual being taken out of their envelope of function (which differs from individual to individual), breaching their threshold, thus not being maintained in homeostasis, so soft tissues are overloaded and the individual experiences pain. Once pain is provoked, the individual can do less and less. Dye has identified four factors that influence an individual’s envelope of function. These are: (1) anatomic factors which relate to an individual’s inherent morphology, structural integrity & biomechanical characteristics (that is the parents they chose!); (2) kinematic factors which signify the dynamic control of the joint, that is the cerebral sequencing of motor units, indicating neural control of the limb and segment; (3) physiological factors which are the genetically determined mechanisms controlling
104 J. McConnell Table 1 Predisposing Factors for PF pain overuse patellar malposition abnormal foot mechanics poor VMO timing PF PAIN tight lateral structures poor pelvic mechanics poor pelvic control training errors quality and rate of repair and [4] the type of rehabilitation or surgery, which can be either beneficial or detrimental to recovery [44]. 5 History The initial part of the examination of the patient involves obtaining a detailed history, so a differential diagnosis can be proposed. The diagnosis is later confirmed or modified by the physical findings. In the history, the clinician needs to elicit, the area of pain, the type of activity precipitating the pain, the history of the onset of the pain, the behaviour of the pain and any associated clicking, giving way, or swelling [45]. This gives an indication of the structure/s involved and the likely diagnosis; for example, if the type of activity that precipitated the patient’s pain is one that involves eccentric loading, such as jumping in basketball or increased hill work during running, patellar tendinopathy would be suspected. On the other hand, if the athlete reports pain following tumble turning or vigorous kicking in swimming, or on delivery of a fast ball in cricket on the landing leg, an irritated fat pad would be suspected, as it is the rapid, forceful, end range extension of the knee, causing the inferior pole of the patella to jam suddenly into the nociceptive IFP [1]. In both these conditions the athlete complains of inferior patellar pain. The patient with an irritated fat pad is aggravated by straight leg raise exercises (SLR), so it is essential the clinician recognises the condition so appropriate management can be implemented to enhance, rather than, impede recovery. The clinical diagnosis of fat pad irritation may be confirmed on MRI on a T2 weighted image where inflammation of the fat pad may be visualised. Patellar tendinopathy can be confirmed on diagnostic ultrasound, particularly using colour doppler or with MRI. It is crucial as a treating clinician, once you have listened to the patient’s history to give the patient some knowledge about why they have pain, where their pain is coming from, and what is the expected length of time it may take for recovery. Knowledge is power and it is the clinician’s responsibility to empower the patient to manage their problem, and to emphasise that musculoskeletal problems are managed, not cured [46]. The importance of education for conceptual understanding (e.g., musculoskeletal diagnosis, pain), for physical performance (e.g., rehabilitative exercise, postural correction), and for behavioural change (e.g., modifying load) in patient management is paramount [45]. By enhancing the patient’s knowledge about their problem(s) and how to ‘self-manage’ it, they are empowered to increasingly take control of the situation and minimise the impact on their lifestyle. Education to improve understanding can
Management of Anterior Knee Pain from the Physical … lead to a decrease in patient fear, greater compliance, and a concurrent improvement in pain experienced and movement impairments [46]. This can be done by explaining Dye’s [44] model of homeostasis and envelope of function (which should be drawn sitting next to the patient) to help the patient have an idea as to why their knee pain started. Informing the patient about the effect of loading the knee with activities is important (such as 05 body weight goes through the knee with level walking, this increases to 3–4 body weight with stairs and 8–10 with running). Additionally, discussing with the patient the effect pain and fear of pain has on quadriceps muscle activity enhances the understanding of their problem. This summary is a helpful tool for the patient to take home and give them time to absorb the information. Knee pain !# quads ! more knee pain ! fear of pain !# VMO ! maltracking of patella ! more knee pain !" hamstrings and gastrocs activity !# ability to lengthen !" relative flexibility in lumbar spine and midfoot, when: (i) lifting !# knee flexion !" flexion of spine !" stress on spine. (ii) descending steps !# dorsiflexion !" pronation !" knee collapsing in !" knee pain. 6 Symptoms of Patellofemoral Pain The patient usually complains of a diffuse ache in the anterior knee, which is exacerbated by stair climbing. For many, the knee will ache when they’re sitting for prolonged periods with the knee flexed—the movie sign. However, patients with an irritated fat pad have pain with prolonged standing rather than prolonged sitting. Some patients will have crepitus, which is often a source of concern for them because they feel, that the crepitus is indicative of “arthritis”. This creates negative emotions, inaccurate etiological beliefs and ultimately leads to altered behaviour [47]. However, the crepitus is mostly due to tight deep lateral retinacular structures and can be improved with treatment. 105 Some patients may experience “giving way” or a buckling sensation of their knee. This occurs during walking or stair climbing i.e., movements in a straight line, and is a reflex inhibition of the quadriceps muscle. It must be differentiated from the giving way experienced when turning, which is indicative of an anterior cruciate deficient knee or patellofemoral instability. Locking is another symptom, which must be differentiated from intra-articular pathology. Patellofemoral locking is usually only a catching sensation where the patient can actively unlock the knee; unlike loose body or meniscal locking, where the patient is either, unable to unlock, or can only passively unlock, the knee. Mild swelling due to synovial irritation may also occur with patellofemoral problems. Mild swelling causes an asymmetric wasting of the quadriceps muscle, whereby the VMO is inhibited before the VL and rectus femoris (RF) [48]. So, an individual, who has primary intra- articular pathology, such as a meniscal or ligamentous injury and is recovering from knee surgery where quadriceps wasting is common, may have great difficulty resolving the subsequent secondary patellofemoral problem, particularly if it is not identified [49, 50]. When considering the possible differential diagnoses, the clinician must remember that the lumbar spine and the hip can refer symptoms to the knee. For example, the prepubescent male with a slipped femoral epiphysis may present with a limp and AKP so can initially be misdiagnosed as having PF pain. Neural tissue may also be a source of symptoms around the PF joint. Lack of mobility of the L5 and S1 nerve roots and their derivatives can give rise to posterior or lateral thigh pain, and dermatomal distribution of anterior thigh pain coming from the L3 nerve root. Symptoms from neural tissue can be relatively easily differentiated from PF symptoms because the pain will be exacerbated in sitting, particularly when the leg is straight rather than in the classic movie sign position of a flexed knee. The slump sitting test or prone knee band will quickly verify the neural tissue as being a source of the symptoms. Similarly, a peripheral nerve may scar down or become entrapped following arthroscopic
106 J. McConnell surgery. The commonest example is the infrapatellar branch of the saphenous nerve. Symptoms are sharp pain inferomedially with/without slightly altered sensation laterally. The symptoms can be reproduced on deep bend and jumping so they are frequently confused with patellar tendinopathy symptoms because of the proximity to the tendon. The clinician can usually reproduce this pain with the patient prone, flexing the knee to 90° and externally rotating the tibia, to put the nerve on stretch [45]. 7 Physical Examination The physical examination confirms the diagnosis and helps determine the underlying causative factors of the patient’s symptoms so the appropriate treatment can be implemented. By examining the patient’s standing position, the clinician should have a fair indication of how the patient will move. The clinician observes the patient from the front, the side and from behind, noting femoral orientation, foot posture, knee position and muscle bulk. For example, femoral internal rotation, a common finding in patients with patellofemoral pain, is often associated with a tight iliotibial band and poor hip muscle control, which can adversely affect the articulation of the patellofemoral joint and foot position. In weight bearing, if a pronated foot position is seen, this could be due to the foot compensating for many proximal deformities or the foot itself may have intrinsic issues causing pronation. The static foot position influences lower limb control and dynamic knee valgus. Additionally, if the patient is standing with hyperextended or ‘locked back’ knees, this can irritate the IFP, a potential source of diffuse knee pain symptoms and be indicative that inner range (0–20° flexion) quadriceps control of the knee is poor. Once the clinician has examined the patient in standing, the clinician then observes the patient during dynamic activities, commencing with the least stress activity of walking and progressing to stairs, squatting, and jumping if necessary. During this process, the clinician is evaluating the effect of muscle action on the limb mechanics. Table 2 summarises the dynamic implications of the static findings. However, the prime aim of the dynamic examination is to reproduce the patient’s symptoms, so if the symptoms are reproduced (>3 on visual analogue scale (VAS) with walking, there is no need to do further strenuous dynamic testing, but if the symptoms are not reproduced, then the clinician systematically increases the functional load until they have a valid objective reassessment activity to determine the effectiveness of their Table 2 Dynamic implications of static findings Foot – Callus medial aspect great toe – Enlarged 1st MTP – Morton’s toe Medial heel whip (unstable push off) – – – – ! ! ! ! Stiff 1st MTP Talus prominent medial Straight calcaneum Tight gastrocnemius early heel off prolonged pronation stiff subtalar joint " subtalar pronation early heel off Knee – Genu valgum – Hyperextended/locked back – Tight hamstrings !" pronation !# shock absorption !# dorsiflexion !" pronation Hip – Internal femoral rotation – Tight psoas !# hip extension & external rotation !# step length Pelvis – Anterior tilt – Posterior tilt – sway back !# hip ext & ER, # step length, " LS rotation !" pelvic tilt, poor glut med ! combination tilt & rotation
Management of Anterior Knee Pain from the Physical … 107 Table 3 Observation conclusions prior to analysing gait • • • • • • • • If If If If If If If If hallux valgus or enlarged MTP ! unstable push off talus prominent medial and straight or inverted calcaneum ! # shock absorption ! " pelvic instability hyperextended/ locked back knees ± pudgy fat pads ! " pelvic instability internal femoral rotation ! # hip extension and external rotation ! " pelvic rotation anterior tilt pelvis ! # hip extension and external rotation ! " pelvic rotation posterior tilt ! " lateral tilt of the pelvis sway back ! combination of lateral tilt & rotation of pelvis base of support > pelvis width ! lateral shift of trunk treatment. Table 3 describes the analysis the clinician performs before observing the patient’s gait. When examining athletes often these dynamic activities are not strenuous enough to reproduce their symptoms, as longer duration activities, such as running 15 kms, provoke symptoms. In this situation the clinician can evaluate the control of the one leg squat to determine the effect of treatment outcome. On the examination table, the clinician aims to reproduce the patient’s symptoms by palpating the around knee, including joint lines IFP and patella, as well as passively flexing and extending the knee with gentle overpressure. The clinician then examines the passive position of the patella relative to the femur, the flexibility of certain soft tissues such as anterior hip structures, hamstrings, gastrocnemius, and iliotibial band, as well as the relative strength of various muscles such as hip rotators, quadriceps, and tibialis posterior. It has been found however, that traditional nonweight-bearing (NWB) hip-strength assessments may not directly translate to functional strength during weight-bearing (WB) activity [51]. Thus, the clinician is advised to examine these muscles in a weight bearing position, so they have an idea of the relative control the muscle has over the lower extremity. 8 Treatment Most patellofemoral conditions are successfully managed with non-operative treatment. The aims of the treatment are to unload the painful structures around the PF joint, so the patient realises there is hope that their symptoms can be improved; to improve the lower limb mechanics to allow the patient to have long term control over managing their symptoms; and to empower the patient to self-manage their condition, emphasising that the condition is managed not cured. If, in the first treatment, the clinician can decrease the patient’s symptoms by at least 50%, the clinician has the patient’s buy-in, so compliance with treatment is almost always assured. Load modification, particularly for the athletic individual, may be necessary at the onset of symptoms to minimize pain flares. Table 4 provides a decision-making algorithm for treatment direction. For a more detailed picture of individualized clinically reasoned patient management, the reader is referred to the chapter ‘A Multifaceted Presentation of Knee Pain in a Forty-Year-Old Woman’ in Clinical reasoning in musculoskeletal practice by Mark A Jones and Darren A Rivett [46]. 8.1 Unloading Pain The immediate reduction in symptoms can be achieved by unloading the painful structures using tape (Fig. 1). Painful, inflamed tissue does respond well to stretch, so the principle of unloading painful tissue is to shorten the tissue, so there is an opportunity for the inflammation to decrease, promoting optimal repair. In this situation the most appropriate tape is a rigid nonstretch tape, as it provides support to the tissue, but still allows knee joint movement. It has been found in asymptomatic individuals, using elastography (supersonic shear imaging to measure muscle shear elastic modulus), that unloading tape reduces stress in the region underlying the tape [52].
108 J. McConnell Table 4 Decision making algorithm for treatment direction 1. # pain (i) tape to unload painful tissues. Tape must make an immediate 50% decrease in symptoms (ii) if patient is walking with knee flexed, as too painful to straighten knee, indicates inflamed IFP, so must unload— no quads sets or SLRs as will increase pain and delay recovery 2. If knee is locking back or hyperextending during walking, then poor inner range quads control (i) if condition irritable small ROM knee bends (0–30°), with soft, not locked back knees (ii) progress to walk standing position, symptomatic knee in front, small ROM knee bends (iii) show strategy of walking up and down stairs with a forward trunk lean- i.e., hip flexed position (iv) to facilitate VMO activity, can inhibit VL and TFL with tape and tape patella medially 3. If dynamic knee valgus on step down (i) check pelvic control (dynamic weight bearing gluteal control)—give subtle gluteal and trunk control training with slight knee bend, in weight bearing simulating walking position (ii) check dorsiflexion ROM (knee to wall test), If # then mobilise talocrural joint in WB (iii) check navicular position, if foot excessively pronated, then may need orthotics, improved footwear with adequate midfoot support (make sure laces are tied firmly), and foot exercises for tibialis posterior in WB ± intrinsic foot muscles. Could tape to control midfoot position—helps decision for orthotics 4. If tight soft tissue structures (i) anterior hip structures tight then prone Fig. 4 stretch (ii) If hamstrings tight, then seated hamstrings stretch, sit tall with LS in neutral (iii) if tight lateral structures, then STM lateral retinaculum, tilt tape (iv) if tight gastrocnemius, then standing stretch off step control foot position (v) if RF tight, then quads stretch care not to over-flex knee, as can aggravate symptoms 5. If you suspect CRPS (i) explanation to patient about pain and central sensitisation (ii) show patient how to desensitise area with different textures, do not focus on the knee A Fig. 1 Unloading the IFP. The patient is in supine with the leg relaxed, if there is too much pain for the patient to have their leg straight, then a small rolled up towel may be placed under the knee. After tilting the patella out of the IFP by commencing the tilt and glide tape half up on the patella from the inferior pole. The clinician lifts the soft B tissue on the medial side of the tibial tubercle, to the medial epicondyle (A) lifting the soft tissue towards the patella to shorten the tissues and on the lateral side to the lateral side of the joint, lifting the tissues towards the patella. The clinician is aiming for a ‘muffin top’ effect
Management of Anterior Knee Pain from the Physical … Taping the patella should be individualised to each patient, so the optimal reduction in symptoms can be achieved. In many cases the patient’s IFP is inflamed, so the clinician needs to ensure that the inferior pole of the patella is tilted away from the IFP so as not to further aggravate the symptoms. This component must always be identified and corrected first, usually with a correction of a lateral tilt tape, so the patient’s symptoms are not aggravated by positioning the tape too low on the patella. If the patella is laterally tilted then the patella won’t be able to engage well in the trochlea, so a lateral tilt correction must be performed before a glide correction. For effective sustained symptom reduction, the tape needs to remain on the knee and changed when it loosens. If the patient is fairly sedentary, one taping application may last a week, even with showering. However, if the patient is playing sport and the skin becomes sweaty, the tape may only last until the end of a run or the game before it needs to be reapplied. Thus, the patient needs to be taught how to tape their own knee. This is done with the patient sitting on the edge of a chair, leg extended and relaxed, foot resting on the floor, so the patella is mobile and can be more easily moved (Fig. 2). The evidence in the literature about the effectiveness of tape is mixed, whether using Fig. 2 Self-tape. A The patient sits on the edge of a chair with the leg extended and the knee relaxed, so they can move the patella B The patient is taught how to tape their own knee A 109 rigid or elasticised tape [53]. However, taping is a means to an end, and as such, is an adjunct to treatment. It was never meant to be used in isolation; it is part of the symptom management program. If the tape does not reduce the symptoms by at least 50%, then the clinician needs to consider whether: (1) the tape positioning was correct—it could be too low on the patella, causing an irritation of the fat pad; (2) the tape application was poor—too much tension, resulting in skin breakdown or not enough tension, resulting in taping that is ineffective and may as well not be there; (3) the tape was applied in too much knee flexion—if the knee is flexed >30° then the patella is already lodged in the trochlea, albeit not well aligned; (4) tape was not appropriate for that patient—you should not put tape on the knee of anyone you suspect has complex regional pain syndrome (CRPS), as it will make them worse, or tape is inappropriate for someone whose symptoms are only mild, and therefore, aren’t bad enough to warrant taping. An understanding of the effect of creep on collagenous tissue helps explain some of the rationale behind certain taping techniques. Creep is the tendency of a viscoelastic material to elongate during a sustained low load. So, if the lateral retinacular tissues are tight, causing a tilt of the patella, tilt tape can be used to provide a B
110 J. McConnell sustained low load on those tissues to progressively elongate them, while at the same time shortening the medial structures to promote a more effective VMO activation. Additionally, tape can be used to facilitate muscle activity by shortening the muscle and taping in the direction of the muscle fibres, as well as to minimise excessive muscle activity, by taping firmly across the muscle belly. This can expedite symptom improvement. Examples would be the use of tape to facilitate external femoral rotation to decrease dynamic knee valgus, taping the gluteals to enhance gluteal activation, taping the mid foot to facilitate tibialis posterior activity and taping firmly across the VL and TFL to encourage VMO and gluteal activity [54, 55]. Figure 3 demonstrates tape to minimise activity in TFL and VL. The clinician needs to be aware that tape use can cause some skin problems: (1) namely A Fig. 3 A Inhibiting VL and distal ITB—firm tape across the VL, just above the lateral patella—from posterior to anterior thigh, making a pucker in the skin to squash the muscle. May do another tape in the same direction higher friction rub, which usually occurs on the medial aspect of the knee, so even tension with the application of tape and the careful removal of the tape will minimize the risk; and (2) less commonly an allergic reaction where the use of hypoallergenic creams or sprays to protect the skin beneath the tape will decrease the possibility of a skin rash. 8.2 Improving Dynamic Lower Limb Loading Focussing on a quadriceps strategy, a hip strategy, or a foot strategy in rehabilitation is unrealistic for the PF patient, as muscles work synergistically to control the limb in weight bearing and it is this subtle muscle control that the patient has lost that needs to be restored. The patient needs to realise that they are requiring B up the thigh, B Inhibiting TFL. On the muscle belly of TFL, firmly taping across from anterior to posterior, again making a pucker in the skin to squash the muscle
Management of Anterior Knee Pain from the Physical … subtle changes in the motor program (body management strategies) and as such it is not necessarily strength changes, they need but the right muscles at the right time. The clinician needs to improve the synergistic patterning of the lower limb muscles, so these muscles respond quickly and dynamically to a new motor program. In individuals with pain, particularly in the chronic situation, an abnormal motor pattern becomes the normal, such that the strong muscles become stronger, and the weak muscles stay weak, as the strong will overpower the weak, which will further enhance the imbalance and increase the loading on the painful tissues. Hence the need for the clinician to implement subtle changes in the way the muscles are working dynamically i.e., brain training. Synergic control can be learned and modified. When learning a new skill or modifying a previously learned skill, cognitive processes contribute to the planning of the movement performance; perception guides the action; and synergies form between different body components to allow flexible, yet stable movement control [56]. It is only through extensive practice that goal- relevant movement solutions are established, so performance and learning improve. Therefore, new movement patterns are shaped by practice, as well as by contextual factors where the practice takes place [57]. So, practicing motor skills needs to be in the specific context in which the behaviour is intended to apply. Perception develops differently depending on the contextual properties in which a motor skill is practiced, and generally motor skills learned in the laboratory or lying on the treatment table in a clinic transfer poorly to contexts outside the controlled environment of the lab or the clinic (i.e., the learned behaviour is not functional to requirements outside the controlled environment) [58]. For example, for an individual with PFP who is experiencing pain on load bearing in an upright position, the training needs to be performed in this context specific position to ensure a change in the synergistic patterning of the lower limb muscles to allow the appropriate muscles to be strengthened (Fig. 4), rather than lying on the table and lifting their leg 111 up in the air (i.e., doing SLRs), often with a weight around the ankle. It has been found that WB or closed kinetic chain (CKC) training is more effective than open chain exercises (OKC), as it promotes a more simultaneous onset of EMG activity of the four different muscle portions of the quadriceps compared with OKC [58]. In OKC, RF activates earliest, while the VMO is activated last with smaller amplitude than in CKC, so CKC exercise promotes a more balanced initial quadriceps activation and increases the thickness of the VMO, than OKC exercises [59]. Additionally, CKC training allows simultaneous training not only of the vasti but also the gluteals and trunk muscles to control the limb position in WB [58]. In performing CKC squat exercises, the range should be restricted to the inner range, not greater than 45° of knee flexion to minimize PFJ stress [60], but preferably only to 30° to enhance VMO activation and improve the seating of the patella in the trochlea. While performing these squats, the patient needs to concentrate on their limb alignment, as well as the control of the movement concentrically and eccentrically. Improving control of lower limb mechanics should therefore be individualised to each patient depending on what was found on assessment. Barton el al. [61] concluded that ‘an individually tailored multimodal intervention programme including gluteal and quadriceps strengthening, patellar taping and an emphasis on education and activity modification should be prescribed for patients with PFP’. This has been validated in a study by Keays et al. [62] who found that individualized treatment supplementing local standard physiotherapy for PFP lead to greater improvement in symptoms. These authors felt that recognition of different subgroups may guide treatment that should include both local and deficit-targeted global treatment. So, for example if a patient exhibiting dynamic knee valgus on stair decent is given hip strengthening exercises without the clinician evaluating their dynamic talocrural ROM, which if found to be restricted on knee to wall test, the patient’s symptoms on stairs will not change until the clinician mobilises
112 A J. McConnell B C Fig. 4 Training the standing leg to improve synergistic control for walking, stairs and running. A To commence the patient stands 45o to the wall, the NWB leg is bent up with the knee touching the wall, for balance no pushing. The patient’s weight is fully on the standing leg, with the weight back through the heel, the knee slightly bent, and the pelvis tucked under slightly. The patient stands tall and externally rotates the standing leg thigh slightly without moving the hip or the foot. The patient should feel the standing leg gluteal is working. The patient holds this position for 15 s. B This exercise can be progressed by getting the patient to stand on a pillow, simulating an unstable surface or rough ground, C The exercise can also be progressed by adding an elasticised band, knotted and then jammed in the door, tying a loop around the other end for the NWB (unaffected) ankle. The patient pulls the band forward and back, while maintaining the position described in 4a to simulate running the talocrurual joint in weight bearing to increase the dynamic dorsiflexion range (Fig. 5). The clinician can help the patient maintain the range by showing the patient how to self-mobilise using a seat belt and giving the patient foot exercises to improve the control of the foot. Addition of an intervention program consisting of short foot exercises has been shown to have positive effects on knee pain, navicular position, and rearfoot posture [63]. Kısacık et al. [63] suggested that the increase in the strength of the hip extensors could be associated with improved stabilization afforded by the foot musculature. Alternatively, the clinician could give the patient a heel raise to decrease the amount of dorsiflexion required, or an orthosis to decrease the compensatory pronation. In this case, the clinician has made the ground different to the foot, whereas mobilising the talocrural joint or training the foot musculature makes the foot look different to the ground. Each can be effective- one is dynamic control; the other is passively changing the starting position. Thus, an evidence-based, holistic approach should include a graded exposure to load with the patient’s activities and exercise, as well as consider other factors such as diet to additionally decrease load, sleep quality and quantity, and external stressors (psychosocial factors). So perhaps, when clinicians are assessing who will benefit from what strategy, clinicians also need to examine patient compliance and motivation to do the exercise program (daily strategies). Compliance to exercise is poor, if the patient experiences increased pain during exercise therefore, strategies to decrease initial pain are important. As some patients may not be as motivated as others, perhaps they would do better in the longer term,
Management of Anterior Knee Pain from the Physical … A 113 B Fig. 5 A Mobilising the talocrural joint in weight bearing with a seat belt. B Self mobilisation with an orthosis rather than do foot exercises or a knee brace rather than do weight bearing functional exercises, as using an external device is simple, taking little time or effort. However, compliance can be an issue with orthotic use, with comfort of the orthotic a key factor in improving compliance. When examining the effectiveness of randomized controlled trials, patients are most compliant in the initial period, so effectiveness of physiotherapy intervention should be evaluated at the end of the physio intervention [64]. At follow up the majority of patients are partially compliant, but the treatment effect is diluted by those who were not compliant [64]. Campbell et al. [64] suggest that clinicians should move away from viewing patients as either compliers or non-compliers with therapy, but to include them as partners in rational decisions about therapy. This would be particularly true of the adolescent age group, who are notoriously noncompliant with exercise. Continued compliance is an interplay between the condition (knee pain), perception about the cause of the pain and the underlying consequence of persistent chronic pain with catastrophizing, kinesiophobia, depression, and belief that the intervention could be effective, as well as the motivation, willingness, and ability to incorporate the exercises into everyday life. This is why, in a maintenance program, the exercises must be easy to do, need no equipment, not be too many (maximum of 4), taking no more than 5 min, so they can be incorporated into everyday life. Empowering the patient to self-manage and have control is critical to the success of PFP management or any chronic musculoskeletal condition for that matter. The most compliant patients want some further input from the physiotherapist, rather than just being discharged (i.e., a body service every 6 months, just like a car service) [64]. A recent study of a 6-week internet-based exercise program for PF pain without seeing a clinician, resulted in only 8% of enrolled participants completing the program (860 initially, 70 completed), highlighting the need for a therapist involved approach for patients with PF pain [65]. 8.3 Treatment Progression Once the patient’s day to day symptoms are more under control, the clinician needs to help the patient incorporate increased knee loading and endurance into their activity program. This will necessitate establishing what activities the patient likes to do, whether it be walking, running, cycling, or swimming. Some patients enjoy and
114 benefit from the routine and camaraderie of a group exercise class, whether it be aquarobics, Pilates, yoga, boxing or a spin or pump class. Participation in the class should be encouraged, provided the patient can learn to pace themselves i.e., don’t do too many classes in a week; and learn to minimize the extremes of range and load in the exercise, as well as to recognize the warning signs of overdoing it, such as when the muscles are fatiguing. Organized exercises classes have huge benefits for mental health, and as such can help minimize some of the psychosocial effects of the patient’s symptoms. As many patients experience pain during stair ascent and descent, one of the aims of treatment is to improve the patient’s ability to negotiate stairs without reproducing symptoms. The patients need to practice stepping up and down, initially using a small step, perhaps with a forward trunk lean and flexed hips to minimize the stress on the PF joint, then they can progress to a more upright position, practicing in front of a mirror so that changes in limb alignment can be observed and deviations can be observed and corrected. Some patients may be able to do only a small number of repetitions with correct lower limb alignment. Since inappropriate practice can be detrimental to learning, using a small number of exercises with correct alignment is sufficient until the patient can perform larger numbers, pain-free and with correct lower limb alignment. Initially, a small number of exercises should be performed frequently throughout the day. The number of repetitions should be increased as the symptoms decrease, and the endurance improves. For further progression, the patient can move to a larger step, initially decreasing the number of contractions and then slowly increasing them again. As the control improves, the patient can alter the speed of their stepping activity and may vary the place on descent where they stop going down. To increase the load, the addition of weights in the hands or in a backpack on the back may gradually be introduced, but with the addition of increased weight, repetitions and movement speed should J. McConnell be decreased, then as control and symptoms improve built back up again. The aim of retraining is to make the transition from functional exercises to functional activities. When advising about power walking or running, the clinician can suggest to the patient to imagine that someone is pushing them forward in the shoulder blade area. This results in a more mid to forefoot strike pattern, which should decrease PF joint stress [66]. Implementation of forefoot strike training programs has been found to be helpful in the treatment of runners with patellofemoral pain [66]. However, it is suggested that the transition to a forefoot strike pattern should be completed in a graduated manner, as this strike pattern can overload the Achilles tendon [66]. Training should also be applicable to the patient’s activities/sport, so that a jumping athlete, for example, should have jumping incorporated in the program. Plyometric routines such as bounding, jumping and turning, jumping off boxes, are an important part of rehabilitation for the high-performance athlete before they return to their sport. Once a more balanced activation pattern of the quadriceps has been established, an extremely beneficial method of improving quadriceps strength is cycling, as this does not load the PF joint as much as running sports, particularly if the activity of the VL is minimized, so a more even quadriceps loading can be attained. Quadriceps strength deficits, particularly medial quadriceps, have been implicated in the research on causes of PF pain [32, 48] and the development of knee osteoarthritis [67]. Endurance training is also essential to ensure more resilience for the patient. The number of repetitions performed by the patient at a training session depends upon the onset of muscle fatigue. Initially, it is important to emphasize quality and not quantity, progressing to increase the number of repetitions before the onset of fatigue. Patients should be taught to recognize muscle fatigue or quivering, so that they do not train through the fatigue and risk exacerbating their symptoms.
Management of Anterior Knee Pain from the Physical … 9 Conclusion To effectively help a patient manage their PF symptoms, the clinician initially needs to explain to patient (1) why they have pain and where their symptoms are coming from; (2) to understand the patient’s goals; and (3) to help manage their expectations. In treatment, it is imperative that the clinician helps the patient manage their symptoms by showing them how to unload their painful structures and improve dynamic limb loading which involves weight bearing hip, knee, and foot muscle training. The clinician needs to emphasise that PFP is not cured but is managed by ensuring that the exercise regime is incorporated into the patient’s daily routine. The exercises should only take five minutes otherwise the patient is unlikely to continue with the exercises. The patient needs to realise that to keep the knee in “good health”, these exercises are like cleaning their teeth—essential part of body maintenance. No more than four, but preferably three exercises should be given as maintenance training, where no equipment is needed so the patient can do the exercises at any time and place. The patient should be encouraged to participate in regular other exercise that they enjoy, as it is a prudent way of ensuring ongoing knee and general wellness. Patients need advice on how to stand, so as not to overload their soft tissue structures (modified ballet 3rd position (Fig. 6), except for patients with large genu varum, as they cannot get their legs to touch) and how to get out of a chair without using their hands, keeping their knees over their feet. The clinician needs to encourage the patient to be actively engaged in their rehabilitation. A follow up every 6 or 12 months for wellness maintenance demonstrates to the patient that you, the clinician, are part of their team and are wanting a continued, successful outcome for them. 10 115 Take-Home Messages (1) AKP is managed, not cured, and requires ongoing maintenance to prevent recurrences. Fig. 6 Modified ballet 3rd position, legs touching, soft knees (2) Understand the patient’s goals and expectations and help manage their expectations. (3) Knowledge is power, so you need to give an appropriate explanation to the patient about where their symptoms are coming from, the causative factors, and what they can do to help. (4) Provide an individualized management program tailored to each patient, based on assessment of their issues.
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Targeted Treatment in Anterior Knee Pain Patients According to Subgroups Versus Multimodal Treatment James Selfe 1 Introduction and Background The current best evidence-based non-surgical treatment for patellofemoral pain (PFP) is multimodal therapy, core components of this approach include, but are not limited to, a diverse mix of exercise therapy (e.g. strengthening, stretching); patellar taping or bracing; foot orthoses [1]. However, multimodal therapy is not uniformly applied either in clinical practice or across research studies [1, 2] and there is limited evidence supporting the longer-term outcomes of this approach [3–6]. In view of the reported poor long-term success of the non-surgical multimodal approach, alternative solutions have been sought, and support for developing stratified care using diagnostic subgrouping with matched interventions for PFP has grown. This mirrors a broader trend in the management of other musculoskeletal conditions such as, low back pain where stratified care has proved effective for optimising patient outcomes [7, 8]. Currently, J. Selfe (&) Faculty of Health and Education, Department of Health Professions, Manchester Metropolitan University, Manchester, UK e-mail: J.Selfe@mmu.ac.uk Visiting Academic in Physiotherapy Studies, Satakunta University of Applied Sciences, Pori, Finland however, within the field of PFP there is limited evidence as to whether a stratified care approach improves patient outcomes. This is mostly due to there being no consensus on what the most important diagnostic subgroups are from a nonsurgical clinical perspective. This chapter reviews the current state of knowledge for PFP subgrouping and introduces readers to some of the modern methodological approaches employed to derive subgroups. 2 Complex PFP Stratification Frameworks Although interest in personalised medicine and stratified care has risen in recent years and the associated methodological approaches to stratified care and subgroup identification have advanced considerably, the concept of identifying subgroups within the PFP population is not new. For example, Holmes and Clancy in 1998 (p. 299), (14) when discussing the management of PFP patients [9], argued that: an adequate classification system should aid in proper diagnosis and treatment of specific problems. If properly devised, it should also aid in the comparison of results between different treatment centres. In addition, it should be a system that is simple and useful in the clinical setting with minimal use of complicated imaging techniques. However, it can be seen in Table 1 that many attempts at producing stratification frameworks © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_8 119
120 J. Selfe Table 1 Complex stratification frameworks containing multiple PFP subgroups (Adapted from Selfe et al. [10]) Author/s Groups and subgroups Merchant [11] 5 major groups • Trauma • Patellofemoral dysplasia • Idiopathic chondromalacia patellae • Osteochondritis dissecans • Synovial plicae Subgroups described for each of these specific conditions (Total = 38 subgroups) Wilk et al. [12] 8 major groups • Patellar compression syndromes • Patellar instability • Biomechanical dysfunction • Direct patellar trauma • Soft tissue lesions • Overuse syndromes • Osteochondritis diseases • Neurologic disorders Subgroups described for some of these specific conditions Treatment suggestions for each of the 8 major groups briefly discussed (Total = 26 subgroups) Holmes and Clancy [9] 3 Major groups • Patellofemoral instability • PFP with malalignment but no episodes of instability • PFP without malalignment Subgroups described for each of these specific conditions (Total = 60 subgroups) Witvrouw et al. [13] 2 Major groups 5 Minor groups • Malalignment – Malalignment of entire leg – Malalignment of Patellofemoral Joint (PFJ) • Muscular dysfunction – Strength deficit – Neuromuscular dysfunction –Flexibility Subgroups described for some of these specific conditions Evidence-based treatment recommendations presented (Total = 13 subgroups) Powers et al. [14] 3 Major groups 4 Minor groups • Reduced cartilage thickness • Decreased PFJ contact area –Patella malalignment or tracking • Increased PFJ reaction forces – Altered tibiofemoral joint kinematics – Muscle tightness – Altered tibiofemoral joint kinetics Literature review and international expert consensus statement on the evidence supporting each subgroup (Total = 15 subgroups)
Targeted Treatment in Anterior Knee Pain Patients According … for PFP, have resulted in complex systems, generating multiple subgroups that often rely on using specialist high-cost equipment for identification. These complex stratification frameworks may be very useful in highly specialised clinical settings and they may also be good for guiding research activity but in routine clinical practice a stratification framework with a double-digit number of PFP subgroups is unlikely to be readily adopted. Recent methodological frameworks on designing subgrouping studies provide further understanding on why many of the attempts to subgroup patients in PFP have not translated well into clinical practice, some of these are discussed in the next section. The PROGRESS partnership [15] provides some broad recommendations and the Medical Research Council (MRC) [16] provides a framework on development, design and analysis in stratification research (Fig. 1). An important issue stressed in both the PROGRESS recommendations [15] and the MRC framework [16] is the consideration throughout the research process of the clinical relevance, especially if the purpose of the 121 identification of subgroups is to improve treatment outcomes. Therefore, researchers need to consider the feasibility and acceptability of implementing the test and the treatment from both patient and health professional perspectives. This helps direct the choice of how many and which tests to use, test thresholds or cut point scores for allocation of patients to subgroups and the overall number of subgroups. Table 1 highlighted one of the key limitations in the search for PFP subgroups to date i.e., each of these stratification frameworks has generated a doubledigit number of subgroups the complexity of which limits their clinical utility. 3 Simple PFP Stratification Frameworks Table 2 presents six PFP papers that have proposed much simpler stratification frameworks resulting in either 3 or 4 subgroups. Although employing differing methodologies and including slightly different and heterogenous populations there are some notable areas of Fig. 1 Key steps in stratification and subgrouping research based on PROGRESS partnership recommendations [15] and MRC [16] framework
122 Table 2 Simple stratification frameworks containing low numbers of PFP subgroups (Adapted from Selfe et al. [10]) J. Selfe Author/s Groups and Subgroups Post [17] 2 Major groups • Unstable PFJ (surgery required) • Stable PFJ – Extremity alignment – Soft tissue mobility/flexibility – Dynamic control (Total = 4 subgroups) Selhorst et al. [18] Elevated fear avoidance Decreased muscle flexibility Functional malalignment Decreased muscle strength (Total = 4 subgroups) Keays et al. [19] Hypermobility Hypomobility Faulty movement pattern Osteoarthritis (Total = 4 subgroups) Selfe et al. [20] Strong Weak and Tight Weak and Pronated (Total = 3 subgroups) Drew et al. [21] Strong Pronation and Malalignment Weak Flexible (Total = 4 subgroups) Willy et al. [22] Overuse/Overload Muscle Performance deficits Movement coordination deficits Mobility impairments (hyper/hypomobile) (Total = 4 subgroups) Also need to consider – Tissue Irritability – Psychological Factors overlap in the proposed subgroups in Table 2 with all papers suggesting a subgroup related to abnormal muscle length/flexibility. The key muscles of interest are the lower limb biarticular muscles. • Rectus femoris • Hamstrings group • Gastrocnemius During gait there is a simultaneous concentric and eccentric contraction at the opposite ends of these biarticular muscles which is overlayed onto and coordinated with uniarticular muscle contraction to enable smooth locomotion. The sophistication and complexity of the neurophysiological control mechanism that enables this to occur is remarkable and so it is therefore unsurprising that these muscles are often implicated in PFP. With respect to the PROGRESS recommendations [15] and the MRC framework [16] (Fig. 1) muscle length tests represent good candidates to include in a PFP subgrouping model. As described above there is a strong mechanobiologic rational for including them, there are objective data on important clinimetric properties such as validity, reliability and there are thresholds/cut points to define excess tightness or excess flexibility which could help guide subgroup allocation. In
Targeted Treatment in Anterior Knee Pain Patients According … addition, from a clinical perspective muscle length tests are feasible and acceptable to both patients and clinicians, they are routine tests familiar to most clinicians, they are quickly performed and they require very low-cost measurement tools such as goniometers or tape measures to collect the relevant data. Most of the papers in Table 2 also refer to a muscle strength subgroup usually including the quadriceps femoris and various combinations of the muscles around the hip that provide proximal control of the femur. The majority of the preceding points supporting the candidacy of muscle length as a potentially important clinical subgroup of PFP also apply to muscle strength. The main difference is that the tools for measuring muscle strength in clinical environments such as hand-held dynamometers although overall not high cost are more expensive than those required to measure muscle length and are therefore not as readily available in all clinical settings. The other main area of consensus is the emergence of a ‘kinematic’ subgroup, which is referred to by a variety of descriptive nonscientific names i.e. dynamic control [17], functional mal-alignment [18], faulty movement pattern [19], movement coordination [22]. As physiotherapy sits firmly within an exercise and movement paradigm it is not surprising to see the emergence of a kinematic subgroup and from a clinical perspective many clinicians would expect to see a movement related subgroup of PFP patients. However, whilst there may be a high degree of ecological validity and clinical acceptability for a kinematic subgroup there are currently a number of technical challenges to establishing this as a viable PFP subgroup. These relate mostly to Stage 3 in Fig. 1 which refers to test measurement properties such as what is the level of validity and reliability of the tests used to assess kinematic deficit? and what thresholds/cut points should be used to define the extent of the deficit? In the field of measuring kinematics complex and expensive three-dimensional motion analysis systems may provide some answers [23] but these are unlikely to become routinely used in clinical practice. Simple to use, low-cost clinical systems have yet to be well 123 developed, and although there is promising work around the use of mobile digital technology such as phones and tablets [24, 25], these approaches have not yet been subjected to large scale testing. It is also important to consider what the interrelationships may be between kiniesiophobia, faulty kinematics and muscle strength. For example it would be anticipated patients who are ‘weak’ would demonstrate poor kinematics but equally in those patients who are strong it may be important to remember the famous Pirelli tyre advertisement that stated. Power is nothing without control. Virtually all the subgroups listed in Tables 1 and 2 are based on physical or biomechanical factors. Only one paper [18] lists a specific psychosocial subgroup and only one other [22] mentions that psychosocial factors should be considered. It is also interesting to consider that no papers refer to any physiological subgroups, only one paper [22] mentions that tissue irritability should be considered. In light of the wellestablished Tissue Homeostasis Model [26, 27] and its extension the Neural Model [28] it is perhaps surprising to see no potential physiological subgroups listed in either Table 1 or 2. Step 2 in Fig. 1 probably explains the reason for this, as defining specific relevant physiological variables that would be relatively easy to measure from a clinical perspective is challenging. 4 Targeted Intervention for Patellofemoral Pains (TIPPs) As previously stated few subgrouping studies in PFP have followed the PROGRESS partnership [15] and the Medical Research Council (MRC) [16] guidance on stratification research. Selfe et al. [20] and Drew et al. [21] are exceptions to this, both studies based their approaches on rigorous statistical methods and adopted hypothesis-driven approaches initially using data to identify clinically important subgroups and then explored the prognostic effect attributed to subgroup membership [29]. The TIPPs programme of work [20, 30] has also in line with the
124 J. Selfe Potenal Subgroups Simple low cost evidence based clinical test Published threshold for test? Evidence based matched intervenon Potenal subgroups Fig. 2 Process for identifying appropriate clinical tests and potential subgroups MRC framework [16] adopted an iterative approach consisting of multiple phases (Fig. 1) in order to identify and validate potential subgroups within the PFP population using readily available, low cost, easy to use tools found in routine clinical practice. We conducted a series of literature searches to draw up an initial ‘long list’ of potential subgroups. One of the key documents guiding this phase of our work was the First International PFP Research Retreat [31]. This consensus proposed three subgroups based on the global anatomical region thought to be responsible for the problem i.e., proximal, local, distal. In order to facilitate implementation into clinical settings, assessments were deemed appropriate when they were: based on evidence of diagnostic performance; applicable to be used in a wide range of clinical settings; easy to learn and administer; free to use or available at a low cost; linked to reported thresholds; matched to a credible evidence-based treatment intervention (Fig. 2). Through this process, seven assessments were identified (Table 3). We then conducted a feasibility study to investigate if these assessments could be performed in routine clinical practice, if they could identify clinically relevant subgroups and what the optimum test thresholds for subgroup allocation might be within a UK population. Four National Health Service (NHS) physiotherapy clinics, serving the general population, in the UK recruited 130 people with PFP. Participants were between 18 and 40 years old, experienced uni- or bilateral PFP for at least three months, and had not yet started physiotherapy treatment. Additional study details and eligibility criteria are presented in Selfe et al. [20, 30]. Participants completed demographic, clinical, and psychosocial questionnaires related to aspects of PFP and were clinically assessed using the seven tests. Baseline demographics, such as, sex and age, were in line with those reported by others [36, 37]. A causal pathway diagram, based on the broader literature review, specific consensus documents and expert opinion around the proximal, local and distal subgroups informed the analytical approach. Both hierarchical agglomerative cluster analysis and latent profile analysis were used to explore the existence of subgroups within the sample. Surprisingly, the Hamstrings length test mean scores were similar across all subgroups identified by preliminary analyses and so this was excluded from further analysis. Three subgroups were found and are illustrated in Fig. 3. Both weak subgroups were consistent with expectations, however, the strong subgroup was Table 3 Seven assessments mapped to the appropriate evidence-based matched treatment option (Adapted from Selfe et al. [30]) Assessments Evidence based matched treatment option Hand held dynamometry for hip abductor strength (Nm/kg) [32] Hip Abductor strengthening Hand held dynamometry for quadriceps strength (Nm/kg) [32] Quadriceps strengthening Medial–lateral patellar mobility test (mm) [33] Patella stabilisation or mobilisation Foot Posture Index (FPI) [34] Foot orthotics ) Rectus femoris length test (degrees) [33] Hamstrings length test (degrees) [35] Gastrocnemius length test (degrees) [33] Muscle stretching
Targeted Treatment in Anterior Knee Pain Patients According … STRONG (22%) WEAK AND TIGHT (39%) Strong leg muscles Weak leg muscles Higher level of function and Quality of Life Lower level of Activity and Function More males Higher BMI Oldest group Highest level of neuropathic pain and longest pain duration Hypomobile patella Tight leg muscles 125 PRONATED AND WEAK (39%) Pronated feet (FPI>6) Weak leg muscles Youngest group Shortest pain duration Hypomobile patella More females Fig. 3 TIPPs subgroups adapted from Janssen 2017 [38] a novel previously unrecognised group that fell outside normal clinical expectation for PFP as no weakness in muscle strength was identified. The people in this subgroup reported high levels of function, therefore it is currently our hypothesis that this group could be overloading their patellofemoral joint, this is in line with previous frameworks [12, 14, 22], which refer to an overload/overuse problem associated with the patellofemoral joint. 5 Verification of TIPPs Subgroups The TIPPS classification system has yet to be applied to patients to determine its efficacy in guiding treatment and improving outcomes [22]. This is beginning to change and the following section provides a brief summary of TIPPs verification papers (Stage 5 Fig. 1) and other papers that have explored the application of TIPPs in patient populations. Normative test score results have been explored between ethnicities and sex from TIPPs clinical assessments conducted on 89 New Zealanders (34% Maori, 45% female), in addition the inter-rater reliability of each test was assessed [39]. Females were significantly weaker than males in normalised strength measures (p < 0.001), and had lower FPI. Mean differences between testers for all measures were small and not significant, except for FPI which had a 2.0 point median difference (p = 0.021). HébertLosier et al. [39] concluded that sex is an important factor worth considering within the TIPPs subgrouping approach, more than ethnicity, especially for normalised strength measures; the sub-optimal reliability of FPI may warrant reconsideration of its inclusion within future TIPPs studies. Greuel et al. [40] confirmed the existence of a strong group of PFP patients. They reported that there were no differences in strength between healthy subjects and a strong group of PFP patients. However, they did report an increased level of muscle inhibition in the strong PFP patients, suggestive of a motor control problem. Drew et al. [41] recruited seventy PFP patients and identified 4 PFP subgroups that showed potentially different outcomes at 12 months. They identified ‘Strong’, ‘Pronation & Malalignment’, ‘Weak’ and ‘Flexible’ subgroups. Furthermore, the natural prognosis of these subgroups was established. By adjusting for known covariates, they reported, compared to
126 a ‘Strong’ subgroup, a substantive directional trend that the’ Weak’ subgroup was the least likely (31% [7/22]; odds ratio [OR] 0.30; 95% CI 0.07, 1.36) and the ‘Flexible’ subgroup most likely (63% [7/11]; OR 1.24, 95% CI 0.20, 7.51) to report a favourable outcome at 12 months follow up [41]. Yosmoaglu et al. [42] validated the TIPPs subgroups in a Turkish PFP population with sixty-one participants and conducted a prospective crossover intervention study. All patients received standardised multimodal treatment three times a week for 6 weeks, nonresponders were then classified into one of the 3 TIPPs subgroups. Non-responders were subsequently administered a further 6 weeks of matched intervention designed according to TIPPs subgroup characteristics. Thirty six percent of the patients (n = 21) demonstrated recovery following the first phase of multimodal treatment and were discharged. In the second phase over 70% (29 patients) of the non-responders demonstrated recovery after treatment matched to subgroup. Kısacık et al. [43] recruited 30 PFP patients specifically from the weak and pronated foot subgroup. Patients were randomised to either a control group or a short foot exercise (SFE) group with concealed allocation and blinding to group assignment. Both groups received hip and knee strengthening and stretching exercises and performed the training protocol under supervision twice per week for 6 weeks. The intervention group received additional SFE. Both groups reported decreased knee pain, but this was only significant in the SFE group. Navicular position, rearfoot posture and hip extensor strength all significantly improved in the SFE intervention group compared to the control group. None of the individual results of the papers presented in this section provide a definitive answer to the question “Does Tipps classification and matched subgroup intervention lead to improved patient outcomes?” However, collectively they are important in contributing to a growing evidence base supporting the TIPPs subgrouping approach and are in line with J. Selfe specific components of the robust methodological approaches suggest by PROGRESS partnership [15] and the MRC framework [16] outlined in Fig. 1. 6 Future Directions Tables 1 and 2 highlight that most of the work on developing stratified care using diagnostic subgrouping with matched interventions for PFP has focussed on the Physical domain and in particular biomechanics. However, there is a growing recognition that with respect to potentially important PFP subgroups the Psychosocial and Physiological domains have been under investigated. 6.1 Psychosocial Domain The Psychosocial domain has recently received a lot of attention with the publication of the 2021 consensus statement on research priorities on pain and psychological features in individuals who have patellofemoral pain [44]. Coping skills, anxiety, and kinesiophobia were considered research priorities. Pain catastrophising, fear-avoidance beliefs (pain-related fear of movement) and pain self-efficacy were considered important clinically and should be considered when undertaking a clinical examination and designing a treatment plan (Fig. 4). Chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients” presents a comprehensive overview of these important psychological factors. These factors are all consistent with elements of the fear avoidance model for persistent musculoskeletal pain and as such may therefore also lend weight to the justification of there being a Kinematic subgroup in the Physical domain. We have previously demonstrated that people with knee pain have elevated scores on the conscious motor processing subscale of the movement-specific reinvestment
Targeted Treatment in Anterior Knee Pain Patients According … Psychosocial Fear avoidance? (Pain-related fear of movement) Physical Muscle strength Muscle length Foot Posture Kinematic? Physiological Vascular / Ischaemic? Fig. 4 Potential PFP subgroups within each of the 3 key domains scale [45]. This means they have concerns about moving effectively or safely, which is also consistent with fear-avoidance models. In future stratification and subgrouping research it will be interesting to explore the relationship between the objective measurement of lower limb kinetics and the degree of self-reported kiniesiophobia to potentially define a kinematic subgroup of PFP. The key challenges will be around which tests to use, test thresholds or cut point scores for allocation of patients to a Kinematic subgroup and what the matched treatment interventions should be. In terms of potential matched treatment interventions for a kiniesiophobia/kinetic subgroup; PFP patients with elevated scores on the conscious motor processing subscale of the movement-specific reinvestment scale may respond well to implicit rehabilitation strategies. Implicit rehabilitation targets unconscious aspects of movement through trial and error without thinking specifically about how to move, whereas explicit strategies target the conscious aspects of movement [45]. 6.2 Physiological Domain Compatible with the theory of Tissue Homeostasis [26, 27] and central to the Neural Model [28] is that physiological factors, such as vascularisation of the knee, could play an important role in PFP 127 and that in some patients with PFP pain may be induced by ischemia [28, 46, 47]. There is a strong biologically plausible link between vasularisation, ischaemia and knee temperature which supports the candidacy of a vascular/ischaemic subgroup of PFP as a potentially important clinical subgroup Figs. 1 and 4. In addition to this laboratory evidence there is also clinical evidence suggesting a variety of circulatory issues may result in pain and altered temperature profiles around the patella and sensitivity to cold surroundings is a commonly reported clinical feature in PFP [48–56]. In the 2021 consensus statement on research priorities on pain and psychological features [44] the role of Quantitative Sensory Testing (QST) was discussed in assessing neural components of PFP. One of the parameters QST can assess is thermal pain thresholds (hot/cold), however, in the consensus thermal pain thresholds did not emerge as clinically important or as research priorities. The challenge therefore appears to be around which are the appropriate clinical tests to use to explore a potential vascular/ischaemic subgroup of PFP patients that may have a thermal component to their problem Fig. 1. It is currently unclear if QST is the appropriate test to investigate this subgroup. We have conducted a series of studies investigating a cold knee group as a potential PFP subgroup [52–54]. On baseline assessment ‘cold’ PFP patients had worse scores on the Modified Functional Index Questionnaire (MFIQ) and time to pain onset on an inclined walking treadmill test compared to PFP patients with ‘nornmal’ skin temperature (Tsk). Following a standardised course of multimodal therapy, three months post discharge the ‘normal Tsk’ PFP patients scores had improved by greater than minimum clinically important change whereas the ‘cold Tsk’ PFP patients had not improved at all [53]. To investigate this more objectively we initially used state of the art high-cost thermal imaging cameras but have now validated a low-cost hand-held digital thermometer as an alternative which would be more suitable for routine clinical use [55] Fig. 5. In a sample of 58 healthy participants and 232 PFP patients we used finite mixture models to examine the presence of PFP temperature subgroups and receiver operating characteristic
128 J. Selfe clinicians will have access even to a low-cost digital thermometer. So we have also investigated the utility of four simple clinical questions which may provide an initial clinical screening to alert clinicians to the possibility of the presence of a vascular/ischaemic disorder [53] Fig. 5 Hand-held digital thermometer measurement of patellar skin temperature (Tsk) (ROC) curves to estimate optimal patella Tsk thresholds for allocation into subgroups [54]. In contrast to healthy participants, participants with PFP patella Tsk had an obvious bimodal distribution. The fitted finite mixture model suggested three temperature subgroups (cold, normal and hot) with discrimination cut-off thresholds for subgroup membership based on ROC analysis of Cold = 29.9 °C; Normal 30.0–35.2 °C; Hot 35.3 °C (Fig. 6). As objective measurement of Tsk is not routine musculoskeletal practice we recognise not all Fig. 6 Histogram showing distribution of patella Tsk and suggested thresholds or cut point scores for allocation of patients to subgroups • Do your knees feel cold even on a warm day • Does cold weather affect your knees • Do you wear extra tights/long johns in winter (because of your knees) • Would you prefer a hot-water bottle or ice pack on your knee Of these the last question often provokes an interesting response, in cases of ‘cold knees’. Don’t you dare come anywhere near my knee with that ice pack! this is quite a strong and negative reaction to the ice pack. This area work needs further validation to define the potential subgroup and formal investigation as to what the appropriate matched treatment interventions should be for this potential subgroup, treatment suggestions based on clinical experience are presented elsewhere [56].
Targeted Treatment in Anterior Knee Pain Patients According … 7 Conclusion 129 Figure 7 proposes a clinical pathway for the assessment of a new patient referred with PFP, highlighting the three overarching domains, potentially important subgroups and areas where there is still uncertainty. Our experience has highlighted some of the challenges in undertaking subgrouping research in PFP. One is small sample size, which precludes many of the more complex, statistical methods for classifying subgroups and/or optimising thresholds. In the Selfe et al. study [20], it also precluded cross-validation studies for internal verification requiring reliance on using two different statistical methods instead. Given sample size is a difficulty in many PFP studies, consideration should be given to establishing large prospective datasets, which may require collaboration across institutions and countries. Such an initiative requires a core dataset of putative markers, such as the TIPPs clinical tests This chapter has reviewed a number of proposed stratification frameworks for PFP and some of the methodological considerations which guide stratification research. With the exception of TIPPs [30] PFP stratification frameworks have not been developed in line with rigorous methodological guidelines and therefore have a number of limitations. The chief limitation particularly of early stratification frameworks is the double-digit number of subgroups which restricts their clinical utility. More recently however there appears to be an emerging evidence base and consensus that there a relatively small number PFP subgroups worth considering from a matched treatment perpective. It is probable that these overlap and /or interact with each other, however the exact nature how they overlap and interact with each other are as yet unknown. Fig. 7 Proposed clinical pathway for managing subgroups Pre-Clinical screening quesonnaires Psychosocial Domain Physiological Domain Fear Avoidance (e.g. TSK) Ischaemic (e.g. 4 Cold Quesons) Physical Domain Clinical assessment Objecve Measure of TsK Lower Limb Kinemacs? Muscle Strength Strong Muscle Length Weak and Tight Cold subgroup? Foot Posture Weak and Pronated
130 J. Selfe described earlier, but also others for which there may be emerging evidence of their prognostic impact, e.g., psychosocial factors [57] and a core set of outcome measures. While progress is being made on the latter with the development of the KOOS-PF [58] there remains a bewildering variety of different tests used to measure the same clinical phenomenon; some are more practical to use than others. The recently published Report PF [59] which is hosted on the Equator Network provides a clearly defined, and widely accepted set of agreed standards for reporting of quantitative PFP research and represents a useful step forwards in terms of standardisation. It consists of 31 items (11 strongly recommended, 20 recommended), covering (i) demographics; (ii) baseline symptoms and previous treatments; (iii) outcome measures; (iv) outcomes measure description; (v) clinical trial methodology and (vi) reporting study results. Finally, we also need carefully collected normative data on key measures to allow for appropriate interpretation of comparative test data in PFP patients. Despite an emerging evidence base and some consensus, to date no definitive RCTs have been conducted to evaluate the potential benefits of matched interventions for PFP subgroups in terms of improved patient outcomes so this continues to warrant further research. 8 Take-Home Messages 1. There is limited evidence supporting the longer-term outcomes of a multimodal approach to therapy. 2. There have been many attempts at producing PFP stratification frameworks and defining subgroups, however no consensus on these has been reached. 3. Robust methodological frameworks for guiding stratification and subgrouping research have been produced but these have yet to be applied fully to PFP. 4. Three overarching domains need consideration within a subgrouping model for PFP: Physical; Psychosocial; Physiological. 5. Within the Physical domain consensus appears to emerging around the importance of: Muscle strength, Muscle length, Foot Posture, Kinematics. The Psychosocial and Physiological domains are under investigated. 6. Candidature for subgroups requires a. a strong mechanobiologic rational b. objective data on test measurement properties such as validity and reliability c. thresholds/cut points to define subgroup allocation d. tests that are feasible and acceptable to both patients and clinicians (e.g. quickly performed and requiring low cost measurement tools to collect relevant data). 9 Key-Message There have been many attempts at defining subgroups within the PFP population, despite these efforts, currently there is no consensus on the optimal subgroups, however there is emerging evidence that a subgrouping approach may improve patients outcomes compared to a multimodal approach to treatment. References 1. Barton CJ, Lack S, Hemmings S, et al. The ‘best practice guide to conservative management of patellofemoral pain’: incorporating level 1 evidence with expert clinical reasoning. Br J Sports Med. 2015:1–13. 2. Smith B, Hendrick P, Bateman M, et al. Current management strategies for patellofemoral pain: an online survey of 99 practising UK physiotherapists. BMC Musculoskelet Disord. 2017;18:181. 3. Crossley KM, Macri EM, Cowan SM, et al. The patellofemoral pain and osteoarthritis subscale of the KOOS (KOOS-PF): development and validation using the COSMIN checklist. Br J Sports Med. 2017;52:1130–6.
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Surgical Treatment of Anterior Knee Pain. When is Surgery Needed? Vicente Sanchis-Alfonso and Robert A. Teitge 1 Introduction Anterior knee pain (AKP) continues to be challenging for the orthopedic surgeon. It is widely accepted that the vast majority of AKP patients only need conservative treatment and do not need a surgery [1–3]. However, the results of conservative treatment for AKP are often frustrating. Some 40% of AKP patients have an unsatisfactory recovery with conservative treatment at 12 months after the initial diagnosis [4]. The high percentage of undesirable outcomes may be due to the fact that some of them actually need surgical treatment. However, they do not receive it because the doctor lacks the adequate knowledge to make a precise diagnosis. The patient with AKP is at high risk of undergoing surgical treatment with little or no scientific basis simply because AKP is a musculoskeletal pathologic entity with a poorly understood etiopathogenesis. Therefore, in more cases than is acceptable, the AKP patient’s condition worsens after surgical treatment [5]. In fact, many surgeries performed on AKP patients are undertaken to address complications, or the unsatis- V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com R. A. Teitge Wayne State University, Detroit, MI, USA factory results of previous poorly performed or badly indicated surgeries intended to treat AKP [5]. The patellofemoral joint (PFJ) does not really tolerate surgical procedures that do not respect its unique anatomical, biological and biomechanical characteristics [6]. For that reason, AKP surgery is currently performed infrequently. This chapter focuses on the patient with AKP without patellofemoral osteoarthritis as the cause of pain. Consequently, techniques such as the anteromedialization of the tibial tubercle (Fulkerson’s osteotomy), fresh allograft transplantation or patellofemoral arthroplasty are not analyzed here. This chapter analyzes the current state of knowledge around the surgical treatment of AKP patients, emphasizing the importance of the diagnosis and treatment of torsional alterations of the lower limb. The surgical techniques used include minimally invasive procedures, such as peripatellar synovectomy or resection of synovial hypertrophy around the inferior pole of the patella and major surgical techniques such as osteotomies. Indeed, osteotomy must be seriously considered a part of the armamentarium for treating AKP patients. 2 General Principles in the Surgical Management of AKP Patients For AKP patients who might benefit from surgery, a knowledgeable surgeon and a correct diagnosis are crucial factors. A careful history, a © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_9 133
134 complete physical examination and the use of imaging must be included. The surgeon must determine which surgical procedure, if any, has the potential to improve the patient´s condition and, most importantly, does them no harm. 2.1 A Right Diagnosis is Paramount— Listen to the Patient Conversation with the patient and a complete physical examination are fundamental, but are too often neglected. This, in turn, triggers a failed patellofemoral surgery. We must listen very carefully to our patients because they will usually tell us what is wrong in their own words. It is our mistake if we fail to understand them and assume we somehow know better than what they are trying to tell us. To reiterate, a complete physical examination is prerequisite. This is an attempt to uncover all of the anatomic abnormalities, of which there are often many. When any abnormal anatomy is uncovered then the following question must be answered. How does this change the normal biomechanics? To arrive at a correct diagnosis, answers are also needed to the following questions: (1) Is AKP secondary to patellar instability, or does it arise from bone rubbing or tension in the soft tissues?; (2) Does the patient have a neutral mechanical axis, or is varus or valgus present?; (3) Does he or she have abnormal torsion (i.e., considerable external tibial rotation or pathological internal rotation of the femur)?; and (4) Is the quadriceps too tight? A critical factor to consider when treating AKP patients is whether patellofemoral instability is present concurrently. Treatment of underlying patellar instability in these patients should be undertaken with caution and the patients must know that surgical patellar stabilization may not relieve AKP. Moreover, a careful assessment of the limb alignment is an essential part of the physical evaluation of the AKP patient. V. Sanchis-Alfonso and R. A. Teitge 2.2 Treat Patients, Not Images Unfortunately, many orthopedic surgeons operate based on what computed tomography (CT) or magnetic resonance imaging (MRI) shows. That might be chondropathy, lateral patellar subluxation, patellar tilt, or an increment in the tibial tuberosity-trochlear groove (TT-TG) distance. It seems as though they are operating on an image instead of a person. Using this information as the basis for surgery is a critical error—and it is responsible for the poor reputation of AKP surgery. In the hands of the wrong orthopedic surgeon, the MRI becomes a license to operate. The MRI does not tell us what hurts. Poor results of surgery in AKP patients may arise either because the diagnosis is inaccurate or because of physio-pathological premises on which surgery are based (i.e., “pathological” TTTG distance) are incorrect. Therefore, the treatment is also incorrect. Many orthopedic surgeons base their surgical indication for patellofemoral surgery on a TT-TG distance greater than 20 mm. The use of this parameter as the deciding factor is a critical mistake because it can be a source of surgical failure and iatrogenic conditions. We must not use imaging numbers to treat a patient. Physical examination is the key part of assessing AKP. Tensho and colleagues [7] have proven that knee rotation affects the TT-TG distance more than tubercle malposition does. For this reason, it should not be used as a surgical indicator for tibial tubercle transfer. However, the TT-TG distance is currently widely used as an indicator for medialization of the tibial tubercle in the AKP patient. Historically, great importance has been given to the presence of a lateral patellar subluxation in the CT or in the MRI, which is attributed to excessive traction of the lateral retinaculum (LR) in the AKP patient. However, the LR does not pull the patella laterally—it prevents it from moving too far medially. Lateral patellar subluxation may be due to inadequate lateral
Surgical Treatment of Anterior Knee Pain … 135 Fig. 1 SPECT-CT in an AKP patient with 40° of external left tibial rotation. External tibial rotation increases pressure on the lateral side of the PFJ. This patient had disabling left AKP recalcitrant to conservative treatment trochlear inclination, genu valgum, or abnormal femoral anteversion. If lateral subluxation of the patella is present, the patellar tendon approaches the tibial tuberosity from a more lateral direction. Specifically, most of its force through the patellar tendon is diverted into pulling the tuberosity laterally when the quadriceps contracts, causing the tibia to rotate more externally on the femur. Therefore, using a lateral retinaculum release (LRR) to correct lateral patellar subluxation is inappropriate. We must treat the underlying cause, for example, excessive femoral anteversion. 2.3 Identify if AKP is Related to Focal Overload of the PFJ A key step in surgical decision-making is to identify whether AKP is related to patellofemoral overload. Pain related to it is generally localized, and worsened or improved depending on the load applied to the PFJ. Patients with localized load-related pain may be more amenable to successful surgical treatment while diffuse constant pain generally does not improve with surgery. A true skeletal malalignment of the lower limb might be responsible for focal overload in the PFJ [8–13]. In those cases, imaging studies like single-photon emission computed tomography (SPECT)-CT can reveal overloaded areas (Fig. 1). We should strive to restore the normal anatomy because that will create a better biomechanical environment for the tissue. Rotational osteotomies may be used to unload bone and peripatellar soft tissue and create an adequate environment for a return to homeostasis. As suggested by Post and Dye, “Think of surgery as a tool used to create an environment in which homeostasis may be restored” [1]. 2.4 If You Repair Failed Tissue (Bone, Ligament or Cartilage) and Ignore the Mechanics Which Caused the Tissue Failure, You Will Usually Have a Failed Result Addressing the involved structures (trochlea, cartilage, and ligaments) does not address the cause of the abnormal force that produces focal overload and the subsequent damage to the tissues.
136 V. Sanchis-Alfonso and R. A. Teitge Osteotomy is quite able to change the direction of the force. This ability is particularly important when abnormal limb alignment (transverse or coronal plane or combination) is present. If the cartilage is repaired but the mechanics that caused its failure are ignored, failure is the likely outcome. It appears to be appropriate to place the trochlear groove under the patella instead of forcing the latter over the trochlear groove. In short, think about limb alignment, not patellar alignment (Fig. 2). A C Fig. 2 Normal knee (A). The rotating movement of the femur underneath the patella in the transverse plane leads to abnormal patellar tracking (lateral patellar subluxation and patellar tilt (1) and therefore patellofemoral imbalance) (B). The patella maintains a horizontal position, while the femur internally rotates. Therefore, the patellar subluxation during weight-bearing conditions is not the result of patella moving on the femur, but of the result of the femur rotating underneath the patella. It would be the rationale for rotational osteotomy surgery. Retracted lateral retinaculum (2), tension increases in the medial retinaculum (3), compression in the lateral patellofemoral 2.5 Identify if There Are Associatted Psychological Factors and Central Sensitization Our data shows that the presence of psychological factors is a limitation to recovery (see chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients”). Therefore, we should not ignore them. However, the presence of psychological impairment is not a contraindication for surgery. B D joint increases (4), inward twisting of the knee (5). The final result: ‘‘patellofemoral imbalance’’. (D) Patellar maltracking after two previous failed distal femoral osteotomies. (C) Postoperative CT. After external femoral rotational osteotomy, we achieve a greater surface of contact and therefore a decrease in patellofemoral joint pressure. (“Republished with permission of Springer Nature BV, from Holistic approach to understanding anterior knee pain, Sanchis-Alfonso V, Knee Surg Sports Traumatol Arthrosc, 22, 2275–2285, 2014; permission conveyed through Copyright Clearance Center, Inc.”)
Surgical Treatment of Anterior Knee Pain … “Crazy” patients with a real pathology get back to normal or are at least much better mentally after effective treatment. A reduction in psychological impairment after a correct surgical treatment that has reduced or eliminated the pain has been seen. What is more, we have observed a reduction in central sensitization after successful surgical treatment. In “crazy” patients, we need to look hard for a real pathology and help them even if it takes more patience and tender loving care from the provider. 2.6 In Short … We must always evaluate the following: (1) skeletal limb alignment (including the trochlea); (2) ligaments (i.e., the presence of hypermobility and its cause and location); (3) articular cartilage (i.e., complete or partial loss, location of the loss, possibility to shift contact to intact cartilage); and (4) muscle (i.e., symmetrical atrophy versus gross imbalance). 3 Minimally Invasive Surgical Procedures Some orthopaedic surgeons consider minimally invasive surgical procedures like LRR and arthroscopic focal synovectomy as minor riskfree surgical procedures. However, we agree with Ronald Grelsamer in that “There is no such thing as minor surgery—only minor surgeons”. 137 arthroscopic procedures. They showed a need for revision surgery in 12% of the cases after a 52month follow-up. Then again, they did emphasize that the surgical procedure is necessary in less than 15% of AKP patients. Nevertheless, the authors drew attention to the need for randomized clinical trials to assess the advantages of this procedure when treating AKP. However, experienced knee surgeons with a special interest in the PFJ rarely perform isolated LRR [16]. In a study [17] that analyzed the current trends in LRR procedures from 2010 through 2017 using a large USA database, the authors showed an incidence for LRR of 481.9 per 100,000 orthopedic surgeries in 2010 that significantly decreased to 186.9 per 100,000 orthopedic surgeries in 2017. LRRs were more commonly performed in younger female patients for a diagnosis of pain with the most common concomitant procedure being meniscectomy, synovectomy, or a microfracture. Iatrogenic medial patellar instability has been described after excessive LRR or in the setting of an LRR performed in cases of patellar tilt without a tight LR or in patients with severe trochlear dysplasia [18]. Lateral retinacular lengthening has been reported as an alternative to LRR to prevent its eventual complications [14]. Moreover, releasing the painful retinaculum in a limited way in a very selected group of AKP patients may relieve pain [19]. Finally, arthroscopic LRR of a symptomatic type III bipartite patella without excision of the accessory bone fragment is related to excellent AKP relief and an early return to sport activities [20]. 3.1 Lateral Retinaculum Release LRR has a long history. It has often been used to treat AKP recalcitrant to conservative treatment in very selected patients with a patellar tilt and a tight LR, which is demonstrated by an inability to evert the lateral patella to a neutral position on physical examination [14]. In a systematic review of literature, Lattermann and colleagues [15] demonstrated that the isolated LRR for AKP yielded good results in 76% of the cases with no significant difference between open or 3.2 Arthroscopic Focal Synovectomy. Patellar Decompression When a focal soft tissue source of AKP refractory to appropriate conservative treatment can be identified (Fig. 3), arthroscopic debridement of this pathological tissue can relieve the pain [21– 23]. The most frequent sources of pain would be synovial hypertrophy around the inferior pole of the patella, Hoffa fat pad impingement and peripatellar synovitis (Fig. 3). Other patients may
138 V. Sanchis-Alfonso and R. A. Teitge Fig. 3 Peripatellar synovitis require removal of a chronically tender synovial band of tissue or plica. Moreover, it has been suggested that the ligament mucosum (i.e., infrapatellar plica) potentially plays a role in the pathogenesis of AKP [23]. Release or resection of the infrapatelar plica, which tethers the Hoffa fat pad, significantly improves AKP in these patients [23]. Use of a superomedial portal may help to prevent potential errors arising from viewing the anterior compartment from a peripatellar tendon portal [2]. These minimally invasive surgical procedures should not be approached lightly. It is essential to circumvent postoperative hemarthrosis, which can be very painful and set back restoration of homeostasis [1, 2]. Therefore, intraoperative hemostasis must be meticulous, and 24-h drainage through one of the arthroscopic portals of the patient’s knee is advised. Soft tissue impingement may also be associated with osseous hypertension, which can produce transitory ischemia and mechanical stimulation of nociceptors and the ensuing pain. Patients with an intraosseous hypertension of the patella with a positive pain provocation test (i.e., pain reproduced by raising intrapatellar pressure) might be good candidates for extra-articular arthroscopic patellar decompression (Fig. 4) [24]. Finally, in patients with AKP recalcitrant to conservative treatment for more than 6 months with no associated structural anomalies, patellar denervation may be an option [25]. 4 Major Surgical Procedures— Osteotomies Skeletal malalignment of the limb (i.e., malalignment on the transverse, coronal, and sagittal planes) is one of the causes of AKP in some young patients. The presence of excessive femoral anteversion, excessive external tibial torsion, or increased varus or valgus abnormalities has a great impact on PFJ biomechanics. In particular, rotational abnormalities are important [11–13]. 4.1 Derotational Osteotomies (Transverse Plane) One of the most powerful causes of AKP that both doctors and the literature forget to mention is the pain resulting from torsional alterations of the lower limb. However, tibio-femoral rotation has yet to be integrated into our thinking. In fact, most of the current literature discusses patellar alignment in association with AKP as a problem of the patella itself (increased tilt or increased shift of the patella). However, in many cases, the problem is not in the patella but in the femur. Thus, it is of a vital importance to assess the rotational profiles of the femur and tibia in an AKP patient. As far back as in 1995, Flandry and Huhgston [26] showed that the most frequent
Surgical Treatment of Anterior Knee Pain … 139 Fig. 4 Pain with knee hyperflexion. Intraosseous hypertension of the patella Patellar decompression cause of failure of an extensor mechanism realignment surgery was the existence of an underlying torsional alteration not diagnosed and therefore not treated. Stevens and colleagues [27] have demonstrated clinical improvement after osteotomies of the femur and/or tibia in patients with a previous failed surgery (tibial tubercle osteotomy, LRR or arthroscopic debridement) to treat AKP in those whom torsional abnormalities of the lower limb had gone unnoticed. Those authors state that many orthopedic surgeons only focus on the knee when they see an AKP patient. Torsional abnormalities often go unrecognized. 4.1.1 Rationale Limb alignment appears to have a very powerful influence on the quadriceps vector [13]. If an abnormal quadriceps vector is an important contributor to AKP and skeletal malalignment of the lower limb explains the offending quadriceps vector, then any torsion or coronal correction is important [13]. It is important to note that small alterations in the skeletal alignment of the lower limb can result in significant alterations in PFJ stresses. Osteotomy has a great ability to change the direction of the force and therefore treat these patients.
140 Lee and colleagues [8, 9, 28] have demonstrated that femoral rotation results in an increase in PFJ contact pressures on the contralateral facet of the patella (i.e., lateral PFJ during internal rotation of the femur and vice versa). Furthermore, tibial rotation results in an increase in PFJ contact pressures on the ipsilateral facet of the patella. Lee and colleagues have demonstrated that tibial rotation not only has an influence on PFJ contact pressures and areas but also on strain in the peripatellar retinaculum [28]. More recently, Passmore and colleagues [10] have shown that idiopathic lower-limb torsional deformities of the femur and tibia in children and adolescents are associated with gait impairments as well as an increase in loading on the hip and PFJ. Thus, idiopathic lower-limb torsional deformities are not a purely cosmetic issue. Using a finite element model, Liao and colleagues [29] have demonstrated that internal rotation of the femur provokes an increment in PFJ stress. 4.1.2 Clinical Evaluation Four types of torsional alteration of the lower limb are possible: (1) femoral anteversion, (2) femoral retroversion, (3) excessive external tibial torsion, and (4) excessive femoral anteversion associated with an increased external tibial torsion.One of the questions yet to be answered, biomechanically, in the last type is whether excess tibial torsion and excess of femoral anteversion are of equal mechanical importance? Then again, does tibial or femoral torsion have a greater negative mechanical influence? The importance of different maltorsions is unclear. When the patient stands with their feet parallel, the patella should be facing forward. In patients with excessive external tibial torsion, we can see a squinting patella and a genu varum (Figs. 5 and 6). The varus in patients with external tibial rotation may be real, or it may be a reflection of the tibial torsion (thus pseudovarus). In the same way, we can observe a “pseudo-valgus” in patients with pathological femoral anteversion (Fig. 7). Evidently, we must only correct the transverse deformity in these cases, not the coronal one. The combination of V. Sanchis-Alfonso and R. A. Teitge increased femoral anteversion and increased external tibial torsion has been termed miserable malalignment syndrome that includes squinting patella, genu varum, genu recurvatum and pronated foot (Fig. 8). In the prone position, the proportion of internal to external rotation of the hips in extension must be measured [30]. If internal rotation exceeds external rotation by more than 30 degrees, there is increased femoral anteversion (Fig. 9). In cases with isolated excessive external tibial torsion, internal and external rotation are similar (Fig. 10). Furthermore, it is important to evaluate the foot progression angle. The “foot progression angle” should be neutral when walking [31, 32]. Excessive femoral anteversion is manifested by a gait pattern with an internal foot progression angle (in-toeing) (Fig. 11) and external tibial torsion by out-toeing. However, if excessive femoral anteversion is associated with excessive external tibial torsion (i.e., pan genu torsion or miserable malalignment), the foot progression angle will be neutral, and this combined longbone deformity may be concealed to the unwary observer. It is therefore important to have a patient appropriately unclad and note that the knee progression angle is inward. 4.1.3 Measuring Torsion In our clinical practice, we use the technique described by Murphy and colleagues in 1987 to measure femoral torsion [33]. This is the most anatomic, accurate and reproducible method for evaluating femoral anteversion (high intra- [ICC: 0.95–0.98] and inter-observer agreement [ICC: 0.93]) [34]. Murphy and colleagues reported that the common method of running a line along the femoral neck on a CT image underestimated the actual anteversion by a mean 13° [33]. The line that is used in the most common method, like the axis of the femoral neck, is not the true axis of the femoral neck. External tibial torsion is measured as the angle between the posterior aspect of the tibial metaphysis and the ankle joint line. Our normal reference values are femoral anterversion of 13º for both sexes and external tibial torsion of 21º in males and 27° in females [35, 36].
Surgical Treatment of Anterior Knee Pain … A 141 B C D Fig. 5 A, B Squinting patella in a patient with excessive external tibial torsion. C Normal skeletal alignment in the transverse plane. Female with femoral anteversion of 13º and external tibial torsion of 27º. D Female with an increase in external tibial torsion. To keep the foot progression angle normal, the knee joint points inward causing increased strain on the knee. The hip appears internally rotated with the greater trochanter pointing somewhat anteriorly. (A, B —Republished with permission of AME Publishing Company. From Sanchis-Alfonso V, et al. Evaluation of anterior knee pain patient: clinical and radiological assessment including psychological factors. Ann Joint, 3:26, 2018. C, D—Republished with permission of Elsevier Science & Technology Journals. From Teitge RA. Patellofemoral Disorders Correction of Rotational Malalignment of the Lower Extremity. In: Noyes´s Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes, 2017; permission conveyed through Copyright Clearance Center, Inc.”) 4.1.4 Surgical Considerations Rotational osteotomies are often performed according to the experience of the surgeon. Since torsion is the angle measured between the joints, a change in torsion of the femur may be anywhere between the hip joint and the knee joint. There is no evidence that the proximal, mid-shaft or distal location of the osteotomy is preferable. The authors prefer femoral rotational osteotomy at the intertrochanteric level to prevent any scarring to the quadriceps muscle in the region of the knee. However, the correction must be made near the knee joint, usually in the supracondylar region, if there is an associated varus or valgus deformity. The situation is similar in the tibia. It matters little whether a rotational correction for maltorsion is performed in the proximal, mid or distal tibia except that it should be performed below the level of the tibial tubercle. Recently, Winkler and colleagues [37] have shown that
142 V. Sanchis-Alfonso and R. A. Teitge 4.2 Coronal Plane Osteotomy for Genu Valgum Fig. 6 Physical findings in a patient with excessive external tibial torsion increased external tibial torsion is an infratuberositary deformity and is not correlated with a lateralized position of the tibial tuberosity. The surgeon may select any internal (or external) fixation device which allows for maintaining the correction. Fig. 7 “Pseudo-valgus” in a patient with pathological femoral anteversion. In this case, the valgus was not real. It was due to the inward position of her flexed knee, that is, in this case it was secondary to a femoral anteversio of 51º. (Courtesy of Robert A. Teitge, MD) Both torsional deformities and coronal plane deformities are associated with AKP patients in many cases. The most common multiplanar deformity in AKP patients is internal femoral torsion and genu valgum (Fig. 12) [13]. A valgus limb with the mechanical axis passing through the knee lateral to its normal position increases the lateral component of the quadriceps vector creating an imbalance in forces acting on the patella. Multiplanar deformity appears to add the effects from each separate deformity [13]. In these cases, both deformities must be corrected [13]. We must combine both varus and external rotation (Fig. 12) [13]. Multiplanar correction is somewhat more challenging than monoplanar correction but very beneficial. Precision surgery is the key to success. It is a common misconception that a valgus deformity should always be corrected with a distal femoral osteotomy. The crucial question in osteotomy surgery is about where the deformity is located. The answer to this question is very important because we must put the osteotomy where the deformity is. In contrast with the widespread belief that valgus malalignment is caused by a femoral deformity, Eberbach and colleagues [38] have demonstrated that the valgus knee is secondary to a tibial deformity in a great number of the cases (41%). Moreover, a combined femoral- and tibial-based deformity
Surgical Treatment of Anterior Knee Pain … A B 143 C D E Fig. 8 A, B, C Miserable malalignment syndrome. D Female with 30º increase in femoral anteversion. The knee joint points in the same direction, slightly inward, as in the normal female, but the greater trochanter points posteriorly. At some point, the hip cannot externally rotate enough to keep the knee joint pointed forward. E Female with a 30º increase in both femoral anteversion and external tibial torsion. Note the trochanter is pointed more anterior than normal, and with the foot progression angle normal, the knee joint axis points markedly inward. (D, E —Republished with permission of Elsevier Science & Technology Journals. From Teitge RA. Patellofemoral Disorders Correction of Rotational Malalignment of the Lower Extremity. In: Noyes´s Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes, 2017; permission conveyed through Copyright Clearance Center, Inc.”) (Fig. 12) is more frequent than an isolated femoral-based deformity (27% vs. 23.6%). The clinical relevance of the paper by Eberbach and colleagues [38] is that varus osteotomies to treat genu valgum must be performed at the proximal tibial site in 41% of the cases or as a double-level osteotomy in a relevant number of patients (45.5% of cases) to avoid an oblique joint line (Fig. 12). The ideal osteotomy site was the distal femur in only 13.6% of cases. One of the most frequent symptoms of genu recurvatum is AKP. In these cases, continuous hyperextension of the knee will provoke a hyperpressure on the anterior cartilage of the tibial plateau on the one hand and infrapatellar fat pad impingement on the other [39]. Fat pad impingement will cause chronic inflammation of the infrapatellar fat pad through repetitive microtrauma [39]. All of this will be accountable for the pain. When the angle of recurvatum is greater than 15º, it is considered pathological [40]. Non-operative treatment consisting of muscle strength training and anti-hyperextension bracing is the first step of treatment. After the failure of non-operative treatment, we must consider surgical treatment. There are several options for surgical treatment: 4.3 Osteotomies in the Sagittal Plane —Genu Recurvatum The term genu recurvatum describes a knee with hyperextension of the tibia on the femur (Fig. 13).
144 V. Sanchis-Alfonso and R. A. Teitge Fig. 9 Evaluation of a patient with excessive right femoral anteversion in the prone position (1) Opening wedge osteotomy (Fig. 14). One cut from anterior to posterior and then a wedge of bone graft anteriorly with a plate anteriorly with compression of the graft. Healing with the bone wedge is not so rapid, which is one complaint. With this osteotomy, we will gain length. (2) Closing wedge posteriorly. This is a much larger dissection and there is more risk of moving the soft tissues away. The wedge may be cut from the side rather than straight posteriorly. The leg is obviously shortened. The correction depends on the accuracy of planning and the removal of the wedge. Placing a sufficiently long plate on the posterior tibia is not so easy as the space is tight. (3) Philipp Lobenhoffer has proposed a crescentic osteotomy using the Synthes crescent saws usually used for veterinary cases referred to as TPLO (tibial plateau leveling osteotomy). There is minimal bone loss and a very broad surface area. The trick is to locate the center of rotation and place a K-
Surgical Treatment of Anterior Knee Pain … 145 wire exactly on the correct coronal and sagittal plane. We can approach the tibia laterally by moving the anterior compartment distally. Then you would not have to move the pes and MCL. This type of osteotomy would be of help in cases with a minus variant of the tibial tubercle in which it would be difficult to make a good osteotomy of the TT (Figs. 15, 16 and 17). 5 Fig. 10 Evaluation of a patient with normal femoral anteversion in the prone position. This patient had an excessive external tibial torsion measured with CT Fig. 11 The patients are always aware of what is wrong with them. The doctor only has to listen to what they say. Here, this girl was asked to walk as she normally walks and then to exaggerate the way she thinks she walks. We Take Home Messages – The gold standard in the treatment of AKP is physical therapy within the patient’s envelope of function. – Surgery for AKP is a last resort, and it is very often not needed. Surgical treatment must be considered only when well-documented anomalies amenable to a specific targeted can clearly see how the patient rotates the limb internally during gait. An excessive femoral anteversion is manifested by an in-toeing gait
146 Fig. 12 Left valgus deformity (22º) in a patient with disabling AKP and lateral patellar instability. Left CD index 1.5. This patient also had a left femoral anteversion of 54º and a left external tibial torsion of 56º. Intraoperative X-rays after lateral supracondylar open wedge Fig. 13 Genu recurvatum. Anterior subluxation of the femur on the tibia related to the recurvatum deformity V. Sanchis-Alfonso and R. A. Teitge varus rotational osteotomy of the femur (7º of varus and 35º of external femoral rotation) and a medial closed wedge varus rotational osteotomy of the tibia below the tibial tuberosity (15º varus and 30º internal rotation) was performed intervention are present, especially when there is evidence of focal patellofemoral overload. – Certain surgical procedures in a carefully selected patient can significantly improve AKP resistant to all non-operative alternatives. Every surgical treatment ought to be tailor-made just because every person is different. For example, when focal pathology, such as synovial hypertrophy around the inferior pole of the patella or peripatellar synovitis can be identified, procedures to debride the inflammatory foci in the synovium can be very successful. – Finally, in some cases, major surgery like the osteotomy to correct abnormal femoral and tibial torsion may be essential for the optimal treatment of AKP. In our experience, AKP patients with an underlying torsional abnormality respond very well to derotational corrective osteotomies.
Surgical Treatment of Anterior Knee Pain … Fig. 14 Genu recurvatum. Opening wedge osteotomy Fig. 15 Genu recurvatum. Crescentic osteotomy above of the patellar tendon insertion 147
148 Fig. 16 Genu recurvatum. Crescentic osteotomy. Preop versus Postop Fig. 17 Genu recurvatum. Crescentic osteotomy. Preop versus Postop V. Sanchis-Alfonso and R. A. Teitge
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The Failed Patella. What Can We Do? Vicente Sanchis-Alfonso, Julio Domenech-Fernandez, and Robert A. Teitge 1 Introduction The title of this chapter has been borrowed from the world of spinal surgery (“The Failed Spine”). It is a term that we are going to use to describe the situation of those patients who did not have a successful outcome after a surgery that was carried out to resolve Anterior knee pain (AKP). It resulted in the pain worsening considerably in most of the patients. That does not necessarily mean that the surgery was botched. Even with the best surgeon and with the best indication, patellofemoral surgery to treat AKP might fail. In this case, the failure is the consequence of a surgical complication, that is, an adverse event caused by factors that are outside the orthopedic surgeon’s control. Obviously, it is a consequence of a wrong diagnosis or an incomplete diagnosis on some occasions. In other cases, it is a result of an error in the surgical indication or in the surgical technique that will create a new pathology. A good example of a “Failed Patella” consequence of a poorly performed or badly indicated surgery for AKP is Iatrogenic medial patellar instability (IMPI). Finally, we must not forget V. Sanchis-Alfonso (&) J. Domenech-Fernandez Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com R. A. Teitge Wayne State University, Detroit, MI, USA that other cause of a failed patella, inadequate physical therapy after surgery. Complications in surgery can occur regardless of the quality of care or competence of the orthopedic surgeon. Obviously, all surgical procedures carry risks of complications. Thus, it is important to prevent unnecessary surgeries to diminish the number of complications. Some types of patellofemoral surgeries are more predictable in alleviating or eliminating pain than others. For instance, in our personal experience, a rotational osteotomy is much more predictable in alleviating AKP than other surgeries. Therefore, a way to avoid a failed patella is to perform only operations with a confirmed high degree of success. Therefore, caution is necessary when recommending surgical treatment for AKP, particularly for “well-meaning, trigger-happy orthopedic surgeons”. The patient with severe pain after a patellofemoral surgery whose objective was to remove pain represents a real challenge for the orthopedic surgeon specialized in the knee. In our experience, most AKP surgeries are done to rectify the complications or bad results from previous, poorly performed or badly indicated AKP surgeries. The goals of this chapter are: (1) to give diagnostic advice for evaluating the failed patellofemoral surgery patient, (2) to provide best practices for avoiding complications around patellofemoral surgery in AKP treatment, and (3) to present operative salvage procedures to treat these cases. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_10 151
152 2 V. Sanchis-Alfonso et al. General Principles in the Management of Failed Patella Having a knowledgeable surgeon and a correct diagnosis of the failure are crucial to solving a “Failed Patella”. The key question we must ask ourselves is: Why did the previous surgery fail? If we do not find an answer to this question, we will not be able to resolve the pain that our patient presents. 2.1 Correct Diagnosis—Listen to the Patient Each patient with a “failed patella” is different. A careful history must be taken, with close attention being paid to what the patient reports. Speaking to a patient is crucial because they will usually tell us, in their own words, what is wrong. It is always important to talk with the patient and especially listen to them. Quite possibly, it is even much more important in the patient with a surgical failure. Moreover, a good physical examination and imaging are also very important. We are particularly surprised by the low quality of imaging studies that we see in patients who are referred to us for patellofemoral revision surgery. 2.2 Rule Out Inappropriate Physical Therapy It is not always the surgeon who is responsible for the failure. We must not forget the damage that the physiotherapist can do during postoperative rehabilitation. Sometimes pain aggravation after surgery is a consequence of inappropriate postoperative physical therapy. For instance, strengthening of the musculature should be performed in a “safe range of flexion–extension” to avoid patellofemoral overload. Steinkamp and colleagues [1] have demonstrated that between 0 and 45° closed kinetic chain exercises cause smaller moments, lesser reaction forces, and less pressure in the patellofemoral joint (PFJ). Due to that, they are less harmful to the patient. Nevertheless, beyond 45°, the open chain exercises are the ones with smaller moment, lesser reaction forces, and less pressure. If we do not follow these premises, we run the risk of causing patellofemoral overload that will result in the appearance of pain in the anterior aspect of the knee. This is just one of the many examples that can cited relative to the damage that the physiotherapist can cause. 2.3 Rule Out Central Sensitization Pain persistence in an operated AKP patients may be the result of central sensitization (CS) [2]. One of the mechanisms that can explain the transition from acute to chronic pain is the phenomenon of CS. It is defined as the “increased responsiveness of nociceptive neurons in the central nervous system” [3]. According to Woolf [3], the hallmarks of central sensitization include: (1) allodynia (that is, pain in the presence of a non-noxious stimulus); (2) primary hyperalgesia, (that is, pain hypersensitivity at the affected site) and (3) secondary hyperalgesia (that is, pain hypersensitivity in uninjured tissues beyond the affected area). CS is the neurophysiological phenomenon in which the persistent transmission of pain produces a reorganization of the transmission mechanisms in the central nervous system (CNS). It is what makes the perception of pain permanent [3]. In a situation of sustained chronic pain, the facilitatory and inhibitory modulatory circuits are reorganized, creating new synapses and producing changes in excitability at the central level. The increase in peripheral nociceptive afferences and the increase in activity at the level of the spinal cord produces an alteration in the processing of pain transmission at the level of the spinal cord and brain. That perpetuates the painful sensation even though the peripheral lesion that initially produced the pain has disappeared. It is noteworthy that there is no injury to the nerve structures in CS, but rather a physiological change that makes the painful sensation persist.
The Failed Patella. What Can We Do? The phenomenon of pain centralization is frequent in different musculoskeletal conditions that present with chronic pain [4, 5]. Thus, it has been estimated that centralization of pain occurs in 30% of cases of osteoarthritis and in close to 100% of patients with fibromyalgia and whiplash syndrome. It has been suggested that it appears in a third of patients with chronic low back pain and in all patients with failed back surgery syndrome. The Central Sensitization Inventory (CSI) is a self-report instrument designed to identify patients who have pain characteristics related to CS. This questionnaire is the most widely method used in clinical setting. Patients are asked 25 questions aimed at assessing CS symptoms. The patient scores each answer on a Likert scale from 0 (never) to 4 (always). A score of more than 40 indicates the presence of CS [6]. Sanchis-Alfonso and colleagues [7] studied the presence of CS using the CSI questionnaire. It was done with a sample of 44 patients with chronic AKP that were compared to a group of 44 healthy subjects matched for age and sex. They found a prevalence of central pain sensitization of 36% in AKP patients versus 4% in the healthy population. The study also explored the participation of CS in both pain and disability as well as in a list of psychological variables that earlier studies have demonstrated as having an influence on the clinical severity of AKP (i.e., depression, anxiety, kinesiophobia and catastrophizing). No differences were found in the level of pain measured with VAS between patients with or without centralized pain. Patients with pain centralization had the same intensity of pain as patients without centralization. However, AKP patients with CS had significantly greater disability than patients without centralization as measured with the Kujala scale (41.6 vs. 53.6, respectively; p < 0,05). This difference coincides with the value of 12 that is considered Minimal clinically important differences (MCIDs) when using the Kujala scale [8]. These findings suggest that pain chronification in AKP patients that is mediated by the phenomenon of CS is more disabling even though their pain intensity may not be greater. In accordance with studies in other musculoskeletal pathologies, the values on 153 the CSI scale correlated with the levels of anxiety and depression, as occurs in our sample of patients. Nevertheless, the CSI score did not correlate with levels of catastrophizing and kinesiophobia, suggesting that they are independent constructs. Catastrophizing and kinesiophobia are psychological variables that have been shown to be associated with disability in AKP patients [9, 10]. CS is a neurophysiological phenomenon in which pain modulation is altered by its facilitatory and inhibitory mechanisms in chronic pain conditions. In some AKP patients, CS is revealed as an explaining factor that influences disability independently of catastrophizing and kinesiophobia. Further research is needed to evaluate the prognostic capabilities of CS and its relationship with therapeutic management. However, we believe that the presence of CS should not be the justification for not continuing to evaluate the patient and send her to a “Pain Unit”. There are patients with high values in the CS score who have objective structural causes that provide an explanation for the pain and that had gone undetected. Once that pain is treated to improve or eliminate it, it causes the CS score to drop drastically. 2.4 Do Not Forget the Psychological Evaluation One must not forget the psychological evaluation of the patient. Our data (see chapters “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients”) shows that the presence of psychological factors in these patients is a limitation to recovery. That is, psychological factors are barriers to recovery. Once again, the presence of those factors should not be the excuse for not continuing to study the patient and refer him to the psychiatrist. “Crazy” patients with a real pathology get back to normal or are at least much better mentally after effective treatment. Therefore, they should not be ignored. We need to look hard for a real pathology and try to help them, even if it takes more patience and tender loving care from the provider.
154 2.5 Do Not Ignore the Mechanics Which Caused the Tissue Failure, if so, Another Failed Result Ensues We must do a complete physical examination to uncover all of the anatomic abnormalities, of which there are often many. You should strive to restore the normal anatomy, because that will create a better biomechanical environment for the tissue. When any abnormal anatomy is uncovered, a question must be answered. How does this change the normal biomechanics? Biomechanics is crucial. Orthopedic surgery is a mechanical engineering discipline. If you repair a failed tissue (bone, ligament or cartilage) and ignore the mechanics which caused the tissue failure, you will usually have a failed result. 2.6 In Short … We must look for, identify and quantify injuries or anatomical anomalies that can be corrected. Moreover, we must have the conviction that they are the most responsible for the pain that the patient we are evaluating has. Find the pain generator is crucial to the success of a surgery. We must always evaluate the following: (1) skeletal alignment (i.e., Does the patient have a neutral mechanical axis, or is varus or valgus present?; Does he or she have abnormal femoral and/or tibial torsion?; Does the patient have a genu recurvatum or genu flexum?); (2) the ligaments (i.e., Does the patient have excessive lateral displacement of the patella or excessive medial displacement or both?); (3) the articular cartilage (i.e., complete or partial loss, location of the loss, possibility to shift contact to intact cartilage); and (4) the muscle (i.e., symmetrical atrophy versus gross imbalance). The surgeon must determine what surgical procedure, if any, has the potential to improve the patient’s condition and, most importantly, not harm them. We, as orthopedic surgeons, must never forget the principles of Hippocratic medicine: “Primum non nocere”. We must not do harm or make a poor situation much worse. We V. Sanchis-Alfonso et al. must make the patients stop saying the typical: “I wish I hadn’t been operated on.” We must note that a failed patella does not necessarily require more surgeries. In some cases, repetitive transcranial magnetic stimulation, radiofrequency neurotomy, spinal cord stimulation or implantable pumps that supply medication to control the pain could be necessary. However, these techniques are beyond the scope of this chapter. Confronting the failed patella of the patient provides a great stimulus for intellectual activity. It provides an opportunity for new observations. It is an opportunity to learn something new each day. 3 Iatrogenic Medial Patellar Instability and Multidirectional Patellar Instability Iatrogenic medial patellar instability (IMPI) is a good example of a new pathology created by the orthopedic surgeon as a result of a poorly performed or badly indicated surgery. IMPI is an objective condition with its own personality that causes disabling AKP and severe disability [11, 12]. In all the cases of the series of the authors of this chapter, there was a previous surgical procedure consisting of an “extensive” isolated lateral retinaculum release (LRR) or an inadequate selection of the patient on whom LRR was performed [11, 12]. Sometimes, LRR has been associated with a proximal and/or distal realignment to treat AKP resistant to conservative treatment or to treat lateral patellar instability [12]. Regarding “extensive” LRR, the first author is weary of hearing this nonsense, “The previous surgeon did not release of the lateral retinaculum. So, I am going to complete this release like it should have been done”. It is a great mistake. Often, the pain and disability from IMPI are much worse and distinct than the preoperative symptoms for which the operation was performed, causing important psychological problems [12]. The percentage of patients with anxiety, depression catastrophizing and kinesiophobia is greater in patients with IMPI than in the more “typical” AKP patients. The figures are as
The Failed Patella. What Can We Do? follows: kinesiophobia (100% vs. 80%), catastrophizing (41% vs. 37%), anxiety (59% vs. 37%), and depression (24% vs. 11%) [12]. Frequently, psychological involvement is overlooked by the orthopedic surgeon. However, it is an important issue because psychological factors are barriers to recovery (See chapter “Evaluation of Psychological Factors Affecting Anterior Knee Pain Patients: The Implications for Clinicians Who Treat these Patients”). IMPI is more frequent than we had thought. It might be underdiagnosed because it is still not a well-known entity. Most of these patients go from one doctor to another until they find a doctor who gives a correct diagnosis and an appropriate solution to their problem. These patients have frequently visited several physicians who had told them that there was nothing that could be done to solve their problem. Then, the patient comes to our office with a large folder full of radiological studies (MRI, CT scan, Xrays) that are identified as normal or as “lateral patellar subluxation” or “chondromalacia patellae”, at the most. There is question we should ask ourselves. Are these radiologically “normal” tests enough to rule out an objective condition that justifies the severe pain the patients suffer? The answer is an emphatic no. Diagnosis of IMPI. Medial Patellar Instability sees you. Do you see it? The first step in diagnosing a pathological condition is to know that it exists. This was clearly stated by Jack Hughston in his well-known sentence: “You may not have seen it, but maybe it has seen you”. In our series, many patients have had to visit more than three doctors before obtaining a diagnosis and an appropriate treatment. This demonstrates that it is a clinical condition that most orthopedic surgeons do not know about. Therefore, we believe that there is a need to communicate the diagnostic procedures for recognizing this clinical condition far and wide. The most important findings for diagnosing IMPI are (1) pain and tenderness at the site of the LR defect; (2) increased passive medial patellar mobility when compared with the contralateral normal knee; (3) pain and apprehension when 155 medial stress is applied to the patella; and (4) a positive Fulkerson relocation test [13]. To perform this test, the patella is held slightly in a medial direction with the knee extended. Then, we flex the knee while letting go of the patella, which causes the patella to go into the femoral trochlea. In patients with medial subluxation, this test reproduces the patient’s symptom. In patients with IMPI, there is significant pain relief with a “reverse” McConnell taping (Fig. 1). Similarly, the application of a patellar brace with the buttress pad or strap on the medial side will minimize or eliminate symptoms (e.g., Trupull brace, DJ Orthopedics, Vista, California, USA). This is a good way to confirm our diagnosis before indicating a surgical treatment. Multidirectional Patellar Instability On some occasions, IMPI is associated with lateral patellar instability due to a deficiency of the medial patellofemoral ligament (MPFL). We must remember that another restraint to medial patellar displacement, apart from the lateral retinaculum, is the MPFL (Fig. 2). In these cases, we are faced with a multidirectional instability of patella. Figure 3 Belongs to a patient operated on for lateral patellar instability with an LRR. The patient had severe trochlear dysplasia. The patient developed an IMPI that was associated with her previous situation of lateral patellar stability. We are therefore facing a typical case of multidirectional patellar instability in which a sulcus sign similar to that seen in multidirectional shoulder instabilities can be seen (Fig. 4). Evaluation of IMPI Ideally, we should evaluate AKP patients, and IMPI should not be an exception, during dynamic activities that trigger or aggravate the symptoms. This should be done under realistic loading conditions, for example, the stair descending test. In patients with IMPI, kinematic analysis demonstrates a stair descending pattern with knee extension (Fig. 5). The knee extension could be a strategy to avoid instability and therefore pain. The patella goes from medial to lateral with knee flexion. This provokes a sudden giving way that
156 A c Fig. 1 Technique for application of reverse McConnell taping on a patient’s right knee. A Protective tape. B, C Application of tape. D Definitive tape in place. (L, lateral; M, medial; P, patella). “Reprinted from V. Sanchis-Alfonso et al. B d Arthroscopy, 31(8): 1628–1632, 2015, Sanchis-Alfonso V and Merchant AC. Iatrogenic medial patellar instability: An avoidable injury, with permission from Elsevier” is much more disabling than a true lateral subluxation. So, the patient will avoid knee flexion to avoid giving way and so avoid pain. Finally, the stress radiograph [14] (Fig. 6) or stress CT [15] (Fig. 7) will document and quantify IMPI objectively. A comparison of the normal side with the pathological side is more important than the absolute amount of displacement. In some cases, IMPI is obvious without stress studies (Fig. 8). In many cases IMPI is associated with cartilage lesions on the lateral patellar facet (Fig. 9). Fig. 2 With medial displacement of the patella the MPFL becomes tight. MPFL is a restraint to medial patellar displacement. (Reused with permission from Baishideng Publishing Group Inc. From Sanchis-Alfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8 (2): 115–129) How to Prevent IMPI? Extensive LRR, or over-release with transection of the vastus lateralis tendon, is a major cause of IMPI (Fig. 10). Moreover, IMPI can be a result
The Failed Patella. What Can We Do? Fig. 3 Multidirectional patellar instability. A Pathological medial displacement of the patella. B, C Pathological lateral displacement. Sulcus sign (black arrow). (Republished with permission of AME Publishing Company. 157 From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018) osteotomy of the tibial tubercle. When it is done, we must do careful preoperative planning. Kelman and colleagues [16] have shown, in a cadaver study, that tibial tubercle medialization does not pull the patella medially as much as it pulls the tibia laterally. In these cases, we must perform a lateral transfer of the tibial tubercle as the first step of revision surgery, that is a reosteotomy of the TT. Treating IMPI Fig. 4 Sulcus sign in a patient with multidirectional shoulder instability of the release of a LR that was lax, showing poor patient selection (Fig. 11A). An isolated LRR should never be performed in the face of trochlear dysplasia (Fig. 11B), patella alta, or hyperelasticity. If the LR is not tight, the surgeon should not release it. Another source of IMPI is the overmedialization of the tibial tuberosity as in the case of Figs. 12, 13 and 14. We must be very cautious when indicating a medialization Reconstructive surgery includes direct ligament repair or reconstruction of the lateral patellofemoral ligament. According to Teitge and Torga [17], IMPI reappears after the first postoperative year after lateral retinacular repair and imbrication. For this reason, the most logical approach should be to reconstruct the lateral patellar retinaculum. The preference of the first author of this chapter is the technique described by Jack Andrish [18] (see video in Arthrosc Tech 2015; 4(3) e245-249) because it is very anatomic (Fig. 15) and allows for fine-tuning of the graft tension by adding sutures to further tighten the graft (Fig. 16). As in reconstruction of the MPFL, the surgeon should tension the lateral reconstruction with the patella engaged within the trochlea with the knee flexed at 30°. The purpose of this technique is to reconstruct the deep transverse layer of the lateral retinaculum
158 V. Sanchis-Alfonso et al. Fig. 5 Knee joint angle during stair descent Table 1 Clinical outcome assessments after reconstruction of the deep transverse layer of the lateral retinaculum [12] (Fig. 15) and not the lateral patellofemoral ligament. The deep layer of the lateral patellar retinaculum is reconstructed using a central strip of the iliotibial band leaving it attached proximally and attaching it to the midpoint of the patella [18]. We must note that it is a “salvage” procedure. It does not address the original source of complaint. Moreover, it cannot improve or reverse the symptoms of osteoarthritis or bony malalignment. Patients with symptomatic IMPI have chronic pain and the etiology of chronic pain is multifactorial with a different pathoneurophysiology than acute pain, including psychological factors like pain modulators. The reconstruction of the LR is a good treatment for this difficult group of severely disabled patients (Table 1 and Fig. 17) [12].
The Failed Patella. What Can We Do? 159 A B C Fig. 6 A 24-year-old woman with severe AKP (10/10— VAS), a disabling disability (4/100—Kujala score), and patellar instability in the left knee distinct and much worse than the previous instability, anxiety, depression, catastrophizing ideas with pain and kinesiophobia. Left knee was operated on 2 years ago, performing an Insall proximal realignment and LRR due to lateral patellar instability. She came to our office with conventional radiographs, which were normal (A), and a CT at 0° that showed correct radiological patellofemoral congruence (B). The right knee was asymptomatic despite the patellar However, we must note that the mere fact that the patient can sublux and even dislocate their patella medially is no guarantee that their pain and disability are directly due to the instability. In cases of IMPI secondary to extensive LRR and over-medialization of the tibial tuberosity, the first step would be to perform a lateralization of the tibial tubercle. After that, a reconstruction of the lateral retinaculum is done. D subluxation and patellar tilt (B). The Fulkerson relocation test for medial subluxation was positive. An axial stress radiograph of the left knee allowed us to detect an iatrogenic medial subluxation of the patella (medial displacement of 15 mm) (C). Axial stress radiograph of the asymptomatic right knee (D). Arrows represent the force applied to displace the patella medially. The symptoms disappeared after an isolated surgical correction of the medial subluxation of the patella using iliotibial band and patellar tendon for repairing the lateral stabilizers of the patella 4 Iatrogenic Patella Infera Patella infera or patella baja is a devastating complication after surgical treatment of AKP or lateral patellar instability. It can provoke disabling AKP and a severe restriction of knee range-ofmotion and can have significant effects on patient function and lifestyle. Weale and colleagues [19]
160 V. Sanchis-Alfonso et al. Fig. 7 A Axial stress CT of right knee. B An axial stress CT of the left knee allows us to detect iatrogenic medial subluxation of the patella (medial displacement of 13 mm). Arrows represent the force applied to displace the patella medially. “Reprinted from Arthroscopy, 31(8): 1628–1632, 2015, Sanchis-Alfonso V and Merchant AC. Iatrogenic medial patellar instability: An avoidable injury, with permission from Elsevier” Fig. 8 IMPI after lateral partial patellar facetectomy. In this case, a patellofemoral prosthesis was put in place that did away with the retropatellar pain but the patient continued with a disabling pain and disability. A reconstruction of the deep layer of the lateral retinaculum according to Andrish’s tecnique was performed with a good result Fig. 9 You can note an evident medial displacement of the patella when we apply a force that displaces the patella medially. Moreover, you can see a chondral lesion of the lateral facet of the patella
The Failed Patella. What Can We Do? Fig. 10 Frequently found in IMPI patients; a sectioned vastus lateralis tendon (red arrow) (A). B Reconstruction of lateral retinaculum with iliotibial band (black arrow) and reattachment of vastus lateralis (green arrow). Fig. 11 A Patellar tilt in a patient with non-tight lateral retinaculum. B Severe trochlear dysplasia. In both cases an LRR was performed resulting in IMPI A have demonstrated that there is a one-degree of loss of knee flexion for each millimeter of patellar tendon shortening. Moreover, if proper treatment is delayed, early patellofemoral osteoarthritis (PFOA) can present itself [20]. Patella infera may be a complication of patellofemoral surgery or a consequence of a surgical planification technique mistake. It often occurs in association with arthrofibrosis following knee surgery. However, it is secondary to distal realignment surgery in some cases. An example is the distal tubercle transfer procedure 161 “Reprinted from Arthroscopy, 31(8): 1628–1632, 2015, Sanchis-Alfonso V and Merchant AC. Iatrogenic medial patellar instability: An avoidable injury, with permission from Elsevier” B for patella instability in patients with patella alta (Fig. 18). Other less frequent causes are patellar tendon contracture after arthroscopic denervation of the inferior pole of the patella (Fig. 19) or after tourniquet paralysis of the quadriceps (Fig. 20). How to Avoid a Patella Infera? Adequate preoperative planning is crucial. Intraoperative visualization before tibial tubercle fixation, and early restoration of quadriceps activation are mandatory.
162 V. Sanchis-Alfonso et al. Fig. 12 Stress axial radiography showing medial left patellar instability. The arrow indicates the direction of the force that displaces the patella medially. (Republished with permission of AME Publishing Company. From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018) Fig. 13 Medial left patellar instability secondary to an over-release of the LR (white arrow) associated with an over-medialization of the tibial tuberosity. Overmedialization of the tibial tubercle can be avoided by means of an intraoperative evaluation of the tubercle sulcus angle. The intraoperative goal should be a tubercle sulcus angle of 0°. (Republished with permission of AME Publishing Company. From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018)
The Failed Patella. What Can We Do? 163 Fig. 14 In this case, we performed a reconstruction of the deep layer of the lateral retinaculum and a lateral transfer of the tibial tubercle. Here you can see the correct postop patellofemoral congruence. There was a severe patellar chondropathy. Despite the correct congruence and kinematics of the PFJ, pain persisted in the anterior aspect of the knee. Therefore, a patellofemoral arthroplasty was performed with a good clinical result. (Republished with permission of AME Publishing Company. From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018) Fig. 15 Anatomy of the lateral retinaculum. Patella (P), deep lateral retinaculum (DLR), superficial lateral retinaculum (SLR), iliotibial band (ITB), and vastus lateralis (VL). The true lateral patellofemoral ligaments are thickenings of the lateral capsule. There is a lateral epicondylopatellar ligament described and present in some individuals, to varying degrees of frequency, but the superficial oblique and deep transverse retinacular layers are more consistent. The superficial oblique retinaculum is quite thin. The deep transverse retinaculum is stout, oriented in an optimal direction to restrain the patella and attached to the lateral boarder of the patella and the deep surface of the iliotibial band
164 A V. Sanchis-Alfonso et al. B Fig. 16 Surgical technique. A The iliotibial band (ITB) is detached from Gerdy’s tubercle and B then reflected proximally beyond the lateral femoral epicondyle to be attached to the lateral border of the junction of the middle and proximal thirds of the patella by suturing to the remaining peripatellar retinacular tissue or by using a suture anchor. To adjust tension, a series of sutures are placed reattaching the posterior border of the transferred tendon to the anterior border of the remaining intact iliotibial band. “Reprinted from Arthroscopy, 31: 422–427, 2015, Sanchis-Alfonso V et al. Results of isolated lateral retinacular reconstruction for iatrogenic medial patellar instability, with permission from Elsevier” Fig. 17 A 25-year-old female came to our institution with a history of chronic severe anterior right knee pain, severe disability, and patellofemoral instability refractory to conservative treatment, for about 5 years. The Kujala preoperative score was 36 points. The patient underwent an Insall’s proximal realignment with LRR procedure at the age of 18 due to recurrent lateral patellar dislocation. Computed tomography (CT) examination at 0° extension and quadriceps contraction shows lateralization of the patella (A). Documentation of medial patellar instability (B). Preoperative gait analysis revealed a significant increment of the vertical heel contact peak force as a result of a knee extension gait pattern (C). Follow-up CT scan at 0° extension with quadriceps contraction demonstrates similar lateral displacement of the patella in both knees (D), and stress CT revealed medial patellar stability (E). Four months after surgery, she was symptom free. Gait analysis was performed at this time to evaluate the effects of surgical reconstruction of the lateral retinaculum on gait parameters. No significant differences were seen when compared to the contralateral limb, the gait pattern being normal (F). At the time of surgery, an arthroscopy of the right knee was performed. All the intra-articular structures were intact, except for a patellar chondropathy grade III, according to the Outerbridge classification, located medially and a peripatellar synovitis. We did not perform chondroplasty or peripatellar synovectomy. After the arthroscopy, we performed an open reconstruction of the lateral patellotibial ligament according to the technique described by Hughston using the iliotibial band and the patellar tendon. “Reprinted from The Knee, 14: 484–488, 2007, Sanchis-Alfonso V et al. Gait pattern normalization after lateral retinaculum reconstruction for iatrogenic medial patellar instability, with permission from Elsevier”
The Failed Patella. What Can We Do? 165 Fig. 18 This is the case of a PFOA in a patient with severe iatrogenic patella infera after TT distalization surgery. In this case, the patellar tendon is of normal length. (Courtesy of JC Monllau, MD) (Republished with permission of AME Publishing Company. From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018) Fig. 19 Patella infera following a patellar tendon contracture after arthroscopic denervation of the inferior pole of the patella to treat disabling AKP. A Pre-operative MRI. B Magnetic resonance image 1.5 years after arthroscopic denervation of the inferior pole of the patella. (Republished with permission of AME Publishing Company. From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018)
166 V. Sanchis-Alfonso et al. Fig. 20 24-year-old woman operated on for AKP recalcitrant to conservative treatment. An LRR was performed. She presented a paralysis of the quadriceps as a consequence of femoral nerve damage by the ischemia cuff. Note the lowering of the left patella (A) when compared with the height of the contralateral healthy limb patella (B). (Republished with permission of AME Publishing Company. From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018) Treating Patella Infera for 8 weeks. Rehabilitation begins at week 8. Burnett and colleagues [24] evaluated two techniques of reconstruction of the extensor mechanism of the knee using an extensor mechanism allograft. There was Group I with the allograft minimally tensioned and Group II with the allograft tightly tensioned in full extension. They demonstrated that the results of surgery depend on the initial tensioning of the allograft. A loosely tensioned allograft results in a persistent extension lag and clinical failure. Allografts that are highly tensioned in full extension can restore active knee extension and result in clinical success. They concluded that an extensor mechanism allograft transplantation will be successful only if the graft is initially tensioned tightly in full extension [24]. Surgery is indicated when the Caton–Deschamps ratio is less than or equal to 0.6 [21]. There are two surgical options. If patella infera is the result of a distalization of the tibial tubercle we should perform an osteotomy of proximalization of the tibial tuberosity (Fig. 18) [22]. If it has resulted from the shortening of the patellar tendon, a Zlengthening of the patellar tendon would be the prefer option (Figs. 19 and 21) [23]. In exceptional cases, the treatment of a patella infera requires an extensor mechanism allograft transplantation. Figure 22 corresponds to a patient with a patella infera at 10 years of performing an extensor mechanism allograft. You can observe a severe degeneration of the patellar tendon. Therefore, it is not feasible to perform a Zlengthening of the patellar tendon. Considering that, a decision was taken to make a new extensor mechanism allograft. There was a good functional result. A crucial technical aspect for the success of this surgery is not to flex the knee intraoperatively to evaluate the result of the reconstruction [24]. After surgery, immobilization with the knee in full extension is put in place 5 The Failed Cartilage Surgery We sometimes see patients operated on due to patellofemoral pain who have undergone surgery on the cartilage of the patella or the femoral trochlea with poor results. The patient usually
The Failed Patella. What Can We Do? Fig. 21 Patella infera with a shortened patellar tendon. Lengthening of the patellar tendon by means of a Z-plasty associated with patellofemoral arthroplasty. A reconstruction of the LR also was performed (white arrow). 167 (Courtesy of JC Monllau, MD) (Republished with permission of AME Publishing Company. From V SanchisAlfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018) Fig. 22 Correction of the patella infera using an extensor mechanism allograft transplantation
168 has more severe pain than before surgery. If we study the patient in detail, an underlying pathological torsion abnormality is detected in most of the cases. In this case, the reason for the failure of the surgery is a badly indicated surgery. An inward pointing of the knee increases the lateral direction of pull of the quadriceps. Therefore, the pull on the MPFL and also medial retinaculum and medial meniscopatellar ligament is increased and the direction of pressure on the patella is altered. This causes an increased compression on the lateral facet and a decrease on the medial facet of the patella (Figs. 23 and 24). It may be what is behind the persistence of pain and the surgical failure of the cartilage surgery. How to Avoid Failed Cartilage Surgery? To avoid a cartilage surgery failure, the restoration of the normal anatomy is crucial as that will create a better biomechanical environment for the tissue. In this case, we are referring to the cartilage. If you repair failed tissue and ignore the mechanics which caused the tissue failure, you will usually have a failed result. Furthermore, only correcting the torsional abnormality will make the pain disappear in many cases even if we do not treat the cartilage injury. We must note that not all PFOA cases are associated with severe pain. In the PFJ, patellofemoral Fig. 23 A If the knee joint moves forward, the compression on the PFJ and ligaments tensioned are balanced. B If the knee joint twists inward from beneath the patella, the MPFL is placed under increased tension, the compression beneath the lateral facet increases, and the compression V. Sanchis-Alfonso et al. congruence and smooth kinematics are much more important than normal articular cartilage. Treating Failed Cartilage Surgery The great problem after failed cartilage surgery lies not in the lesion itself but in the age of the patients, who are too young for “metal and plastic”. In these cases, fresh allograft transplantation should be considered as a salvage treatment procedure (Figs. 25 and 26). Before any resurfacing technique, the PFJ and the skeletal mal-alignment of the extremity must be optimized to obtain satisfactory results. A resurfacing technique is not a substitute for skeletal realignment. In cases where the patellar tracking and skeletal alignment of the extremity are correct, an isolated resurfacing technique can be performed (Figs. 25 and 26). 6 Rotational Osteotomy. A Game Changer in the Treatment of “Failed Patella” What is a game changer? It might be a sudden strategy that the usually winning opponent has never imagined being used by the underdog team to win the game. We really believe that rotational osteotomy is a game changer in the treatment of beneath the medial facet decreases. (Reused with permission from Elsevier. From Teitge RA. Patellofemoral Disorders Correction of Rotational Malalignment of the Lower Extremity. In: Noyes’s Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes, 2017)
The Failed Patella. What Can We Do? 169 Fig. 24 If the knee joint twists inward because the femur twists inward, the lateral displacement pull on the patella is increased, the strain on the MPFL is increased, the compression on the lateral patellar facet is increased, and the compression on the medial patellar facet is decreased. The treatment must be to decrease the inward twist on the knee joint, not to move the tubercle medially. A similar increase of inward pointing of the knee joint occurs in the presence of excess external tibial torsion when the foot is pointed forward. (Reused with permission from Elsevier. From Teitge RA. Patellofemoral Disorders Correction of Rotational Malalignment of the Lower Extremity. In: Noyes’s Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes, 2017) the “failed patella”. The patient in Fig. 27 had severe chronic patellofemoral pain with extensive and severe involvement of the patellar cartilage in both knees. In addition, she presented an external tibial torsion of 49° in the left knee and 45° in the right knee. A bipolar fresh patellofemoral allograft procedure was performed on her right knee with a good result in the short term. Due to problems of availability of fresh allografts in the tissue bank, a decision was taken to perform an internal rotational tibial osteotomy on her left knee. The results were very good. The patient is happier with her left knee than with her right one, which is now the bad knee for her (Fig. 28). As far back as 1995, Flandry and Huhgston [25] showed that the most frequent cause of failure of an extensor mechanism realignment surgery was the existence of an underlying undiagnosed torsional alteration that, of course, had gone untreated. In 2009, Paulos and colleagues [26] compared two surgical techniques in a cohort of patients with patellar instability and limb malalignment. In one group, they performed a proximal
170 V. Sanchis-Alfonso et al. Fig. 25 Severe diffuse patellar chondropathy in a 40year-old woman with disabling AKP after two previous failed surgeries performed to treat AKP. A Surgical image of the chondral lesion. B Patellar fresh allograft in situ. C Anteroposterior radiograph D Lateral radiograph and E Axial radiograph at the 5-year follow-up. (Republished with permission of AME Publishing Company. From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018) realignment associated with a rotational tibial osteotomy. In the other one, a Elmslie-TrillatFulkerson proximal–distal realignment was done. They concluded that rotational abnormality correction produced significantly better results than conventional proximal–distal realignment. Stevens and colleagues [27], in 2014, analyzed 16 consecutives patients (23 knees) with a failed knee surgery (tibial tubercle osteotomy in 12 knees and arthroscopic debridement in 9) before which a femoral or tibial torsional abnormality was recognized and subsequently treated by means of rotational osteotomy. They demonstrated clinical improvement after osteotomies of the femur and/or tibia in these patients. Those authors state that many orthopedic surgeons only focus on the knee when they see an AKP patient. Torsional abnormalities often go unrecognized. These authors observed that addressing rotational abnormalities in the index surgery provides better clinical results than osteotomies performed after previous knee surgeries for treating AKP and/or patellar instability. Drexler and colleagues [28] evaluated 15 knees (12 patients) in 2013 in which a rotational tibial osteotomy proximal to the tibial tuberosity associated with a tibial tubercle transfer was performed based on a diagnosis of recurrent patella subluxation secondary to excessive external tibial torsion. The authors showed a satisfactory clinical outcome at a median follow-up of 84 months (range 15–156). The high number of patients with previous failed surgeries in this series provides some evidence that tibial tubercle medialization associated with soft tissue plication is not sufficient to correct patellar instability in patients with excessive external tibial torsion. Finally, Franciozi and colleagues [29] evaluated 48 patients who underwent an MPFLr associated with a tibial tubercle osteotomy due to recurrent patellar dislocation. They classified the patients in 2 groups. One was with excessive
The Failed Patella. What Can We Do? 171 Fig. 26 CT of the same case from Fig. 25 Fig. 27 Patient with bilateral AKP and similar structural changes in both knees including pathologic excessive external tibial torsion. A bipolar patellofemoral fresh allograft procedure was done on the right knee. Some 2 years later, a rotational tibial osteotomy was carried out on the left knee
172 V. Sanchis-Alfonso et al. Fig. 28 In these images of the same patient as in Fig. 27, the deterioration of the fresh bipolar allograft was observed as the months went by. This deterioration was due to the disadvantageous biomechanical environment into which the graft was implanted and which had not been corrected. In other words, we did not correct the pathological external tibial torsion that this patient presents. The external tibial torsion will lead to an augmentation of the lateral vector of the quadriceps femoris muscle and therefore to a mechanical overload on the lateral aspect of the patellofemoral joint with the ulterior development of a severe patellofemoral chondropathy, as in fact is observed on the CT images. It is absolutely essential to correct the anomalous biomechanical environment in order to avoid the surgical failure performed on the cartilage. Do not ignore the mechanics which caused the tissue failure, if so, another failed result ensues femoral anteversion (FAV) and the other one with normal FAV. The patients with increased FAV had significantly lower functional scores than the patients without FAV. We can conclude that increased FAV can negatively affect the postoperative prognosis. Femoral rotational osteotomy combined with MPFLr should be considered for the treatment of recurrent patellar dislocation associated with FAV. – Ideally, treating a complication should address the problem that led to the primary surgery and the damage caused by the failed surgical procedure. – A poorly indicated or poorly performed surgical treatment can be disastrous for the patient. Orthopedic surgeons must never forget the principles of Hippocratic medicine: “Primum non nocere”. We must not cause harm or make an already bad situation much worse. 7 Take Home Messages – The best way to avoid a patellofemoral surgery that will lead to an unsuccessful result is to stick to operations that have shown a high degree of success. – By reducing the large number of unnecessary surgeries to treat AKP and by paying attention to technical details, we also can considerably reduce the number of surgical complications. – We must be sure that an anatomic lesion that is amenable to surgical correction is identified preoperatively. References 1. Steinkamp LA, Dillingham MF, Markel MD, et al. Biomechanical considerations in patellofemoral joint rehabilitation. Am J Sports Med. 1993;21:438–44. 2. Sigmund KJ, Hoeger Bement MK, Earl-Boehm JE. Exploring the pain in patellofemoral pain: a systematic review and meta-analysis examining signs of central sensitization. J Athl Train. 2021;56(8):887– 901. 3. Woolf CJ. Central sensitization: Implications for the diagnosis and treatment of pain. Pain. 2011;152(3 Suppl):S2.
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Risk Factors for Patellofemoral Pain: Prevention Programs Michelle C. Boling and Neal R. Glaviano 1 Epidemiology of PFP Patellofemoral pain (PFP) is one of the most common knee injuries among those who are physically active. It is a challenging condition to manage due to the exacerbation of symptoms during tasks that require weight-bearing knee flexion, which is common during activities of daily living. While conservative treatment is the cornerstone to PFP management, long-term outcomes are less optimal [1]. Therefore, identifying those at greater risk for PFP and implementing prevention programs are essential to minimizing the long-term sequelae associated with PFP. To fully appreciate the risk factors for PFP, it is essential to consider the epidemiology across various populations. The epidemiology of PFP is commonly measured with prevalence and incidence. Prevalence is the proportion of a population reporting PFP regardless of the initial diagnosis, while incidence is the number of new cases of PFP during a specific period of time. M. C. Boling (&) Clinical and Applied Movement Sciences, Brooks College of Health, University of North Florida, Jacksonville, USA e-mail: m.boling@unf.edu N. R. Glaviano Department of Kinesiology, College of Agriculture, Health and Natural Resources, University of Connecticut, Mansfield, USA Prevalence and incidence rates have been measured across numerous populations who commonly experience PFP. The prevalence of PFP varies greatly among sampled populations, ranging from 7.2 to 45.3% [2–5]. The prevalence of PFP has been reported to be 25% in patients attending a sports medicine clinic [6], 22.7% in a university community [3], 13.5% in military cadets [7], and 20.7% in the general Chinese population [5]. The prevalence of PFP among runners has a greater range, with recreational runners in the United Kingdom having a prevalence of 16.7% [8] and amateur runners in Nigeria having a prevalence of 45.3% [4]. Furthermore, the point prevalence among a pooled adolescent cohort has been reported to be 7.2% [2], while the annual prevalence has been reported to be as high as 28.9% [9]. The incidence of PFP also varies considerably based on the sampled population. Within military cadets the incidence of PFP has been reported to range from 9.7 to 571.4 cases per 1000 personyears. Among female novice recreational runners, the incidence rate over a 10-week period was reported as 1080.5 cases per 1000 personyears [2, 10]. Furthermore, in an adolescent population participating in physical education classes, the incidence rate for PFP was reported to be 42.6 cases per 1000 person-years [11]. Patellofemoral pain has also been suggested to impact females more commonly than males. Evidence supports females are at a 2-times greater risk for developing PFP across the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_11 175
176 M. C. Boling and N. R. Glaviano general population [3], adolescent population [12] and military cadets [7]. The high prevalence and incidence rates for PFP among various populations, and the increased risk among females, highlight the need for clinicians to understand the risk factors for PFP to implement specific prevention programs to target those at the greatest risk for developing this chronic condition. 2 Risk Factors Patellofemoral pain is considered a multifactorial condition in which various intrinsic factors, such as altered movement patterns, muscle strength, and postural alignment could predispose an individual to the development of PFP. It is important to consider extrinsic factors, (i.e. training load) as well, and how this may lead to the development of PFP. Overall, factors that can influence loading of the patellofemoral joint have been investigated in prospective cohort studies, as abnormal loading of the patellofemoral joint is theorized to be the underlying cause of PFP [13]. The following paragraphs summarize risk factors assessed in prospective cohort investigations. 3 Intrinsic Risk Factors Altered Movement Patterns Prospective investigations have assessed lower extremity kinematics during various functional tasks as risk factors for the development of PFP. The influence of lower extremity joint motion on patellofemoral joint contact forces and loading of the patellofemoral joint provides the theoretical foundation for the investigation of lower extremity kinematics as risk factors for the development of PFP [13]. Patellofemoral pain is a prevalent condition among runners and therefore, this population is frequently included in prospective investigations. Noehren et al. [14] assessed gait mechanics in female runners to determine if there were any lower extremity kinematics during running gait that increased the risk for the development of PFP. Based on their findings, female runners who developed PFP displayed greater hip adduction throughout the stance phase of running when compared to those who did not develop PFP. Transverse plane motion at the hip and rearfoot angles at the ankle were not found to be risk factors for PFP in female runners. Three prospective cohort investigations have assessed lower extremity movement patterns during a jump-landing task as risk factors for the development of PFP [15–17]. In two of these studies (one study was a follow up investigation to the initial study), three-dimensional lower extremity kinematics during a jump-landing task were evaluated in male and female military cadets. In the initial study, military cadets who displayed an increased hip internal rotation angle and decreased peak knee flexion angle during the jump-landing task were at an increased risk for developing PFP. In the follow up study, Boling et al. [15] analyzed risk factors separately for male and female military cadets during the same jump-landing task. In female military cadets, decreased hip abduction angle and increased knee internal rotation angle when landing from a jump increased the risk for developing PFP. In male military cadets, decreased knee flexion angle and increased hip external rotation angle increased the risk for developing PFP. In another prospective study, two-dimensional knee valgus displacement during a landing task was assessed as a risk factor for the development of PFP in adolescent females. Increased twodimensional knee valgus angle displacement was associated with an increased risk of developing PFP in adolescent females [17]. Holden et al. [17] reported knee valgus displacement 10.6° predicted PFP development in adolescent females with a sensitivity of 75% and specificity of 85%. It is important to note that frontal and transverse plane motion at the hip likely
Risk Factors for Patellofemoral Pain: Prevention Programs contributes to the measurement of twodimensional knee valgus displacement in this investigation. Therefore, the findings from this investigation are further supported by the previous prospective investigations reporting increased frontal and transverse plane motion at the hip as risk factors for the development of PFP [14, 15]. An additional prospective investigation assessed performance on the Y-balance test and frontal plane knee projection angle during a single leg squat as risk factors for the development of PFP in male military recruits [18]. Asymmetry 4.08 cm in the posterolateral reach on the Y-balance test and frontal plane knee projection angle 4.81° during a single leg squat were significant predictors for the development of PFP in this population. In summary, altered lower extremity movement patterns appear to play a role in the development of PFP in males and females. Increased frontal plane and transverse plane motion, most notably at the hip and knee, have been reported in multiple studies during various dynamic tasks as potential risk factors for the development of PFP in both males and females. When assessing individuals who may be at risk for the development of PFP, clinicians should pay particular attention to increased frontal and transverse plane motion during dynamic tasks and address these altered movement patterns to potentially decrease the risk for future PFP development. Muscle Strength Both isometric and isokinetic strength of lower extremity muscle groups have been investigated as risk factors for the development of PFP. Due to the influence of hip musculature on the ability to control lower extremity movements, strength of the hip musculature has been investigated as a risk factor for PFP. Furthermore, quadriceps strength has been investigated as a risk factor for the development of PFP due to the quadriceps serving as the main dynamic stabilizer of the patella. Prospective investigations have assessed isometric strength of the hip flexors, extensors, 177 abductors, adductors, internal rotators and external rotators in male and female military cadets [15, 16], male and female high school runners [19], female high school basketball players [20], and female adult runners [10]. None of these studies reported an association between decreased isometric strength of the hip musculature and an increased risk of developing PFP. Interestingly, increased isometric strength of the hip external rotators was associated with an increased risk of developing PFP in male and female military cadets [16]. However, in a larger cohort as a follow-up study to this previous investigation, no isometric hip strength measures were found to be associated with an increased risk of developing PFP in male or female military cadets [15]. Specific to male and female high school runners [19] and female high school basketball players [20], increased isometric strength of the hip abductors was associated with an increased risk for the development of PFP. A systematic review with meta-analysis pooled the data from prospective studies and regardless of cohort population, strength of the hip musculature was not found to be a risk factor for the development of PFP [21]. Both isometric and isokinetic measures of quadriceps strength have been included in prospective investigations of risk factors for PFP in various populations. Three investigations have assessed isometric quadriceps strength in military cadets [15, 16, 22]. In a combined cohort of male and female military cadets, decreased isometric quadriceps strength was associated with an increased risk for the development of PFP [16]. However, when male and female military cadets were analyzed separately, isometric quadriceps strength was not found to be a risk factor for the development of PFP [15]. Isometric strength of the quadriceps has also been investigated in female high school basketball players and was not reported as a risk factor for the development of PFP [20]. Based on the three prospective investigations assessing isokinetic torque of the quadriceps, decreased isokinetic torque of the quadriceps was not a risk factor for the development of PFP in male and female physical education students [11] but was found to increase
178 the risk of development PFP in male military cadets [23] and female military recruits [24]. When pooling the data from all studies assessing strength of the quadriceps musculature, regardless of cohort and type of measurement (isometric or isokinetic), decreased strength of the quadriceps was found to be a risk factor for the development of PFP [21]. Postural Alignment Q-angle is the angle formed by force vectors of the quadriceps musculature and the patellar tendon [25]. A larger Q-angle is proposed to increase the lateral force vector placed on the patella by the quadriceps and therefore, cause lateral tracking of the patella [26]. Three prospective cohort investigations have assessed Q-angle in female and male military recruits [16], novice female runners [10], and male and female physical education students [11]. All three studies reported static Q-angle is not a risk factor for the development of PFP. Foot Posture Excessive pronation at the foot has been associated with increased frontal and transverse plane motion up the kinetic chain [27, 28]. Because motion at the foot and ankle may influence the mechanics at the patellofemoral joint, excessive pronation has been theorized to predispose individuals to PFP. Various plantar pressure measures during gait have been assessed as risk factors for the development of PFP. During walking, a more laterally directed pressure at initial contact, slower movement of the center of pressure from lateral to medial, and shortened time to maximal pressure on the fourth metatarsal were found to be associated with an increased risk of developing PFP in military cadets [29]. During running, increased vertical peak force under the second metatarsals and a shortened time to peak vertical force at the lateral heel were associated with an increased risk for the development of PFP in novice female runners [30]. In a systematic review with meta-analysis, data for time to peak force measures were pooled and no significant M. C. Boling and N. R. Glaviano associations were found between these measures and risk of developing PFP [21]. Static measures of foot posture have also been investigated as risk factors for the development of PFP; however, no studies have used the same measure. Witvrouw et al. [11] reported measures of foot arch on a podograph, lower leg-heel alignment, and heel-forefoot alignment were not risk factors for the development of PFP in physical education students. Thijs et al. [30] investigated static foot posture using the foot posture index (FPI) in recreational runners. They reported measurements of FPI were not associated with the risk of developing PFP. Boling et al. [16] investigated foot posture using the navicular drop assessment. Increased navicular drop was identified as a risk factor for the development of PFP. However, in a follow up study on gender specific risk factor profiles in a larger cohort of military cadets, navicular drop was not a risk factor for the development of PFP in males or females [15]. Based on the current data available, foot posture does not appear to predispose individuals to the development of PFP. 4 Extrinsic Risk Factors Overload/Overtraining The envelope of function can be used to understand how excessive loading of the patellofemoral joint may lead to the development of PFP [31]. Dye et al. [32] describes how supraphysiologic loading of an otherwise normal patellofemoral joint could cause the loss of homeostasis within the joint tissues. This loss of tissue homeostasis can lead to pain and loss of function. Repetitive loading of the patellofemoral joint is common during military recruit training and thus, many prospective studies have investigated risk factors for PFP in this population. In two prospective investigations conducted during basic military training, the majority of cases of PFP were reported within the first four weeks of training [33, 34]. It may be speculated that the
Risk Factors for Patellofemoral Pain: Prevention Programs individuals who developed PFP had lower levels of physical activity prior to basic training and underwent a significant increase in training load in the first few weeks of training (operating outside of the envelope of function) leading to a loss of tissue homeostasis. When developing prevention programs, it is important to consider training load along with intrinsic risk factors for the development of PFP. 5 Prevention of PFP One of the most common injury prevention models was developed by van Mechelen et al. [35]. This injury prevention model includes four steps: establishing the incidence of an injury, establishing the etiology of the injury, implementing a preventative program, and assessing the effectiveness of the program. The injury incidence following the intervention is compared to the initial injury incidence rate to determine the effectiveness. The model is continuous, as step four leads into step one, repeating the process (Fig. 1). Optimizing injury prevention requires the programs to be adopted into clinical practice, placing a significant focus on implementation. Finch [36] modified the initial van Mechelen 179 model [35] to the Translating Research into Injury Prevention Practice (TRIPP). The TRIPP model includes two additional steps, evaluating the prevention measure in ideal scientific conditions and evaluating the program’s feasibility in clinical practice by describing the intervention context to inform implementation strategies (Fig. 1). The two other steps recognize the value of implementation. They also demonstrate one of the challenges of the current prevention programs within the patellofemoral pain literature, as most studies have been conducted within military settings. While many risk factors have been evaluated in the PFP literature, altered movement patterns and decreased knee extensor strength have emerged as specific intrinsic risk factors. There is limited evidence of implementing a prevention program to mitigate the risk of developing PFP. Foot orthoses and footwear, knee braces, and combined stretching and strengthening exercises have been implemented to reduce the incidence of PFP, with most being conducted in a military population. Muscle Strength Decreased isometric and isokinetic knee extensor strength is a risk factor for PFP, suggesting Fig. 1 Comparison of van Mechelen injury prevention model [35] and translating research into injury prevention practice framework [36]
180 strength-based interventions that focus on the quadriceps would be a viable intervention. Three randomized control trials have evaluated the effect of a strength-focused program on preventing PFP, two in military recruits [33, 37] and a third in elite volleyball players [38]. A randomized controlled trial of 1020 Army recruits was the first prevention program to investigate an intervention with the goal of reducing the occurrence of PFP [33]. A 12-week program that combined strengthening and stretching was implemented three times a week, compared to a control group that completed upper extremity exercises. Those allocated to the prevention program had improvements in their running fitness assessment but the program did not reduce the risk of developing PFP in the Army recruits. The second randomized control trial was a 16week prevention program on an elite volleyball team over a single season [38]. The prevention program included isometric open kinetic chain exercises, isometric closed kinetic chain exercises, sports specific or plyometric exercises, and eccentric exercises. The program was conducted two times a week, with exercises adjusted weekly, and integrated into the regular volleyball training. The control group maintained their regular training program, with no additional exercises. After the volleyball season, there was no reduction in PFP risk among those completing the prevention program compared to the control group. The third prevention program was a randomized control trial of 1502 military recruits over 14-weeks [37]. Individuals in the prevention group completed four lower extremity strengthening exercises as a warm-up to military training and four lower extremity stretching exercises during the session warm-down. In contrast, the control group completed their regular training. The prevention program was completed on average seven times per week, which was the highest number of completed sessions in a week across the three randomized controlled trials. This prevention program effectively reduced the risk of developing PFP by 75% compared to the control group. M. C. Boling and N. R. Glaviano The three randomized controlled trials included a wide range of exercises within the prevention program, but all included a squat and lunge task (Table 1). Brushoj et al. [33] included a squat and lunge task to target the quadriceps, with both exercises being prescribed only in weeks 5–8. Cumps et al. [38] included three exercises per week that targeted the quadriceps, hamstrings, and gluteal muscles. Coppack et al. [37] included isometric hip abduction, lunge, step-down, and squatting tasks. With evidence supporting knee extension strength as a risk factor for the development of PFP, each of these studies likely targeted the quadriceps with the prescribed exercises. However, none of the studies measured strength pre-and postintervention. The inability to objectively assess strength is essential to determine the prevention program’s effectiveness. Future randomized control trials are necessary to determine the prevention program’s effectiveness at improving knee extension strength and reducing the risk of PFP. Altered Movement Patterns Altered frontal and sagittal plane kinematics, assessed in three-dimensional and twodimensional motion analysis, increase the risk of developing PFP. Implementing an intervention program to decrease hip adduction and internal rotation, and increase knee flexion may reduce the risk of developing PFP among physically active individuals. Motor learning and gait retraining have demonstrated promise at reducing frontal plane kinematics in females with PFP [39, 40]; however, no studies have evaluated these interventions to prevent the development of PFP. There is a need for randomized controlled trials to determine if movement patterns can be altered and if this reduces the risk for developing PFP. Other Prevention Programs Previous studies have identified various foot posture impairments in those with PFP, supporting early prevention program interventions. Three studies, ranging between 9 and 14 weeks, have evaluated the effect of orthoses and
Population Military cadets Elite volleyball players Authors Brushoj et al. [33] Cumps et al. [38] 16-weeks 2x/week 12-weeks 15-min 3x/week Duration/frequency Month 2: Isometric strength in CKC • Oscillating squat: 3 20 s • SLS circles: 3 10 • Oscillating hamstrings: 3 20 s • Quad sets: 3 10 at 7 s • Oscillating quad: 3 20 s • Oscillating lunge: 3 20 s • Co-Contraction: 3 10 7 s • Oscillating lunge: 3 20 s • Oscillating hamstrings: 3 20 s • Quad sets: 3 10 at 7 s • Oscillating quad: 3 20 s • SLR: 3 10 at 7s • Quad sets: 3 10 at 7 s • Co-Contraction: 3 10 at 7 s • SLR: 3 10 at 7s • Quad sets: 3 10 at 7 s • Oscillating quad: 3 20 s • SLR abduction: 3 10 at 7 s Week 1 Week 2 Week 3 Squat/lunge: 3 10–20 Hip ABD/ER: 3 12–20 Forefoot lift: 3 5–15 Coordination: 3 10–15 Quadriceps stretch: 3 15 s Month 1: Isometric strength in OKC • • • • • Exercises with load Table 1 Summary of exercises included in injury prevention programs • Jump lunge 3 10 • Oscillating drop jump: 3 30 s • Bilateral squat: 3 20 • Drop squat 3 10 • Front step up & down: 3 10 • Lunge: 3 10 (continued) •Drop squat: 3 12 •Shuffle sideways: 3 20 •Jump and reach: 3 15 • Unilateral squat: 3 10 • Lateral step up & down: 3 10 • Oscillating jump lunge: 3 20 s Month 4: Eccentric load • Bilateral squat: 3 10 Oscillating lunge: 3 20 s • Lateral step up & down: 3 10 • Oscillating squat: 3 20 s • Oscillating hamstring: 3 20 s • Bilateral squat: 3 10 Month 3: Sports specific & plyometric Risk Factors for Patellofemoral Pain: Prevention Programs 181
Military cadets Coppack et al. [37] 14-weeks each physical training session (mean = 7/week) Duration/frequency • • • • • • SLR abduction: 3 10 at 7 s • Oscillating squat: 3 20 s • Oscillating lunge: 3 20 s • SLR abduction: 3 10 at 7-sec • Bilateral squat: 3 10 • Shuffle sideways: 3 20 Isometric hip abduction: 3 10–20 Forward lunge: 3 10–14 SL step-down: 3 10–14 SLS squat: 3 10–14 Quadriceps, iliotibial band, hamstring, and calf stretch: 3 20 s each • Quad sets: 3 10 at 7 s • Oscillating quad: 3 20 s • Co-contraction: 3 10 7 s Exercises with load Week 4 Note ABD = abduction, ER = external rotation, SL = single leg, SLS = single leg squat Population Authors Table 1 (continued) • Oscillating drop jump: 4 30 s • Front step up & down: 3 10 • Unilateral squat: 3 10 182 M. C. Boling and N. R. Glaviano
Risk Factors for Patellofemoral Pain: Prevention Programs 183 footwear in military recruits [41–43]. Prescribing orthoses and footwear did not reduce the risk of developing PFP in any of these investigations. The use of knee braces with patellar support has also been investigated in reducing the risk of developing PFP. Two studies, ranging from 6 to 8 weeks, compared the use of a knee brace to no knee brace on PFP risk [44, 45]. When compared to the individuals not wearing a brace, both studies reported those wearing a knee brace had a reduced risk (ranging from 50 to 74%) of developing PFP. The findings from these studies suggest the use of knee braces with patellar support may be effective in reducing the risk of developing PFP. past decade, additional research is needed to better understand how these risk factors may differ by gender and sampled population. Based on the available evidence, increased frontal and transverse plan motion of the lower extremity during dynamic tasks, asymmetry in the posterolateral reach of the Y-balance test and decreased strength of the quadriceps may be considered intrinsic risk factors for the development of PFP. Gaining a better understanding of risk factors for PFP will help to inform future studies investigating the effectiveness of prevention programs in reducing the risk for developing PFP. Overload or Overtraining 7 Prevention programs for PFP have primarily targeted intrinsic risk factors; however, extrinsic risk factors may be an additional avenue. Increases in physical activity that exceed the envelope of function is likely a common occurrence in military recruits as they initiate basic training. Advancements in technology allow for quantification of external load with subjective measures, such as the rate of perceived exertion scale, and objective measures with accelerometers or global positioning systems. Future studies could measure the external load of military cadets before basic training and during the initial few weeks to understand how this may play a role in the development of PFP among military cadets. Additionally, studies could investigate the effects of altering external loading based on the risk of developing PFP during the initial weeks of basic training. 6 Take-Home Messages • Patellofemoral pain is a prevalent condition among physically active individuals. • The incidence of patellofemoral pain is reported to be the highest among recreational runners and military cadets. • Altered lower extremity movement patterns in the frontal and transverse planes during dynamic tasks, such as running and landing from a jump, likely increase the risk for developing patellofemoral pain. • Decreased strength of the quadriceps musculature is a risk factor for the development of patellofemoral pain. • Increased levels of training leading to overloading of the patellofemoral joint likely increase the risk for developing patellofemoral pain. • There is limited evidence for effective injury prevention programs targeting risk factors for the development of patellofemoral pain. Conclusions Patellofemoral pain is a prevalent knee condition affecting individuals who are physically active, with the highest incidence among recreational runners and military cadets. Although there has been an increase in the number of prospective studies investigating risk factors for PFP over the 8 Key-Message • Risk factors for the development of patellofemoral pain include altered frontal and transverse plane motion at the hip and knee
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Anterior Knee Pain After Arthroscopic Meniscectomy: Risk Factors, Prevention and Treatment Jorge Amestoy, Daniel Pérez-Prieto, and Joan Carles Monllau 1 General Considerations The menisci are essential to the normal functioning and biomechanics of the knee. Their functions include shock absorption, load transmission, stability, and proprioception [1, 2]. Meniscal injuries are common conditions in the knee joint, particularly in sports medicine. They can be classified mainly as either traumatic or degenerative injuries. It depends on the mechanism of injury, the pattern of rupture, the age of the patient and the previous state of the meniscal tissue [3–5]. A better understanding of the role of meniscus anatomy, its biomechanics and pathogenesis led to the development of the “meniscus preservation” concept over recent decades. Nevertheless, arthroscopic resections of parts of the menisci probably continue to be the most common surgical procedures around the knee [3, 5–8]. Depending on the type of tear, the time of evo- J. Amestoy (&) D. Pérez-Prieto J. C. Monllau Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain e-mail: jamestoyramos@gmail.com Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain Universitat Autònoma de Barcelona (UAB), Barcelona, Spain lution since the injury and the patient profile, partial meniscectomy is the treatment of choice in many cases [9–12]. In those cases, arthroscopic surgery is an elegant procedure that often results in a remarkable improvement in joint line pain [13]. However, a non-negligible number of patients have developed characteristic and usually temporary anterior knee pain after the surgical procedure. This phenomenon has also been seen in patients that have undergone distinct types of knee surgery, namely anterior cruciate ligament (ACL) reconstruction or total knee arthroplasty [14, 15]. The incidence of postoperative PFP after arthrocopic partial meniscectomy in patients who did not previously have this pain is 23.8% at 6 weeks after the surgery [16]. That percentage is quite similar to the incidence in patients who have pain after ACL reconstruction (22–24%) [17]. Patellofemoral pain after knee arthroscopy usually appears around the sixth postoperative week, which is just the moment when the patient begins to return to their usual sports activities after an arthroscopic partial meniscectomy [18, 19]. It is at this point that the patient should be able to fully activate the quadriceps femoris muscle [20]. Despite referring to improvement in the discomfort at the level of the knee joint interline, the patients with postoperative PFP describe the appearance of a generally nonspecific pain that is sometimes located directly © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_12 187
188 J. Amestoy et al. anterior to the knee. They will often place a hand over the anterior knee when asked about the location of their pain. They often complain with anterior pain with prolonged sitting that it is usually relieved by passive extension as well as worsening pain when going downstairs. Noisy knees are common and not necessarily a cause of concern in the postoperative period [21]. Crepitus or a rubbing sensation under the kneecap that hurts could be pathological if associated with chondral lesions in the patellofemoral joint. However, the excess synovial fluid still present in the knee after arthroscopic meniscectomy may also be the cause of this patellar crepitation. 2 Risk Factors for Patellofemoral Pain After Knee Arthroscopy The cause of anterior knee pain that has been extensively described in this book is likely to be multifactorial, which means a wide range of factors are involved in its etiopathogenesis. Neuromuscular, anatomic, mechanical, and even psychological factors have all been suggested as causative [22–24], which explains the unpredictable results of treatment. In the case of patellofemoral pain that appears after arthroscopic partial meniscectomy, there are several specific risk factors that may influence the development of this pain during the postoperative period. 2.1 Postoperative Quadriceps Muscle Atrophy Classically, one of the suggested etiopathogenesis factors of anterior knee pain was a muscle imbalance between the vastus medialis (VM) and the vastus lateralis (VL) of the quadriceps femoris muscle. It was assumed that hypotrophy or lack of neuromuscular activity of the VM, particularly its oblique fibers (VMO), caused a lateral patellar tilt and abnormal patellofemoral tracking that led to excessive compressive stress on the patellar facets and anterior knee pain. However, Chester et al. have found that the VM/VL imbalance is not present in all patients experiencing PFP [25]. They stated that some other agents must be causative. Quadriceps muscle hypotrophy that occurs following knee surgery contributes to persistant muscle weakness [26, 27] due to alterations in muscle architecture [28], selective fibre atrophy [29, 30], or even neural deficits like quadriceps activation failure [31]. It might also cause postoperative patellofemoral pain. Amestoy and colleagues studied 120 patients who underwent arthroscopic partial meniscectomy. In the study, an MRI of the thigh, surface electromyography and isokinetic tests were performed before and after surgery. They observed that patients who developed PFP at 6 weeks after the surgery showed a greater decrease in muscle thickness (5.11 cm2 for VL15 cm, 6.80 cm2 for VM15 cm, and 7.80 cm2 for VM3.75 cm or VMO) with respect to patients who did not develop this anterior knee pain (1.38, 2.28, and 2.69 cm2, respectively) at 6 weeks after surgery (P < 0.001 for all) [16]. This decrease in muscle thickness was much more noticeable in the VM than in the VL muscle. The weakness of the hip abductor and external rotator muscles might also influence the appearance of this post-operative patellofemoral pain. Weakness of said muscles allows the femur to abduct/internally rotate more than normal, thereby increasing lateral patellar contact pressure and causing subsequent increased anterior knee pain [32–35]. No study has evaluated the atrophy of these muscles after knee arthroscopy. However, it is logical to think that arthrogenic inhibition after knee surgery will be more notable in the quadriceps muscle group than in the gluteal muscle group due to the greater proximity of the knee. 2.2 Delayed Quadriceps Activation Activation failure is the inability to completely volitionally contract the muscle due to alterations in neural signalling. It is common following any type of knee surgery [36, 37]. Quadriceps activation failure occurs due to alterations in neural
Anterior Knee Pain After Arthroscopic Meniscectomy … signalling caused by a reduction in alpha motor neuron pool recruitment and/or the firing rate [38]. It is not simply an isolated local phenomenon related to atrophy. If left untreated, quadriceps activation failure can significantly impede strength gains by only allowing portions of the muscles to be volitionally utilized during active exercise [39]. In the same way as after knee arthroscopy, decreased quadriceps activation has also been observed in the acute stage of an ACL injury and in patients with ACLdeficient knees who experience instability (noncopers) [40, 41]. In addition to muscle atrophy, delay in the activation of the quadriceps femoris muscle could be another risk factor in the development of patellofemoral pain after knee arthroscopy. A deficiency of the VMO weakens the medial quadriceps vector, thereby allowing greater pulling of the lateral quadriceps vector with a resultant increase in the dynamic Q-angle. Due to this loss of the medial force, the patella is pulled laterally out of its normal tracking. Additionally, studies have shown more delayed activation of the VMO in comparison to the VL, at 15, 30, and 45 degrees of knee extension, using electromyography [42]. In their study, Amestoy and colleagues observed that the electrical contractility of the queadriceps femoris muscle evaluated by means of surface electromyography (sEMG) decreased to a greater extent in patients that developed patellofemoral pain at 6 weeks after the surgery (804.25 mV in the VL and 1250.80 mV in the VM) than in patients that did not develop this pain (486.95 and 680.82 mV) (P = 0.036 and P < 0.001, respectively) [16]. This decrease in muscle activation was again much more noticeable in the VM than in the VL muscle (Fig. 2). Briani and colleagues described similar differences in the activation of the quadriceps heads during contraction among adolescent female patients with anterior knee pain when compared with healthy controls [43, 44]. Therefore, patients who develop PFP after APM not only have greater loss of muscle thickness but also a greater decrease in the electrical contractility of the quadriceps femoris. 189 Thus, this should be considered as an independent risk factor for the development of anterior knee pain after meniscus surgery. Some studies have demonstrated that tourniquet use resulted in a significantly decreased thigh circumference as well as significant negative electromyographic changes at 3 weeks after ACL reconstruction [45]. In this sense, intraoperative tourniquet use may be detrimental to the quadriceps femoris muscle after knee arthroscopy. No significant differences were found in muscle strength or in the functional results between patients on whom a tourniquet was used and patients on whom it was not used. 2.3 Postoperative Quadriceps Muscle Weakness In addition to quadriceps muscle hypotrophy and quadriceps activation failure, postoperative strength deficit has been identified as another independent risk factor in the development of patellofemoral pain after arthroscopic partial meniscectomy. Amestoy and colleagues observed that patients who developed anterior knee pain in the postoperative period of meniscal knee surgery had lower quadriceps muscle strength than patients who did not develop this pain (12.27 kg vs. 20.02 kg respectively, P < 0.001). Both groups started from comparable levels of strength before surgery [16]. To assess the muscle strength values, an isokinetic test (Biodex dynamometer) was performed both pre-surgically and 6 weeks postsurgically. It provided data on muscular strength through range-of-motion at 60°/s. 2.4 Preoperative Quadriceps Muscle Thickness Despite the important role that the quadriceps muscle plays in this pathology, no study had studied the influence of preoperative quadriceps femoris muscle thickness on the development of patellofemoral pain after knee arthroscopy until now.
190 J. Amestoy et al. In a recent study, the Monllau and colleagues study group observed that there is a direct correlation between the preoperative muscle thickness of the quadriceps femoris muscle and its neuromuscular activation in the postoperative period of knee arthroscopy [18]. The results suggest that patients who have less VL muscle thickness and especially the VM preoperatively have a greater risk of developing patellofemoral pain around the sixth week after APM. On the other hand, they also suggest that the delayed onset of electromyographic activity of the quadriceps femoris muscle, regardless of muscle thickness prior to surgery, could be considered a risk factor for the development of patellofemoral pain. This is of great importance, because they establish a direct relationship between preoperative muscle thickness, which is relatively easy to assess and quantify clinically, and the risk of developing patellofemoral pain in the arthroscopic meniscal surgery postoperative period. 3 Prevention For all this, achieving early activation of the quadriceps femoris with an early recovery of its muscle thickness and strength after arthroscopic partial meniscectomy would be beneficial in preventing postoperative anterior knee pain. In this way, monitoring the neuromuscular activation of the quadriceps and its muscle thickness may facilitate the identification of patients at risk of developing this postoperative complication. It would also allow them to start an early treatment. Recently, research has focused on developing specific disinhibitory interventions to improve voluntary quadriceps activation. Neuromuscular electrical stimulation (NMES) has been shown to improve quadriceps function and strength, as well as decrease its atrophy in the ACL surgery postoperative period [39, 46]. Five of the seven studies included in a systematic review found a significant improvement in quadriceps strength with the application of NMES following knee arthroscopy [47–49]. Moreover, high intensity NMES resulted in more strength recovery than low intensity or no application of NMES 6 weeks following surgery (p < 0.05) [50]. Eccentric exercise, whereby the muscle is lengthened and an external force exceeds that produced by the muscle, has been shown to be more effective than traditional concentric strengthening at minimizing muscle atrophy and improving muscle force production [51]. The ability to eccentrically contract the quadriceps is critical to optimal knee range-of-motion during the weight-acceptance phase of gait [52, 53], which is necessary in the early phase of rehabilitation after meniscal surgery [19, 54–56]. The combination of NMES with eccentric exercises in the postoperative rehabilitation protocol after meniscal surgery may improve early activation of the quadriceps femoris muscle. Therefore, they may aid in preventing the development of anterior knee pain even in those patients with poor quadriceps muscle thickness. Based on the current evidence, sEMG application should be considered in postoperative protocols following arthroscopic surgery. Some studies that assessed the effect of sEMG following arthroscopic knee surgery reported a benefit in terms of quadriceps strength measured by muscle force, knee range-of-motion and functional knee scores when compared to standard rehabilitation alone [57–59]. Among these studies, the sEMG group had greater VM and VL muscle activity and maximum contraction values when compared to NMES or rehabilitation alone (p < 0.05). It has recently been shown that there is a direct relationship between the preoperative muscle thickness of the quadriceps femoris and neuromuscular activation and muscle strength at 6 weeks after arthroscopic partial meniscectomy [18]. Therefore, having the quadriceps femoris muscle in a correct preoperative state might be protective against the development of postoperative patellofemoral pain. In this sense, a progressive rehabilitation program that is mainly focused on strengthening the quadriceps femoris of subjects who have undergone meniscal
Anterior Knee Pain After Arthroscopic Meniscectomy … surgery leads to improved knee function and prevents the developement of PFP. Much the same happens in patients who have undergone ACL reconstruction [46, 60, 61]. 4 Treatment An ideal meniscal rehabilitation protocol should consider the size, tear pattern, location, quality of the repaired tissue and any concomitant procedures. Proper postoperative rehabilitation of the meniscetomized knee is essential, not only to prevent the development of anterior knee pain but specially to return to regular sports activities. The return would also include running or jumping at approximately 6 weeks [21, 62]. The mainstay of treatment for postoperative PFP after APM is currently the strengthening of the quadriceps femoris muscle, abductor and external rotator hip muscles and core muscles. Additional measures include gait retraining, the passive correction of patellar maltracking with bracing and taping or hyaluronic acid or plateletrich plasma injections. It is well known that knee pain and effusion can lead to quadriceps dysfunction and atrophy. This is particularly true in the setting of a meniscal tear, both preoperatively and postoperatively [20]. Strengthening exercises for PFP management originally focused on strengthening the knee via quadriceps strengthening as VM weakness is a known factor in the etiology of PFP. The return of full quadriceps function and strength is often hard won on the road to recovery. So, it is prudent to have early strengthening included in a patient’s rehabilitation protocol [21]. The American College of Sports Medicine recommends a resistance training load of 70– 85% of the one repetition maximum to promote muscle hypertrophy [63]. It is often challenging for postoperative patients to achieve these loads early in the recovery process after an arthroscopic surgery. Blood flow restriction therapy (BFRT) has become a growing part of the preoperative and postoperative rehabilitation regimen of arthroscopy to combat this difficult 191 problem [62]. This therapy results in the development of an anaerobic environment along with the subsequent release of growth factors. It is the release of these growth factors that promotes muscle hypertrophy [64–66]. The beauty of BFRT is that it can stimulate an anaerobic environment using loads that are much lower than the traditional 70–85% of the one repetition maximum. According to a recent meta-analysis, strength and muscle hypertrophy were significantly greater in the groups performing exercise with BFR 2–3 days per week when compared to those exercising 4–5 days per week without BFR [66]. The use of this therapy may be beneficial in those patients who developed PFP pain after arthroscopic meniscal surgery because it would cause greater quadriceps muscle growth with lower loads and less overload of the patellofemoral joint. In recent years, the importance of hip abductors and external rotators strengthening has been identified as an important pillar in the management of PFP. Two recent systematic reviews that investigated the importance of hip and knee strengthening as compared to knee strengthening alone. Both reviews found that the combination therapy significantly reduced pain in patients with PFP [67]. Core strengthening has also been recently revealed to be an important component to add to postoperative anterior knee pain treatment regimens [68, 69]. In addition, they are exercises that can be easily performed from the first postoperative weeks after a simple knee arthroscopy [70]. Patellar bracing has shown some short-term benefit in PFP in small studies [71]. According to a systematic review by Saltychev, of the 37 studies included in their review, only 7 demonstrate a significant benefit with patellar bracing [72]. Kinesio taping of the VMO has been shown to decrease pain and improve quadriceps function in athletes with PFP. However, these results were seen among only 15 patients with PFP, limiting the power of the results [73]. Probably knee taping and patellar bracing may be beneficial in reducing PFP after meniscus surgery, but only as an adjunct to targeted strengthening therapy.
192 J. Amestoy et al. Surgical treatment for postoperative PFPS is very uncommon and is reserved for cases due to femoropatellar chondral lesions refractory to conservative treatment, or severe osseous and ligamentous abnormalities that prevent normal patellar tracking despite non-operative treatment programs. 5 Summary – PFP after APM affects almost 1 in 4 patients. Its appearance can be prevented with a series of preventive measures that are relatively easy to apply. – Muscle atrophy, late neuromuscular activation and early non-recovery of muscle strength are identifiable risk factors in the development of PFP after simple knee arthroscopy. A thinner quadriceps femoris muscle prior to arthroscopic knee surgery is directly correlated with less neuromuscular activation of the same in the postoperative period. VM seems to have a greater influence than VL on the development of this pathology. – The main preventive strategy is to strengthen the quadriceps femoris muscle prior to surgery through a pre-rehabilitation program until an adequate muscle thickness of the quadriceps femoris is achieved. Promoting early neuromuscular activation, recovering the thickness and muscle strength of the quadriceps femoris should also be preventive strategies for patellofemoral pain after arthroscopy. For this purpose, the combination of NEMS, sEMG and eccentric exercises might be a good option. – Recovering good functionality of the quadriceps femoris muscle is the main objective of the treatment of PFP after knee arthroscopy, for which BFRT has become a very usefull tool. The strengthening of the hip abductors and core muscles should not be forgotten in the treatment of this pathology. They are exercises that can be easily performed from the first postoperative weeks after knee arthroscopy. References 1. Greis PE, Bardana DD, Holmstrom MC, Burks RT. Meniscal injury: I. Basic science and evaluation. J Am Acad Orthopaedic Surg. 2002;10:168–76. https://doi. org/10.5435/00124635-200205000-00003. 2. Walker PS, Erkman MJ. The role of the menisci in force transmission across the knee. Clin Orthop Relat Res. 1975;109:184–92. 3. Abram SGF, Hopewell S, Monk AP, Bayliss LE, Beard DJ, Price AJ. Arthroscopic partial meniscectomy for meniscal tears of the knee: a systematic review and meta-analysis. Br J Sports Med. 2020;54:652–63. https://doi.org/10.1136/bjsports2018-100223. 4. Verdonk P, Vererfve P. Traumatic lesions: stable knee, ACL knee. In: The meniscus. Springer;2010. pp. 45–51. 5. Boyer T, Dorfmann H, Podgorski A. Degenerative lesions-meniscal cyst. Springer; 2010. pp. 51–61. 6. Feeley BT, Lau BC. Biomechanics and clinical outcomes of partial meniscectomy. J Am Acad Orthop Surg. 2018;26:853–63. https://doi.org/10. 5435/JAAOS-D-17-00256. 7. Gauffin H, Tagesson S, Meunier A, Magnusson H, Kvist J. Knee arthroscopic surgery is beneficial to middle-aged patients with meniscal symptoms: a prospective, randomised, single-blinded study. Osteoarthritis Cartilage. 2014;22:1808–16. https:// doi.org/10.1016/j.joca.2014.07.017. 8. Wesdorp MA, Eijgenraam SM, Meuffels DE, Bierma-Zeinstra SMA, Kleinrensink G-J, Bastiaansen-Jenniskens YM, Reijman M. Traumatic meniscal tears are associated with meniscal degeneration. Am J Sports Med. 2020;48:2345–52. https:// doi.org/10.1177/0363546520934766. 9. Matsusue Y, Thomson NL. Arthroscopic partial medial meniscectomy in patients over 40 years old: a 5- to 11-year follow-up study. Arthroscopy. 1996;12:39–44. https://doi.org/10.1016/s0749-8063 (96)90217-0. 10. Paxton ES, Stock MV, Brophy RH. Meniscal repair versus partial meniscectomy: a systematic review comparing reoperation rates and clinical outcomes. Arthroscopy. 2011;27:1275–88. https://doi.org/10. 1016/j.arthro.2011.03.088. 11. Seil R, Becker R. Time for a paradigm change in meniscal repair: save the meniscus! Knee Surg Sports Traumatol Arthrosc. 2016;24:1421–3. https://doi.org/ 10.1007/s00167-016-4127-9. 12. Stein T, Mehling AP, Welsch F, von Eisenhart-Rothe R, Jäger A. Long-term outcome after arthroscopic meniscal repair versus arthroscopic partial meniscectomy for traumatic meniscal tears. Am J Sports Med. 2010;38:1542–8. https://doi.org/10.1177/03635465 10364052. 13. Fayard JM, Pereira H, Servien E, Lustig S, Neyret P. Meniscectomy global results-
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Anterior Knee Pain Prevalence After Anterior Cruciate Ligament Reconstruction: Risk Factors and Prevention Antonio Darder-Sanchez, Antonio Darder-Prats, and Vicente Sanchis-Alfonso 1 Introduction Anterior cruciate ligament (ACL) tears are nowadays one of the most prevalent knee injuries with an estimated incidence of 68.6 per 100,000 person-years [1]. Surgical treatment through ligament reconstruction accounts approximately for 100,000 procedures each year in the United States [2]. Although the results are considered satisfactory as 90% of the patients have a normal knee function restored, ACL reconstructions have been linked to various complications [3]. Anterior knee pain (AKP) is one of the most frequent postoperative complications in this type of surgeries [4–6]. Several causes have been described to be responsible of AKP such us patellar tendinopathies, Hoffa´s disease, postoperative flexure contracture, quadriceps weakness donor site morbidity or injuries to the infrapatellar branches of the saphenous nerves [7–9]. However, the exact origin and pathophysiology is still unknown. A. Darder-Sanchez (&) Department of Orthopaedic Surgery, Hospital Clínico Universitario, Valencia, Spain e-mail: toni-9486@hotmail.com A. Darder-Prats V. Sanchis-Alfonso Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain 2 Prevalence There is an important variability in the literature when it comes to determine the exact prevalence of AKP after an ACL reconstruction. The general estimation, rates the prevalence of AKP between 5 and 40%. This variability may appear, on one hand, due to the differences in the type of patients, grafts or techniques used, and on the other hand, because some studies talk exclusively about AKP while others refer to donor site morbidity, a wider term, which includes other symptoms such as numbness. Some classic reviews estimate a prevalence of AKP ranging from 5 to 19% [10] while others talk about 40–60% of patients experiencing AKP, disturbance in anterior knee sensitivity or inability to kneel [11]. In 2012, a retrospective comparative study on 171 patients, showed an overall prevalence of 42% at 3 months which fall to a 11% at 2 years postoperatively [7]. Moreover, according to the results, 95% of the patients who presents AKP at 2 years also presented it at 3 months, meaning that the origin of AKP is acute in the vast majority of cases. Some years later, Kanamoto et al. conducted a prospective study on 57 patients who underwent anatomic double bundle ACL reconstruction with hamstring tendon (HT) graft. Six months postoperatively, 32 out of 57 patients referred anterior knee symptoms using the Kujala patellofemoral score, which reflects a total incidence © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_13 197
198 A. Darder-Sanchez et al. of 56.1% [6]. More recently, Rousseau et al. confirmed a 16% of AKP prevalence (130 of 811) during the 2 years after the intervention of ACL reconstruction [4]. According to this study, patellar tendinopathies represented 40% of these cases whereas the other 60% was due to nonspecific causes not linked to patellar tendinopathies [4]. Most of the study periods include the first 2 years after surgery, and it is a frequent conclusion in the bibliography that AKP decreases within these 2 years. Corry et al. demonstrated an important decrease of AKP over time, detecting a 55% prevalence of AKP at 1 year whereas at 2 years the prevalence was 31% [12]. In 2019, in the study mentioned before, the prevalence reduced to a 2.7% after a correct rehabilitation at the end of the 2-year study period [4]. 3 Risk Factors for AKP After ACL Reconstruction The origin of AKP after ACL reconstruction is multifactorial and a clear cause has not been identified yet. Different aspects regarding range of motion, type of graft or technical errors during surgery are involved in the appearance of AKP. It is important to take into account this risk factors in order to reduce the incidence of AKP. 3.1 Range of Motion (ROM) Deficits Shelbourne and Trumper highlighted the importance of regaining full hyperextension to avoid the appearance of AKP, stablishing in their study there was a relationship between AKP and extension deficits [11]. Sachs et al., years before had stablished flexion contracture as an important factor of AKP [13]. In 2001, Kartus et al., reinforced this association, confirming there is consensus in literature about the importance of recovering hyperextension when it comes to reducing AKP [9]. Recently, in 2020, da Silva Marques et al. detected that the presence of knee extension deficit increased the probability of suffering from AKP by 5.3 times [14]. Moreover, Niki et al. concluded that different factors where related to the time of appearance of AKP [7]. Donor site morbidity and knee extension deficits were related to early AKP whereas decreased quadriceps strength and a poor Lysholm score associated with late AKP. On the other hand, flexion deficits generate controversy between authors. While some older studies stated that the loss of flexion was related to AKP [15], recent studies did not find statistical differences between groups despite a 5°–15° flexion deficit [7]. 3.2 Type of Graft Most of the studies about AKP stablish a relation between the type of graft used in the ACL reconstruction and its prevalence. According to the bibliography, donor site morbidity is a crucial factor and it is directly related to the technique and the type of graft chosen. Classically, bone patellar tendon bone (BPTB) graft has been known as a risk factor for AKP. But, does the evidence nowadays support this? How does the appearance of new grafts affect the prevalence of AKP? Do anatomical or double bundle techniques decrease AKP? BPTB graft has been one of the most used and reliable techniques for ACL reconstruction despite some drawbacks such as postoperative AKP, patellar fracture risk or patellar tendon rupture [16, 17]. An important meta-analysis back in 2003, comparing BPTB grafts and hamstring (HT) grafts concluded that although there were no statistically differences between both groups in relation to loss of extension, there was a slightly higher incidence of it in the BPTP group (1.9 vs. 0.7%) [18]. Moreover, this study demonstrated that the BPTB group presented a higher rate of AKP compared to HT patients with significant differences (17.4 vs. 11.5%). According to Freedman et al., surgical damage to the extensor mechanism during graft harvest is the main responsible [18]. Webster et al., in a randomized clinical trial with a 15 year follow up period described significant differences in AKP between both groups at 8 months postoperatively (BPTB group 73%
Anterior Knee Pain Prevalence After Anterior Cruciate … vs. HT group 35%) and at 2 years postoperatively (BPTB group 52% vs. HT group 17%) [19]. However, the study found out that at 15 years postoperatively there were no significance differences between both groups (BPTB group 38% vs. HT group 27%). The authors concluded that donor site morbidity differences between both groups found after 3 years [19], were not present in a 15 year follow up. Moreover, according to this study, although the incidence of AKP was high, the severity of pain was low with a mean of 3 on the BPTB group and 2.3 on the HT group on a 10-point scale. These findings, are similar to those described in previous studies [20−21]. Recently, in a new metaanalysis, five studies reported results on anterior knee pain prevalence in BPTB and HT groups [22]. The statistical results showed that HT group had advantages in AKP and kneeling pain on the short and medium-term postoperative period as the incidence of AKP in the BPTB group was significantly higher. Da Silva Marques et al., who studied 438 patients in order to predict the main variables causing AKP after ACL reconstruction, found a higher incidence in the BPBT group compared to the HT group (9.7 vs. 2.7%) with a 3.4 odds ratio between both groups [14]. The authors refer that this happens because closing the defect of the patellar tendon can lower the patella leading to AKP and hypersensitivity specially when the patellofemoral joint suffers extra pressure, for example during squatting. All these findings lead us to the conception that BPTB graft is related to a higher incidence in AKP. Contrary to this general idea, in 2009, an important systematic review conducted by Samuelsson et al. evaluated that, out of 16 articles analyzing AKP, 9 studies found no difference between both graft groups [23]. The other 7 articles found a higher incidence of AKP in the BPTB group between the third and eighth months after surgery, but this difference decreased thereafter. Another interesting fact analyzed was that there was no association between different functional scores or clinical variables and a higher occurrence in AKP. 199 According to the bibliography reviewed, AKP is generally more frequent in patients treated with BPTB grafts, but the fact that some studies have not found difference, suggests that as we mentioned before there are other factors affecting the appearance of AKP. Currently, single-bundle technique is the most frequently used in ACL reconstruction. However, studies comparing it with a double-bundle technique are frequent, due to the theoretical advantage of the latter of reproducing more exactly the ACL anatomy. Aga et al., studied quality of life parameters, including AKP, in double-bundle and single-bundle reconstructions [24]. They found no differences between both groups. In 2010, another study published similar conclusions [25]. In cadaveric studies, the reconstruction of the posterolateral bundle (PLB) causes an increased control of rotational stability [26]. Considering this, an excessive tension of the PLB could generate too much constrain on tibial rotation affecting negatively to the patellofemoral joint and consequently anterior knee pain. However, there are no studies to this day that conclude there is a higher incidence of anterior knee pain in double-bundle reconstructions. Further studies, focusing of patellofemoral tracking symptoms and anterior knee pain are needed. In the last years, with the desire to prevent some of the morbidities caused by the graft harvest, alternative grafts are being used. Quadricipital tendon (QT) was first introduced by Blauth et al. as it was thought it could reduce donor site morbidity caused by traditional grafts [27]. Studies have demonstrated good clinical results with QT in ACL reconstruction when compared to BPBT showing less incidence of pressure pain, pain associated to knee flexion or kneeling [28, 29]. Furthermore, a better extension capacity has also been noticed. However, in this study, the authors found a higher postoperative level of activity in the BPTB group. In 2016, Jon Kyu Lee et al. compared the functional outcomes of a bone QT graft and a double-bundle HT graft [30]. The study proved that the BQT graft was not significantly different
200 from the HT graft in terms of knee stability and functional outcomes. In order to evaluate AKP, the Shelbourne and Trumper questionnaire [11] was analyzed, and no significant difference was found between both groups. There was not a single item of the test were the BQT was superior to HT group. Furthermore, the BQT showed a better knee flexor muscle recovery, fact that has also been reported in other studies [31]. Regarding knee extensor recovery no differences were detected. Recently a meta-analysis comparing the three main graft types was published [32]. When it comes to AKP, six studies compared donor site pain between 439 patients in the QT graft group and 287 patients in the BPTB group. They found a significant difference, as the QT graft group presented less incidence of AKP (risk ratio for QT vs. BPTB group, 0.25; 95% CI, 0.18–0.36; P < 0.00001). Besides that, four studies compared AKP between 136 patients who underwent ACL reconstruction with QT graft and 135 patients with HT grafts. No significance differences were found between them. It has also been described that QT patients achieve similar levels of quadriceps isokinetic strength at 1-year postoperatively [33]. Other advantages reported of the QT autograft include less pain and analgesic use than with an HT reconstruction and the earlier capacity to achieve complete knee extension and range of motion compared with BPTB reconstruction [34]. Taking into account the bibliography reviewed, the type of graft used influences the appearance of AKP. Nevertheless, it is not the only factor. Evidence nowadays support that BPBT is the graft associated with a higher incidence of AKP. Although QT grafts, which are popular lately, present similar risk of AKP when compared to HT grafts, more quality studies need to be conducted in order to evaluate all the clinical outcomes of this graft in an ACL reconstruction compared to more traditional grafts. A. Darder-Sanchez et al. 3.3 Intraoperative Technical Errors There is a wide variety of technical errors that can modify the normal biomechanics of the knee causing patellofemoral symptoms. Arthrofibrosis and more specifically the well-known cyclops syndrome (Fig. 1), are complications after ACL reconstruction which can limit the knee range of motion, especially the knee hyperextension. Therefore, they can cause the appearance of AKP. In a recent study, 9% of the patients after an ACL reconstruction presented an extension deficit [4]. Half of this cases were caused by a cyclops syndrome. The authors found no significant differences on the rate of cyclops syndrome between the HT graft group and the BPTB group [4]. Cyclops syndrome has been related to a too anterior placement of the graft as well as to an insufficient resection of the native ACL possible remnants [35]. The most accepted treatment in these cases is the arthroscopic resection of the anterior fibrosis. Another type of arthrofibrosis is the appearance of pretibial patellar tendon adhesions. According to Stedman et al., this scarring of the patellar tendon to the anterior face of the tibia causes pain during the last degrees of extension, a reduced mobility of the patella and a patella infera due to traction of the tibial adhesions [36]. This traction modifies the force vector and the angle between the quadriceps and the patellar tendon, increasing the load to the patellofemoral joint, causing therefore AKP [36−37]. The treatment in this case, just as with the cyclops syndrome, consists on arthroscopic resection. A correct graft placement is vital in order to recover a full range of motion. When the tibial tunnel is done too anterior, it causes an impingement in the intercondylar notch in the last degrees of extension. Moreover, an anterior femoral tunnel will also produce a lack of extension and consequently AKP. Evidence shows that transtibial techniques are related with higher incidences of knee extension deficits
Anterior Knee Pain Prevalence After Anterior Cruciate … Fig. 1 Cyclops syndrome compared to anatomical techniques [38]. Furthermore, a correct position of the graft on the coronal plane can also affect both extension and flexion because of an impingement with the posterior cruciate ligament (PCL). When the tibial tunnel is medial to the lateral tibial spine, it can cause an impingement with the PCL with the knee in flexion causing a deficit in flexion. Related with the PCL impingement, Strobel et al., reported an atypical cause of AKP [39]. According to their study, a 12 o’clock or “high noon” position of the femoral tunnel causes an impingement with PCL at the last degrees of extension. This impingement triggers a proprioceptive reflex that restrains the last 20° of extension. This limitation disappears when the patient is anesthetized. A 3-D MRI reconstruction is the only image test capable of detecting it and the treatment is a new ACL reconstruction with correct tunnel placement. Residual anterior instability has also been proven to be a risk factor of AKP [15]. 4 Prevention of AKP After ACL Reconstruction Problems with technique, grafts election and postoperative range of motion achieved, are all related to the appearance of AKP. In order to 201 prevent it, there are different solutions or alternatives which have proven to be effective. One of the first studies that analyzed this problem, concluded that the key aspect in prevention was to reach full knee hyperextension [11] (Fig. 2). On one hand, the correct position and size of the graft is crucial to avoid impingement that cause a reduced range of motion. On the other hand, a loss of complete ROM can also be caused by an incorrect rehabilitation program. The main goals of rehabilitation after an ACL reconstruction in order to prevent AKP must be returning to full range of motion with especial emphasis on early hyperextension and avoiding both quadriceps and hamstrings strength compared with the contralateral knee [9]. In order to avoid range of motion loss, rehabilitation must start preoperatively just as Van Melick et al. stated in the practice guidelines for ACL rehabilitation published in 2016 [40]. Cryotherapy as well as immediate weight bearing have demonstrated to reduce anterior knee pain in the short and medium postoperative period. Andersson et al., in their systematic review, confirmed that closed kinetic chain (CKC) quadricep exercises were related to less pain than open chained (OKC) quadriceps exercises [41]. Based on this findings, Van Melick et al., recommend starting the rehabilitation with CKC exercises, and only start with OKC rehabilitation when the quadriceps has gained some strength, around 4 weeks postoperatively. According to the literature, graft harvest, especially in BPBT reconstructions, is a cause of AKP due to the injury of the infrapatellar branches of the saphenous nerves and the inflammation in the donor site [42]. It has been established a relationship between preserved anterior knee sensitivity and a significantly lower AKP incidence [43]. In order to prevent damage to these structures, several studies have described different harvest techniques as a possible solution. One of the first improvements proposed was suturing the peritenon just to obtain a more anatomic and functional scarring tissue [44]. Mini invasive
202 A. Darder-Sanchez et al. Fig. 2 Knee hyperextension harvest techniques using a double incision have been proposed by some authors [42, 45]. Tsuda et al. assert that the use of horizontal incisions reduces the possible damage to the nervous structures mentioned before and allows better access to the tibial tunnel and the graft width [45]. However, most of the authors use vertical incisions just as exposed by Beaufils et al. [42]. According to them, graft harvest is done with the knee at 90° of flexion. Two vertical incisions each of approximately two centimeters are made. The distal one is done just on the anterior tibial tubercle while the proximal incision is done just above the apex of the patella which allows not damaging neither the peritenon nor the nervous branches. In their study they observed a decreased sensory morbidity as well as a lower incidence in anterior knee pain in the double incision group with a significant difference (19 vs. 58%) [42]. Gaudot et al. found similar results in their study, strongly recommending this double incision harvesting technique [46]. Moreover, it has also been observed a decrease in AKP with the filling of autologous bone or beta-tricalcium phosphate (BTCP) to reduce the bone defect in the harvesting site. Higuchi et al., observed morphologically and histologically that BTCP helped and accelerated bone and patellar tendon remodeling [47]. One year later Argawalla et al., described this technique and exposed that the main advantages of using BTCP instead of autologous bone was the absence of donor site morbidity and a bigger graft availability [48]. Kato et al. who also studied the use of BTCP concluded that the protrusion of the BTCP graft had no adverse effects and still reduced AKP [49]. Recently, a new graft harvesting incision has been exposed with encouraging results [50]. Janani et al. described a small incision which allowed a mobile window to both harvest the graft and use it to drill the tibial tunnel. They use an oblique incision of about four to five centimeters done with the knee at 30° of flexion over the patellar tendon with the proximal border on the lateral side with a distal and medial direction. With the help of retractors, they create a rectangular window. The patellar tendon is harvested with the knee at 100–120° while the tibial tuberosity bone plug is obtained with the knee at 30º of flexion. Finally with the knee in complete extension, the patellar bone plug is harvested. In this study, Janani compared the incidence of AKP between patients who underwent this technique and people who underwent ACL reconstructions with HT grafts. They concluded there were no differences between both groups, the incidence at 3 months was 28.9% and 25.5% respectively while at 18 months was 6.59% and 6.05% respectively. The use of the contralateral autograft patellar tendon is not common between surgeons due to the donor site morbidity caused in a completely healthy knee. Nevertheless, Shelbourne et al. a few years ago studied the IKDC and the quadriceps muscle strength using either
Anterior Knee Pain Prevalence After Anterior Cruciate … ipsilateral or contralateral patellar tendon [51]. After surgery, a rehabilitation protocol based on antagonistic exercises on both knees was used: rehabilitation on the donor site knee was focused on recovering strength while the main goal in the ACL reconstructed knee was gaining range of motion. The results showed that in the contralateral knee group both knees showed significantly more quadriceps strength than the ACL reconstructed knee in the ipsilateral group after a 2-year follow-up period. Although a better quadriceps strength has been related to less AKP, this study showed no differences on subjective symptoms such as kneeling pain or range of motion between groups. More studies correlating contralateral patellar grafts with symptoms such as AKP must be done to evaluate if there really exists any benefit. The infrapatellar fat pad (IPFP) is known to have a relevant role in the patellofemoral pathophysiology as it has a biomechanical function and it is responsible for modulating the inflammatory response at this level. Therefore, it has been hypothesized it could be a source of AKP. Kanamoto et al., added as an independent risk factor for AKP after an ACL reconstruction, the increased blood flow in the IPFP measured by ultrasounds [6]. This finding took other authors to study if a smaller resection of the IFP in the ACL footprint resulted in a decrease of AKP. Recently, Asai et al. concluded that removing the IFP had no effects on clinical outcomes after ACL reconstruction including AKP [52]. Further studies may elucidate what is the exact role of the IPFP in the appearance of AKP. In the last years, biological treatments such us platelet rich plasma (PRP) or plasma rich in growth factors (PRGF) have been used in a wide variety of pathologies in orthopedic surgery to try to accelerate the maturation of different tissues. When it comes to ACL surgery, several studies have investigated its effects on the harvesting site, especially with the BPTB graft technique in order to reduce the AKP that appears due to the donor site gap. Walters et al., hypothesized that PRP in the donor site could reduce AKP [53]. They concluded that there were no differences between groups neither in 203 kneeling pain nor in AKP with the daily activities at 12 weeks and 6 months postoperatively. These results contradict a previous study which confirmed a decrease in subjective pain at twelve-month follow-up in the group treated with PRP [54]. Therefore, more studies must be conducted in order to elucidate the real effect of PRP in AKP. Seijas et al., carried a randomized prospective trial, measuring with ultrasound if PRGF accelerated maturity of the patellar tendon [55]. The results showed significant differences exclusively in the fourth month of follow-up but not in the rest of follow-up times. However, studies investigating if there is a correlation between a faster regeneration and a decrease in the occurrence of AKP need to be conducted. To sum up, in order to prevent the appearance of AKP we can act both over rehabilitation and technical aspects of the surgery. When it comes to rehabilitation, gaining muscle strength as well as complete range of motion are key points, especially early complete hyperextension. A delicate surgical technique is also fundamental. On one hand, a correct placement of the femoral tunnel is vital to avoid notching and loss of extension. On the other hand, orthopedic surgeons must try to use harvesting techniques that reduce morbidity on the donor site. 5 Take Home Messages • AKP is one of the most frequent complications after ACL reconstruction. Although the severity of the symptoms is usually not much, its prevalence is really high specially during the first two years after surgery. • The risk factors are multiple and the phisiopathological mechanism is still unclear but literature agrees that a loss of range of motion, the graft harvesting site and the surgical technique have a direct relation with the occurrence of AKP. • A loss of hyperextension and BPTB graft seem to be associated with a higher incidence of AKP. The popular QT graft has demonstrated less donor site morbidity than the BPBT and no differences when compared
204 with HT graft, therefore it may be a good alternative. • In order to prevent AKP different solutions have been proposed: specified rehabilitation protocols, modifications of the graft harvesting technique, the use of bone to fill de donor site gap or the possible effectiveness of orthobiological techniques. • More studies need to be conducted in order to define what are the exact causes of AKP after ACL reconstruction and consequently reduce both the incidence and prevalence of this frequent complication. References 1. Sanders TL, Maradit Kremers H, Bryan AJ, et al. Incidence of anterior cruciate ligament tears and reconstruction: a 21-year population-based study. Am J Sports Med. 2016;44(6):1502–7. 2. Campbell W, Canale S, Beaty J, et al. Campbell’s operative orthopaedics. Philadelphia: Elsevier; 2017. 3. Ardern CL, Taylor NF, Feller JA, et al. 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Patellar Tendinopathy: Risk Factors, Prevention, and Treatment Rochelle Kennedy and Jill Cook 1 Introduction Patellar tendinopathy is an overuse injury characterised by localised pain at the inferior pole of the patella during activities that mechanically load the tendon [1]. It is most common in young, athletic males participating in sports that place substantial demands on the knee extensors. Activities such as jumping or changing direction are often most provocative, as these tasks require large amounts of energy storage and release in the patellar tendon [2]. Patellar tendinopathy can be a chronic and debilitating condition, which can result in prolonged absence from sport and may be career threatening [3]. Previous research has found that more than one third of athletes presenting for management of patellar tendinopathy were unable to return to sport at 6-month follow-up [4], and more than 50% were forced to retire from sport altogether [5]. Research in sub-elite athletes reported that patellar tendinopathy is most common in volleyball and basketball athletes, with prevalence rates reported to be 14.4% and 11.8% respectively [6]. The National Bas- R. Kennedy (&) J. Cook La Trobe University, Melbourne, Australia e-mail: Rochelle.Kennedy@latrobe.edu.au J. Cook e-mail: j.cook@latrobe.edu.au ketball Association (NBA) also reported that 0.8% of missed games annually were attributable to patellar tendon injury, however this time-loss definition of injury may not capture those athletes who continue to play despite patellar tendon pain [7]. Tendinopathy is the clinical term for persistent tendon pain and loss of function related to mechanical load [1]. This is distinct from tendinosis, which is a pathological term used to describe tendon pathology [1]. A high proportion of physically active individuals who have no history of lower limb tendinopathy will demonstrate abnormalities on tendon imaging, with nearly one in five physically active individuals demonstrating asymptomatic Achilles or patellar tendon changes [8]. Careful interpretation of imaging findings is critical, as asymptomatic tendon changes can co-exist with other painful conditions. For example, 32–72% of individuals with patellofemoral joint pain also exhibit asymptomatic patellar tendon abnormalities, confusing an already complex clinical picture [9, 10]. It is important to highlight that tendinopathy is principally a clinical diagnosis and imaging is not required as part of the diagnosis. Clinicians should be aware of the high prevalence of asymptomatic pathology on imaging and interpret any imaging findings in accordance with the clinical presentation. Patellar tendinopathy presents a significant diagnostic challenge, with much clinical overlap with other conditions of the anterior knee such as © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_14 207
208 patellofemoral joint pain [11]. Common diagnostic criteria include palpation tenderness, reproduction of symptoms during pain provocation testing and imaging abnormality [12]. However, these tests are non-specific and may aggravate other structures of the anterior knee [12], and the prevalence of asymptomatic imaging abnormalities is high [8]. Current evidence suggests the combination of pain provocation tests with localised pain under load increases diagnostic accuracy [12]. A recent study of anterior knee pain in basketball players found that although diffuse anterior knee pain was very common, pain localised to the inferior pole of the patella, a key diagnostic criterion for patellar tendinopathy, was not [12]. Additionally, the types of movements that aggravate the patellar tendon may differ from those that aggravate other structures of the anterior knee. The patellar tendon is exposed to the highest magnitude of tensile load when being used like a spring to store and release energy [13]. This movement must be fast, as the tendon is viscoelastic, therefore slower movements do not result in energy storage [14]. In the case of the patellar tendon, tensile load is the primary consideration, as there are no friction or compressive loads on the patellar tendon. Clinicians should pay close attention to the types of activities that cause aggravation, and if these are of low tensile load such as slow heavy resistance, this should raise suspicion of a non-tendon cause of pain. Therefore, it is important that both the pain location and the type of provocative load is considered during the clinical reasoning process. Despite numerous hypotheses regarding the aetiology and pathogenesis of patellar tendon pathology, the exact pathoaetiology remains unknown. The continuum model of tendon pathology is based on a cell-driven response and describes four primary states of pathology; reactive, dysrepair, degenerative and reactive on degenerative [15]. It is important to note that although the model is described in discrete stages, it is a continuum, and therefore there is fluidity between the stages [15]. Several changes occur within the tendon as pathology progresses along the continuum. R. Kennedy and J. Cook Tenocytes are upregulated, there is an increase in large proteoglycan content and bound water infiltration, matrix changes, collagen disorganisation and a progressive loss of hierarchical structure [16]. As pathology becomes degenerative, there may be vascular infiltration [16]. These changes may be reversible with load modification and exercise early in the continuum, but as pathology progresses to the degenerative stage, changes become largely irreversible and this region of the tendon is unlikely to be able to transmit tensile load [16]. Critically, these changes usually occur in a localised region within the tendon, and there is usually significant volume of normal tendon surrounding the degenerative area [17]. Therefore, despite degenerative changes being irreversible, there is still capacity to load the tendon and change symptoms [17]. Reactive on degenerative pathology refers to reactive tendinopathy within the normal part of a degenerative tendon [15]. As degenerative regions of a tendon are unable to transmit load due to the loss of matrix structure, this may result in overload of the normal part of the tendon if loads are not managed appropriately [15]. As with reactive tendon pathology, this state is reversible if overload is addressed. The relationship between tendon pathology and pain is not absolute, however the presence of pathology is a risk factor for an individual becoming symptomatic [18]. In professional football players, an association has been found between ultrasound detected patellar tendon abnormalities at the beginning of the season and increased risk of developing symptoms throughout the season [19]. Furthermore, a cohort study of professional dancers showed that the presence of focal hypoechoic changes was associated with the future development of tendon-related pain [20]. Conversely, in Australian football players, pre-season imaging was not able to predict the development of symptoms in-season, whereas simply asking the players whether they had experienced symptoms previously had greater predictive value [21]. This tenuous relationship between pathology and symptoms suggest that clinicians should be more
Patellar Tendinopathy: Risk Factors, Prevention, and Treatment concerned with aberrant loading patterns as opposed to the presence of pathological changes within the tendon. 2 Clinical Presentation Subjective Examination Patellar tendinopathy pain increases in a dose dependent manner with increasing patellar tendon load but remains localised to the inferior pole of the patella [3]. Typically, individuals with patellar tendinopathy present with gradual onset, localised pain at the inferior pole of the patella, which began following changes in their training load or intensity [3]. Patellar tendon pain is mechanical in nature and occurs when the tendon is loaded, ceasing or reducing when loading stops [22]. The ‘warm-up phenomenon’ is a common and misleading feature of tendon pain, whereby pain decreases throughout a loading bout but is often worse after activity or the next morning [22]. Consequently, the early warning signs of tendinopathy are frequently ignored, as the importance of this initial pain is often underestimated. 3 Risk and Associated Factors Changes in Load While load is essential to maintain tendon structure, mechanical properties and capacity, excess load is linked to pathology and pain. Tendon pain is commonly preceded by rapid changes in demand on the tendon to store and release energy [22]. The increased prevalence of patellar tendinopathy during the pre-season period is indicative of this, as this time of the season is characterised by rapid increases in load after a period of relative unloading [23]. Clinicians should identify and address any relevant changes in load preceding the development of symptoms, as this forms a key component of effective management and prevention. 209 Age The onset of patellar tendon pathology may occur earlier than in other tendons. While pathology in other tendons has been linked to load accumulation [14], patellar tendinopathy is highly prevalent in young, jumping athletes, primarily aged between 14 and 18 [24]. Furthermore, longitudinal research has indicated that pathology in the patellar tendon is less likely to develop after adolescence [25]. The maturation process of the patellar tendon differs from other tendons as it does not have an apophysis, and instead matures through a cartilage plate at both the proximal [20] and distal ends [26]. A mature tendon bone attachment is reached approximately 2 years after peak height velocity [20]. Exposure to repetitive, high magnitude tendon load during this maturation period may disrupt the developing bone-tendon junction [20, 26], leading to pathological changes indistinguishable from tendon pathology seen later in life [27]. This is clinically important as patellar tendon pathology that develops during adolescence will remain throughout life [25]. However, whether an individual will develop symptoms associated with this pathology is related to aberrant loading patterns. Quadriceps/Calf Strength Atrophy or reduced strength in anti-gravity muscles including gluteus maximus, quadriceps and calf is often observed in longstanding cases of patellar tendinopathy [3]. Patellar tendinopathy has been linked with significant motor cortex inhibition [28], which may explain the persistent atrophy sometimes present in chronic cases. Additionally, persistent pain with mechanical loads in patellar tendinopathy may result in profound unloading, as the individual quickly learns the movements to unload the tendon. Clinically, atrophy in the calf muscle complex may be just as substantial as quadriceps wasting, and it is therefore important to examine the entire lower limb kinetic chain to identify relevant deficits.
210 Biomechanical Factors Biomechanical factors associated with PT include restricted ankle dorsiflexion range of movement and a rigid, supinated foot [29, 30]. It has been found that having less than 45° of ankle dorsiflexion is associated with patellar tendinopathy [29]. This is likely due to decreased shock-absorption at the ankle when landing that leads to increased knee loading during take-off [29]. Therefore, it may be important to be aware of both inherent restrictions of dorsiflexion range of movement, as well as other confounding factors that may reduce dorsiflexion range, such as recent or repeated ankle inversion injuries or anterior ankle impingement [29]. Sex Patellar tendinopathy is more prevalent in men compared to women, men have twice the prevalence of women across different sports [2, 31]. It is proposed that this is due to a reduced force-generating capacity of the knee extensors in women, thereby reducing the amount of force transmitted through the patellar tendon [2]. Additionally, an observational study of male and female volleyball players found that women have a substantially lower average jump frequency compared to men [32]. Investigations of the jumping and landing kinematics of both male and female volleyball players found that when participants were matched for jump height, they generated similar patellar tendon loads irrespective of sex [33]. Clinically, women with patellar tendinopathy tend to be elite jumping athletes, who can transmit exceptionally high forces through their patellar tendon. It is therefore likely that that sex-based differences in prevanlence R. Kennedy and J. Cook rates are attributable to the force generating capacity of the knee extensors. Jumping Ability Excellent jumping ability has also been identified as a risk factor for the development of patellar tendinopathy. Prospective studies have found that those athletes who had a better jumping ability were more likely to develop patellar tendinopathy [34]. This phenomenon is known as the ‘jumper’s knee paradox’ [34]. It has been proposed that this may be due to the amount of force these athletes are able to transmit through the patellar tendon [34]. Level of Sporting Participation Patellar tendinopathy prevalence seems to increase with level of sporting participation. Athletes competing at an international level have been shown to be up to three times more likely to develop patellar tendinopathy when compared to their sub-elite counterparts [35]. This association may be related to the ‘jumper’s knee paradox’, or the high training loads associated with elite level sport [35]. Comparison of the landing kinematics and patellar tendon loads has found no significant differences between elite and sub-elite players, indicating that training load may be the primary contributing factor to the difference between these groups [35] (Table 1). 4 Athletes with patellar tendinopathy should be able to indicate with one finger the location of their pain. Pain is localised to the inferior pole of the Table 1 Risk and associated factors for patellar tendinopathy Young males Jumping athlete Decreased ankle dorsiflexion range of movement Natural jumping ability Level of sporting participation Changes in load Physical Examination/Differential Diagnosis
Patellar Tendinopathy: Risk Factors, Prevention, and Treatment 211 Table 2 Progressive loading test for the patellar tendon Progressive loading test for patellar tendon Double leg squat or double leg decline board squat Single leg squat or single leg decline squat Double leg jump Single leg jump Stop jump patella and does not move or spread with load [3]. It is important to ask the athlete to indicate the location of their pain under load, as opposed to tenderness on palpation, as palpation has been shown to have low clinical utility when diagnosing patellar tendinopathy [36]. As normal tendons may be tender to palpate, the absence of palpation tenderness may be more useful clinically, as it may indicate a non-tendon diagnosis [36]. Patellar tendon pain should increase in a dosedependent manner in response to increases in patellar tendon load. Examination should begin with low patellar tendon load activities and progress towards tasks requiring greater energy storage and release in the patellar tendon (Table 2). For example, assessment should commence with a low load task such as a double leg squat, and progress towards double and single leg jumps. Throughout this progressive loading test, the individual is asked to indicate the location of their pain under load, which should remain localised, and rate the intensity of pain on a numerical pain rating scale. Pain consistent with patellar tendon origin should increase in a dose-dependent manner throughout the progressive loading test. It is also important to be aware of any aberrant movement patterns during assessment. For example, individuals with patellar tendinopathy often demonstrate poorer lower leg power with jumping and hopping tasks and avoid deeper ranges of knee flexion when hopping. Hip mechanics during hopping are often relatively good, especially when compared with those commonly demonstrated by individuals with other conditions of the anterior knee such as patellofemoral pain syndrome. The decline squat (Fig. 1) is a useful pain provocation test for diagnosing patellar tendinopathy [37], and when combined with pain location [12], can be useful to differentiate it from other conditions of the anterior knee. High levels of pain will be experienced early in range, and this can be used to assess the degree of tendon irritability. The knee flexion angle when pain is first experienced should be recorded, and this can be used as an outcome measure throughout rehabilitation [38]. 5 Differential Diagnosis Numerous conditions can cause anterior knee pain, and it can be a diagnostic challenge to distinguish between several pain-producing structures (Table 3). These structures include the patellofemoral joint, fat pad, bursae, or plica. Patellofemoral Pain Syndrome The patellofemoral joint is a common source of anterior knee pain [39]. It is primarily a diagnosis of exclusion, as there are no sensitive or specific clinical tests to confirm the diagnosis [39]. Patellofemoral joint pain can be diffusely located around the patella including inferiorly over the tendon and is aggravated by tasks requiring weight-bearing knee flexion, such as running, squatting and stair-climbing [39]. In contrast to those with patellar tendinopathy, individuals with
212 R. Kennedy and J. Cook Fig. 1 Decline board squat Table 3 Differential diagnosis Differential diagnosis for patellar tendinopathy Differential diagnosis Defining characteristics Patellofemoral joint pain – Diffuse anterior knee pain – Aggravated by weight-bearing knee flexion Quadriceps tendinopathy – Located superior/superolateral to the patella – Older athlete – Aggravated by deep knee flexion tasks such as squatting Distal patellar tendinopathy (OsgoodSchlatter disease) – Younger athlete (10–15) – Localised pain and swelling around the tibial tuberosity Fat pad syndrome – Often initiated by knee hyperextension injury – Aggravated by end of range knee extension – Hoffa’s fat pad tender to palpate Pre/infrapatellar bursitis – Superficial swelling anterior aspect of the knee – Pre-patellar bursitis often initiated by direct trauma to the anterior knee or repetitive kneeling Plica – Sharp pain and snapping sensation around the superior aspect of the patellar – Thickened band may be palpable medial to the patellofemoral joint patellofemoral joint pain often demonstrate poorer hip control and greater knee flexion with hopping tasks [40] and will have lower levels of pain deeper into range with the decline squat test [38]. Taping may reduce patellofemoral joint pain during provocative manoeuvres such as the squat or lunge. The diamond taping method (Fig. 2) can be used clinically to assist in differentiating patellofemoral joint pain from patellar tendinopathy. Pain during provocative movements should significantly decrease with the use of tape in cases of patellofemoral joint pain, whereas patellar tendon pain remains largely unchanged. Fat Pad Syndrome Hoffa’s fat pad can become painful and swollen following an acute traumatic hyperextension injury to the knee or after repetitive, end of range knee extension [41]. Pain is diffusely located around the anterior to inferior aspect of the knee and is aggravated by knee hypertension or direct palpation of the fat pad [41].
Patellar Tendinopathy: Risk Factors, Prevention, and Treatment 213 Fig. 2 Patellofemoral joint diamond taping Pre-and Infra-patellar Bursitis Pre-patellar bursitis is typically characterised by superficial swelling at the anterior aspect of the knee [42]. It is aggravated by direct trauma, or by kneeling for extended periods. Although uncommon, infective bursitis can occur if a wound is present, and this requires immediate medical management [42]. Infra-patellar bursitis is less common and is located at the tibial insertion of the patellar tendon and can be associated with tendon pathology at this insertion. Pain is typically more variable in both nature and location when compared with patellar tendinopathy. Imaging may be of assistance if history and clinical examination are equivocal. Plica Although it more closely mimics quadriceps tendinopathy, synovial plica may cause sharp pain and a snapping sensation around the superior aspect of the patella [43]. A tender, thickened band may be palpable around the medial aspect of the patellofemoral joint [43]. MRI can assist in the differentiation between quadriceps or patellar tendinopathy and a synovial plica irritation [3]. Quadriceps Tendinopathy Quadriceps tendinopathy is characterised by pain at the superior/superolateral aspect of the patella [44]. Comparatively few studies have investigated quadriceps tendinopathy, perhaps due to relatively low prevalence rates, which are estimated to be between 0.2 and 2% in athletic populations [44]. This condition is often aggravated by a deep squat, where the tendon becomes compressed against the femoral condyle [44]. The combination of the tendon being used like a spring from a position of compression is most provocative, such as at the bottom of a squat during weightlifting movements. As quadriceps tendon pathology is a load accumulation condition, quadriceps tendinopathy is more common in older athletes, particularly those involved in sports such as weightlifting that require deep squatting, or if the athlete uses a deep knee flexion strategy when decelerating or changing direction [44]. It is managed in a similar manner to patellar tendinopathy, with the avoidance of deep knee flexion in the early stages of rehabilitation until the tendon is tolerant of these loads. Distal Patellar Tendinopathy In younger athletes (typically aged between 10 and 15), repetitive and excessive traction at the distal attachment between the patellar tendon and the tibial tuberosity can result in Osgood-Schlatter disease [45]. This is characterised by localised pain and swelling around the tibial tuberosity and changes in the tendon and bone can persist into adulthood [45]. These changes predispose the individual to tendinopathy in adulthood. The management is like that of all tendinopathies, with load management and strengthening exercises forming the cornerstones of management.
214 6 R. Kennedy and J. Cook Outcome Measures The Victorian Institute of Sport Assessment scale for the patellar tendon (VISA-P) is a validated outcome measure that can be used to assess severity of symptoms and monitor outcomes [46]. The VISA-P is scored out of 100, with higher scores representing better function and less pain. The minimum clinically important difference is 13-points [46]. It is best used at monthly intervals as it is less sensitive to small changes in clinical presentation. It is recommended to be used in conjunction with a daily 24 h response test, such as the decline squat, to evaluate shorter-term changes in pain and function, and to determine tolerance to rehabilitation. The 24 h response test should be completed at a similar time each day, and the amount of pain recorded using a numerical pain rating scale. This can be used to assess the effect of activity on the tendon from the previous day. 7 Role of Imaging Patellar tendinopathy is a principally a clinical diagnosis, and imaging is not required to confirm the diagnosis. While imaging can provide clinically useful information it is mostly unnecessary and potentially harmful. Imaging has the potential to identify clinically unimportant incidental findings that may lead to unnecessary escalation of treatment. Additionally, appropriate communication of imaging findings is crucial, as the use of more medicalised terminology to describe imaging findings is associated with increased anxiety and perceived severity, and may lead to a preference for more invasive treatments [47]. Therefore, it is important to be discerning as to when to request imaging and to understand its potential benefits and limitations. Both ultrasound and MRI can show focal patellar tendon abnormalities. However, there is a high prevalence of tendon pathology on imaging, and there is little association between this pathology and reduced function or pain [8]. Tendon abnormality on imaging does not confirm that pain and dysfunction are generated by the tendon, however, a pristine tendon on imaging may exclude it as a potential source of pain [8]. Additionally, as degenerative pathological changes are likely irreversible, the serial imaging of tendons is not recommended, as pathology is unlikely to change despite changes in functionality and pain [17]. With these limitations in mind, imaging should not be used to confirm a patellar tendinopathy diagnosis or to monitor improvement, but rather used to rule out coexisting pathology or provide an alternate diagnosis. 8 Management Exercise and load management form the cornerstones of patellar tendinopathy management. A four-stage, progressive tendon-loading exercise program is proposed (Table 4), with the aims of developing load tolerance of the tendon itself, the musculoskeletal unit, and the rest of the kinetic chain. This approach has been shown to be more effective than traditional eccentric exercise protocols [48], and involves progression through isometric, heavy slow resistance, energy storage and sport-specific exercises. Isometric exercises are indicated to reduce tendon pain, improve the mechanical stiffness of the tendon and to commence loading of the musculotendinous unit when pain limits the ability to complete isotonic exercises [3]. They are stage 1 of the four-stage program when required for these purposes. Research has shown that isometric exercise of the quadriceps can result in pain-relief and a reduction in cortical inhibition in individuals with patellar tendinopathy [28], and can also improve the mechanical properties of the tendon by increasing tendon stiffness [49]. It is preferable that this is completed single leg, using a leg extension machine in mid-range (60° knee flexion) (Fig. 3). However, if equipment is not available, the Spanish squat exercise has also been shown to be effective (Fig. 4) [50]. The most evidence exists for a 5 45 s protocol at 70% of maximal
Patellar Tendinopathy: Risk Factors, Prevention, and Treatment 215 Table 4 Four-stage progressive loading program Isometrics – Isometrics on leg extension machine, 5 45 secs at 70% MVIC with 2 min recovery – Spanish squat 5 30-secs if equipment not available Heavy slow resistance – – – – Functional endurance – Walking lunges – Stair climbing on toes Energy storage – Stair running – Jump into lunge – Split squats Sport-specific – Deceleration – Jumping – Change of direction drills Fig. 3 Single leg knee extension Fig. 4 Spanish squat Leg extension Leg press Seated calf raise Standing calf raise
216 voluntary isometric contraction (MVIC), with 2min rest between repetitions to allow for muscle and cortical recovery [28]. The aim of this stage of the 4-stage program is to provide sufficient pain-relief for the individual to commence heavy, slow resistance exercises. Therefore, this stage of the program is the shortest in duration, and rarely completed in isolation. Isometrics should be used to gain control of pain, reduce cortical inhibition, and to allow the individual to commence their strength program. The second stage of the program involves heavy slow resistance exercises and should be commenced as soon as feasible. What constitutes a ‘heavy’ load is highly individual, however, as most people with patellar tendinopathy are young, athletic men, it is likely that sufficient loading will require weighted, gym-based exercises. It is crucial that exercises are completed single leg, and that each muscle and leg is loaded maximally and independently, so deficits are not hidden within the kinetic chain. Exercises should be completed on both sides, as the strength of the affected side can be enhanced by improvements of the unaffected side, a phenomenon known as cross education [51, 52]. Loads for each side may differ initially, with the aim of achieving symmetry by the end of rehabilitation. It is important to target the affected musculotendinous unit in isolation initially, before introducing exercises to incorporate the rest of the kinetic chain. Exercises should be completed slowly, and the use of Fig. 5 Single leg press R. Kennedy and J. Cook a metronome to externally pace exercises may assist in modulating excitatory and inhibitory control of the muscle [53]. The key exercises during this phase include the leg extension, leg press (Fig. 5), seated and standing and seated calf raises (Figs. 6 and 7), all completed single leg. Calf strengthening is an essential and often overlooked component of this phase of rehabilitation. The soleus muscle is a key contributor during both deceleration and change of direction manoeuvres, as it decelerates the tibia and attenuates load through the anterior knee, while gastrocnemius is important for both jumping and sprinting. As all these movements are provocative for patellar tendinopathy, targeted strengthening of both gastrocnemius and soleus is crucial. These exercises should be commenced at plantar-grade, and dorsiflexion range can be increased as strength improves. Sessions during this phase are ideally completed 2–3 times per week on non-consecutive days. Once a strength base has been established, a functional endurance program including exercises such as stair climbing or walking lunges can be commenced. The third phase of rehabilitation involves the re-introduction of energy storage and release loads in the patellar tendon. This is the first time the tendon is exposed to provocative load during rehabilitation. The rate of loading is increased, using exercises such as low-level skipping, jumping, hopping and deceleration (Figs. 8, 9 and 10). These exercises should be completed
Patellar Tendinopathy: Risk Factors, Prevention, and Treatment 217 Fig. 6 Single leg seated calf raise with bodyweight loads only, as increasing the rate of loading increases the load on the tendon substantially. If possible, energy storage should be introduced prior to energy storage and release. Exercises should be completed every 2–3 days, as it can take up to 72 h for tendon structure to return to baseline following a loading bout [54]. Weighted, gym-based exercises from phase two are continued concurrently throughout this stage. Symptoms should be carefully monitored with a 24 h load response test such as the decline squat the next morning, to determine if the tendon has tolerated the increase in load. If pain remains low and stable, these drills can be progressed in quantity and intensity. The final phase of rehabilitation is characterised by the gradual re-introduction to sport specific drills. This phase is highly specific and depends on the chosen sport of the athlete. Stage three drills are ceased during this phase and replaced by more sport specific drills, to avoid overload of the tendon. Specific, gym-based strength exercises as per phase two must be maintained twice per week. High patellar tendon load activities such as jumping, deceleration and change of direction must be carefully quantified and graduated throughout the training block. Return to play may be considered when the athlete can sustain repeated high patellar tendon load activities without an increase in symptoms the following day. 9 In-Season Rehabilitation Depending on the severity of symptoms, some athletes may be able to continue to train and play whilst managing patellar tendinopathy. As improving and maintaining strength are the cornerstones of patellar tendinopathy management, a gym program must be maintained throughout the season. The removal of some provocative loads during training such as agility drills may be required to control symptoms. It may be necessary to limit training to three times per week during this stage. Isometrics may be used prior to training and games for analgesia and to reduce cortical inhibition. Adjunct treatments may be considered if they allow the athlete to load the tendon, however, treatments that directly target tendon pathology are generally invasive and are discouraged. 10 Adjuncts Various adjunct treatments for patellar tendinopathy have been investigated. Extracorporeal shockwave therapy (ESWT) has been shown to provide no additional benefit over placebo for the in-season management of jumping athletes with patellar tendinopathy [55]. A further randomised controlled trial compared
218 Fig. 7 Single leg standing calf raise R. Kennedy and J. Cook
Patellar Tendinopathy: Risk Factors, Prevention, and Treatment Fig. 8 Skipping Fig. 9 Jumping Fig. 10 Hopping 219
220 the use of focused or radial shockwave therapy, found no significant difference between groups [56]. Interestingly, both of these groups improved significantly, but it was concluded that this change was unlikely to be clinically worthwhile [56]. The addition of ESWT to an eccentric exercise program has also been studied, finding no additional benefit compared to eccentric exercise alone [57]. The use of a patellar strap or sports tape has also been investigated. Both patellar taping and a patellar strap have been found to decrease pain in the short term, however neither method was more effective than a placebo taping method [58]. Various injection therapies have been proposed to be of benefit in patellar tendinopathy. A systematic review of injection therapies found that a steroid injection decreased pain in the short-term, however symptoms relapsed at longer-term follow-up [59]. Various other injection therapies have also been studied, but insufficient evidence was available to determine superiority of one over the other, or over placebo treatment [59]. As adjunct treatments do not address muscle, tendon, or kinetic chain dysfunction, it is not recommended that they are used in isolation. They may be considered in cases when the use of an adjunct treatment enables the athlete to complete their rehabilitation program and there is no evidence of potential harm. Surgery for resistant patellar tendinopathy may be considered if pain persistently disrupts training and playing and when adequate conservative rehabilitation has failed. Traditional surgical treatment for patellar tendinopathy involves open patellar tenotomy and excision of the pathological region [60], and is associated with a prolonged recovery period and poorer outcomes [61]. Surgical techniques that remain external to the tendon, such as arthroscopic shaving, are recommended over more invasive procedures. Surgery is performed under ultrasound guidance on the region of neovascular ingrowth on the dorsal aspect of the tendon, adjacent to the pathological region, with minor resection of Hoffa’s fat pad [60]. Disruption of the fat pad- R. Kennedy and J. Cook tendon interface and the anterior peritendon decreases nociception, and may enable an earlier return to sport [60]. Rehabilitation after surgery involves immediate weight-bearing, followed by a structured rehabilitation period, with return to play in 2–4 months [60]. 11 Prevention Many of the same principles apply for both the prevention and management of patellar tendinopathy. These principles include appropriate load management, the maintenance of sufficient strength and addressing individual risk and associated factors as required. Appropriate load monitoring and management is essential, as large fluctuations in load can be provocative for the tendon especially in those with a history of patellar tendinopathy. It is particularly important to be cognisant of high patellar tendon load activities such as jumping, deceleration and change of direction, and to monitor the volume of these activities. Recent decreases and subsequent increases in training load due to other injuries is also relevant, especially in the case of injuries that affect ankle dorsiflexion range and calf strength such as inversion ankle sprains, as this can increase patellar tendon load. The maintenance of strength, particularly of the knee extensors and calf complex is crucial. A formal gym program targeting these muscle groups should be completed at least twice weekly as a key preventative strategy for athletes competing in sports requiring high patellar tendon load. This program should consist of single leg press, single leg extension, seated and standing single leg calf raises. Pre-season screening for patellar tendinopathy risk and associated factors may assist in preventing the development of symptoms throughout the season. Screening for previous selfreported patellar tendon pain is a stronger predictor of in-season tendinopathy than ultrasound imaging findings [21], and this information may be used to inform individualised training
Patellar Tendinopathy: Risk Factors, Prevention, and Treatment program design with the aim of addressing any relevant deficits or factors, such as lack of dorsiflexion range. Finally, it is important to act early if the tendon becomes symptomatic. The early signs of tendinopathy are often ignored, due to the warmup phenomenon and the fact that many athletes can often continue to train and play in the early stages of tendinopathy. Addressing load early often prevents the sequelae of pain and disability associated with severe patellar tendinopathy. 12 Take Home Messages 1. Patellar tendinopathy is characterised by localised pain at the inferior pole of the patella, which increases in a dose-dependent manner with increasing demand on the knee extensors. 2. Patellar tendinopathy presents a significant diagnostic challenge, with much clinical overlap with other conditions of the anterior knee. It is critical to determine the exact location of pain during pain provocation tests to increase diagnostic accuracy. 3. The relationship between patellar tendon pathology and pain is limited. The prevalence of imaging abnormalities in sporting populations is high, and these abnormalities are not always associated with pain or loss of function. 4. Patellar tendinopathy is a clinical diagnosis, imaging is not required to make the diagnosis. Imaging can be of assistance when ruling out co-existing pathology or an alternate diagnosis, but clinicians should be discerning as to its use. 5. While load is essential to maintain tendon structure and capacity, excess load is linked to pathology and pain. The development of patellar tendon symptoms is preceded by a change in loading patterns, usually an increase in tensile load being transmitted through the patellar tendon. 6. Exercise and load management are the cornerstones of patellar tendinopathy management. A four-stage, tendon-loading 221 exercise program has been shown to be more effective than traditional eccentric loading protocols. 13 Key Message – It is crucial to distinguish patellar tendinopathy from other common conditions of the anterior knee. Patellar tendinopathy is found almost exclusively in young, athletic men participating in sports that place significant demands on the knee extensors. Pain is localised to the inferior pole of the patellar and does not move or spread. Pain increases in a dose-dependent manner with increasing tensile load being transmitted by the patellar tendon. Diagnosis can be difficult due to significant clinical overlap with other anterior knee conditions, but the combination of pain location and the use of common pain provocation tests may assist with the clinical reasoning process. A four-stage tendon loading exercise program is recommended for management, with the aim of increasing the load tolerance of the tendon itself, musculotendinous unit, and the rest of the kinetic chain. References 1. Scott A, Squier K, Alfredson H, Bahr R, Cook JL, Coombes B, et al. Icon 2019: international scientific tendinopathy symposium consensus: clinical terminology. Br J Sports Med. 2020;54(5):260–2. 2. Lian ØB, Engebretsen L, Bahr R. Prevalence of jumper’s knee among elite athletes from different sports: a cross-sectional study. Am J Sports Med. 2005;33(4):561–7. 3. Malliaras P, Cook J, Purdam C, Rio E. Patellar tendinopathy: clinical diagnosis, load management, and advice for challenging case presentations. J Orthopaedic Sports Phys Therapy. 2015;45(11):887–98. 4. Cook J, Khan K, Harcourt P, Grant M, Young D, Bonar S. A cross sectional study of 100 athletes with jumper’s knee managed conservatively and surgically. The Victorian Institute of Sport Tendon Study Group. Br J Sports Med. 1997;31(4):332–6. 5. Kettunen JA, Kvist M, Alanen E, Kujala UM. Longterm prognosis for Jumper’s knee in male athletes: prospective follow-up study. Am J Sports Med. 2002;30(5):689–92.
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Pathophysiology of Patellar Instability William R. Post Effective and rational treatment depends upon a clear understanding of all the factors that go into patellofemoral instability. How can you solve a problem without understanding the contributing factors? Some of these will be able to be modified surgically. Some cannot and depend on muscle strength and control. Some pertinent morphological features such as rotational deformities and trochlear dysplasia are well known to be familial [1, 2]. Before we can meaningfully discuss the pathophysiology of patellofemoral instability, we must clearly define our understanding of patellofemoral stability. Patellofemoral stability has previously been defined as “constraint by passive soft tissue tethers and chondral/bony geometry that, together with muscular forces, guide the patella into the trochlear groove and keep it engaged within the trochlear groove as the knee flexes and extends” [3]. Let us first consider each of these factors separately There are important soft tissue constraints on both the medial and lateral aspect of the patella. The anatomy and function of these structures has W. R. Post (&) Mountaineer Orthopedic Specialists, LLC, Morgantown, WV, USA e-mail: wpost@wvortho.com been well defined in multiple publications [4–8]. The medial patellar restraints include the medial patellofemoral ligament which is a very important structure extending from the medial femoral condyle to the upper third of the medial border of the patella. Although medial patellofemoral ligament reconstruction is commonly discussed as the treatment for patellar instability one must realize that the medial patellofemoral ligament complex includes much more than just the medial patellofemoral ligament alone. There is a proximal extension of the medial patellofemoral retinaculum into the distal quadriceps tendon and the more distal portions of the medial patellofemoral complex include the medial patellotibial and patellomeniscal ligaments [5]. The more proximal portions of the medial soft tissue constraints have more influence on patellar constraint early in knee flexion while the more distal portions of the medial soft tissue constraints exert more of their influence when the knee is in greater flexion [4]. As our understanding of the specific characteristics of each of these portions of the medial soft tissues expands, we must take this into consideration as we refine our understanding of patellofemoral stability. Not only do the medial soft tissues contribute to constraint of the patella but the lateral soft tissues also play a key role. The lateral tissues certainly restrain the patella from displacement in the medial direction but they also contribute to preventing lateral displacement of the patella with respect to the trochlea. This has been © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_15 225
226 W. R. Post demonstrated in the laboratory [9] and also is evident in clinical results reported for lateral release which can exacerbate lateral instability in certain clinical situations [10–12]. When considering the true effects of the medial and lateral soft tissue restraints, it is important to realize that there is a very significant posterior component to the anatomical position (Fig. 1A). The articular shape of the patella and the trochlea also have a strong influence on stability. The deeper the concavity of the trochlea is, the more stable the patellofemoral articulation will be. This is especially true in the proximal portion of the trochlea where the patella enters the trochlea in early flexion. If the proximal portion of the trochlea is flat or even convex it is more difficult for the patella to be well-contained within the trochlea. In this regard it is important to consider not only how flat the proximal portion of the trochlea is but to evaluate at which degree of flexion the distal patella begins to enter he proximal (hopefully concave) portion of the trochlea. Once the patella has entered the concave trochlea weightbearing and quadriceps force Fig. 1 A Note the prominent posterior vector associated with both the medial and lateral soft tissue constraints (yellow arrows). B In the knee with normal alignment and anatomy the compression resulting from weightbearing and quadriceps force increases patellar stability (red arrow) A increase patellar stability (Fig. 1B). We must consider how far proximally the trochlea itself extends on the distal femur and also the relative height of the patella itself when we consider at which degree of flexion engagement of the patella within the trochlea begins [13]. This is an important source of variability among patients. Neither patella alta itself, nor trochlear morphology should be logically considered separately considering that the critical issue is the interaction and stability of the patella and the trochlea in early flexion. Axial and coronal plane skeletal alignment also play crucial roles in patellofemoral biomechanics. For example the lower extremity with a significant valgus alignment at the knee increases the lateral vector of quadriceps force, causing lateral displacement of the patella unless it is appropriately controlled by soft tissue constraints and the articular shape and alignment of the patellofemoral articulation (Fig. 2). One factor that can contribute to increasing the valgus angle and resultant lateral vector of quadriceps force is an abnormally lateral position of the tibial
Pathophysiology of Patellar Instability Fig. 1 (continued) 227 B tuberosity. It is for this reason historically that medial tuberosity transfer has been proposed when the patellar tendon insertion at the tibial tuberosity can be proven to be abnormally lateral. This is most commonly considered clinically when the excessive lateral quadriceps vector is severe enough to result in lateral translation of the patella on axial imaging studies. There are several methods of measuring this clinically by comparing the axial position of the tibial tuberosity to either the center of the trochlear groove (TT-TG distance) or the PCL insertion site (TT-PCL distance). Most commonly the depth of the trochlea is the reference point, although it still remains uncertain which measurement is more clinically reproducible and important [14]. Similarly rotational alignment of the extremity plays a critical role in positioning the trochlea underneath the patella [15]. Excessive internal rotation of the femur relative to the patella essentially moves the trochlea anteromedially away from the patella (Fig. 3). Excessive internal rotation of the femur can result from excessive femoral anteversion as well as relative weakness of the hip external rotators producing dynamic valgus. Since as a profession we have typically discussed patellofemoral tracking as keeping the patella over the trochlea we might misunderstand this very important point. Sometimes it is just as important or even more important to consider putting the trochlea back under the patella by externally rotating the femur. In this case we are not putting the train back on the track, but rather putting the track back underneath the train (Figs. 4A and B). Clinically it is not always purely one or the other. Internal rotation of the trochlea away from the patella can result from bony rotational abnormalities of the femur with excessive femoral anteversion or from lack of strong hip external rotation and pelvic stability which can produce relative dynamic internal rotation of the trochlea even in the absence of bony abnormality. It is this dynamic loss of control that is referred to as a functional valgus knee which can be easily diagnosed on physical examination. Hyperpronation of the foot can also produce internal
228 Fig. 2 Valgus alignment of the knee resulted in a lateral vector on the patellofemoral joint (yellow arrow). Relative contributions to the quadriceps vector come from the medial and lateral portions of the quadriceps (red arrows). Constraint to resist this lateral vector must come from medial and lateral soft tissue constraints (orange arrows) as well as the medial component of the quadriceps vector rotation of the lower extremity resulting in the same unhealthy internal rotation of the trochlea relative to the patella [16]. W. R. Post Each of these previous factors can affect the ability of muscular forces to be a positive influence on patellar stability. The effect of weightbearing and muscular contraction compresses the patella to the trochlea. Assuming that the patella has a stable environment by virtue of soft tissue constraints and articular constraint the compression resulting from muscular and weightbearing forces increases stability of the joint. The concept here is identical to that discussed in the glenohumeral joint where concavity compression is a recognized factor in joint stability [17, 18]. However if the patella is not adequately constrained by soft tissue and/or the articular surfaces muscular and weightbearing forces can produce instability. For example if the patella is just starting to enter the trochlea and the trochlea is nicely concave, a strong contraction even in a valgus knee will produce compression of the patella into the groove thus increasing stability (Fig. 5a). However, if the patella either has not entered the trochlea by this point due to patella alta, if the soft tissue constraints are not adequate to guide the patella into the groove, if the trochlea is internally rotated away from the patella and/or if the proximal portion of the groove is not actually concave but rather convex (such as is the case with severe trochlear dysplasia), muscular contraction can become part of the problem instead of part of the solution (Fig. 5b). When one takes away the concavity there is no concavity/compression affect. The practical application of the role of muscle strength and control is in non-operative treatment of patellofemoral instability when one must focus on neuromuscular control of the core and the entire lower extremity to improve dynamic control of femoral position. Increased quadriceps strength will improve stability by increasing the concavity/compression effect. Patellar taping or bracing may add to patellar constraint and possibly provide helpful proprioceptive feedback. Now that we have developed an understanding of the factors which contribute to patellofemoral stability, we need to consider exactly what we mean by patellofemoral instability. The same authors that defined patellofemoral stability as
Pathophysiology of Patellar Instability Fig. 3 Internal rotation of the femur moves the trochlea posterior medially away from the patella (white curved arrow). Such internal rotation can be from excessive anteversion of the femoral neck and/or relative weakness of the hip external rotators producing dynamic valgus Fig. 4 A In a normally aligned patellofemoral joint with normal articular congruity the train is on the track. B. When there is pathological bony deformity causing femoral internal rotation it makes more sense to put the track back underneath the train as opposed to trying to move the patella (the train) to the trochlea (the track). In this situation femoral osteotomy should be considered A 229
230 Fig. 4 (continued) W. R. Post B above define patellofemoral instability as “symptomatic deficiency of the aforementioned passive constraint (patholaxity) such that the patella may escape partially or completely from its asymptomatic position with respect to the femoral trochlea under the influence of displacing force. Such displacing force could be generated by muscle tension, movement and/or externally applied forces” [3]. To think precisely about this problem it is important to further define several key words. Laxity when used biomechanically is a word which refers to passive displacement under load. As an example an excessively lax medial patellofemoral ligament complex would allow excessive lateral translation under load. This can be seen in such cases during physical examination by applying lateral pressure to the patella in different degrees of flexion. Such a finding can also be imaged by stress radiography although this is not widely done [19]. So if the ligament does not have the physical capacity to adequately constrain the joint to which it is attached we say that there is patholaxity of the joint. This can occur after trauma or may exist in the setting of hyperlaxity syndromes such as Ehlers-Danlos syndrome. Laxity itself should not be confused with instability. Instability is more properly used to define a symptom. For example, patients may lack normal intact soft tissue constraints and be without actual symptoms of instability. In other words though the ligaments are lax, other stability factors such as neuromuscular control, activity level and articular alignment may be sufficient to allow the patient to remain asymptomatic. In this setting with findings of laxity on clinical evaluation, it is not appropriate to say
Pathophysiology of Patellar Instability Fig. 5 A In this CT image in full extension the posterior weightbearing and quadriceps force vector produces stability. B With trochlear dysplasia and a convex proximal trochlea the convex patella articulates with a convex trochlea and the quadriceps vector may produce instability if composite forces are even slightly lateral to the convex trochlea A B 231
232 W. R. Post that this patient has patellofemoral instability since instability itself is a symptom and not a physical finding. Indeed the symptom of patellofemoral instability is most often episodic even in the presence of severe patholaxity of the soft tissue constraints. To summarize, factors which cause displacement of the patella are a combination of muscle forces, insufficient articular congruency, skeletal alignment variables, dynamic positioning of the extremity as well as direct or indirect trauma. Patellofemoral instability injuries most often result from non-contact injuries by excessive internal rotation of the femur relative to the patella with significant muscular forces causing lateral displacement resulting in failure of the medial soft tissue constraints. If underlying laxity of the soft tissue constraints exists from either congenital hypermobility or previous injury, less force is required to produce the pathological displacement. MRI studies have consistently shown disruption of the medial soft tissues with acute dislocation [20]. The key clinical question is to begin to understand which of the variables must be addressed clinically by surgery or nonoperative management to assure normal function in the absence of recurrent instability episodes which can produce severe articular injury resulting in posttraumatic osteoarthritis and recurrent disability. 1 Using Pathophysiology to Understand Different Types of Patellofemoral Instability Given our understanding of factors affecting the pathophysiology of patellar instability, we can now address different types of patellofemoral instability. The most common type of patellofemoral instability involves dislocation of the patella laterally with respect to the trochlea in early flexion (<45°). This is essentially a failure of the patella under load to enter the trochlea and remain in the trochlea as the knee flexes. While this is far and away the most common type of patellofemoral instability, it is not the only type. Clinical studies have consistently revealed trochlear dysplasia, patella alta and increased TTTG distance in patients with lateral instability to be factors which make recurrent dislocation more likely [21–23]. As such information evolves, patient selection for treatment after primary dislocation will become more objective. Less common types of patellofemoral instability include lateral patellar instability with flexion. In this situation referred to as obligate lateral dislocation the patella enters the trochlea normally but with further flexion suddenly dislocates lateral to the trochlea. This typically occurs each time the patient goes from full extension to full flexion. In order to understand the situation we can apply the same principles addressed above. In this situation there is excessive lateral tightness as well as concomitant relative deficiency of the lateral aspect of the trochlea. In some cases there may be shortening of the extensor mechanism exacerbating the lateral tightness and contributing to obligate lateral dislocation in flexion. Understanding these factors, lateral release with possible lengthening of the quadriceps mechanism is the mainstay of such treatment with elevation of the lateral trochlea as an additional component of the repair. In addition to these 2 types of lateral patellofemoral instability, medial patellar instability also occurs. This problem is usually iatrogenic related to prior surgery with excessive lateral release and sometimes surgical injury to the vastus lateralis tendon. In this case the root causes are less than appropriate lateral soft tissue constraints as well as imbalance of the quadriceps related to the vastus lateralis weakness. One must also be aware when planning treatment for medial patellar instability that any pathologic factors present contributing to the original lateral instability may still need to be effectively treated. Restoring medial and lateral soft tissue constraints along with considering possible treatment of pre-existing issues such as trochlear dysplasia
Pathophysiology of Patellar Instability or patella alta is a logical approach based on understanding of pathophysiological principles. In addition to the 2 types of lateral patellofemoral instability and the usually iatrogenic medial patellar instability, patients may experience multidirectional instability of the patella. In this setting all the potential factors known to contribute to patellofemoral instability must again be carefully evaluated. Pathologic laxity may exist and be either traumatic, iatrogenic, congenital or a combination of all three. Underlying bony alignment issues and potential deficiencies of dynamic control are also common factors in patients who truly have multidirectional instability. This does not mean that all these factors need to be addressed by surgery in each patient. Such patients are highly complex with multifactorial pathology creating difficult decision making. One must always carefully balance potential morbidity of surgical intervention with proven efficacy. 2 Conclusion A good understanding of the pathophysiology of patellofemoral instability is essential for any clinician treating such patients. Such knowledge must be combined with ongoing clinical research to treat patients wisely. Careful evaluation of all known pathophysiological elements is indicated before surgical decision making. As a profession we have much to learn about how much surgery and what surgery is necessary in any given clinical scenario. Recent consensus suggests avoiding a cookbook approach of operating on every identified factor (trochlear dysplasia, patella alta, pathologic laxity, tibial tuberosity position, femoral and tibial rotational deformities) [3]. As always, risks and benefits must be considered and we must always remember: primum non nocere—first do no harm. 233 References 1. Chan CJ, Chau YJ, Woo SB, Luk HM, Lo IF. Familial patellar dislocation associated with t(15;20) (q24;q13.1). J Orthop Surg (Hong Kong). 2018;26 (2):2309499018777026. 2. Rebolledo BJ, Nam D, Cross MB, Green DW, Sculco TP. Familial association of femoral trochlear dysplasia with recurrent bilateral patellar dislocation. Orthopedics. 2012;35(4):e574-9. 3. Post WR, Fithian DC. Patellofemoral instability: a consensus statement from the AOSSM/PFF patellofemoral instability workshop. Orthop J Sports Med. 2018;6(1):2325967117750352. 4. Hinckel BB, Gobbi RG, Demange MK, Pereira CAM, Pecora JR, Natalino RJM, et al. Medial patellofemoral ligament, medial patellotibial ligament, and medial patellomeniscal ligament: anatomic, histologic, radiographic, and biomechanical study. Arthroscopy. 2017;33(10):1862–73. 5. Tanaka MJ, Chahla J, Farr J 2nd, LaPrade RF, Arendt EA, Sanchis-Alfonso V, et al. Recognition of evolving medial patellofemoral anatomy provides insight for reconstruction. Knee Surg Sports Traumatol Arthrosc. 2019;27(8):2537–50. 6. Shah KN, DeFroda SF, Ware JK, Koruprolu SC, Owens BD. Lateral patellofemoral ligament: an anatomic study. Orthop J Sports Med. 2017;5 (12):2325967117741439. 7. Capkin S, Zeybek G, Ergur I, Kosay C, Kiray A. An anatomic study of the lateral patellofemoral ligament. Acta Orthop Traumatol Turc. 2017;51(1):73–6. 8. Reider B, Marshall JL, Koslin B, Ring B, Girgis FG. The anterior aspect of the knee joint. J Bone Joint Surg Am. 1981;63(3):351–6. 9. Desio SM, Burks RT, Bachus KN. Soft tissue restraints to lateral patellar translation in the human knee. Am J Sports Med. 1998;26(1):59–65. 10. Betz RR, Magill JTd, Lonergan RP. The percutaneous lateral retinacular release. Am J Sports Med 1987;15(5):477–82. 11. Dandy DJ, Desai SS. The results of arthroscopic lateral release of the extensor mechanism for recurrent dislocation of the patella after 8 years. Arthroscopy. 1994;10(5):540–5. 12. Christensen F, Soballe K, Snerum L. Treatment of chondromalacia patellae by lateral retinacular release of the patella. Clin Orthop. 1988;234:145–7. 13. Biedert RM, Albrecht S. The patellotrochlear index: a new index for assessing patellar height. Knee Surg Sports Traumatol Arthrosc. 2006;14(8):707–12.
234 14. Brady JM, Sullivan JP, Nguyen J, Mintz D, Green DW, Strickland S, et al. The tibial tubercleto-trochlear groove distance is reliable in the setting of trochlear dysplasia, and superior to the tibial tubercle-to-posterior cruciate ligament distance when evaluating coronal malalignment in patellofemoral instability. Arthroscopy. 2017;33(11):2026–34. 15. Post WR, Teitge R, Amis A. Patellofemoral malalignment: looking beyond the viewbox. Clin Sports Med. 2002;21(3):521–46, x. 16. Imhoff FB, Cotic M, Dyrna FGE, Cote M, Diermeier T, Achtnich A, et al. Dynamic Q-angle is increased in patients with chronic patellofemoral instability and correlates positively with femoral torsion. Knee Surg Sports Traumatol Arthrosc. 2021;29(4):1224–31. 17. Halder AM, Kuhl SG, Zobitz ME, Larson D, An KN. Effects of the glenoid labrum and glenohumeral abduction on stability of the shoulder joint through concavity-compression: an in vitro study. J Bone Joint Surg Am. 2001;83(7):1062–9. 18. Lippitt SB, Vanderhooft JE, Harris SL, Sidles JA, Harryman DT 2nd, Matsen FA 3rd. Glenohumeral W. R. Post 19. 20. 21. 22. 23. stability from concavity-compression: a quantitative analysis. J Shoulder Elbow Surg. 1993;2(1):27–35. Teitge RA, Faerber WW, Des Madryl P, Matelic TM. Stress radiographs of the patellofemoral joint. J Bone Joint Surg Am. 1996;78(2):193–203. Sallay PI, Poggi J, Speer KP, Garrett WE. Acute dislocation of the patella. A correlative pathoanatomic study. Am J Sports Med. 1996;24(1):52–60. Huntington LS, Webster KE, Devitt BM, Scanlon JP, Feller JA. Factors associated with an increased risk of recurrence after a first-time patellar dislocation: a systematic review and meta-analysis. Am J Sports Med. 2020;48(10):2552–62. Jaquith BP, Parikh SN. Predictors of recurrent patellar instability in children and adolescents after first-time dislocation. J Pediatr Orthop. 2017;37 (7):484–90. Arendt EA, Askenberger M, Agel J, Tompkins MA. Risk of redislocation after primary patellar dislocation: a clinical prediction model based on magnetic resonance imaging variables. Am J Sports Med. 2018;46(14):3385–90.
Evaluation of the Patient with Patellar Instability: Clinical and Radiological Assessment Andrew E. Jimenez, Lee Pace, and Donald C. Fithian 1 Introduction The initial evaluation of a patient with patellar instability relies heavily on a detailed history and physical examination. These two pieces of the evaluation are vitally important. The use of radiologic evaluation and advanced imaging studies are also key components that act as an adjunct to the history and physical. As will be discussed in this chapter, the etiology of patellar instability is often due to anatomic risk factors and can at times be multifactorial in nature. The initial evaluation should serve to properly identify these etiologies. Patellofemoral instability is a common orthopaedic problem and is among the most frequent acute knee injuries in pediatric and adolescent age groups with an annual incidence between 23 and 43 per 100,000 [1]. Typically, patellofemoral instability is due to anatomic abnormalities in the lower extremity that lead to A. E. Jimenez (&) Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT, USA L. Pace Children’s Health Andrews Institute, Plano, TX, USA D. C. Fithian Senta Clinic, San Diego, CA, USA medial retinacular deficiency. Multiple risk factors have been associated with recurrent patellar instability. Most of these risk factors are anatomic in nature and include trochlear dysplasia, patella alta, genu valgum, femoral anteversion and ligamentous laxity. Other identified risk factors include skeletal immaturity, history of a contralateral dislocation, and participation in sport. While these non-anatomic factors have been identified, it is unclear if they are true risk factors or are coincident to the underlying anatomic abnormalities. As a result, recurrence rates have been described from as little as 34% to as high as 88% depending on the presence of risk factors [2]. The use of a detailed history, physical examination, and imaging allows for proper evaluation of these variables and thus allows the clinician to best guide the patient in shared decision making. It is helpful to think of patellar instability as the symptom of the underlying pathoanatomy. Evaluating the patient from this perspective helps the clinician to identify the underlying problem(s) most effectively. 2 History The history is the first component of any patient presenting with patellar instability and often is the key component of establishing a diagnosis. There are several ways in which a patient with patellar instability can present. The classic scenario in which a patient sustained a traumatic © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_16 235
236 dislocation that required relocation is typically self-explanatory. However, there are several other ways in which a patient with instability can present. Some patients present with atraumatic recurrent subluxations while others may at best describe multiple episodes of buckling or giving way. Conversely, other patients may describe pain as a large component of their symptoms. For these more subtle cases, it is important to keep instability on the differential diagnosis. Despite the oft cited example of a twisting injury in sports, a good percentage of instability events happen at random, and subluxations can be a common instability episode. It is helpful to establish the total number of instability events, age at first instability event, post instability swelling and if manual reduction of the dislocation was necessary [3, 4]. Additionally, prior treatments or surgery should be noted along with a relevant family history of patellofemoral instability [5]. Noting the presence of pain is also important as some patients may cite pain as their presenting complaint but their examination and imaging will uncover that instability has been the source of the problem. While it is normal to have pain during and after an instability event, some patients, particularly those with severe anatomic risk factors, may often have pain in between episodes which may represent concomitant cartilage injury. Pain should not be totally separated out from instability. Noting symptoms or dislocation events on the contralateral knee is also valuable. A history of a contralateral patellar dislocation greatly increases the risk of recurrence and may be influential in establishing an appropriate treatment plan [6]. Reporting of mechanical symptoms such as locking or catching combined with a history of significant swelling after dislocation episodes may be related to osteochondral injury and loose bodies which may indicate timely surgical intervention. Reviewing any prior surgery and knowing the specific procedures performed can help provide a complete picture of the patient’s pathology. If possible, prior operative reports and operative pictures should be reviewed. A. E. Jimenez et al. 3 Physical Examination After obtaining a detailed history, the next step is physical examination with the goal of identifying specific pathology. The examination for patellofemoral instability allows for an efficient yet complete assessment of the patient, and the details identified in the history can help to focus the exam. In addition to a holistic exam of the knee, the exam should evaluate the four principle anatomic risk factors: trochlear dysplasia, patella alta, genu valgum and femoral anteversion. It is important to keep in mind that these can sometimes coexist. In the non-acute setting, the exam commences with an evaluation of coronal plane alignment with the patient supine on the examining table and bringing the lower extremities into contact with one another. If the knees are touching but the feet do not, a concern for genu valgum is raised and consideration is given for a standing hip to ankle radiograph. Patella alta can be evaluated in two ways. First, with the patient supine, the presence of a bulging fat pad distal to the patella is consistent with patella alta. Also, with the patient seated at the edge of the examining table with the knees flexed to 90°, the position of the patella is assessed. If the patella is high riding in the trochlea and is not engaged in the intercondylar notch, this is consistent with a long patellar tendon/patella alta (Fig. 1). Lastly, lateral patellar apprehension in high degrees of knee flexion is also consistent with patella alta [7]. This will be discussed more below as this is seen more often with trochlear dysplasia. Femoral anteversion is evaluated in the prone position with the knee flexed 90°. Two principle exams can be conducted with the patient in this position. The first is Craig’s test. This involves internally and externally rotating the hip until the examiner can feel the patient’s greater trochanter at its point of greatest prominence. In this position the angle between the thigh and the leg is recorded (Fig. 2). If this angle is >30°, there is concern for pathologic femoral anteversion and a rotational profile CT scan is considered. In
Evaluation of the Patient with Patellar Instability … 237 Fig. 1 Physical exam finding of patella alta. With the knee flexed to 90° the position of the patella can be assessed. In the setting of patella alta, the patella (white arrow) will not be engaged in the intercondylar notch (black arrow) addition, if the total amount of internal hip rotation is 45° or greater than the total amount of external rotation, this can also be consistent with pathologic femoral anteversion [8]. Trochlear dysplasia is by far the most common anatomic risk factor for patellar instability. There are a couple different ways to evaluate for this pathology. As all are familiar, patellar apprehension is the keystone examination to evaluate for instability [9]. However, this test should be done in various degrees of knee flexion, not just in full extension. Around 30° of flexion, the patella begins to engage in the trochlea which, in the absence of dysplasia, is able to catch the patella and direct it into the trochlear groove. In the setting of dysplasia, the patella will still be highly unstable in this position. Often, it takes up to 60° or more of flexion before the most proximal aspect of the patella has traversed past the dysplastic portion of the trochlea and becomes seated and stable. If a patient Fig. 2 (Reproduced from Magee DJ: Orthopedic physical assessment, ed 3, Philadelphia, 1997, WB Saunders) Demonstration of Craig’s Test. The patient is positioned prone with the hip in neutral and the knee flexed 90°. The examiner may palpate the position of the leg where the greater trochanter is most prominent. The angle between a line down the shaft of the tibia and a vertical line perpendicular to the examination table represents the degrees of femoral anteversion demonstrates continued apprehension up to this degree of knee flexion, that is consistent with high grade trochlear dysplasia. As mentioned above, this can also be consistent with high grade patella alta as it takes higher degrees of knee flexion to engage the patella in the trochlea if the
238 A. E. Jimenez et al. A B C D Fig. 3 (Reproduced with permission from SanchisAlfonso V., Montesinos-Berry E., Serrano A., MartínezSanjuan V. (2011) Evaluation of the Patient with Anterior Knee Pain and Patellar Instability. In: Sanchis-Alfonso V. (eds) Anterior Knee Pain and Patellar Instability. Springer, London) The moving patellar apprehension test begins with the knee held in full extension and the patella is manually translated laterally (black arrow) with the thumb A. The knee is then flexed to 90° and then brought back to full extension while the lateral force on the patella (black arrow) is maintained B. In the second part of the test, the knee is started in full extension C, brought back to 90° of flexion D, and then brought back to full extension while the index finger is used to translate the patella medially (black arrow). For a positive test, in the first part, the patient expresses apprehension and may activate his or her quadriceps in response to the apprehension. However, in the second part of the test, the patient experiences no apprehension and allows free flexion and extension of the knee patellar tendon is pathologically long. Ahmad et al. described a variation of this evaluation called the “moving patellar apprehension test” (Fig. 3) [9]. The moving patellar apprehension test has demonstrated a sensitivity as high as 100%, specificity of 88.4%, a positive predictive value of 89.2%, a negative predictive value of 100%, and an accuracy of 94.1%. This dynamic provocative test is similar to the pivot shift test for the ACL-deficient knee. The “J” sign is another exam observation that can be diagnostic for dysplasia. With the patient seated on the examination table and the legs hanging over the side with the knees flexed 90˚, the patient is asked to extend the knee actively to a fully extended position (Fig. 4). Normally, the patella follows a straight line as the knee is extended. In the setting of trochlear dysplasia, the patella will be pushed lateral by the flat or convex trochlea as the knee is extended making the shape of an inverted “J”. Conversely, as the knee is flexed, the patella will move from lateral to midline as it centers in the trochlear groove. A “lazy J” sign can be seen in the setting of lowgrade dysplasia and patella alta. A “jumping J sign” is usually found in patients with trochlear dysplasia and a large supratrochlear spur which is often irritating to the patient [10]. In addition to these focused exams, the knee should be evaluated for range of motion, swelling, cruciate and collateral ligament integrity, joint line tenderness and crepitus. Patients presenting with an acute dislocation often will have an effusion and tenderness over the medial retinacular structures and may not be amenable to the entirety of the exam listed above.
Evaluation of the Patient with Patellar Instability … A 239 B C Fig. 4 (Reproduced with permission from SanchisAlfonso V., Montesinos-Berry E., Serrano A., MartínezSanjuan V. (2011) Evaluation of the Patient with Anterior Knee Pain and Patellar Instability. In: Sanchis-Alfonso V. (eds) Anterior Knee Pain and Patellar Instability. Springer, London) The “J” sign. When the knee is extended from 90° A to 0° C the patella outlines an inverted J-shaped course. Intermediate positions between 90˚ and 0˚ B The Quadriceps angle or Q angle has been commonly referenced in the evaluation of patients with patellar instability. The Q-angle is described at the intersection of lines drawn from the anterior superior iliac spine to the center of the patella and from the center of the patella to the tibial tubercle. Normal values have been reported 10° in men and 15° in women. The Q angle is mainly of historical interest and is not routinely necessary to measure or evaluate in modern day evaluation of patients with patella instability as it does not provide any information that drives treatment. Patients with patellofemoral instability may also demonstrate elements of hypermobility. It is therefore important to evaluate the presence of ligamentous laxity. Patellofemoral instability patients are six times more likely to have hyperlaxity compared to age matched controls, but outcomes of intervention as still promising in this patient population [11]. Hypermobile patients may demonstrate excessive skin laxity, and the presence of Ehlers-Danlos syndrome should be evaluated especially given the significant systemic pathologies which may be present. In all patients, generalized ligamentous laxity should be quantified using the Beighton hypermobility score [12]. Referred pain from the hip should always be a consideration as well when evaluating these patients and a basic hip examination for range of motion and anterior impingement is warranted. Hip pathologies in younger patients such as Perthes disease, slipped capital femoral epiphysis, or femoroacetabular impingement syndrome may uncommonly manifest as referred knee pain. 4 Evaluation of Failed Prior Stabilization Surgery Patients who have undergoing previous surgery and continue to have recurrent patellar instability fall into one or more categories: improper surgical indication, surgical technical error, or incorrect assessment and treatment of risk factors for instability (trochlear dysplasia, patella alta, femoral anteversion, etc.) [13]. If the patient was properly indicated and continues to have instability postoperatively, technical errors of the index surgery or surgeries must be considered in addition to failure to address other anatomic risk factors of stability. Parikh et al. [14] reported that 47% of the complications that occurred after MPFL reconstruction surgery were due to
240 A. E. Jimenez et al. technical errors, the most common of which was malposition of the femoral tunnel. The femoral attachment is critical for the function and kinematics of the reconstructed MPFL graft. In the normal knee, the MPFL is tighter in extension than in flexion. If the femoral attachment site of a reconstructed MPFL is placed too anterior, the graft will tighten when the knee is flexed, and patellofemoral overload can occur [15]. Similarly even with a properly placed femoral tunnel, excessive graft tension is another technical error that can lead to failure of reconstructive surgery [16] and can manifest with a painful and relatively immobile patella. Crepitus through a range of motion is important to document. Most patients with patellar instability will have some degree of cartilage damage. This damage can accelerate if an improper surgery is performed and some patients in revision settings may require concomitant chondral resurfacing. It is important to document any surgical scars as it will need to be determined if they can be used for a revision surgery or if new ones need to be made. In particular, a history of a prior lateral release reduces lateral restraint and may increase the risk of iatrogenic medial instability [17]. Lastly, a history of prior tibial tubercle osteotomy (TTO) can alter patellofemoral mechanics with over-distalization resulting in loss of terminal flexion and over medialization potentially contributing to medial instability [18]. 5 Evaluation of Medial Patellar Instability The direction of any instability is extremely important. Most of the time instability is in the lateral direction; however, some patients may have medial instability and some patients may suffer from multidirectional instability. Medial patellar instability is much less frequent than lateral patellar instability, but should be suspected, especially in patients who remain symptomatic after any lateral retinacular release surgery. Medial instability was first described by Hughston and Deese who reported on medial patellar subluxation in 54 patients who had previously undergone an overzealous lateral release [19]. Recent biomechanical finite element analysis has demonstrated that lateral retinacular release even in the setting of a tibial tuberosity transfer can result in multidirectional instability [20]. Less commonly, hyperlaxity, trochlear dysplasia, and deficient quadriceps can rarely be associated with medial patellar subluxation events. Bollier et al. detailed that patients with medial patellar subluxation can occur in cases with a malpositioned MPFL graft [21]. Patients with prior surgery should be carefully examined as medial instability can sometimes be mistaken for lateral patellar instability. In the case of medial patellar instability, the patella is subluxated medially in full extension and then as the knee flexes, it jumps laterally to center in the trochlear groove. On exam, static medial patellar subluxation, vastus lateralis atrophy, or a lateral patellar void may be seen. Our primary method for diagnosis of medial patellar subluxation is Fulkerson’s relocation test (Fig. 5). To perform this test, we hold the patella slightly in a medial direction with the knee extended. Then, we flex the knee while letting go of the patella, which causes the patella to go into the trochlea. In patients with medial subluxation this test reproduces the patient’s symptom. Further, the gravity subluxation test has also been described where the patient is placed in the lateral decubitus position with the affected limb supported by the examiner at the ankle and knee [22]. The knee is flexed from the extended position. If medial instability is present, the patient cannot tolerate passive knee flexion without upward force on the patella, which reduces the patella and allows it to enter the groove as the knee is flexed passively by the examiner. A positive test is indicative of medial instability and confirms deficiency of the lateral retinacular constraints. Further evaluation on imaging should follow the standard protocol for patients with lateral patellar instability, but additional views such as stress radiographs of the patellofemoral joint as described by Teitge et al. can be helpful in establishing a diagnosis [23].
Evaluation of the Patient with Patellar Instability … A B 241 6 Imaging studies are next in the diagnostic algorithm after the history and physical exam. Relying on imaging results prior to consideration of a history and physical can lead to diagnostic errors and at times improper treatment. Surgical indications should be based on history, physical exam findings, and imaging working together in tandem. Imaging modalities may be used to confirm the diagnosis established by the history and physical exam, quantify pathology, and to identify other concomitant pathologies that may warrant treatment. 7 C Fig. 5 (Reproduced with permission from SanchisAlfonso V., Montesinos-Berry E., Serrano A., MartínezSanjuan V. (2011) Evaluation of the Patient with Anterior Knee Pain and Patellar Instability. In: Sanchis-Alfonso V. (eds) Anterior Knee Pain and Patellar Instability. Springer, London) Fulkerson’s relocation test. We hold the patella slightly in the medial direction (black arrow) with the knee extended A. Contralateral asymptomatic knee B. Then, we flex the knee while letting go of the patella, which causes the patella to go into the femoral trochlea C Imaging Studies Radiographs Initial imaging for patients with patellofemoral instability are standard radiographic views including standing anteroposterior (AP) view, a 45° bent knee posteroanterior Rosenberg vie, and a true lateral view (defined as <2 mm offset of the posterior femoral condyles). Weightbearing AP and 45° PA views allow one to evaluate evidence of joint space narrowing of the medial or lateral compartment as well as large varus and valgus deviations. Such deviations would need further quantification with long leg standing films if indicated. Of note, with the advent of advanced axial imaging, the diagnostic utility of these radiographic views is falling out of favor. The lateral view is the workhorse view to qualify anatomic risk factors for patellar instability. However, the x-ray should be used to support advanced imaging and not as a sole diagnostic tool. Patellar height (patella alta vs patella baja) can be quantified using several methods including the Insall-Salvati, Blackburne-Peel, and Caton−Deschamps ratio. The Caton-Deschamps and Balckburne-Peel ratios are used by many clinicians because the value remains constant despite minor variations in knee flexion and can be used for skeletally immature patients.
242 A perfect lateral view can evaluate for trochlear dysplasia. Radiographic findings such as the crossing sign, trochlear spur, and double contour sign are pathognomonic for trochlear dysplasia. The crossing sign is when the curve of the trochlear floor crosses the anterior contour of the lateral femoral condyle, which represents flattening of the trochlear groove and absence of trochlear constraint. A trochlear spur (also described as a trochlear prominence, boss, bump, or eminence) is when the proximal trochlea begins to elevate away from the distal femoral metadiaphysis and can become convex with larger spurs. The spur size can be quantified via the distance between the most anterior point of the spur and a line drawn along the distal aspect of the anterior femoral cortex. The double contour sign is a double line at the anterior aspect of the femoral condyles that represents the chondral outline of a hypoplastic medial trochlea. The Dejour classification is based on these lateral radiographic and axial imaging findings [24]. Type A is characterized by a shallow trochlea, with a crossing sign on the lateral view and a sulcus angle >145 on the axial view. Type B is characterized by the appearance of a flat trochlea on axial radiographs and a supratrochlear spur on lateral images. Type C has the presence of a crossing sign and a double contour sign in lateral radiographs combined with medial hypoplasia and lateral convexity on axial radiographs. Type D dysplasia has asymmetry of the trochlear facets and a cliff between the medial and lateral facets on the axial view [24]. A summary of radiographic signs of trochlear dysplasia can be found in Fig. 6. In patients with a prior MPFL reconstruction, the femoral tunnel position can be evaluated on the lateral radiograph (Fig. 7). In addition, the lateral view can diagnose degenerative changes in the patellofemoral joint. In a Merchant view of the knee in 45˚ of flexion, patellofemoral pathoanatomy is often overlooked because pathology at the proximal part of the trochlear groove may not be readily visible, and a supratrochlear spur may be missed. Alternatively, a Laurin radiograph with the knee flexed to 20° and the imaging beam directed from A. E. Jimenez et al. inferior to superior is better at evaluating trochlear morphology. However, this is still difficult to obtain at times and a “normal” appearing axial view does not rule out conditions such as trochlear dysplasia. The axial radiograph can also be used for stress images of the patella. In these images, axial radiographs are obtained while an examiner applies approximately constant pressure to the patella in either the medial or lateral direction. Relaxation of the quadriceps must be maintained and the displacement can be measured on the radiograph by a technique described by Laurin et al. [25]. Lastly, a long leg standing film, or AP hip to ankle x-ray, is ordered based on physical exam concerns for coronal plane malalignment. This imaging study is crucial to quantify varus and valgus alignment. 8 Magnetic Resonance Imaging (MRI) Advanced imaging with MRI is currently the gold standard to diagnose and quantify pathoanatomy and articular cartilage injuries in patients with patellar instability. An MRI should be performed before any surgical intervention for patellar instability and the authors advocate for MRI examination of all acute, traumatic, first time dislocations to evaluate for osteochondral or chondral injuries that may warrant surgical fixation [26]. Axial MRI allows for thorough and quantitative evaluation of bony and cartilaginous anatomy and injury as well as patellar height. While evaluation of bony anatomic risk factors and chondral injuries are the primary concern, MRI is also useful for viewing the status of the MPFL [27]. Axial MRI is key to quantifying trochlear dysplasia. Given that trochlear dysplasia is the most common anatomic risk factor associated with patellar instability, it must be diagnosed and assessed for in every patient. Historically, dysplasia has been categorized via the Dejour classification scheme on axial MRI, however, there has been poor inter-rater reliability with this
Evaluation of the Patient with Patellar Instability … 243 Fig. 6 (Reproduced with permission from Dejour D, Saggin PRF: Sulcus-deepening trochleoplasty in Scott WN, ed: Insall and Scott Surgery of the Knee, ed 5. Philadelphia PA, Elsevier, 2012, pp 688−695) Illustrations of the knee joint demonstrating the appearance of various types of trochlear dysplasia on the lateral and axial radiographic imaging. A Dejour Type A, the crossing sign is visible on lateral views and the trochlea appears shallower than normal but still symmetric and concave. B Dejour Type B, the crossing sign and trochlear spur are visible on lateral imaging. On axial views the trochlea appears flat, with prominence of the entire trochlea. C Dejour Type C, the crossing stign and double-contour sign are visible on the lateral view, but no prominence is visible. On the axial view, the lateral facet appears convex and the medial facet is hypoplastic. D Dejour Type D, the crossing sign, supratrochlear spur, and doubler-contour sign are visible. On the axial view, there is clear symmetry of the height of the facets, which is known as a cliff pattern approach and better reliability has been shown by a binary classification of low-grade (Dejour A) and high-grade (Dejour B-D) dysplasia. Recent literature has documented the value of lateral trochlear inclination (LTI) to help quantify trochlear morphology [28]. Currently, as described by Joseph et al. LTI is measured using a twoimage technique on axial MRI sequences at the levels of the most proximal extent of the trochlear cartilaginous surface and the posterior femoral condyles (Fig. 8). An LTI value that is positive denotes that there is some degree of a trochlear groove at the most proximal extent of the trochlea. An LTI of 0° represents a flat proximal trochlea and a negative LTI represents a convex proximal trochlea. LTI has been used extensively to quantitatively evaluate trochlear dysplasia in the setting of patellar instability. LTI as measured on MRI can better characterize the proximal trochlea than radiographic imaging which has been traditionally used for the Dejour classification [29, 30]. Carrillon, et al. (using a single image technique) have established that an LTI <11° is associated with a 95% specificity of having patellar instability secondary to trochlear dysplasia [31] although this number has not been reassessed since the advent of the two-image technique. Patellar height is also evaluated on MRI via sagittal imaging. MRI is currently considered to be more reliable than x-ray for measuring patellar height due to inconsistencies in the angle of the
244 Fig. 7 Lateral radiograph of a patient status-post medial patellofemoral ligament reconstruction with recurrent instability. Femoral tunnel position is indicated by the yellow arrow and patellar tunnels are indicated by the white arrows Fig. 8 [28] (Reproduced from Joseph et al., Reprinted with permission from SAGE Publishing) Measurement technique for 2-image lateral trochlear inclination (LTI). A An angular measurement was taken on an axial MRI image between the most proximal aspect of the lateral trochlear cartilaginous surface and a horizontal reference line represented by the red lines. This angle measured 15°. This angle’s apex was medial, so it was assigned a positive value. B An angle was measured between the A. E. Jimenez et al. x-ray beam, and all the indices mentioned above can be measured on MRI as well as x-ray. Further, one can measure the patellotrochlear index (PTI) on MRI (Fig. 9). This measures the amount of cartilaginous overlap between the patella and the trochlea and is thought to be a more functional representation of patellar height. While there is no scientific data to say at what point a PTI value represents pathologic patella alta, expert opinion puts it between 0.1 and 0.25. Biedert et al. showed the mean value in a normal population was 0.31 with a 95% CI of 0.125 −0.50 [32]. Of note the values established on MRI by Biedert et al. were with the knee in full extension, but many knee MRIs, particularly in the United States, are obtained with the knee in 10° of flexion. This discrepancy should be kept in mind when interpreting the results. The tibial tubercle-trochlear groove (TT-TG) distance is a popular and well-known measure for patients with patellar instability. It has, by and large, replaced the Q angle as a measure of malalignment and may be helpful in guiding decision making for tubercle osteotomies. While posterior condyles and a horizontal line represented by the red lines. This angle measured 2°. It was assigned a positive value because the apex of the angle was medial. The 2-image LTI was determined by subtracting the angle of the posterior femoral condyles relative to the horizontal from the angle of the proximal lateral trochlea relative to the horizontal. In this example, the LTI calculation was 15°−2° = 13°
Evaluation of the Patient with Patellar Instability … 245 9 Fig. 9 [32] (Reproduced from Biedert et al., Reprinted with permission from Springer Publishing) Patellotrochlear index measurement. BL(P) Baseline patella (2 superior most aspect of articular cartilage to 3 inferior most aspect); BL(T) Baseline trochlea (length of trochlear articular surface from 1 superior most aspect with respect to 3 the inferior most aspect of the articular patellar cartilage using a right angle and parallell lines); The ratio is BL(T)/BL(P); LT Length of trochlear cartilage (superior most aspect to inferior most aspect of trochlea using a vertical line) recommendations vary, most surgeons consider a TT-TG value >20 mm to be an indication for a tibial tubercle osteotomy. However, recent work has challenged the concept that an elevated TT-TG is a sole representation of a lateralized tibial tubercle. Rather, the TT-TG looks to be a multifactorial measure that is influenced by trochlear groove anatomy and tibial rotation [33, 34]. As a result, the notion of a pathologically lateral tibial tubercle is not as common as previously thought. If there is still concern for a lateralized tibial tubercle, some have argued that measurement of the tibial tubercle-posterior cruciate ligament distance (TT-PCL) offers a better measure of tubercle lateralization because both points are referenced from the tibia [35–37]. For this reason, TT-PCL distance is independent of tibiofemoral rotation as well as the position of the groove. It can be useful to measure both TT-TG and TT-PCL in order to assess whether TT-TG might be falsely elevated due to rotation or an abnormal groove. Computed Tomography (CT) CT scans are less commonly utilized in the evaluation of patellofemoral instability than radiographs and MRI. They are preferred by some for TT-TG measurements, and they are central to quantifying torsional deformities of the lower extremities. In this setting, the decision to obtain a CT scan is typically not routine but instead dictated by physical exam findings consistent with increased femoral anteversion or external tibial torsion (8). Further applications of CT scans include three-dimensional CT (3D-CT) scans which have been used to show realistic volumetric representations of the patella and trochlea. The complex geometry of the trochlea can be challenging to interpret on 2 dimensional images and the addition of 3D-CT can help provide a qualitative evaluation and may be useful for preoperative planning for some surgeons [38] (Fig. 10). 10 Ultrasound The advancement of high-definition ultrasound devices has allowed for an expansion of its clinical application including the evaluation of trochlear morphology [39]. Due the limitations of image acquisition with ultrasound as compared with MRI, most notably the inability to visualize the posterior condyles of the femur, most ultrasound evaluations have focused on measurements of trochlear depth and sulcus angle measurements. Despite these shortcomings, ultrasound has been used as a cost effective way to evaluate the prevalence of trochlear dysplasia in a general population of patients [40]. A particular advantage of ultrasound is that it can evaluate the trochlea along the curvature of the distal femur, while maintaining an orthogonal alignment to the trochlear groove. This is in contrast with MRI, where the angle of the image acquired must be set beforehand and maintained over the area of interest. The role for ultrasound may continue to evolve in the evaluation of patients with patellar instability but further
246 A A. E. Jimenez et al. B C E D F Fig. 10 (Reproduced with permission from SanchisAlfonso V., Montesinos-Berry E., Serrano A., MartínezSanjuan V. (2011) Evaluation of the Patient with Anterior Knee Pain and Patellar Instability. In: Sanchis-Alfonso V. (eds) Anterior Knee Pain and Patellar Instability. Springer, London) 3D-CT reconstruction of the patellofemoral joint. Axial plane showing degenerative changes of the articular cartilage of the medial patellar facet A, frontal plane B, and sagittal plane C. 3D-CT shows great fidelity of the surface anatomy D, E, but it is unable to show undersurface detail which is clearly shown by conventional CT scans F or MRI
Evaluation of the Patient with Patellar Instability … research is warranted to develop ultrasoundspecific criteria for trochlear dysplasia rather than using MRI obtained values. 11 Summary The evaluation and treatment of patients with patellofemoral instability requires an in-depth knowledge and consideration of all potential contributing pathologies through the history, physical examination, and imaging studies. Properly identifying patients with recurrent patellar instability using provocative clinical tests and appropriate imaging is critical in identifying patients who would benefit from surgical intervention. Advanced imaging modalities can identify patients with loose bodies, chondral fractures which will require concomitant treatment. The assimilation of all this information helps the treating surgeon counsel the patient on treatment options and select the ideal intervention to address their instability. 12 Take Home Messages • MRI is a key component of a diagnostic workup and should be obtained on every patient prior to surgical intervention and in all patients • Trochlear dysplasia is the most common anatomic risk factor associated with patellar instability, and it should be assessed for every patient 13 Key Message • A careful history, detailed physical examination, and focused imaging studies are the key components of establishing and accurate diagnosis and developing a properly indicated treatment plan. 247 References 1. Sanders TL, Pareek A, Hewett TE, Stuart MJ, Dahm DL, Krych AJ. Incidence of first-time lateral patellar dislocation: a 21-Year population-based study. Sports Health. 2018;10(2). 2. Jaquith BP, Parikh SN. Predictors of recurrent patellar instability in children and adolescents after first-time dislocation. J Pediatr Orthop. 2017;37(7). 3. Grimm NL, Levy BJ, Jimenez AE, Crepeau AE, Lee Pace J. Traumatic patellar dislocations in childhood and adolescents. Orthop Clin N Am. 2020;51(4). 4. Chotel F, Bérard J, Raux S. Patellar instability in children and adolescents. Orthop Traumatol Surg Res OTSR. 2014;100(1 Suppl). 5. Post WR, Fithian DC. Patellofemoral instability: a consensus statement from the AOSSM/PFF patellofemoral instability workshop. Orthop J Sport Med. 2018;6(1). 6. Fithian DC, Paxton EW, Stone ML, Silva P, Davis DK, Elias DA, et al. Epidemiology and natural history of acute patellar dislocation. Am J Sport Med. 2004;32(5). 7. Colatruglio M, Flanigan DC, Harangody S, Duerr RA, Kaeding CC, Magnussen RA. Identifying patients with patella alta and/or severe trochlear dysplasia through the presence of patellar apprehension in higher degrees of flexion. Orthop J Sport Med. 2020;8(6). 8. Kozic S, Gulan G, Matovinovic D, Nemec B, Sestan B, Ravlic-Gulan J. Femoral anteversion related to side differences in hip rotation. Passive rotation in 1,140 children aged 8–9 years. Acta orthopaedica Scandinavica. 1997;68(6). 9. Ahmad CS, McCarthy M, Gomez JA, Shubin Stein BE. The moving patellar apprehension test for lateral patellar instability. Am J Sport Med. 2009;37 (4). 10. Diduch DR, Kandil A, Burrus MT. Lateral patellar instability in the skeletally mature patient: evaluation and surgical management. J Am Acad Orthop Surg. 2018;26(12). 11. Hiemstra LA, Kerslake S, Kupfer N, Lafave MR. Generalized joint hypermobility does not influence clinical outcomes following isolated MPFL reconstruction for patellofemoral instability. Knee Surg Sports Traumatol Arthroscopy Offic J ESSKA. 2019;27(11). 12. Beighton P, Solomon L, Soskolne CL. Articular mobility in an african population. Ann Rheum Dis. 1973;32(5). 13. Sanchis-Alfonso V, Montesinos-Berry E, RamirezFuentes C, Leal-Blanquet J, Gelber PE, Monllau JC. Failed medial patellofemoral ligament reconstruction: causes and surgical strategies. World J Orthop. 2017a;8(2).
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Paiva M, Blønd L, Hölmich P, Barfod KW. Effect of medialization of the trochlear groove and lateralization of the tibial tubercle on TT-TG Distance: a cross-sectional study of dysplastic and nondysplastic knees. Am J Sport Med. 2021;49(4). Tensho K, Shimodaira H, Akaoka Y, Koyama S, Hatanaka D, Ikegami S, et al. Lateralization of the tibial tubercle in recurrent patellar dislocation: verification using multiple methods to evaluate the tibial tubercle. J Bone Jt Surg Am Vol. 2018;100(9). Seitlinger G, Scheurecker G, Högler R, Labey L, Innocenti B, Hofmann S. Tibial tubercle-posterior cruciate ligament distance: a new measurement to define the position of the tibial tubercle in patients with patellar dislocation. Am J Sport Med. 2012;40(5). Anley CM, Morris GV, Saithna A, James SL, Snow M. Defining the role of the tibial tubercle-trochlear groove and tibial tubercle-posterior cruciate ligament distances in the work-up of patients with patellofemoral disorders. Am J Sport Med. 2015;43(6). Dong C, Zhao C, Li M, Fan C, Feng X, Piao K, et al. Accuracy of tibial tuberosity-trochlear groove distance and tibial tuberosity-posterior cruciate ligament distance in terms of the severity of trochlear dysplasia. J Orthop Surg Res. 2021;16(1). Fuchs A, Feucht MJ, Dickschas J, Frings J, Siegel M, Yilmaz T, et al. Interobserver reliability is higher for assessments with 3D software-generated models than
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Evolving Management of Acute Dislocations of the Patella Vicente Sanchis-Alfonso, Erik Montesinos-Berry, and Marc Tompkins 1 Background The acute lateral dislocation of the patella or First-time lateral patellar dislocation (FTLPD) is a relatively frequent injury in the young physically active population. Its incidence in the general population is 42 cases (95% CI 37−47) per 100,000 person-years and it is 108 cases (95% CI 101−116) per 100,000 in female patients aged 10−17 [1]. Furthermore, the possibility of a recurrence of the dislocation is relatively high in the general population, 22.7% (95% CI 22.2−23.2) at a mean of 10 years. Young females, aged 10−17, show the greatest risk at 36.8% (95% CI 35.5−38.0) [1]. Therefore, this is a frequent knee pathology that causes chronic instability in an important number of patients. Perhaps even more important than the abovementioned facts, is that the dislocation of the patella is a significant risk factor for the development of patellofemoral osteoarthritis V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com E. Montesinos-Berry ArthroCentre–Agoriaz, Riaz & Clinique CIC Riviera, Montreux, Switzerland M. Tompkins University of Minnesota, TRIA Orthopedic Center, Minneapolis, MN, USA (PFOA) in the young adult and the physical limitations that accompany early PFOA [2]. Sanders and colleagues [2] have shown an accumulated incidence of PFOA of 1.2% at 5 years, 2.7% at 10 years, 8.1% at 15 years, 14.8% at 20 years, and 48.9% at 25 years. Moreover, it is thought that 71% of patients with an FTLPD will develop either a chondral injury or an osteochondral injury [3]. In 2017, Salonen and colleagues observed that 70% of patients with an FTLPD sustained cartilage injuries in the patellofemoral joint (PFJ) that were visible on MRI [4]. At a mean 8 years of follow-up, patellofemoral cartilage deterioration was visible in 100% of the patients with a single FTLPD with nonsurgical treatment [4]. Redislocation was not related to the severity of the cartilage damage [4]. It is interesting to highlight the fact that an osteochondral injury, recurrent patellar instability and trochlear dysplasia are associated with the development of PFOA [2]. FTLPD is thus a frequent pathology that is not self-limiting and furthers the development of early-onset PFOA which can result in anterior knee pain (AKP) and a decrease in the level of physical activity and quality of life. Since one of the factors that favors the appearance of PFOA at long-term, with no good solution in the young patient, is the recurrence of the dislocation, an effort must be made to implement therapeutic strategies to minimize the risk of recurrence and the consequent future complications. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_17 251
252 V. Sanchis-Alfonso et al. A B Fig. 1 Evident MPFL disruption. MPFL injury pattern assessment by MRI. A Coronal view. B Axial view. Laterally subluxated patella. The contralateral patella has a normal alignment. (Republished with permission of AME Publishing Company. From Sanchis-Alfonso V and Montesinos-Berry E. Acute dislocation of the patella: should these patients be operated on more often? Ann Joint, 3:20, 2018) Currently, there is a controversy regarding the best treatment for FTLPD despite the high incidence of this pathological condition. Classically, it was thought that these patients were candidates for non-surgical treatment in the majority of cases. The exceptions were when the dislocation was irreducible, in cases with an evident disruption of the medial patellar stabilizers (Fig. 1), in the presence of osteochondral fragments secondary to a dislocation that behave like intraarticular loose bodies (Fig. 2), or when there is a large and displaced bone avulsion facture off the medial aspect of the patella (Fig. 3). Interestingly, 84% of patellar avulsion fractures affect the inferomedial border of the patella, which is the zone where the medial patellotibial ligament and the medial patellomeniscal ligament are attached [5]. The avulsion site is very important because 20% of patients with inferomedial border fractures showed recurrence compared with 0% of superior patellar avulsion fracture patients after acute surgical repair [5]. Therefore, fixation of the avulsion fracture may not be sufficient in these cases, and some of these patients may require an MPFL reconstruction (MPFLr) [5]. A B Fig. 2 MRI signs of FTLPD: contusions of the anterior portion of the lateral femoral condyle and of the medial patellae, osteochondral defects (black thick arrow), intra- C articular bodies (white thick arrow), and joint effusions (asterisk). A & B Axial FSE PDW Fat Sat MR images. C Coronal FSE PDW Fat Sat MR image
Evolving Management of Acute Dislocations of the Patella 253 A B Fig. 3 A large, displaced bone avulsion fracture of the MPFL. A Surgical image. B CT-3D image. (Republished with permission of AME Publishing Company. From Classic dogma suggests that these patients “do well” with non-surgical treatment. However, current scientific evidence puts the classic standard of treatment in doubt and suggests that an FTLPD should be treated surgically more often than it is normally done [6]. The aim of this chapter is to describe the present-day indications clearly and concisely for the surgical or nonsurgical treatment after an FTLPD. The treatment of this injury should be personalized as we will see throughout this chapter. We consistently speak about non-surgical treatments instead of referring to them as conservative treatments, but it is important to note that any treatment of the PFJ, whether surgical or non-surgical, should be as conservative as possible. Treatment for the PFJ should include whatever is necessary for appropriate treatment, no more, no less. Sanchis-Alfonso V and Montesinos-Berry E. Acute dislocation of the patella: should these patients be operated on more often? Ann Joint, 3:20, 2018) 2 Who Needs Early Surgery?– Factors Affecting Decision-Making Medical providers for patients with patellofemoral pathology need to keep themselves up to date with the current literature on the particular patellofemoral pathology they are treating, including randomized clinical trials (RCTs) and systematic reviews with a meta-analysis. There are several studies that analyze surgical versus non-surgical treatment for FTLPD [7–17]. In some of them, the recurrence rates of patellar dislocation reported were lower in the surgical treatment group [7–11]. Nonetheless, other authors did not find differences in recurrence rates between surgical and non-surgical treatment [12–17].
254 The functional results were similar in both modalities of treatment in most of the studies, suggesting that surgical treatment does not improve the outcomes [8–17]. However, there are several key issues to acknowledge if we analyze the above papers in-depth. The first is that the follow-up times and ages are very heterogeneous, therefore, the recurrence rates as well as ages are not comparable in all the studies. The small number of patients in these papers is a limiting factor that could lead to non-detection of statistically significant differences between the groups. Finally, the conservative treatment protocol is not the same in all studies, and the types of surgical treatment are also different (realignment surgery, MPFL repair and MPFLr). Consequently, it is difficult to draw conclusions when doing systematic reviews with a meta-analysis using these studies. Pagliazzi and colleagues [18], in a metaanalysis of RCTs, showed a greater redislocation rate in non-surgical patients after an FTLPD. Better clinical outcomes were found with surgical treatment up to the 6-year follow-up, but the results were similar in both groups, surgical and non-surgical, at longer term follow-up. In 2020, Migliorini and colleagues [19] recommend up front surgical treatment after an FTLPD in a systematic review of randomized and nonrandomized clinical trials with meta-analysis. Better function is achieved with the therapeutic approach proposed by these authors, as demonstrated by higher values in the Kujala score as well as a significant reduction in redislocations and persistent feelings of instability in comparison with non-surgical treatment. In 2020, Fu and colleagues [20] conducted a systematic review with a meta-analysis of solely RCTs and concluded the same as Migliorini and colleagues [19], that surgical treatment is better than nonsurgical treatment in patients with an FTLPD. It is important to note that these systematic reviews include both MPFL repairs and MPFL reconstructions within the surgical treatment group and we must bear in mind that the results of a repair are not the same as those of a reconstruction. In 2018, Askenberger and colleagues [21] published their results of a randomized controlled V. Sanchis-Alfonso et al. trial in which they compare the non-surgical treatment of the FTLPD (knee brace for 4 weeks and physical therapy) with surgical treatment (arthroscopic-assisted repair of the MPFL with anchors followed by 4 weeks of immobilization and physical therapy). The authors conclude that the percentage of redislocations is significantly less in the surgical group than in the non-surgical group (22 vs. 43%), but the overall function was not different between groups and the majority of patients in both groups were satisfied with the function of the knee. Although there are no differences with regard to patient function, the fact that the number of dislocations is reduced with surgical treatment is clinically relevant because the recurrence of dislocation is a factor that favors PFOA, as we have already stated. The take-home message might be that surgical treatment has a lower recurrence rate and better shortterm clinical outcomes but a higher rate of complications and similar clinical outcomes in the long-term. We can conclude that the currently available evidence is not sufficiently conclusive to recommend one treatment over the other. That is, the results of these papers are not enough to answer the relevant question as to who needs early surgery. To answer this question for each individual patient, it is necessary to keep other issues in mind, ones that we will analyze next. 2.1 First-Time Patellar Dislocation with an Associated Loose Body Even though the current standard treatment for FTLPD is non-surgical, an operation would be considered to fix the osteochondral fragment if the patient presents with an osteochondral injury and an associated loose body. If it cannot be fixed, then generally the loose body is excised arthroscopically. According to Pedowitz and colleagues, if the treatment of an osteochondral injury is not pared with an MPFL repair or MPFLr, the percentage of recurrent instability is 61% [22]. If we compare the cases in which an MPFLr is performed to those cases in which the
Evolving Management of Acute Dislocations of the Patella MPFL is repaired or nothing at all is done, then we see that there is a lower rate of recurrent instability (10 vs 58.7%), a higher percentage of return to sports activity (66.7 vs 38.1%), and an even smaller risk of a second surgery (56.7 vs 47%) with MPFLr [23]. Given this body of literature, it would be reasonable to perform an MPFLr on all adolescents with an FTLPD with an associated loose body. 2.2 Pathoanatomy−Risk Factors for Recurrence After an FTLPD−Predictive Models Analysis The decision-making with regard to either surgical or non-surgical treatment can be based on the risk of recurrence after non-surgical treatment. The key question is whether recurrent patellar dislocation be predicted after an FTLPD. The idea is to identify those risk factors that can predict the failure of non-surgical treatment and to design predictive models of recurrent dislocation after an FTLPD treated non-surgically. Predictive models may assist in the decisionmaking process aimed at achieving better clinical outcomes as well as reducing costs [24]. The end point of using predictive models in the FTLPD population is to identify individuals at high risk for recurrent patellar instability that might benefit from early surgical treatment. Several scoring systems to assess the risk of recurrence after an FTLPD have been published. An analysis of this literature demonstrates that the redislocation risk can only be assessed using combined risk factors. In 2013, Lewallen and colleagues [25] analyzed the factors that predict a lateral patellar dislocation recurrence in pediatric patients and adolescents with a mean age of 15 years (ranging from 9 to 18 years). They discovered that successful conservative treatment after an FTLPD was 62% and that around half of the patients with recurrent lateral patellar dislocation need surgical treatment. The most important risk of dislocation recurrence appeared in skeletally immature patients with trochlear 255 dysplasia. The combination of both factors (trochlear dysplasia and skeletal immaturity) conferred a risk of 69% at 5 years. The results of this study are in accordance with those of Askenberger and colleagues [26] who recognized that trochlear dysplasia is the main anatomic patellar instability risk factor in skeletally immature children. Balcarek and colleagues [27] developed the Patellar instability severity score (PISS) which was the first multivariable scoring system. This score might allow us to differentiate between responders and non-responders to nonsurgical treatment after an FTLPD. PISS has six factors. They are age, the bilaterality of the instability, trochlear dysplasia severity, patella alta, tibial tuberosity-trochlear groove (TT-TG) distance, and patellar tilt. Jaquith and Parikh [28] also presented a predictive score to calculate the risk of recurrence. According to these authors, trochlear dysplasia, skeletal immaturity (age of 14 years or less), Caton-Deschamps index (CDI) > 1.45, and a history of contralateral patellar dislocation were all significant risk factors for recurrence after an FTLPD. The presence of all 4 risk factors had a predicted recurrence risk rate of 88%. The presence of any 3 risk factors had a predicted risk of about 75% and the presence of any 2 risk factors had a predicted risk of about 55%. Arendt and colleagues [29] evaluated sixty-one patients out of 145 with FTLPD that had had a recurrent dislocation within 2 years of follow-up. Stepwise logistic regression analysis demonstrated that skeletal immaturity, the sulcus angle and Insall-Salvati ratio were significant predictors of redislocation. The cut points were determined to be a sulcus angle 154° and Insall-Salvati ratio 1.3. The probability of redislocation was of 5.8% with no factors present and 22.7% with any 1 factor present, increasing to 78.5% if all 3 factors were present. Natural history studies of recurrent lateral instability show that the mean time to recurrence is 3.7 years [29]. For this reason, Hevesi and colleagues [30] chose a minimum follow-up time of 4 years in their study, in contrast to previous studies [25–27]. They developed a model to predict the risk of recurrence after an
256 FTLPD that is entitled “Recurrent Instability of the Patella Score” (RIP Score). This score is based on age (<25 years old), skeletal immaturity, trochlear dysplasia (A-D according to the Dejour classification) and TT-TG/PL ratio 0.5 (TT-TG, tibial tubercle to trochlear groove distance; PL patellar length). This score gives a maximum of 5 points and a minimum of zero; if the patient is under 25 years of age, the score will be 2; the remaining items score 1. According to the score obtained, the risk of recurrent instability is low (0−1 points), intermediate (2−3) or high (4−5). In low-risk patients, there were no further dislocation episodes at 1, 2, 5, and 10 years. In intermediate-risk patients the percentages of recurrent instability-free patients were 83, 72, 69 and 69% respectively. These figures are 84, 62, 34 and 21% in the same time periods in the high-risk group. In 2020, Huntington and colleagues demonstrated in a systematic review with meta-analysis that the key risk factors for recurrence were younger age, open physes, trochlear dysplasia, radiographic patella alta, and an elevated TT-TG distance, while sex and MPFL injury pattern were not predictive. The presence of 3 factors increased the recurrence risk to over 70% [31]. In 2022, Wierer and colleagues [32] proposed the “The Patellar Instability Probability Calculator” to estimate the individual risk of early recurrence after FTLPD. They have shown that at 16 years of age with a FTLPD, trochlear dysplasia (Dejour type B-D; lateral trochlear inclination 12°) and history of contralateral instability are significant risk factors for recurrent lateral patellar dislocation within 2 years after FTLPD. The prediction accuracy including these 3 risk factors was 79%. However, patella alta, an increased TT-TG distance, and patellar tilt did not have an association with increased recurrence rates or an influence on prediction accuracy of recurrent lateral patellar dislocation either. In summary, predictive models can help us to predict which patients are most likely to redislocate after FTLPD treated conservatively. This approach helps us with our decision-making for V. Sanchis-Alfonso et al. the optimum treatment of a patient with an FTLPD. It can also be useful when we want to inform patients and their families about the prognosis after an FTLPD. 2.3 Patient’s Goals–Return to Sports at a Pre-Injury Level When we consider a therapeutic indication, be it surgical or non-surgical, it must not only be based on the best available scientific evidence, pathophysiological arguments and predictive models, but also on the patient´s expectations and wishes. These three elements constitute the three cornerstones of evidence-based medicine. There are patients for whom sports is important for leisure or professional reasons. We have to offer the treatment with the greatest guarantees of making it possible for them to return to their sports activity of choice. In 2017 Magnussen and colleagues [6] showed that those patients in whom there is no recurrence of the dislocation after non-surgical treatment of an acute dislocation are quite limited by this injury up to three years after the FTLPD. Interestingly, patient-reported outcomes of non-surgical treatment without recurrence are not different from those non-operated with dislocation recurrence [6]. It is important to note that only 26.4% of patients without further dislocations were able to practice their sport again with no limitations at a pre-injury level [6]. These studies demonstrate that the absence of recurrent dislocation as an isolated finding may not be sufficient to evaluate the outcomes of a patient after an FTLPD. In contrast, Regalado and colleagues [11] showed, in 2014, that 80% of adolescent patients who were treated surgically after an FTLPD attain an excellent result with regard to the return to sports at a pre-injury level. This percentage was only 47% for patients who were treated conservatively. These studies suggest that surgery increases the likelihood of returning to sports at a pre-injury level compared with a non-surgical treatment for athletic adolescents.
Evolving Management of Acute Dislocations of the Patella 2.4 Economic Decision Model Nwachukwu and colleagues [33] used a costeffectiveness model to compare non-surgical treatment to surgical treatment of recurrent dislocations and surgical treatment done immediately after an FTLPD. In their analysis, the authors describe both the direct and the indirect costs of each therapeutic strategy. Direct costs include direct medical costs, cost of surgery, and physical therapy. Indirect costs were calculated based on the lost productivity associated with caregiver (parental) work absenteeism. Effectiveness was expressed in quality-adjusted life years (QUALYs). The authors found that both immediate surgical treatment as well as delayed surgery are cost-effective treatment options. However, with a perspective of 10 years, immediate surgery offers the most QUALY gains. As a result, the conclusion was that early operative intervention was the most cost-effective treatment. These findings are important considerations for therapeutic decision-making when we see a patient with an FTLPD. 3 Take Home Messages – The FTLPD patient may benefit from operative intervention more often than has generally been indicated previously. – Non-operative management is recommended in patients with an FTLPD with no significant risk factors for recurrence and no osteochondral fracture. – The isolated MPFL repair may not be adequate for stabilizing the patella. – The risk of recurrent dislocation after an FTLPD is increased by a number of factors and to a greater extent, when multiple risk factors are present. Published stratification models allow for an evaluation of the individual risk profile. Low-risk patients may be treated non-surgically while surgery should be considered for high-risk patients. Moreover, we should include individual preferences (patient´s goals such as sports) in the decision protocols. 257 – The optimization of the treatment of the FTLPD will improve short-term disability from the dislocation and will reduce the longterm risk of PFOA from repeated chondral injuries. – High quality clinical trials are obviously needed to further refine what FTLPD patients would benefit from surgical intervention and which patients can be managed nonoperatively. References 1. Gravesen KS, Kallemose T, Blønd L, et al. High incidence of acute and recurrent patellar dislocations: a retrospective nationwide epidemiological study involving 24.154 primary dislocations. Knee Surg Sports Traumatol Arthrosc. 2018;26(4):1204−9. 2. Sanders TL, Pareek A, Johnson NR, et al. Patellofemoral arthritis after lateral patellar dislocation: a matched population-based analysis. Am J Sports Med. 2017;45(5):1012–7. 3. Stanitski CL, Paletta GA Jr. Articular cartilage injury with acute patellar dislocation in adolescents. Arthroscopic and radiographic correlation. Am J Sports Med. 1998;26(1):52–5. 4. Salonen EE, Magga T, Sillanpaa PJ, et al. Traumatic patellar dislocation and cartilage injury: a follow-up study of long-term cartilage deterioration. Am J Sports Med. 2017;45:1376–82. 5. Mochizuki T, Tanifuji O, Watanabe S, et al. The majority of patellar avulsion fractures in first-time acute patellar dislocations included the inferomedial patellar border that was different from the medial patellofemoral ligament attachment. Knee Surg Sports Traumatol Arthrosc. 2020;28(12):3942–8. 6. Maggnussen RA, Verlage M, Stock E, et al. Primary patellar dislocations without surgical stabilization or recurrence: how well are these patients really doing? Knee Surg Sports Traumatol Arthrosc. 2017;25 (8):2352–6. 7. Camanho GL, Viegas Ade C, Bitar AC, et al. Conservative versus surgical treatment for repair of the medial patellofemoral ligament in acute dislocations of the patella. Arthroscopy. 2009;25(6):620–5. 8. Sillanpää PJ, Mattila VM, Mäenpää H, et al. Treatment with and without initial stabilizing surgery for primary traumatic patellar dislocation. A prospective randomized study. J Bone Joint Surg Am. 2009;91 (2):263–73. 9. Bitar AC, Demange MK, D’Elia CO, et al. Traumatic patellar dislocation: nonoperative treatment compared with MPFL reconstruction using patellar tendon. Am J Sports Med. 2012;40(1):114–22.
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How to Deal with Chronic Patellar Instability Vicente Sanchis-Alfonso and Erik Montesinos-Berry 1 Introduction Patellar displacement is limited by passive retinacular tethers and the chondral/bony geometry of the trochlea and patella. Together, they guide the patella into the trochlear groove and keep it engaged in the groove throughout knee range-ofmotion [1]. Patellar instability is defined as a symptomatic deficiency of the abovementioned constraints, either alone or in combination. Thereby, the patella can escape partially or completely from its normal position with respect to the femoral trochlea under the influence of a displacing force [1]. Out of all the anatomic factors that play a role in the pathogenesis of patellar instability, the most important are the medial patellofemoral ligament (MPFL) and the trochlea. Currently, no one doubts that the major soft-tissue stabilizer of the patella is the MPFL. Moreover, trochlear dysplasia is the main risk anatomic factor for lateral patellar instability [2– 5]. However, Diederichs and colleagues [6] have recently analyzed rotational limb alignment in patients with non-traumatic patellar instability V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com E. Montesinos-Berry ArthroCentre–Agoriaz, Riaz and Clinique CIC Riviera, Montreux, Switzerland and in controls using Magnetic resonance imaging (MRI). They have found that patellar instability patients have greater internal femoral rotation, greater knee rotation, and a tendency to genu valgum in comparison to healthy controls. They conclude that rotational malalignment may be a primary risk factor in patellar instability that has so far been underestimated. As there are many types of patellar instability, it is necessary to be familiar with all of them to provide the right treatment. To classify the patellar instability, several factors must be considered. The factors are the direction of the instability and degree of knee flexion at which there is instability. In terms of the direction of the instability, it could be lateral, medial (usually iatrogenic) or multidirectional (lateral and medial). Based on the degree of flexion, it could be lateral instability in the first 30° (the most common type of patellar instability), lateral instability in the first 30° and beyond 30° and lateral instability in flexion. Then, we must consider the pathoanatomic variables that favor instability. Here, one sees that there are many varieties of instability and, therefore, several subpopulations of patients with chronic patellar instability. Lateral instability is found with or without the concomitant risk factors for instability like trochlear dysplasia, patella alta, and rotational malalignments such as medial femoral torsion or external tibial torsion. Therefore, not all patellar instabilities are equal. The etiology of the disorder is © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_18 259
260 V. Sanchis-Alfonso and E. Montesinos-Berry multifactorial. Knowing this, a clear understanding of the cause of instability is crucial for appropriate surgical treatment. The goal of this chapter is to identify how to best treat patellar instability to achieve good outcomes and prevent future patellofemoral osteoarthritis (PFOA). 2 Lateral Patellar Instability During the Early Arc of Knee Flexion It is during the early arc (0°–30°) knee flexion when most cases of lateral patellar instability typically occur. It accounts for 70% of the cases of lateral instability in our series. Moreover, the vast majority of patients who have chronic lateral patellar instability also have cartilage damage in their patellofemoral joint (PFJ). A Fig. 1 A Medial knee anatomy. Adductor tubercle (AT), medial patellofemoral ligament (MPFL), medial quadriceps tendon femoral ligament (MQTFL), superficial medial collateral ligament (sMCL) and vastus medialis obliquus (VMO). B Articular-sided view of proximal medial patellar restraints. Attachments of the MPFL on 2.1 What to Do–Rationale Various anatomic and biomechanical studies have shown that the MPFL (Fig. 1) is the most important limitation to lateral patellar displacement between 0° and 30° of knee flexion [7–9]. In this subset of patients with lateral patellar instability, the MPFL deficiency is thought to be the all-important lesion [10]. The present surgical approach, in this subgroup of patients who have had a minimum of two documented patellar dislocations, is to stabilize the patella by means of an anatomic MPFL reconstruction (MPFLr). In that reconstruction, a mini-open technique and a graft that is stronger that the native MPFL are employed [11]. This approach is used to compensate for the underlying predisposing factors to patellar instability [11]. B the patella, and the MQTFL on the quadriceps tendon. (“Republished with permission of Springer Nature BV, from Recognition of evolving medial patellofemoral anatomy provides insight for recognition, Tanaka MJ, et al., 27, 2537–2550, 2019; permission conveyed through Copyright Clearance Center, Inc.”)
How to Deal with Chronic Patellar Instability The decisive steps to guarantee a successful outcome after MPFLr are the suitable graft positioning on the femur and the right tension on the graft [11]. A lot less attention has been given to the patellar attachment of the MPFL than to the femoral attachment [11]. According to Mochizuki and colleagues [12] the MPFL mainly attaches to the vastus intermedius tendon (Fig. 1). Therefore, some surgeons propose a medial quadriceps tendon femoral ligament (MQTFL) reconstruction (Fig. 1) [13]. 261 Not only does the MPFLr prevent further patellar dislocation but it might also detain the progression of knee osteoarthritis [15]. With second-look arthroscopy, the effect of MPFLr on articular cartilage in the PFJ showed that the status of the patellofemoral chondral was only modified at the central ridge of the patella [16]. Consequently, it is not necessary to treat chondral lesions in most cases even though it is a good idea to remove loose bodies in some (Figs. 3 and 4). 3 2.2 The Treatment of Associated Chondral Lesions If the patellar instability has gone on for a long time, the probability and the extent of patellofemoral chondral injuries will be greater [14]. Of patients with recurrent lateral patellar instability, 58% have patellar lesions and trochlear lesions have been observed in 13% (Fig. 2) [14]. Fig. 2 The severity of chondral injury in patients with lateral patella instability is highly variable. Even in the most severe cases the isolated MPFLr is sufficient to eliminate the pain Lateral Patellar Instability Persisting Beyond 30° of Knee Flexion This condition accounts for 25% of the cases of lateral instability in our series. Lateral patellar instability beyond 30° of knee flexion suggests severe trochlear dysplasia (grade C or D) or a pathological femoral anteversion associated with a deficient MPFL (Fig. 5). It is not enough to
262 V. Sanchis-Alfonso and E. Montesinos-Berry Fig. 3 Loose body in a patient with lateral patellar instability Fig. 4 Loose bodies and severe patellar chondropathy in a patient with chronic lateral patellar instability. The isolated MPFLr was sufficient to eliminate the pain have an isolated MPFL or a MQTFL reconstruction to achieve good clinical results when treating this type of instability. The predisposing anatomic factors for instability should be corrected along with the MPFLr. Step one is to correct the patellofemoral maltracking (J-sign) to neutralize the lateral displacing forces. In step two, only when the patellofemoral joint is realigned, do we stabilize the joint. That means to restore the passive restraining elements to get good patellofemoral balance. This restoration is achievable by doing an MPFL or an MQTFL reconstruction. One should never use the MPFL/MQTFL reconstruction to pull the patella medially because it will give rise to an overload on the PFJ and cause future PFOA. 3.1 The Medial and Anteromedial Tibial Tuberosity Transfer According to several authors, a medialization of the tibial tuberosity (TT) must be done when the TT-TG distance is more than 20 mm [17]. However, there is not any strong evidence in the medical literature to support this recommendation. The TT-TG distance depends on weight-bearing and joint size [18–20]. Moreover, the intra and interobserver reliability for TT-TG distance measurements is seen less in patients with severe trochlear dysplasia when compared to those with a lowgrade trochlear dysplasia [20]. Some authors have also demonstrated that there are no differences in TT-TG distance between the stable and the
How to Deal with Chronic Patellar Instability 263 Fig. 5 Lateral patellar instability persisting beyond 30° of knee flexion in a patient with pathological femoral anteversion unstable knee in patients with unilateral patellar instability [21]. Other authors have not found any differences in the outcomes of isolated MPFL reconstructions in the setting of a TT-TG index >20 mm when compared to those with a TT-TG distance <20 mm [22]. As a result of what was previously described, prudence should be exercised when interpreting the TT-TG distance. In other words, the TT-TG distance alone is not a good enough indicator for a TT osteotomy. Other factors ought to be considered. Examples include a prominent J-sign, the circumstances around the initial and posterior dislocation episodes (traumatic vs atraumatic), bilaterality, level of activity as well as patient expectations. An anteromedialization of the TT (Fulkerson osteotomy) for patients with distal patellar articular damage could be indicated. This will not only correct the maltracking, but it will also unload the distal pole of the patella and consequently reduce or eliminate the anterior knee pain. 3.2 Patellar Distalization by Osteotomy or Patellar Tendon Imbrication According to several authors, we must perform a distalization of the TT (Fig. 6) when the CatonDeschamps index is more than 1.2 [17]. However, there is no strong evidence to support this recommendation in the medical literature. Controversy exists as to how to measure patellar height [23]. Moreover, TT distalization is not a panacea. TT distalization always implies some degree of medialization [24]. Additionally, distalization is risky in patients with chondral lesions of the distal pole of the patella because it provokes an overload of this area in initial flexion. Yang and colleagues [25] have demonstrated that excessive patellar distalization can cause increased patellofemoral contact pressures during early flexion at 0° and 10°. Finally, we must take into consideration that MPFLr brings about a descent of the patella [26, 27].
264 V. Sanchis-Alfonso and E. Montesinos-Berry Fig. 6 Patella alta in a patient with lateral patellar instability. A distalization osteotomy of the anterior tibial tubercle followed by a double bundle MPFLr, using an anatomic femoral tunnel. 5 years after his surgery he is still a professional dancer. The result of his surgery is excellent despite a patellar tilt of 29°, a severe trochlear dysplasia and a TT-TG distance of 33 mm A pathological ratio or index is not enough to indicate a tibial tubercle distalization. A prominent J-sign, the circumstances relative to the initial and posterior dislocation episodes (traumatic vs atraumatic), bilaterality, the level of activity, and patient expectations are other factors that should be taken into consideration. Patellar tendon imbrication is a useful alternative to osteotomy in the skeletally immature patient. D) was considerably more frequent in the surgical failure group (89%) than in the control group (21%) [2]. Even so, no statistical differences in the patellar height ratio (Insall-Salvati index) or the TT-TG distance were observed between the two groups [2]. Trochlear dysplasia seems to be an important risk factor for the failure of operative stabilization of the recurrent patellar dislocation [2]. There is a correlation between high degrees of trochlear dysplasia and a poor clinical outcome. This is because the MPFL graft may be overloaded because of the increased instability present in dysplastic situations [3]. A more tailored operative procedure along with the MPFLr and a trochleoplasty would be advisable. When there are cases with high degrees of trochlear dysplasia, a trochleoplasty should be considered. An acceptable revision option for the surgical treatment of patients with persistent 3.3 Trochleoplasty Trochlear dysplasia seems to be the most important of all the main risk factors for the development of chronic lateral patellar instability [2–5]. Incidentally, in an analysis of failed surgery for patellar instability, it has been shown that a severe trochlear dysplasia (Dejour type B-
How to Deal with Chronic Patellar Instability patellar dislocation and high-grade trochlear dysplasia is the sulcus-deepening trochleoplasty [5]. Trochleoplasty is a widely used and reliable surgical technique to treat patellofemoral instability in patients who have a dysplastic trochlea. Nonetheless, while improved stability can be predicted, pain is less predictable and could even increase after surgery. The overall results depend on the type of dysplasia, types B and D having a significantly better clinical outcome [28]. With reference to trochleoplasty, there is concern about the long-term consequences to healthy cartilage. Even so, the vast majority of patients, candidates for trochleoplasty, present severe chondropathy. However, many patients with trochlear dysplasia will go on to develop PFOA at some point in the future [17]. When assessing the indications for trochleoplasty, caution is called for. In our clinical experience, it is a valuable tool only in a small subset of patients with lateral patellar instability. This is the case when there is a severe trochlear dysplasia, when the patella dislocates not only during the first 30° of knee flexion but also at higher degrees of knee flexion, and when there is a positive J-sign. In a consensus statement from the AOSSM/PFF about patellar instability, the Deepening trochleoplasty is considered when all the following are present: a positive J-sign, a boss or 5 mm supratrochlear spur, and a convex proximal trochlea [1]. In a systematic review with a meta-analysis published in 2021, Leclerc and colleagues [29] determined that trochleoplasty is an effective surgical procedure to stabilize the patella. The deepening trochleoplasty, described by Dejour, was the most effective among all the trochleoplasty techniques with only 1 recurrence out of 349 knees (0.28%). Nevertheless, we should point out that the trochleoplasty in general is not a problem-free technique. Leclerc and colleagues [29] have shown that patellar instability without dislocation occurred in 82 out of 754 knees (8% [95% CI: 3–14%]), PFOA in 117 out of 431 knees (27%), knee stiffness in 59 out of 642 knees (7% [95% CI: 3–12%]) and the need for subsequent surgery in 151 out of 904 knees 265 (17%). Therefore, we must be cautious when we decide to perform a trochleoplasty as the surgical procedure. 3.4 The Rotational Femoral Osteotomy And The Femoral Varization Osteotomy Versus Growth Modulation Lateral patellar instability originates from a deficient MPFL that may have become incompetent due to trochlear dysplasia, patella alta, genu valgum, abnormal limb torsion or a combination of these factors [30]. The MPFL might not be strong enough to withstand the normal lateral pull of the quadriceps when the trochlea is dysplastic. In the same way, when abnormal limb torsion is present, the lateral displacement force acting upon the patella will be increased, and the ligament will most likely fail. This leads to lateral patellar instability (Fig. 7) [30]. Kaiser and colleagues [31] highlight the importance of internal femoral torsion in the etiopathogenesis of lateral patellar instability. They have shown that 20° of increased internal femoral torsion is a significant risk factor for patellar instability in a knee with an intact MPFL. However, with an insufficient MPFL, 10° of increased internal femoral torsion is a significant risk factor for patellar instability. When the limb is realigned, the lateral displacement force acting upon the patella will be decreased, which eliminates lateral patellar instability [30]. Excessive external tibial torsion as well as a pathological femoral anteversion have been correlated with chronic patellofemoral instability. We consider rotational osteotomies along with an MPFLr in those cases with severe rotational deformity (femoral anteversion >40°, external tibial torsion > 40°) and a positive Jsign. Milinkovic and colleagues [32] have shown that a high-grade J-sign and an increased body mass index (BMI) are the most relevant parameters influencing the quality of life in patients with lateral patellar instability measured using the Banff Patella Instability Instrument (BPII 2.0
266 V. Sanchis-Alfonso and E. Montesinos-Berry Fig. 7 Lateral patellar instability persisting beyond 30° of knee flexion. Haglund excavation on the patella with sclerotic edges in a patient with valgus and left femoral anteversion. According to Robert A. Teitge, MD abnormal sclerotic joint surfaces suggests abnormal loading. A rotational supracondylar femoral osteotomy was performed. After osteotomy, coronal plane alignment was evaluated. A normal mechanical axis is near the medial tibial spine, not in the middle of the knee joint score). Nelitz and colleagues [33] as well as Lee and colleagues [34] have shown that femoral rotational osteotomies may result in an increment of knee valgus. Therefore, the assessment of coronal plane alignment is crucial after a femoral rotational osteotomy performed for treating patellar instability. In the author´s clinical practice, knee valgus is often associated with femoral torsional abnormalities in cases of chronic lateral patellar instability. If there is genu valgum, the treatment will depend upon the stage of maturation of the patient. In patients with an open physis, a therapeutic option is growth modulation (hemiepiphysiodesis). In skeletally mature patients, a therapeutic option to correct the valgus is the open or closed osteotomy of the distal femur. In skeletally mature patients with genu valgum ( zone II or a mechanical lateral distal femoral angle (mLDFA) <83º) and patellar instability (Fig. 8), Palmer and colleagues [35] recommend performing a distal femoral osteotomy. In both cases, that is to say, in skeletally immature and mature patients these authors proposed the MPFL reconstruction as a second surgery, since in 80% of the cases with the genu valgum correction it is sufficient to resolve the patellar instability. The first study in which the use of the femoral varus osteotomy is described in patients with lateral patellar instability and genu valgum dates back to 2009 [36]. The objective of the varus osteotomy is to reduce the lateral vector applied to the patella. In a systematic review with a meta-analysis published in 2019 assessing the outcomes of a distal femoral varus osteotomy performed to treat patellar instability in patients with genu valgum, Tan and colleagues [37] concluded that this type of osteotomy was useful in the management of this subset of patellar instability patients. The problem is that out of the 5 studies analyzed in this systematic review, in 4 of them the varus osteotomies are performed along with other associated procedures. For this reason, we cannot know for sure if the good clinical result achieved with this particular procedure is due to the varus osteotomy or to any of the other associated surgeries, or even to all the surgical procedures as a whole. The only study of the 5 included in this systematic review in which the osteotomy is analyzed as an isolated
How to Deal with Chronic Patellar Instability 267 Fig. 8 Evaluation of the magnitude of the genu valgum with the quadrant method procedure was published by Wilson and colleagues in 2018 [38]. These authors [38] observed a disappearance of lateral patellar instability in most of the cases after an isolated osteotomy of the distal femur without any other associated surgical procedures. They analyzed 10 patients, out of which 2 (20%) presented new episodes of instability. This shows how important genu valgum is in the etiopathogenesis of lateral patellar instability. Therefore, a logical approach would be to treat genu valgum and in a second procedure, if necessary, do an MPFLr. On the contrary, in the other 4 studies no recurrences of instability are reported. This systematic review also evaluates the performance of a closing wedge osteotomy or an opening wedge osteotomy. The results obtained with both types of osteotomies are similar. Nevertheless, the authors draw attention to the fact that the opening wedge osteotomy lowers the Caton-Deschamps index, something that did not occur with the closing wedge osteotomy. The clinical relevance of this finding is that patients with a normal height patella or with a low-riding patella may profit from a closing wedge osteotomy in order to prevent patella infera. On the other hand, patients with a high-riding patella, which is a well-known risk factor for the appearance of lateral patellar instability, may profit from an opening wedge osteotomy because it will distalize the patella. Therefore, it is essential to evaluate preoperatively the height of the patella before deciding between a closing or opening wedge osteotomy. 3.5 Additional Surgery on the Lateral Retinaculum Isolated lateral retinacular release (LRR) is not recommended to treat patellar instability [1]. Isolated Lateral release or lengthening is only necessary in rare cases. Biomechanical studies by Amis and Merican [39] have shown that the lateral retinaculum (LR) actually contributes to
268 resisting lateral patellar displacement. It is a restraint on lateral patellar displacement. Therefore, lateral patellar instability increases after LRR. Moreover, to guide the patella towards the trochlear sulcus during the first degrees of knee flexion, both the MPFL and the LR must interplay in a harmonious way. Both ligaments behave similarly to the reins of a horse. Both reins must have some degree of tension. They are not very tense but they are not loose either. If one of the reins is completely loose the horse is inclined towards the opposite direction, as occurs in the patella. This will provoke a patellofemoral imbalance that could be responsible for iatrogenic anterior knee pain. In cases with severe patellar tilt where, in theory, we could consider LRR or lengthening, we always find severe trochlear dysplasia. In these cases, trochleoplasty automatically relaxes the deep layer of the LR and therefore LRR or lengthening can be avoided. Likewise, we must avoid LRR in trochlear dysplasia. An LRR in a patient with trochlear dysplasia will provoke medial patellar instability (MPI) [40]. Our advice is not to perform an LRR but a lengthening. It has the same effect as the LRR relative to the elimination of hypercompression on the lateral side. Moreover, LR lengthening is an individually adapted technique. Finally, it prevents the secondary complications of LRR such as MPI. A surgical procedure on the LR is an intraoperative decision [41]. To decide, it is helpful to perform the intraoperative patella tilt test [41]. V. Sanchis-Alfonso and E. Montesinos-Berry This is done by putting a transverse K wire through the proximal patella, from medial to lateral. The K wire must be parallel to the operating table with the knee in full extension and at 20° of flexion [41]. If the K wire is tilted (positive test), one should consider doing a lateral patellar retinaculum lengthening or think about an LRR. 4 Fixed Lateral Patellar Instability in Knee Flexion This type of lateral patellar instability is the least frequent. It accounts for 5% of the cases of lateral instability in our series. It may be congenital or acquired. In this type of instability, the patella is centered or almost centered on the femoral trochlea when the knee is in extension or almost in extension (Figs. 9, 10 and 11). But in flexion, the patella is always dislocated and making contact with the lateral surface of the external femoral condyle (Figs. 9, 10 and 11). The natural history of this type of instability consists in the development of severe trochlear dysplasia and finally PFOA (Figs. 12 and 13). Therefore, an early diagnosis is important as is early surgical correction so that the trochlea can develop correctly. In this way, late-onset sequelae, including osteoarthritis can be held back. The pathophysiology of this type of lateral instability is diametrically opposed to the two types analyzed previously. The quadriceps is Fig. 9 Fixed lateral patellar instability in knee flexion. The patella is well-centered in extension, but in flexion is dislocated and cannot be reduced to the midline due to severe quadriceps retraction
How to Deal with Chronic Patellar Instability A 269 C B Fig. 10 Fixed lateral patellar instability in knee flexion. The patella is well-centered A on the femoral trochlea when the knee is in extension. In flexion, the patella is dislocated and contacting B, C the lateral surface of the external femoral condyle. (A, B. Reused with permission Fig. 11 Fixed lateral patellar instability in knee flexion. (C, D, E. Reused with permission from Baishideng Publishing Group Inc. From SanchisAlfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8(2): 115–129) from Baishideng Publishing Group Inc. From SanchisAlfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8(2): 115–129) A C short and is displaced laterally (Fig. 14) [42]. Therefore, the extensor mechanism becomes a flexor and external rotator of the knee. Moreover, a flat lateral condyle is seen around the sulcus B D E terminals [43]. These factors collectively lead to an MPFL insufficiency. The patella is permanently dislocated in flexion and cannot be reduced manually.
270 V. Sanchis-Alfonso and E. Montesinos-Berry Fig. 12 Fixed lateral patellar instability in knee flexion. Severe trochlear dysplasia and severe PFOA Fig. 13 Fixed lateral patellar instability in knee flexion. Severe PFOA. (Republished with permission of AME Publishing Company. From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018) Currently, the standard surgical approach in patients with fixed lateral patellar instability in knee flexion involves Lateral retinaculum lengthening, the release of the vastus lateralis from the superolateral border of the patella, and Quadriceps tendon lengthening on the coronal plane after isolating the central tendon of the quadriceps from the vastus medialis and lateralis (Fig. 15). Afterwards, a side-to side repair of the quadriceps tendon is performed (Figs. 15). Then, a side-to side repair of the vastus lateralis and vastus medialis is carried out. If needed, the lateral condyle may be raised. The final step is an MPFLr. In order to calculate the length necessary for quadriceps tendon lengthening it is essential to achieve 90º of flexion or more by maintaining the patella reduced. Once this objective has been achieved, end-to-end suture of the quadriceps tendon is performed. We use a brace postoperatively for 6 weeks with weight bearing
How to Deal with Chronic Patellar Instability 271 Fig. 14 Fixed lateral patellar instability in knee flexion. The quadriceps is short and displaced laterally with knee flexion immediately after surgery depending on the tolerance. The brace is locked in 0º of knee extension for ambulation. At the third week, the brace is unlocked allowing flexion increments from 10 to 20º per week. The return to full activity varies from 6 to 12 months. In 2019 Song and colleagues [44] presented a novel surgical technique to lengthen the extensor mechanism of the knee in skeletally mature patients with fixed lateral patellar instability in knee flexion. The authors perform a tibial tubercle proximalization (“bony release”) associated with a lateral retinaculum release, tibial tubercle medialization and a MPFL reconstruction. The objective is to avoid the possibility of extensor lag during the postoperative rehabilitation after quadriceps lengthening. This technique allows early postoperative rehabilitation. However, a possible problem with this surgical technique is the patella alta, which is a well-known risk factor for patellar instability. Nevertheless, we must note that this surgical technique is always associated with a MPFL reconstruction that provokes a descent of the patella. Moreover, the patellar height is evaluated before definitive fixation. 5 Medial Patellar Instability and Multidirectional Patellar Instability Medial patellar instability (MPI) is an objective condition with its own characteristics that frequently brings on disabling anterior knee pain, significant disability as well as important psychological problems [40]. In most cases, it is secondary to an “extensive” LRR [40, 45]. In other cases, it is due to the release of the LR in patients with trochlear dysplasia or hyperelasticity [40]. It can also be attributable to the release of a previously lax LR, which shows poor patient selection [39]. Typically, the patient feels new pain and new instability that are different and much worse than that prior to surgery. The first step in diagnosing a pathological condition is to know that it exists. This was clearly reflected by Jack Hughston in his well-
272 V. Sanchis-Alfonso and E. Montesinos-Berry Fig. 15 Lengthening of the quadriceps tendon on the coronal plane. Side-to side repair of the quadriceps tendon known sentence: ``You may not have seen it, but maybe it has seen you''. Normally, MPI appears in the first 30º of knee flexion. It is frequently missed because patients complain of the patella moving laterally with early knee flexion. In our series, many patients have had to visit more than three doctors before obtaining a diagnosis and an appropriate treatment. This demonstrates that it is a clinical condition that most orthopedic surgeons do not know about. Therefore, we believe that there is a need to spread the word about the diagnostic procedures for recognizing this clinical condition. The physical findings are crucial to the diagnosis. The most important are pain and tenderness at the site of the LR defect, an increment in passive medial patellar mobility, especially when compared with the opposite normal knee. There are also the issues of pain and apprehension when we apply medial stress to the patella and a positive “Fulkerson relocation test” (Fig. 16) [46]. Moreover, all our patients experienced significant relief from their pain with a “reverse” McConnell taping [40]. We believe that it is a good and useful diagnostic approach to take. When the standard radiological studies are normal, it puts the orthopedic surgeon on the defensive when seeing this kind of patient. Stress axial radiography [47] or stress axial CT scans [48] allow for the objective documentation and quantification of MPI. At the present time, our preference for reconstructing the lateral retinaculum is the technique described by Jack Andrish because it is very anatomic and allows us to fine tune the graft-tension by adding sutures to further tighten the graft [49]. He uses a central strip or an
How to Deal with Chronic Patellar Instability 273 A B C D Fig. 16 Fulkerson relocation test A, B. A The patella is held medially in extension (arrow) and B then released on abrupt knee flexion. It is a provocative test, and therefore reproduction of symptomatology with this maneuver strongly suggests medial patellar instability. Sulcus sign C. Excessive medial displacement of the patella D anterior strip of the iliotibial band, leaving it attached proximally and attaching it to the midpoint of the patella. The objective of this technique is to reconstruct the deep transverse layer of the LR. The lateral reconstruction must be tensioned with the patella engaged within the trochlea with the knee at 30º of knee flexion. Take note that it is a “salvage” procedure. It does not address the original source of pain. Moreover, it cannot improve symptoms from osteoarthritis, malalignment, or lateral instability due to a deficient MPFL. This may explain the satisfactory results of only 65% in isolated reconstructions [45]. The LR is a restraint on medial patellar displacement. Another restraint on medial patellar displacement is the MPFL. The MPFL tightens with medial displacement of the patella. Therefore, we must reconsider medial instability after the MPFLr in cases of multidirectional instability. If the MPI is corrected after the MPFLr, it is not necessary to reconstruct the LR. 6 Take Home Messages – Not all the patients with chronic patellar instability are equal. – The etiology of chronic patellar instability is multifactorial. Therefore, its treatment must be personalized. Let’s call it “bespoke treatment.” This is the only way to avoid failures and subsequent operations.
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Limitations of Patellofemoral Surgery in Children Mahad Hassan and Marc Tompkins 1 Rehabilitation Challenges in Children with Patellofemoral Instability Patellofemoral instability is a common knee pathology in the acute injury setting within the pediatric population [1–4]. Recurrence can be as high as 75% in patients with open physes who also have risk factors present such as patella alta and trochlear dysplasia [5]. In addition to anatomic and surgical considerations outlined later in this chapter, rehabilitation poses a challenge in this population. Pediatric patients can have difficulty adhering to post-surgical restrictions and rehabilitation programs. This can result in inadequate healing of bony or soft tissue realignment or reconstruction procedures. Availability of physical therapists with experience to treat children, especially therapists with experience treating patellofemoral pediatric patients, may impact the management of the patient following surgery. This may result in inadequate restoration of musculoskeletal function or inability to address underlying biomechanical issues that predisposed the patient to injury in the first place. Parental M. Hassan M. Tompkins (&) University of Minnesota, Minneapolis, MN, USA e-mail: mtompkin@umn.edu engagement, as well as availability to provide transport to rehabilitation facilities, are important challenges unique to this population. 2 Anatomic Considerations There are several anatomic risk factors for patellofemoral instability to consider when treating pediatric patients with open physes. Patella alta is poor overlap, or engagement, of the patella and the trochlea [6]. The risk of instability in patella alta occurs because there is a delayed engagement of the patella on the trochlear sulcus as the knee goes from extension into flexion. This decreases the trochlea’s function as primary restraint to lateral displacement of the patella potentially resulting in the patella moving lateral to the trochlea. In adults, patella alta is addressed surgically with tibial tubercle distalization. This is not recommended in pediatric patients with open physes because violation of the tibial tubercle apophysis can result in its arrest and resultant recurvatum deformity. Extensor mechanism malalignment creates an angle at the patellofemoral joint resulting in a laterally directed force vector on the patella, which puts the patella at risk of lateral instability. In adults, this can be addressed with a anteromedialization tibial tubercle osteotomy. Similar to tibial tubercle distalization, this will put the patient at risk of apophyseal arrest [7]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_19 277
278 M. Hassan and M. Tompkins Trochlear dysplasia is a risk factor for patellofemoral instability because the poorly formed, or medialized, sulcus increases the lateral tracking of the patella and risk for lateral instability [5]. Various procedures have been described to address dysplasia and increase the effective depth of the trochlea [7–11]. However, these procedures have been contraindicated in skeletally immature patients as they can damage the distal femoral physis [7]. Genu valgum can contribute to patellar instability because it also creates a laterally directed force vector on the patella. In skeletally immature patients, the physis can be utilized to correct this deformity via guided growth [1, 12]. Coronal plane abnormalities can also be addressed with osteotomies, but the physis must be considered when performing an osteotomy. Increased femoral version and/or tibial torsion can cause poor overlap of the patella and trochlea in the axial plane resulting in lateralizing of the patella relative to the trochlea increasing the risk of lateral instability. In adults, axial plane abnormalities can be addressed at the proximal, midshaft, or distal aspects of the femur or tibia. Midshaft osteotomies are typically fixed with an intramedullary nail which is difficult in skeletally immature patients because most nailing systems approach the intramedullary canal in a manner which penetrates through the physis [13, 14]. 3 Surgical Techniques Due to the aforementioned anatomic considerations, surgical techniques unique to the pediatric population have been devised. For skeletally immature patients with patella alta, a patellar tendon shortening procedure can be done in lieu of a distalizing tibial tubercle osteotomy in skeletally immature patients. This is performed by using sutures to imbricate the tendon with the aim of improving the engagement between the patella and trochlea [15, 16]. There a few limitations to this technique and care should be taken with the sequence of performing concomitant procedures such as medial imbrication and MPFL reconstruction. Ligament isometry is significantly altered following patellar tendon shortening and could necessitate rebalancing if these procedures are performed prior to the patellar tendon shortening. Complications from this technique can arise and patella baja may result as it can in a distalizing osteotomy. This can result in significantly increased contact pressures in the patellofemoral joint throughout early flexion [15, 16], Patellar tendon rupture through the imbrication site can also occur. Subsequent repair can be done but may lead to worse outcomes and extended recovery [15, 16]. Multiple techniques have been described in the past to address extensor mechanism malalignment. The Roux-Goldthwait procedure was originally described over one hundred years ago and involves longitudinally dividing the patellar tendon and transferring the lateral limb deep and medial to the medial limb [17, 18]. Galeazzi described a tenodesis technique in the 1920s in which the semitendinosus tendon is harvested and secured to the medial patella in an oblique manner while keeping its insertion intact [19]. When performed in isolation, the outcomes of this procedure are variable when recurrent dislocation and knee function are considered. While the original description of the procedure and follow up studies showed good results with lower than 10% recurrent instability rates, a recent long term follow up study showed a greater than 80% redislocation with approximately 40% of those patients requiring surgical stabilization [19–21]. Treating trochlear dysplasia with a deepening trochleoplasty has been described in skeletally immature patients, but only in those who are close to skeletal maturity [22]. There are currently no descriptions or indications for performing trochleoplasty in very skeletally immature patients as this will put the anterior distal femoral physis at risk of injury and subsequent growth disturbance. Genu valgum can be addressed surgically via hemi-epiphysiodesis or guided growth. Guided growth in this case is the temporary slowing of the medial distal femoral physis until the patient’s mechanical axis is corrected to the
Limitations of Patellofemoral Surgery in Children center of the knee [12]. Limitations with this approach include undercorrection if not enough growth remains or overcorrection if not followed closely. Hence, the patient must be followed closely to monitor for correction and the patient and family must be prepared for further surgery to remove hardware. Axial plane correction can be performed surgically with a plate and screws at any level: proximal, midshaft, or distal. Midshaft requires more dissection and soft tissue disruption than would be done in adults with intramedullary nailing. With proximal and distal osteotomies, the physis must be taken into account and protected when performing these osteotomies. 3.1 Medial Patellofemoral Ligament Reconstruction Medial patellofemoral ligament (MPFL) reconstruction can be a powerful operation to decrease the dislocation risk in patients with patellar instability, but requires adjustment in surgical technique for skeletally immature patients. The attachment of the MPFL on the femur is in close proximity to the physis, so in some patients it is not possible to place the fixation on the femur in a perfect anatomic position [23]. If the MPFL is not in an anatomic location, it can affect the tracking of the patella and result in instability or overconstraint [24]. Care must therefore be taken to place the MPFL as close to anatomic as possible, while also protecting the physis. MPFL reconstruction has been shown to decrease dislocation risk even in patients with anatomic risk factors such as patella alta and trochlear dysplasia [25]. However, further procedures may still be necessary at skeletal maturity such as addressing the trochlear dysplasia which would be contra-indicated in patients with an open distal femoral physis. As such, it is important to counsel parents and patients that 279 when there are anatomic risk factors present which cannot be adequately addressed during skeletal growth, an MPFL reconstruction may be a temporizing procedure and there may be a need to perform additional procedures as the child achieves skeletal maturity. 4 Risk of Recurrence and Return to Activity Failure of surgical patellar stabilization is believed to be due to many reasons, but includes: (1) technical failure of the primary stabilization method, (2) unaddressed static and dynamic pathoanatomy and (3) intrinsic risk factors such as collagen disorders and ligamentous laxity [26]. Age at the time of surgery has been shown in multiple studies to affect risk of recurrence following surgery, with younger patients at higher risk [27, 28]. This is something in which patients should be counseled at the time of the surgical discussion. The greater the presence of anatomic risk factors at the time of surgery also increases the risk of further instability [29]. All of the anatomic risk factors, therefore, that can be addressed must at least be considered for intervention at the time of surgery. There is limited literature on return to play after patellar stabilization surgery in pediatric patients [26, 30]. A systematic review on return to play highlighted a lack of objective guidelines for return to play. Moreover, there was a wide range of timing and criteria in the studies identified in the review [30]. Return to play timeframes are varied and can range from 3 to 8 months. The variation in return to play timeline also depends on concurrent procedures performed [26, 30]. A recent review recommended using the criteria for return consisting of no pain, full motion, no effusion, no objective patellofemoral instability on exam, near symmetric strength and excellent dynamic stability [31].
280 5 M. Hassan and M. Tompkins Summary Patellofemoral surgery in children is multifaceted and complex. It is possible to stabilize the patellofemoral joint and achieve good clinical outcomes, but there are many limitations that must be understood when planning surgery for these patients. References 1. Hennrikus W, Pylawka T. Patellofemoral instability in skeletally immature athletes. J Bone Joint Surg Am. 2013;95(2):176–83. 2. Weeks KD 3rd, Fabricant PD, Ladenhauf HN, Green DW. Surgical options for patellar stabilization in the skeletally immature patient. Sports Med Arthrosc. 2012;20(3):194–202. 3. Khormaee S, Kramer DE, Yen YM, Heyworth BE. Evaluation and management of patellar instability in pediatric and adolescent athletes. Sports Health. 2015;7:115–23. 4. Fithian DC, Paxton EW, Stone ML, Silva P, Davis DK, Elias DA, White LM. Epidemiology and natural history of acute patellar dislocation. Am J Sports Med. 2004;32:1114–21. 5. Arendt EA, Askenberger M, Agel J, Tompkins MA. Risk of redislocation after primary patellar dislocation: a clinical prediction model based on magnetic resonance imaging variables. Am J Sports Med. 2018;46(14):3385–90. 6. Dejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994;2(1):19–26 7. Dejour D, Saggin P. The sulcus deepening trochleoplasty−the Lyon’s procedure. Int Orthop. 2010;34:311–6. 8. Kuroda R, Kambic H, Valdevit A, et al. Distribution of patellofemoral joint pressures after femoral trochlear osteotomy. Knee Surg Sports Traumatol Arthrosc. 2002;10:33–7. 9. Masse Y. Trochleoplasty. Restoration of the intercondylar groove in subluxations and dislocations of the patella. Rev Chir Orthop Reparatrice Appar Mot. 1978;64:3–17. 10. Bereiter HG, Gautier E. Die trochleoplastik ale chirurgishe therapie der rezidivierenden patellauxation bei trochleodysplasie des femurs. Arthroskopie. 1994;7:281–6. 11. Desio SM, Burks RT, Bachus KN. Soft tissue restraints to lateral patellar translation in the human knee. Am J Sports Med. 1998;26(1):59–65. 12. Kearney SP, Mosca VS. Selective hemiepiphyseodesis for patellar instability with associated genu valgum. J Orthop. 2015;12(1):17–22. 13. Pandya NK, Edmonds EW. Immediate intramedullary flexible nailing of open pediatric tibial shaft fractures. J Pediatr Orthop. 2012;32:770–6. 14. Metaizeau JD, Denis D. Update on leg fractures in paediatric patients. Orthop Traumatol Surg Res. 2019;105:S143-51. 15. Andrish J. Surgical options for patellar stabilization in the skeletally immature patient. Sports Med Arthrosc. 2007;15:82–8. 16. Parvaresh KC, Huddleston HP, Yanke AB. Patellar tendon shortening for treatment of patella alta in skeletally immature patients with patellar instability. Arthrosc Tech. 2021;10(8):e1979-84. 17. Marsh JS, Daigneault JP, Sethi P, Polzhofer GK. Treatment of re- current patellar instability with a modification of the roux−goldthwait technique. J Pediatr Orthop. 2006;26(4):461–5. 18. Vahasarja V, Kinnunen P, Lanning P, Serlo W. Operative realign−ment of patellar malalignment in children. J Pediatr Orthop. 1995;15(3):281–5. 19. Letts RM, Davidson D, Beaule P. Semitendinosus tenodesis for repair of recurrent dislocation of the patella in children. J Pediatr Orthop. 1999;19 (6):742–7. 20. Hall JE, Micheli LJ, McManama GB Jr. Semitendinosus tenodesis for recurrent subluxation or dislocation of the patella. Clin Orthop Relat Res. 1979;144:31–5. 21. Grannatt K, Heyworth BE, Ogunwole O, Micheli LJ, Kocher MS. Galeazzi semitendinosus tenodesis for patellofemoral instability in skeletally immature patients. J Pediatr Orthop. 2012;32(6):621–5. 22. Nelitz M, Dreyhaupt J, Williams SRM. No growth disturbance after trochleoplasty for recurrent patellar dislocation in adolescents with open growth plates. Am J Sports Med. 2018;46(13):3209–16. 23. Shea KG, Martinson WD, Cannamela PC, Richmond CG, Fabricant PD, Anderson AF, Polousky JD, Ganley TJ. Variation in the medial patellofemoral ligament origin in the skeletally immature knee: an anatomic study. Am J Sports Med. 2018;46(2):363–9. 24. Burrus MT, Werner BC, Conte EJ, Diduch DR. Troubleshooting the femoral attachment during medial patellofemoral ligament reconstruction: location, location, location. Orthop J Sports Med. 2015;3 (1):2325967115569198. 25. Schlumberger M, Schuster P, Hofmann S, Mayer P, Immendörfer M, Mayr R, Richter J. Midterm results after isolated medial patellofemoral ligament reconstruction as first-line surgical treatment in skeletally immature patients irrespective of patellar height and trochlear dysplasia. Am J Sports Med. 2021;49 (14):3859–66.
Limitations of Patellofemoral Surgery in Children 26. Vellios EE, Trivellas M, Arshi A, Beck JJ. Recurrent patellofemoral instability in the pediatric patient: management and pitfalls. Curr Rev Musculoskelet Med. 2020;13(1):58–68. https://doi.org/10.1007/ s12178-020-09607-1. 27. Hiemstra LA, Kerslake S. Age at time of surgery but not sex is related to outcomes after medial patellofemoral ligament reconstruction. Am J Sports Med. 2019;47(7):1638–44. 28. Hiemstra LA, Kerslake S, Kupfer N, Lafave M. Patellofemoral stabilization: postoperative redislocation and risk factors following surgery. Orthop J Sports Med. 2019;7(6). 29. Nelitz M, Theile M, Dornacher D, Wölfle J, Reichel H, Lippacher S. Analysis of failed surgery 281 for patellar instability in children with open growth plates. Knee Surg Sports Traumatol Arthrosc. 2012;20(5):822–8. 30. Zaman S, White A, Shi WJ, Freedman KB, Dodson CC. Return−to−play guidelines after medial patellofemoral ligament surgery for recurrent patellar instability: a systematic review. Am J Sports Med. 2017;363546517713663. 31. Menetrey J, Putman S, Gard S. Return to sport after patellar dislocation or following surgery for patellofemoral instability. Knee Surg Sports Traumatol Arthrosc. 2014;22(10):2320–6.
The Failed Medial Patellofemoral Ligament Reconstruction. What Can We Do? Vicente Sanchis-Alfonso and Cristina Ramírez-Fuentes 1 Introduction A torn medial patellofemoral ligament (MPFL) is considered the focal lesion in chronic lateral patellar instability (CLPI). Therefore, it is logical that the most frequently performed surgery to treat CLPI is MPFL reconstruction (MPFLr). Failed MPFLr is the term that we are going to use to describe the situation of those patients who have not seen a successful outcome after a surgery that was done to resolve CLPI. As a result, the patient will have a recurrence, anterior knee pain (AKP) and a limitation in knee range-ofmotion. The three complaints can be present in combination or in isolation. Note that a “failed” MPFLr does not necessarily mean that the surgery was botched. It may be the consequence of a surgical complication, that is an adverse event caused by factors that are outside the orthopedic surgeon’s control. However, it is a consequence of an error in surgical indication or in the surgical technique on most occasions. Schneider and colleagues [1] reported a reoperation rate of 3.1% (95% CI, 1.1–5.0%) after an isolated MPFLr. V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com C. Ramírez-Fuentes Medical Imaging Department, Hospital Universitario y Politecnico La Fe, Valencia, Spain The objectives of this chapter are four-fold. They are (1) to analyze the causes of failure, (2) to describe how to avoid surgical failure, (3) to explain how to solve the problem and (4) to analyze the outcomes after MPFL surgery revision. 2 Causes of Revision Surgery— MPFLr Failure Etiology The reasons revision surgery is called for after MPFLr are varied. They include (1) an incorrect surgical indication, (2) a technical failure, (3) a failure to recognize and correct an existing pathoanatomy, (4) intrinsic risk factors like collagen disorders and (5) a patellar fracture. 2.1 Incorrect Surgical Indication The first requisite for a successful MPFLr is appropriate patient selection. The ideal indication for an isolated MPFLr would be: (1) a patient with CLPI with at least two documented episodes of dislocation and confirmation of dislocation with examination under general anesthesia, (2) a TT-TG distance <20 mm, a positive apprehension test until 30º of knee flexion, a patellar Caton-Deschamps index of <1.2, and trochlear dysplasia grade A [2]. An MPFLr should not be performed if the patella cannot be laterally dislocated. The objective of an MPFLr is not to pull © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_20 283
284 the patella to its proper position within the trochlear groove but to stabilize it once the patellofemoral tracking (J-sign) has been corrected. Therefore, an isolated MPFLr is not indicated to eliminate the J-sign. In this way, Zhang and colleagues [3] have demonstrated that a preoperative high-grade J-sign is associated with residual graft laxity after isolated MPFLr. 2.2 Technical Mistakes and Surgical Technique Issues According to Parikh and colleagues [4] 47% of the complications that occur after MPFLr are related to technical errors. 2.2.1 Incorrect Femoral Attachment Point The most frequent serious technical error that can lead to MPFLr failure is the incorrect location of the femoral attachment point (Figs. 1, 2, 3, 4, 5 and 6). Walker and colleagues [5] analyzed MPFLr revision surgeries in a systematic review that was done as recently as 2021. In it, the authors showed that the most frequent cause for revision surgery is the malposition of the femoral attachment point (38%). The femoral attachment point is crucial as it determines the length change behavior of the graft and thereby the graft tension at different angles of knee flexion [6]. It is determinant in the kinematic behavior of the graft [6]. How to avoid an incorrect femoral attachment point? To accurately locate the femoral attachment point, Schoettle and colleagues [7] recommended using intra-operatory fluoroscopy. Having a true intra-operative lateral image is indispensable when this radiological method is used. However, various authors have demonstrated that Schoettle's radiological method, which is accepted as the gold standard, is no guarantee of a true anatomical attachment point [8–11]. Therefore, the radiological method is only an approximation. It should not be used as the sole way of locating the femoral attachment point. To locate the real anatomical attachment point most V. Sanchis-Alfonso and C. Ramírez-Fuentes accurately, make an incision that is large enough to identify the most relevant anatomical landmark, the adductor magnus tendon (AMT). The AMT is easily identifiable and leads right to the origin of the MPFL on the femur. It is situated 10.6 ± 2.5 mm distal to the apex of the adductor tubercle (AT) and parallel to the long axis of the femur [12]. The great variability in the location of the AT (Fig. 7) is behind the variability in the location of the femoral insertion of the MPFL. This explains the large number of errors when Schoettle's method is used to identify the femoral fixation point during MPFLr. But, is the anatomic femoral tunnel position so relevant in MPFLr? A poor outcome is not always seen with femoral tunnel malpositioning. In our experience, those ligaments with a non-anatomical femoral fixation point that behave kinematically like an anatomical MPFL have excellent clinical outcomes at long-term follow-up [6]. However, those nonanatomical grafts that do not show physiological kinematic behavior are those that have a poor clinical outcome [6]. What should we do in those cases? We believe every MPFL graft should be placed anatomically, because an anatomical femoral tunnel position maximizes outcomes and provides the best chance of excellent short-term and long-term success. In summary, an anatomical MPFLr is a fast and reproducible way to achieve an MPFL that is long enough to act as an isometric “leash” from 0º to 30º and becoming loose after 30º of knee flexion (Fig. 8). In conclusion, the relevant anatomy and biomechanics must be identified and restored to avoid complications. 2.2.2 Excessive Graft Tension Another technical error that can lead to surgical failure is excessive graft tension. The concept of ‘‘tensioning’’ the MPFL graft is not correct from a conceptual point of view because the MPFL is not under constant tension in its native state. It only comes under tension when a lateral force acts on the patella to displace it laterally. Philip Schoettle makes a very intelligent simile, comparing the MPFL to a dog leash. The leash is
The Failed Medial Patellofemoral Ligament … 285 Fig. 1 CASE # 1. A 19-year-old male patient presented with severe AKP and CLPI. He had undergone an MPFLr with a single bundle semitendinosus tendon graft some 3 years earlier. Upon physical examination, no patellofemoral tracking disorder was detected (negative J-sign). The patient was first placed under general anesthesia. During the procedure, it was determined that dislocation beyond 40° of knee flexion was not possible. The femoral tunnel of the MPFLr was seen excessively anterior. It is a significant error. Severe chondropathy of the articular surface of the patella was also observed. Moreover, the distance between the patellar fixation point and the femoral fixation point increased with knee flexion. Clinically speaking, it results in increased patellofemoral pressure during knee flexion, which may have been the origin of the patient’s severe patellar chondropathy. The resolution was found in the anatomic MPFLr in which the contralateral semitendinosus tendon with a double-bundle technique was used. (Reused with permission from Baishideng Publishing Group Inc. From SanchisAlfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8(2): 115–129) loose most of the time, except when the dog (the patella) wants to run away (dislocate), and then it becomes tight. If the leash (the MPFL) were tight all the time, it would choke the dog. Continuing with our simile, it would create patellofemoral pressure that would be great enough to lead to chondropathy and finally PFOA. In vivo studies of the kinematics of the MPFL have shown that the greatest distance between the femoral and patellar attachment points is between 0 and 60º of knee flexion (the greatest at 30º) and that this distance decreases significantly from 60º to 120º of flexion [6]. With this, we make it such that excessive compression forces are not produced in the patellofemoral joint during high degrees of knee flexion. Finally, it is important to note that
286 Fig. 2 CASE # 2. A 28-year-old female patient came to us with very severe AKP and CLPI. A clear case of patellofemoral maltracking was seen in the physical examination (positive J-sign). Moreover, we were able to dislocate the patella laterally beyond 60° of knee flexion. She had been operated on various times over the previous 8 years. She had undergone a lateral retinacular release, proximal realignment, osteotomy for medialization of the tibial tubercle and MPFLr. It was noted that the femoral tunnel was overly proximal and anterior. With knee flexion, the space between the patellar and the femoral fixation points increases a great deal. Clinically, it V. Sanchis-Alfonso and C. Ramírez-Fuentes brings about a significant increase in patellofemoral pressure during knee flexion. It was considered a possible explanation for the patient’s severe case of patellofemoral osteoarthritis (PFOA). In this specific instance, the pain went away after a sulcus deepening trochleoplasty. After carrying out an anatomic double-bundle MPFLr with a semitendinosus tendon graft, the CLPI also totally disappeared. (Reused with permission from Baishideng Publishing Group Inc. From Sanchis-Alfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8 (2): 115–129)
The Failed Medial Patellofemoral Ligament … 287 A B C D Fig. 3 CASE # 3. This clinical case highlights the importance of the femoral attachment point in MPFLr outcomes. Both knees were operated on, the left with an excellent result B, D and the right with a bad result A, C. In this case, there are no confusion variables that can influence the result. There is no patellar tilt, no patella alta, no severe trochlear dysplasia, and the TT-TG distance is normal. Therefore, the only variable that counts is the femoral attachment point and therefore we are able to compare the failed operated knee with the contralateral successful knee. The right knee was reoperated on performing a new reconstruction with a new femoral attachment (blue arrow) with an excellent result. Finally, we must note that the patient is an athlete and therefore she is more demanding and a surgical procedure that is not 100% perfect will be more noticeable in an athlete than in a sedentary person. In short, the only difference between both knees was the femoral attachment point. (C, D. Reused with permission from Baishideng Publishing Group Inc. From Sanchis-Alfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8 (2): 115–129)
288 V. Sanchis-Alfonso and C. Ramírez-Fuentes Fig. 4 CASE # 3. Here we analyze the knee with an excellent outcome. This knee was operated on performing a double-bundle MPFLr with semitendinosus. In the graphs on the right you can see the kinematics of the reconstructed MPFL in vivo. The blue lines represent the reconstructed MPFL. The femoral attachment point is clearly non-anatomic (blue arrow). The red dot represents the anatomic femoral attachment. The red lines represent the virtual anatomic MPFLr that we have drawn using an anatomic femoral attachment (red dot). We can see that the length of the MPFL-graft (the blue line) is quite similar to the length of the virtual anatomic MPFL (the red line). Anatomic and reconstructed MPFL are isometric from 0 to 30° of knee flexion, that is there is less than 5 mm of length change throughout this range of motion. In conclusion, the MPFL-graft behaves physiologically, that is, it is isometric from 0 to 30º of knee flexion the MPFL is not tight when the patella is not subject to a lateral displacing force. In a state of rest, the MPFL is not under tension. attachment points is greatest [6]. If the fixation were made in the flexion range in which the two anchor points are closer, we would be subjecting the graft to excessive tension when we flex the knee further. Therefore, it would cause a significant increase in patellofemoral pressure that would result in the future development of a patellofemoral chondropathy and pain. To prevent excessive tension, do not pull the graft tight at the time of fixation. If the other knee is How to avoid excessive tension on the graft? When we go to fix the graft, the assistant should keep the patella well-centered in the femoral trochlea with the knee at 30º of flexion. We do it at 30º because it is at this knee flexion angle that the distance between the femoral and patellar
The Failed Medial Patellofemoral Ligament … A 289 B Fig. 5 CASE # 3. Now, we are going to analyze the knee with a bad result (right knee). In this knee, you can also observe a clearly non-anatomic femoral attachment point. It is too anterior A. However, in this knee unlike the left one the graft does not behave physiologically. It was isometric from 0 to 120° of knee flexion B. (B, Reused with permission from Baishideng Publishing Group Inc. From Sanchis-Alfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8(2): 115–129) asymptomatic, the aim is to reproduce the degree of patellar mobility of the healthy contralateral knee. We must note that tighter is never better in MPFL reconstruction surgery. revision MPFLr surgery is unaddressed trochlear dysplasia (18.4%). While an isolated MPFLr is sufficient in the group of patients with patellar instability from 0 to 30º, this might fail to control instability in the group with instability beyond 30º [14]. Thus, surgical failure in MPFLr might be due to not considering risk factors for patellar instability such as trochlear dysplasia or pathologic femoral anteversion. Apprehension that is relieved at 30° of knee flexion suggests a good clinical result with an isolated MPFLr. An apprehension beyond 30° of knee flexion suggests severe trochlear dysplasia, a significant femoral anteversion or both. With that, an associated surgical procedure such as trochleoplasty and/or femoral rotational osteotomy might be necessary [14, 15]. If the trochlear geometry is insufficient to provide restraint, osteotomy to change the shape of the trochlea has proven its value. Nelitz and colleagues [16] performed an analysis of failed surgery for patellar instability. They observed that severe trochlear dysplasia (Dejour type BD) was significantly more frequent in the surgical failure group (89%) than in the non-surgical failure group (21%). However, they did not find 2.2.3 Single Versus Double-Bundle Patellar Graft Insertion Migliorini and colleagues [13] performed a systematic review in which the isolated singlebundle (SB) was compared to the double-bundle (DB) graft for recurrent lateral patellar instability. In the DB group, there was more improvement in function and a reduction of overall complications when compared to the SB group. The authors concluded that the current scientific evidence support the use of the DB tendon graft for the isolated MPFLr. 2.3 Failure to Recognize and Correct Concomitant Risk Factors for Instability In a 2021 systematic review analyzing MPFLr revision surgery by Walker and colleagues [5], the authors showed that the second cause for
290 V. Sanchis-Alfonso and C. Ramírez-Fuentes A B C D Fig. 6 CASE # 3. Right knee after revision surgery. After a quasi-anatomical MPFLr the pain disappeared. Femoral tunnel excessively anterior (blue arrow). New femoral attachment (red arrow). The new ligament is isometric from 0 to 30º of knee flexion C, D. That is, the graft behaves physiologically. An interesting finding was that the pain disappeared completely in spite of the fact that the severe patellar chondral lesion was left alone. We can conclude that femoral tunnel position is crucial for a successful MPFLr. (A, B. Reused with permission from Baishideng Publishing Group Inc. From Sanchis-Alfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8(2): 115–129) differences relative to the patellar height ratio and the TT-TG distance between the two groups. In the same way, Wagner and colleagues [17] also found that high degrees of trochlear dysplasia correlate with poor clinical outcomes because the MPFL graft might be overloaded given that there is more instability in dysplastic situations. Similarly, Kita and colleagues [18] reported that severe trochlear dysplasia is the most important predictor of residual patellofemoral instability after an isolated MPFLr. They have shown that a combination of severe trochlear dysplasia with an increased TT-TG distance was more likely to affect the outcomes of MPFLr. We can conclude that considering that high degree trochlear dysplasia seems to be a major risk factor for failure of isolated MPFLr, an associated trochleoplasty might be considered in such cases (Fig. 9). Moreover, trochlear dysplasia seems to be a major risk factor for failure of MPFLr for recurrent patellar dislocation in children and adolescents [16]. These results in children are in agreement with the literature in adults. Dejour and colleagues [19] have shown that the sulcus-deepening trochleoplasty is a good revision option for the surgical treatment of patients with persisting patellar dislocation after MPFLr and high-grade trochlear dysplasia. Similarly, Fucentese and colleagues [20] have demonstrated that trochleoplasty is a useful and
The Failed Medial Patellofemoral Ligament … Fig. 7 The anatomic variability of the adductor tubercle may explain the anatomic variability of the MPFL femoral fixation point. (Reused with permission from Baishideng Publishing Group Inc. From Sanchis-Alfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8 (2): 115–129) reliable surgical technique to improve patellofemoral instability in patients with a dysplastic trochlea. However, the same is not the case with pain even though the significant improvement in Fig. 8 A normal MPFL is tighter in extension (C) than in flexion (A, B). Beyond 60º the graft is loose A 291 stability after trochleoplasty is highly predictable. The pain may even increase after surgery. In conclusion, severe trochlear dysplasia can be successfully treated with a trochleoplasty. The trochleoplasty procedure not only corrects the trochlear dysplasia, but also the increased TT-TG distance. Another risk factor that has been given great importance is the pathological TT-TG distance (>20 mm). Matsushita and colleagues [21] demonstrated that isolated MPFL reconstructions performed in CLPI with a TT-TG distance greater than 20 mm yielded similar clinical outcomes to those performed with a TT-TG under 20 mm. Moreover, there were no re-dislocations in either group. They concluded that a TT-TG distance greater than 20 mm may not be an absolute indication for medialization of the tibial tubercle. Less and less importance is being given to the TT-TG distance when indicating a surgery. What is now emerging more and more strongly is the importance of torsional alterations in the genesis of patellar instability, specifically B C
292 V. Sanchis-Alfonso and C. Ramírez-Fuentes Fig. 9 CASE # 4. Chronic lateral patellar instability in a patient with grade D trochlear dysplasia (positive J-sign). We note that the patella dislocates beyond 40° of knee flexion. She had been operated on performing a proximal realignment surgery. Lateral patellar instability resolved after a MPFLr associated with a sulcus deepening trochleoplasty. (Reused with permission from Baishideng Publishing Group Inc. From Sanchis-Alfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8 (2): 115–129) the increment in femoral anteversion. Diederichs and colleagues [22] have analyzed rotational limb alignment in patients with non-traumatic patellar instability and in controls using magnetic resonance imaging (MRI). They found that patellar instability patients have greater internal femoral rotation, greater knee rotation, and a tendency for genu valgum when compared to healthy controls (Figs. 10, 11, 12 and 13). They conclude that rotational malalignment may be a primary risk factor in patellar instability that has so far been underestimated. Cao and colleagues [23] have shown that increased femoral anteversion along with a high-grade J sign is associated with MPFLr failure. These authors have shown that MPFLr revision surgery by means of rotational distal femoral osteotomy associated with MPFLr provides satisfactory clinical outcomes in patients with increased femoral anteversion along with a high-grade J sign. Finally, Zhang and colleagues [3] evaluated 15 patients who presented with MPFL-graft laxity. A preoperative high-grade J-sign was identified in 66.7% of these patients in comparison to 13.3% in the control group with no graft laxity. Moreover, they demonstrated that the presence of a preoperative high-grade J-sign and femoral tunnel malposition were independent risk factors associated with residual graft laxity after MPFLr. Both torsional deformities and coronal plane deformities are associated with patellar instability in some patients. The most common multiplanar deformity is internal femoral torsion and genu valgum.
The Failed Medial Patellofemoral Ligament … 293 Fig. 10 CASE # 5. This is the case of a 19-year-old male patient who came to my office due to left lateral patellofemoral instability. You can observe instability beyond 30º. At the age of 12 years and 11 months, he underwent surgery on his left knee (MPFLr + hemitransfer of the patellar tendon following the Goldthwait technique + lateral retinaculum release). His lower-left extremity showed significant valgus malalignment and pathological femoral anteversion. At the age of 14 years and 10 months, his right knee was operated on (MPFLr + hemitransfer of the patellar tendon according to Goldthwait technique). Both knees were bad but the one that really disabled him was the left one (positive Jsign). In short, the patient is looking for a solution to the left patellar instability, which is what really limited him. He would have never bothered to go to the doctor because of the right side as he was able to live with it. This case highlights the importance of the knee valgus and femoral anteversion in the genesis of patellar instability 2.4 Intrinsic Risk Factors Such as Collagen Disorders 2.5 Patellar Fracture. How to Avoid It Generalized joint hypermobility (4 or more points on the Beighton score) has frequently been considered a risk factor for patellar instability (Fig. 14). However, Hiemstra and colleagues [24] have shown that the presence of generalized joint hypermobility has no influence on diseasespecific quality-of-life, physical symptoms score or functional outcomes after MPFLr. Patients with Ehlers-Danlos syndrome (Fig. 15) are prone to patellar instability. In these patients, it is important to consider the use of allografts for MPFLr given the problems we may have with autografts in this patient population [25]. Additionally, patients with Ehlers-Danlos suffer from combined medial and lateral patellar instability that requires reconstruction of both the MPFL and the lateral patellofemoral ligament to achieve adequate stability [26]. In a systematic review analyzing MPFLr revision surgery performed by Walker and colleagues [5] in 2021, the authors showed that the third cause for revision surgery is a patellar fracture (11.8%). Fulkerson and Edgar [27] described the medial quadriceps tendon-femoral ligament -MQTFLreconstruction. This surgical technique avoids the risk of patella fracture. 3 Reasons for Consultation in a Patient with Failed MPFLr Those patients who have a failed MPFLr are going to consult for three reasons: (1) recurrence of instability, (2) AKP, (3) limitation of the range of motion of the knee or a combination of them.
294 V. Sanchis-Alfonso and C. Ramírez-Fuentes Fig. 11 CASE # 5. X-rays show left-limb malalignment on the coronal plane (knee valgus). Valgus 10º (4º femur + 4º joint deformity + 2º tibia) (Mechanical axis— red line). The patella is subluxed externally. In X-rays, we can see a curvature of the left femur which represents the normal anterior bow of the femur. This is highly suggestive of internal rotation of the femur. It would suggest a femoral anteversion. CT study: LEFT–femoral anteversion = 43º (According to Murphy´s method)/ TT-TG distance = 26 mm/external tibial torsion = 25º/ tibio-femoral rotation (knee rotation) = 29º/Trochlear inclination 3º; RIGHT–femoral anteversion = 26º/TTTG distance = 25 mm/external tibial torsion = 30º/knee rotation = 25º/trochlear inclination 5º 3.1 Re-dislocation or Persistence of Apprehension Without Dislocation tear again due to an indirect trauma to the knee. If we add the high frequency of return to sports practice, and the ensuing possibility of a new knee trauma to the fact that more and more MPFL are reconstructed, we can infer that the number of re-dislocations after MPFLr will be greater each time even though it is not as much as we might think because only 31% of graft ruptures are due to knee trauma [29]. In most cases, re-dislocation after an isolated MPFLr is non-traumatic (69%) [29]. In the rest of the cases, it is secondary to an obvious trauma (31%) [29]. In both cases, it can be due to a femoral tunnel malposition or the presence of anatomic risk factors. There are numerous risk factors such as (1) trochlear dysplasia (types B through D), (2) patella alta (CD index >1.2), (3) genu valgum (>5º), (4) TT-TG distance Schneider and colleagues [1] reported an instability recurrence rate of 1.2% (95% CI, 0.3– 2.1%) and a rate of apprehension persistence of 3.6% (95% CI, 0–7.2%) after isolated MPFLr for the treatment of CLPI. However, Shah and colleagues [28] showed that recurrent apprehension represents 32% of all the complications found in MPFLr. Instability might be due to a rupture of the MPFL graft, or could be secondary to the failure to recognize associated risk factors for instability. It has been reported that 84.1% (95% CI, 71.1–97.1%) of patients return to sports after an isolated MPFLr [1]. Thus, the return to sports puts the reconstructed ligament at risk and so its
The Failed Medial Patellofemoral Ligament … Fig. 12 CASE # 5. Intraoperative X-rays. The patella is well centered on the distal femur after biplanar supracondylar osteotomy (lateral supracondylar open wedge varus and rotational osteotomy of the femur) Fig. 13 CASE # 5. 3D model. The patella is well centered on the distal femur after biplanar supracondylar osteotomy (lateral supracondylar open wedge varus and rotational osteotomy of the femur) 295
296 V. Sanchis-Alfonso and C. Ramírez-Fuentes Fig. 14 Beighton score greater than 20 mm and (5) torsional abnormalities (femoral anteversion greater than 25º and external tibial torsion greater than 35º). Of all these factors, the most prevalent in re-dislocation cases are trochlea dysplasia (50%) and valgus malalignment (35%) [29]. In atraumatic redislocations, 2 or more risk factors are present in 65% of cases [29]. Sappey-Marinier and colleagues [30] have evaluated the importance of the J-sign prior to isolated MPFLr surgery and have observed that it is a risk factor for predicting surgical failure. Furthermore, they have shown that a CDI > 1.3 is also another risk factor for surgical failure. Cregar and colleagues [31] have found that severe trochlear dysplasia (types C and D) and a femoral tunnel malposition (10 mm from Schottle's point) appear to be responsible for the increased prevalence of recurrent dislocation as well as worse patientreported outcomes. Despite this, the role of concomitant bony procedures along with MPFLr to correct the pathoanatomy remains unknown. An incorrect femoral/patellar attachment point can also lead to the excessive obliquity of the
The Failed Medial Patellofemoral Ligament … 297 might lead to graft laxity in extension and graft tension in flexion with a clinical presentation of AKP and loss of flexion. Moreover, excessive graft tension with knee flexion could stretch the graft and lead to its failure, predisposing the patient to re-dislocation even though the tendon graft used for MPFLr is substantially stronger than the native MPFL. In contrast, an excessively distal femoral attachment point may lead to graft tension in extension and laxity in flexion. Its clinical presentation would be an extension lag. The femoral attachment point should mimic the native anatomy as closely as possible to avoid the problems cited. Therefore, it is essential to accurately check the femoral tunnel placement intra-operatively. 4 Fig. 15 Skin laxity in Ehlers-Danlos syndrome graft, making it ineffective in preventing excessive lateral patellar displacement in the first 30º of knee flexion (Fig. 16). This might explain a persistent lateral dislocation of the patella sometimes seen with a healthy graft (Fig. 16). In this case, remedying the instability can be achieved simply by modifying the attachment points (Fig. 16). 3.2 Knee Pain and Limitation of the Range of Motion Medial knee pain after MPFLr is estimated to occur in 30% of cases [32]. A normal MPFL is tighter in extension than in flexion [6]. When the femoral fixation point is placed too anteriorly, the graft tightens when the knee is flexed [6]. At the mid-term, it might provoke a severe patellar chondropathy as well as PFOA in the long-term. Thaunat and Erasmus [33] suggested that an overly far proximal femoral attachment point Revision Surgery After Failed MPFLr 4.1 How Should We Plan It? To plan a revision surgery on a patient with a failed MPFLr, a dynamic 3D-CT study at 0º, 30º, 60º, 90º and 120º of knee flexion is performed [6]. The objectives are to locate the femoral attachment point and to evaluate the kinematic behavior of the graft in vivo. Evaluation of the length change behavior of the graft with knee flexo-extension is very important because it indirectly allows us to know whether the graft is taut in flexion or not [6]. Take note that a non-anatomic femoral fixation point is not necessarily associated with a failed reconstruction. In other words, the expected long-term clinical result should be good if an MPFLr has a non-anatomic femoral fixation point but in the in vivo kinematic study it has an adequate change of length pattern and an optimal isometry from 0 to 30º [6]. Hence, the persistent pain and instability could not be attributed to this non-anatomic femoral fixation point. Thus, causes of graft failure other than the choice of the femoral fixation point should be highlighted.
298 V. Sanchis-Alfonso and C. Ramírez-Fuentes Fig. 16 CASE # 6. A 30-year-old female patient suffering from very severe left AKP had had an MPFLr done. It had been carried out with a partial thickness quadriceps tendon. Clinically, there was no evidence of patellofemoral tracking disorders (negative J-sign). Despite having an intact MPFL, the patella could be dislocated laterally while the patient was under general anesthesia. In her case, the instability was caused by an inappropriate graft length change pattern during knee flexion and extension. The lateral patellar instability and the pain completely went away following an anatomic double-bundle MPFLr with a semitendinosus tendon graft. (Reused with permission from Baishideng Publishing Group Inc. From Sanchis-Alfonso V, et al. Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies. World J Orthop, 2017; 8(2): 115– 129) 4.2 General Principles in the Management of Failed MPFLr question, we will not be able to find a solution to the problem that our patients present. A knowledgeable surgeon and a correct diagnosis of the failure are crucial factors to resolve a “Failed MPFLr”. There is a key question that we must ask ourselves. Why did the previous surgery fail? If we do not find an answer to this 4.2.1 Confirm Diagnosis Stress X-rays can confirm the diagnosis. We must apply force for medial and lateral displacement of the patella. Then, we measure the displacement, compare it with the contralateral normal knee, and record it.
The Failed Medial Patellofemoral Ligament … 4.2.2 Define the Deficient Restraints Which Caused the Instability—Reconstruction of the Deficient Restraints and Limb Realignment When It is Grossly Abnormal What causes patellar instability? That is the key question when we indicate surgery to a patient with CLPI. Patellar Instability is the result of a failure of the patellar restraints (MPFL, lateral retinaculum and trochlear geometry) and an increment of the lateral vector of the quadriceps. This vector is increased by knee valgus, increased internal torsion of the femur and increased external torsion of the tibia (abnormal limb alignment). Instability occurs in the range between 0º and 30º of knee flexion in approximately 70% of the cases. In this range-of-motion, patellar stability depends mainly on the MPFL [14]. Beyond 30º of knee flexion, patellar stability mainly depends on the bony anatomy of the femoral trochlea and femoral anteversion [14]. The primary soft tissue restraint to lateral patellar dislocation is the MPFL. That is the reason why MPFLr is very important. Trochlear dysplasia will cause stress on the MPFL for which this ligament is not designed. The lateral retinaculum prevents lateral displacement of the patella. Therefore, an increment in lateral patellar instability is expected after LRR. 4.3 Steps In Revision MPFLr Surgery 4.3.1 Correction of Patellofemoral Tracking When there is a maltracking (positive J-sign), the first step would be to correct it. In my series, the most frequent cause of patellar maltracking is severe trochlear dysplasia. However, in some cases, the patellar maltracking is secondary to excessive femoral anteversion. Trochleoplasty should be only performed when the patella dislocates at high degrees of knee flexion, mostly in revision surgeries. When the maltracking can be detected only actively, selective epidural 299 analgesia can help to evaluate intraoperatively the active patellar excursion after realignment surgery. After realignment, the anesthesiologist wakes the patient and we ask her to flex the knee (see Video Case # 6). In this way, we can observe the correction of the patellofemoral tracking after sulcus deepening trochleoplasty before fixing the MPFL. 4.3.2 Stabilization of the Patella Once the patellofemoral maltracking has been corrected, we stabilize the patella by performing an MPFLr. In some infrequent cases, once the MPFL has been reconstructed, patellar tilt may still be abnormal. In these cases, a third surgical step in the lateral retinaculum (LR) may be necessary to achieve good patellofemoral balance. The decision to operate or not on the lateral patellar retinaculum is an intraoperative decision based on the patella tilt test [34]. To do this test, a transverse K wire is placed in the proximal patella, from medial to lateral. With the knee in full extension and at 20º of flexion, the K wire should be parallel to the surgery table. If the K wire is tilted (positive test) within this range-of-motion, lateral patellar retinaculum lengthening is needed. In cases of multidirectional patellar instability, the LR reconstruction should be the final step. The reason we perform LR reconstruction as the last step is because MPFLr not only stabilizes the patella laterally but also medially. To guide the patella towards the trochlear sulcus during the first degrees of knee flexion, both the MPFL and the LR must interplay in a harmonious way. Both ligaments behave similarly to the reins of a horse. Both reins must have some degree of tension. They are not very tense but they are not loose either. If one of the reins is completely loose, the horse is inclined towards the opposite direction as occurs in the patella. This patellofemoral imbalance may be responsible for pain. Following the same simile, we can compare the patella with the mouthpiece and the trochlea with the tongue. If we tense the reins very much we will nail the mouthpiece into the tongue and that hurts the horse. Similarly, if we tense both ligaments during surgery, we will
300 increase the patellofemoral joint reaction and it will provoke a patellar overload and patellar chondropathy and PFOA in the long-term. 4.3.3 Patellar Chondropathy. What Can We Do? Patellar condropathy is very common in cases of CLPI (Figs. 17 and 18). We only remove unstable cartilage flaps, but other cartilage lesions are not addressed. Patellar chondropathy could be responsible for AKP in the patient with CLPI. However, in the vast majority of the cases, once the patella has been stabilized, the pain disappears even though the chondral lesion is left alone. Loose bodies are removed. Fig. 17 Patellofemoral chondropathy after an inadequate MPFLr. In this case, the cartilage lesion was left alone, and only patellofemoral balance was corrected by means of a new anatomic MPFLr and an LR lengthening procedure. The patient is pain-free even though nothing was done to the cartilage. Moreover, the patellar tilt was V. Sanchis-Alfonso and C. Ramírez-Fuentes 4.4 Complex Revision Cases—MPFLr Without Bone Tunnels In multi-operated patients, revision surgery might be a real challenge because we have found multiple tunnels and implants in both the patellar insertion area as well as in the femoral insertion area. Therefore, there may be an increased risk of patella fractures as well as tunnel collisions that may compromise the fixation. In these cases, we might consider surgical techniques without bone tunnels. One option would be to use an autologous quadriceps tendon graft along with its native patellar insertion site and using the AMT not completely corrected. A Preop-CT. B Iatrogenic patellar chondropathy. C Postop-CT. (Republished with permission of AME Publishing Company. From V Sanchis-Alfonso, Treating complications of operative management for patellofemoral pain, Ann Joint, 3:27, 2018) Fig. 18 Patellofemoral chondropathy after an inadequate MPFLr. In this case, the cartilage lesion was left alone, and only a new anatomic MPFLr was performed. The patient is pain-free even though nothing was done to the cartilage
The Failed Medial Patellofemoral Ligament … as an elastic femoral fixation. With this technique, we avoid a two-stage procedure. 4.5 Outcomes After Revision Surgery Chatterton and colleagues [35] have reported acceptable patellar stability after revision surgery. However, knee pain and subjective outcomes do not improve significantly. In this sense, Zimmermann and colleagues [36] have observed better outcomes when revision surgery is performed to solve recurrent instability than when it is performed for patellofemoral pain or limitation of the range of mobility. 5 Take Home Messages – An MPFLr should not be performed if the patella cannot be laterally dislocated. – An MPFLr does not work to pull the patella into position. Its role is only to stabilize the patella once the patellofemoral tracking has been corrected. – An anatomic femoral fixation point is an easy and reproducible way to achieve the optimal length change behavior of the graft with knee flexo-extension to obtain satisfactory longterm clinical results. – To avoid a failed MPFLr, we must respect the anatomy. – Not all patients with lateral patellar instability are equal. The etiology of lateral patellar instability is multifactorial. Therefore, there are several subsets of patients with lateral patellar instability. In that light, treatment must be tailor-made. – In cases of multidirectional instability, we must first correct the maltracking. Second, we must reconstruct the MPFL. The final step is to reconstruct the LR. 301 6 Key Message – A failed MPFLr can be more disabling than primary patellar instability. Some patients who have experienced more than one patellar dislocation are still highly functional and may not need surgery. Only when patients are significantly limited in their daily living activities should the MPFLr be considered. We must be extreme care with recommending surgery. References 1. Schneider DK, Grawe B, Magnussen RA, et al. Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent lateral patellar dislocations: a systematic review and meta-analysis. Am J Sports Med. 2016;44:2993– 3005. 2. Sanchis-Alfonso V. Guidelines for medial patellofemoral ligament reconstruction in chronic lateral patellar instability. J Am Acad Orthop Surg. 2014;22(3):175–82. 3. Zhang Z, Song GY, Zheng T, et al. The presence of a preoperative high-grade J-sign and femoral tunnel malposition are associated with residual graft laxity after MPFL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2021;29(4):1183–90. 4. Parikh SN, Nathan ST, Wall EJ, et al. Complications of medial patellofemoral ligament reconstruction in young patients. Am J Sports Med. 2013;41 (5):1030–8. 5. Walker M, Maini L, Kay J, et al. Femoral tunnel malposition is the most common indication for revision medial patellofemoral ligament reconstruction with promising early outcomes following revision reconstruction: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2021. https://doi.org/10. 1007/s00167-021-06603-x. 6. Sanchis-Alfonso V, Ramírez-Fuentes C, MontesinosBerry E, et al. Femoral insertion site of the graft used to replace the medial patellofemoral ligament influences the ligament dynamic changes during knee flexion as well as clinical outcome. Knee Surg Sports Traumatol Arthrosc. 2017;25:2433–41.
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Surgical Treatment of Recurrent Patellar Instability: History and Current Concepts Christopher A. Schneble, David A. Molho, and John P. Fulkerson 1 Introduction: Background and History Treatment for recurrent patella instability in the 1970s and 1980s centered around two main schools of thought: John Insall’s viewpoint, which advocated for an aggressive lateral advancement of the medial soft tissue [1], and the collective position of Hauser, Southwick, Trillat and Elmslie who supported the use of a standalone tibial tubercle transfer [2–4]. Both schools of thought were effective in preventing recurrent patella dislocation [5–9]. Despite short term success, both the imbrication type procedures and the posteromedial tibial tubercle transferring osteotomies (TTOs) eventually often led to medial patellofemoral arthritis [7, 10, 11]. Many of the stand-alone tibial tubercle transfers, notably the Hauser procedure, resulted in movement of the patella quite far medially, distally, and posteriorly along the proximal tibia. This often would induce altered articular loading, eventually leading these patients to develop arthritis C. A. Schneble D. A. Molho J. P. Fulkerson (&) Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT, USA e-mail: john.fulkerson@yale.edu C. A. Schneble e-mail: Christopher.schneble@yale.edu D. A. Molho e-mail: david.molho@yale.edu from persistent overload [2, 12]. Around the same time, Maquet proposed anteriorization of the tibial tuberosity to unload an arthritic patellofemoral joint [13, 14]. The Maquet procedure became an effective option for alleviating arthritic patellofemoral pain, but anteriorization alone fell short in resolving patellofemoral instability [15]. During the late 1970s when surgical treatments for patellar instability were continuing to evolve, John Fulkerson was receiving his training under Wayne Southwick. Southwick’s approach for surgically addressing recurrent patellar instability often involved a dovetailed patellar tendon transfer that moved the tibial tuberosity medially [3]. The insight that Fulkerson gathered from these experiences led him to consider tibial tuberosity transfers as his preferred technique for patella stabilization. For the rest of his career he sought the optimal implementation of TTOs in the treatment of recurrent patella instability. In 1983, John Fulkerson first described the anteromedial tibial tuberosity transferring osteotomy (AMTTO) for the treatment of patellar malalignment [16], as well as for lateral patellofemoral arthritis, which at the time was called excessive lateral pressure syndrome by Paul Ficat [17–19]. The AMTTO combined the benefits of articular unloading with those of improved extensor mechanism vector alignment [16]. This also came with the added benefit of bone-to-bone healing at the osteotomy site without distraction © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_21 305
306 C. A. Schneble et al. Fig. 1 A, B Bilateral Merchant axial radiographs of a patient with recurrent right patellar instability and recurrent dislocations. On subsequent follow-up examinations she exhibited persistent lateral tracking. The top row of images (1A) was immediately after the first dislocation event for the right knee, showing increased lateral subluxation and tilting in comparison to the nonsymptomatic left side. The bottom row of images (1B) were acquired a few years later following multiple repeat dislocations on the right, while the left side remained asymptomatic. Progression of lateral patellar tilting and lateral subluxation can be seen. It is important to note that the magnitude of patellar tilt and subluxation can be be dampened on axial radiographs with knee flexion beyond 30 degrees across the osteotomy site as seen in a Maquet procedure [20, 21]. AMTTO was effective in minimizing the likelihood of medial patellofemoral overload and subsequent arthritis due to over medialization, posteromedialization or distalization during the previously described patellar tendon transfers [22–24]. Fulkerson was a strong advocate for using AMTTO procedures to treat lateral patellar instability for almost 20 years, finding the procedure to work remarkably well for both recurrent patellar instability and the prevention of overload induced arthritis [11, 25– 27]. Jack Farr, William Post, Brian Cole, John Albright, Seth Sherman and others have all contributed towards our understanding of how effective an AMTTO can be [19, 28–32]. A salient lesson gathered from Fulkerson’s experiences was that the correction of a laterally tracking extensor mechanism was rather effective at preventing recurrent instability. Even without medial patellofemoral reconstruction, anteromedialization (AMZ) of the tibial tuberosity surfaced as a viable solution for restoring patellar stability in most patients who had evidence of a laterally tracking patella on Merchant view axial radiographs [16, 25, 27] (Fig. 1A, B). The notion that correction of a laterally tracking vector alone can often result in adequate stability became an important principle in John Fulkerson’s practice. Despite the utility of a TTO, restoring soft tissue support can improve success rates, particularly in patients with trochlea dysplasia, while adding little additional risk when done properly [33–36]. In contrast, failure to balance lateral tracking, by either a medial or anteromedial TTO, can leave a patient vulnerable to late patellofemoral arthritis secondary to lateral focal overloading (Fig. 2A–C). Apart from the tibial tubercle, other osseous locations can be osteotomized for treatment of patellofemoral instability. Robert Teitge correctly pointed out that patellar instability can be related to femoral rotation problems, including excessive femoral anteversion that results in a more lateralized extensor mechanism vector [37]. He went on to suggest that a femoral derotational osteotomy would be an appropriate treatment option [37]. Performing a compensatory TTO, however, proves to be a much more benign and consistently effective treatment, so few orthopedic surgeons do femoral de-rotation
Surgical Treatment of Recurrent Patellar Instability … A B 307 C Fig. 2 A–C Radiographic and arthroscopic images of a patient who developed lateral focal articular overloading from persistent lateral patellofemoral instability. Figure A shows a 30-degree Merchant axial radiograph with joint space narrowing laterally, osteophyte formation, and slight lateral patellar tilting and translation. Figure B shows an MRI of the same knee, however this was acquired in 20° of knee flexion. The magnitude of lateral patellar tilting and translation is more accentuated in this early flexion range. Articular cartilage wear and thinning along the lateral patellar facet is present. Figure C shows an intra-articular view of the lateral patellofemoral compartment as viewed from the anterolateral portal. The lateral patellar facet exhibits chondral fibrillation, fissuring and cartilage loss has extended down to nearly the level of the subchondral bone osteotomies for the treatment of patellar instability, even in the presence of excessive femoral anteversion, with an exception being if anteversion were to need correction for other reasons, in which case it will usually be done bilaterally. Since the time of Insall, an increased understanding of the intricate patellofemoral stabilizing anatomy has led to advancements in soft tissue stabilization procedures. João Ellera Gomes first described the notion of medial patellofemoral ligament (MPFL) reconstruction for the treatment of recurrent lateral patella instability in 1992 [38]. Subsequently, Don Fithian popularized the technique in the United States and referred to the MPFL as the primary restraint to lateral dislocation of the patella [39, 40]. In an attempt to translate the anatomical location of the MPFL to its corresponding radiographic position, Schöttle developed radiographic criteria that could be used to identify the femoral origin of the MPFL [41]. These criteria have proved helpful in MPFL reconstruction procedures, however others, like SanchisAlfonso, have emphasized the importance of an open dissection to assure precise, anatomical placement of the femoral tunnel in every case [42, 43]. MPFL reconstructions became very popular given they were, and continue to be, very effective procedures for treating recurrent instability [44]. Thanks to Mochizuki, Smigielski, Tanaka, Baldwin, Hinckel, Chahla, and others, the complex anatomy of the medial patellofemoral restraints have been further elucidated [45–50]. Their work identified the MPFL as only a portion of a much more intricate medial patellofemoral complex (MPFC), a term coined by Miho Tanaka [51, 52]. In a quest to understand the intricate medial patellofemoral anatomy, Tanaka described the midpoint of the proximal MPFC, located at the junction of the MPFL and the medial quadriceps tendon-femoral ligament (MQTFL) (Fig. 3A, B) [52]. With the MQTFL being roughly equivalent to the MPFL in resisting lateral patellar translation and dislocation, there has been an increased interest in reconstructing this portion of the complex [53–56]. Despite advancements in our understanding of the MPFC and the MQTFL, more time is still needed for long-term outcome studies to surface regarding MQTFL or combined reconstructions. Thus far, MQTFL reconstructions have shown promise as a viable option for restoring medial soft tissue restraint [56] (Fig. 4A, B). In addition to proximal patellofemoral restraints, there are also more distally located patellotibial and patellomeniscal restraints. Hinckel found that the distal medial restraints are primarily responsible for maintaining patellar stability in flexion [49, 57].
308 Fig. 3 A, B Figures 3A and 3B show are an artist rendition of the medial patellofemoral restraints. Figure A illustrates the medial side of the knee, with the medial patellofemoral complex (MPFC) marked by a gold star. Figure B illustrates an anterior view of the distal femur, and the bony undersurface of a reflected patella. The MPFC is outlined in light blue, extending from the medial femur to its insertion on the medial quadriceps A Fig. 4 A, B Axial right knee MRI slices of an adolescent patient with recurrent patellar instability and dislocations. The left image (A) was acquired after a traumatic dislocation that resulted in a medial patella osteochondral flap. She was treated with a medial patellofemoral ligament (MPFL) reconstruction and debridement of this osteochondral flap. Her instability unfortunately recurred C. A. Schneble et al. tendon (medial quadriceps tendon femoral ligament) and the medial osseous patella (medial patellofemoral ligament). AMT = Adductor magnus tendon; VMO = Vastus medialis obliquus; R = Rectus femoris; QT = quadriceps tendon; PT = patellar tendon; MCL = Medial collateral ligament; SM = Tibial insertion of semimembranosus; MQTFL = Medial quadriceps tendon femoral ligament; MPFL = Medial patellofemoral ligament B and two years later she presented with worsened patellar tilt and subluxation, which is exhibited in the MRI image on the right (B). Her physes were not yet closed, and she was successfully treated with a medial quadriceps tendonfemoral ligament (MQTFL) reconstruction without recurrence of instability
Surgical Treatment of Recurrent Patellar Instability … In recent years with MPFL reconstructions becoming more frequently performed, outcomes data has become more available. In 2018, Liu and Shubin Stein demonstrated that isolated MPFL reconstruction was effective at restraining the patella from lateral dislocation, even in patients with Dejour B and D dysplastic trochleae [58]. Further, MPFL reconstruction was shown to be effective in the setting of high TT-TG measurements, raising further questions about when a TTO of any sort is appropriate [58]. The concept of trochleoplasty was first raised by Albee [59], then Masse [60], being subsequently popularized by Schöttle, Dejour, Bereiter, Diduch, and others [61–66]. Often being performed to address patellar instability in Dejour B or D patients, little popularity was adopted in the United States because of the potential adverse effects on articular cartilage, the magnitude of the surgery, potential long-term consequences, and evidence suggesting a successful stabilization could be obtained without the need for trochleoplasty [63, 67–72]. While Hiemstra has indicated trochleoplasty is an acceptable procedure for instability in patients with high-grade dysplasia, outcomes data stems from lower evidence studies with substantial heterogeneity amongst study populations [63, 72, 73]. Additionally, Rouanet has noted concerningly high rates of arthritis occurring 15 years post-trochleoplasty [72]. Distalization of the extensor mechanism has been proposed for patients with patella alta to facilitate earlier engagement of the patella into the deeper distal portion of the trochlea [74, 75]. A distalizing TTO (DTTO), can achieve this, however it carries an increased risk of non-union that occurs as a result of the increased load experienced across the osteotomy site with knee flexion [76]. Although lateral instability is exceedingly more common, medial patellar instability can also occur. Sanchis-Alfonso described the risks and symptoms of medial patellar instability, often iatrogenic in nature, and suggested this diagnosis must be considered in patients with recurrent symptoms of instability after surgery [77]. 309 2 Putting It All Together: What Does Fulkerson Do Now? For patients with recurrent patellar instability, Fulkerson’s approach is a distillation of the work of many patellofemoral scholars. Ultimately, the goal is to design an optimal procedure, or combination of procedures, to maximize stability, function, and long-term joint preservation. Surgical planning for patellar instability can be complex particularly given the dynamic forces seen across the patellofemoral joint and the complex three-dimensional (3D) morphology of the trochlea. Traditional two-dimensional (2D) imaging gives only a glimpse of the whole multidimensional problem, limiting one’s ability to assess the confluence of factors that affect patellar stability. Cross sectional imaging provides a limited depiction of the trochlear topography that drives patellar instability. In many cases, however, this often adequate to successfully develop a treatment plan. An understanding of the dynamic plane of patellar tracking over the dysplastic trochlea, however, is often necessary to develop an optimal reconstruction plan in more complex cases. In most cases, instability is derived from several influencing factors. Treatments should be designed using information from the history and clinical examination, along with observations from gait and imaging. For instance, a patient with recurrent patellar dislocations, minimal Jsign, central tracking, a normal gait pattern, and mild to moderate trochlear dysplasia will likely do very well with a medial patellofemoral complex reconstruction alone, and further diagnostic studies likely are not needed. The majority of patients with recurrent patellar dislocations happen to fall in this category. Deciding when to add a TTO is challenging in some cases, making the history and physical examination even more critical. If there is increased ligamentous laxity, valgus, or internal rotation during gait, a more prominent J sign, obvious clinical lateral maltracking, or a history of failed prior surgery, one should consider a TTO and the potential benefit it may confer.
310 A good primary screening tool for deciding when to add a TTO is a properly done neutral rotation 30-degree knee flexion axial radiograph, known as a Merchant view, which can generally be acquired in the office. If the patella sits laterally on this view (see Fig. 1a, b) adding a TTO may be in the patient’s best interest. Other traditional radiographic measurements like the CatonDeschamps ratio (C-D ratio), the tibial tubercletrochlear groove (TT-TG) distance, the lateral trochlear inclination (LTI) angle, and the Dejour classification are also helpful in surgical decision making. With these clinical and radiographic parameters, one gains a general overview of the collective problem and whether a TTO will provide added benefit. Three-dimensional imaging can be very helpful when one is unsure about whether to perform a TTO. Using 3D images one can better discern the obliquity and curvilinearity of the trochlea, thereby providing an appreciation for the expected path of patellar tracking (Fig. 5a–c). In particular, one can infer the entry point for the patella as it enters the trochlea, and its coronal plane distance from the central trochlea. Threedimensional reformats from a 20-degree knee flexion weight bearing CT yields a very helpful depiction of how the patella engages with trochlea in early knee flexion. This early interaction of engagement is important in instability patients when considered in the context of a dysplastic trochlea and the aforementioned factors. Deciding whether to add a TTO also comes down to risk and reward for each patient. As part of this assessment the surgeon should gauge the following: 1. What is the projected risk of redislocation without a TTO? 2. What is the likelihood of developing lateral patellofemoral arthritis if a TTO is not done? 3. What is the patient’s healing and rehabilitation potential? Over time, certain findings have consistently influenced the likelihood that Fulkerson would C. A. Schneble et al. perform a TTO in a given patient, however no single finding was ever considered as absolute or in isolation. These findings are: 1. A prominent J sign with evidence of a lateral patella entry point 2. A TT-TG over 15–20 mm (causes consideration for the need to medialize the tibial tubercle) 3. C-D ratio > 1.3 (causes consideration for the need to distalize the tibial tubercle) 4. A curvilinear dysplastic trochlea 5. The presence of a connective tissue disorder, or ligamentous laxity 6. Evidence of excessive femoral anteversion 7. Evidence of patellofemoral articular damage that would benefit from the unloading effects of an AMTTO. It is important to synthesize the magnitude of contribution from each factor, and the risks associated with their correction. Not all forms of malalignment need be corrected when identified, but when found to confer a sizeable influence towards persistent instability they will often need to be addressed for successful treatment. Tibial tubercle transfer can serve as a powerful procedure, when indicated, with the potential to provide improved extensor mechanism tracking while also off-loading painful or progressive articular lesions. Compared to a TTO, trochleoplasty has been quite uncommon in Fulkerson’s approach to patellar instability over the years. Nonetheless, in selected cases, recession of a prominent proximal medial trochlear ridge or spur, usually done arthroscopically, has been performed occasionally, usually done to facilitate patellar entry into the femoral trochlea at the time of a concomitant distalizing tibial tubercle transfer, as recommended by Rush and Diduch [64]. In summary, recurrent instability of the patella can often be treated successfully by reconstruction of the medial patellofemoral complex (MPFC) in most patients, without additional procedures. If lateral maltracking is a definable
Surgical Treatment of Recurrent Patellar Instability … 311 Fig. 5 A–C From left to right, the top row depicts progressively distal axial MRI slices of a right distal femur afflicted with trochlear dysplasia and recurrent right patellar instability and dislocations. Prior medial patellofemoral ligament (MPFL) reconstruction was unsuccessful in preventing recurrence. The second row, from left to right, shows progressively distal axial CT scan slices. Both the MRI and CT images shown reveal a flattening of the trochlea consistent with dysplasia, however the nadirs of the trochlea at each slice level can be difficult to synthesize in order to garner a fluid understanding of what patellar tracking path would result in the most optimal bony constraint. The bottom series of images are 3Dimensional CT reformats that were created using ScanIP (Synopsys, Mountain View, CA). The red lines reveal the estimated deepest points of the trochlea along its entirety. Visualizing the trochlea in this manner, while also considering the extent of lateral bony constraint, can help one to understand and validate plans for tibial tubercle transferring osteotomies. It provides a more digestible, tangible depiction of the vector corrections necessary to result in the optimal pathway for patellar tracking problem, particularly when associated with a J-sign, a laterally curved trochlea, a distal or lateral articular lesion on the patella, ligamentous laxity, or patella alta, moving the tibial tubercle in addition to medial reconstruction is often indicated. Trochleoplasty is uncommon and is often reserved for unusual cases in which a prominent proximal medial ridge or spur exists or when a severely deformed trochlea requires alteration to facilitate tracking. This is typically less than 1% of all patella instability surgeries. References 1. Insall JN, Aglietti P, Tria AJ, Jr. Patellar pain and incongruence. II: clinical application. Clin Orthop Relat Res. 1983;(176):225–32. 2. Hauser ED. Total tendon transplant for slipping patella: a new operation for recurrent dislocation of the patella. 1938. Clin Orthop Relat Res. 2006;452:7–16. 3. Southwick WO, Becker GE, Albright JA. Dovetail patellar tendon transfer for recurrent dislocating patella. Jama. 1968;204(8):665–9.
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Chondral and Osteochondral Lesions in the Patellofemoral Joint Kevin Credille, Dhanur Damodar, Zachary Wang, Andrew Gudeman, and Adam Yanke 1 Introduction to Focal Cartilage Defects Focal cartilage defects may be associated with impaired quality of life in a similar manner to osteoarthritis. Patients can present with limited activity due to severe pain, recurrent effusions, dysfunction, and the eventual progression of joint degeneration [1, 2]. This is clinically important as between 30,000 and 100,000 procedures are performed each year in the United States to help treat and alleviate symptoms secondary to cartilage lesions in the knee [2]. Symptomatic lesions can present acutely as a result of trauma after anterior cruciate ligament (ACL) tears or patellar dislocations or chronically from repetitive patellofemoral stress often with a component of genetic predisposition. On the other hand, asymptomatic lesions can also occur and may be found incidentally at the time of MRI or arthroscopy and are NOT an indication for surgical intervention [3]. Regardless of the etiology, these defects may progress in light K. Credille D. Damodar Z. Wang A. Yanke (&) Midwest Orthopedics at Rush University Medical Center, Chicago, IL, USA e-mail: adam.yanke@rushortho.com A. Gudeman Indiana University School of Medicine, Indianapolis, IN, USA of the known poor regenerative properties of hyaline articular cartilage. In a subset of patients these focal lesions may eventually progress to osteoarthritis [4]. 2 Modified Outerbridge Classification / International Cartilage Repair Society (ICRS) Classification The two major cartilage lesion categorizations are the Modified Outerbridge Classification and the International Cartilage Repair Society (ICRS) Classification. The Outerbridge Classification was developed in 1961 and is based on inspection of the cartilage surface through arthroscopy and also through an open approach. Grade 0 is normal cartilage, grade 1 is cartilage softening, grade 2 are partial thickness fissures less than 1.5 cm, grade 3 are fissures greater than 1.5 cm with a full thickness fissure, and grade 4 is complete cartilage loss with exposed subchondral bone. The Modified Outerbridge Classification separated the dimensions from Grades 2 and 3. That is, the grades are as before except Grade 2 is now for lesions less than 50% in depth and Grade 3 lesion are from 50% to full thickness with the dimensions of the lesion reported independently. The ICRS Classification is also based on visual inspection of the cartilage surface. Grade 0 is normal cartilage, grade 1 lesions have softening, © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_22 315
316 K. Credille et al. blistering, and/or fissures, grade 2 lesions are fissures <50% of cartilage depth, grade 3 lesions are >50% cartilage depth, and grade 4 lesions are full-thickness lesions with exposure and involvement of the subchondral bone. 3 General Isolated Cartilage Lesion Evaluation At the time of presentation, patients do not report a chondral lesion. Rather, patients complain of pain and, at times, associated swelling, diminished motion, stiffness, and mechanical symptoms such as catching or locking [3]. Of note, knee effusions persisting after an aggravating event are one of the most important clinical indicators suggestive of an underlying cartilage injury. This type of effusion progresses slowly as opposed to acute effusions seen with cruciate ligament injuries or patellar dislocations. These slow, latent effusions are reflective of the insidious nature of chondral lesions. When a chondral defect of the knee is suspected, patients are questioned and examined for malalignment, knee instability, patellar instability, and other pathologies [3]. In patients with acute pain from a cartilage lesion, radiographs do not show pathology other than an effusion or loose body [5]. However, standard weight bearing knee radiographic views (AP and PA flexed) as well as standing long leg limb alignment films are required to rule out coronal plane malalignment as malignment in any plane may contribute to a failed cartilage restoration procedure [6]. MRI is also ordered to evaluate the location, size, and depth of cartilage defects and any concomitant ligamentous or meniscal pathology. Once a chondral lesion is identified as the root cause of a patient’s symptoms, non-operative treatment consisting of rest, non-steroidal antiinflammatory drugs (NSAIDs), steroid and hyaluronic acid injections, and physical therapy needs to be trialed for six weeks to six months before considering surgical options [3]. For lesions that fail conservative management, arthroscopic evaluation can be considered. Importantly, higher failure rates of cartilage restoration procedures occur when coexisting pathologies go unaddressed [6]. Therefore, ligament reconstruction, meniscal repair, or meniscal allograft transplant should precede or be addressed concomitantly with any cartilage defect repair procedures to minimize the excessive stress in the patellofemoral joint PFJ and increase the chances of a successful cartilage treatment [5]. Select patients may also need treatment concomitantly with a distal femoral osteotomy, proximal tibial osteotomy, or tibial tubercle osteotomy. 4 Evaluation of the Patient with Patellofemoral Specific Lesions Patellofemoral patients typically present with anterior knee pain with activities such as walking, stairs, squatting, jumping, or running as these increase contact pressures in the knee during flexion due to mechanical loading. While posterior knee pain can also be present, this is often secondary to an effusion and most patients will still localize their pain just deep to their patella. A subset will have patellar or trochlear chondral lesions. Locking and catching symptoms can also occur but are associated with chondral flaps. Clinicians should pay particular attention to acute and/or chronic nature of the patient’s patellofemoral instability and whether they are experiencing apprehension, subluxation, or full dislocations. It is important to uncover whether the patient’s pain is transient and occurs secondary to an acute subluxation or dislocation event or if it is a result of a persistent chondral defect stemming from chronic instability or malalignment [3]. At the time of physical and radiographic examination of patellofemoral lesions, focus should be paid to lower extremity alignment, the patient’s gait, and the patient’s Q angle. The Q angle is increased by a lateralized tibial tubercle, and valgus alignment and may appear decreased by chronic subluxation of the patella until it is reduced into the central trochlear groove. That is, the most accurate Q angle measurement needs to be made while the patella is in the trochlear
Chondral and Osteochondral Lesions in the Patellofemoral Joint groove and a Merchant extended goniometer extends to the ASIS. The knee should also be evaluated for effusion, patellar displacement in quadrants, patellar tracking during flexion and extension and evaluation for a J sign. Concomitant ligamentous injury should also be ruled out [3]. One should also perform the patellar grind exam by applying direct compression to the patella with translation. This may signify an underlying chondral lesion or stress overload. To best interpret the results of this test, it should also be performed on the contralateral knee [7]. If history and physical examination suggest the possibility of a patellofemoral cartilage defect, Merchant and lateral knee views will aid in the diagnose patella alta or patella baja via the Caton-Deschamps index [8], patellar tilt and subluxation, and bony contour indicative of trochlear dysplasia [9, 10]. MRI is essential to evaluate chondral and/or osteochondral lesions of the PFJ and other factors such as trochlear dysplasia [3]. While MRI is a helpful tool in the evaluation of chondral lesions, it may underestimate true lesion size by up to 60% and does not provide lesion structural or edge stability data like diagnostic arthroscopy [11]. However, it is important for identifying meniscal pathology, ligamentous injuries, subchondral bone edema, and patellar height and tibial tubercle to trochlear groove (TT-TG) distance which can be associated with developing cartilage defects [12]. One should also consider a CT arthrogram as an adjunct for patients with poorly visualized chondral lesions on MRI and significant patellar maltracking to help assess tibial version, plan osteotomies, and further evaluate bony anatomy (in cases with suspected axial malalignment, MRI or CT hip/knee/ankle assessment is indicated) [13]. If major anatomic factors placing the patient at increased risk for patellar dislocation or excess patellofemoral stresses are identified, the patient may end up needing concomitant procedures including, but not limited to a tibial tubercle osteotomy (TTO), medial patellofemoral ligament reconstruction, and lateral retinacular lengthening. These procedures serve to correct 317 pathologic anatomy that may have contributed the initial cartilage lesion and to decrease the contact stresses through mechanical offloading. An anteromedialization (AMZ) TTO is an example of a procedure that reduces the lateral force vector by moving the tubercle medially and reducing patella contact pressures by moving the patella tendon attachment anteriorly [5]. 5 General Indications for Cartilage Restoration Procedures In general, surgical treatment of full thickness cartilage lesions is reserved for persistently symptomatic patients who have failed conservative treatment or those with cartilage flaps and unstable osteochondral fragments. Full thickness lesions can be treated with a variety of surgical options including chondroplasty/debridement, open reduction and internal fixation (ORIF) of osteochondral fragments, microfracture, osteochondral autograft transfer (OAT), osteochondral allograft transplantation (OCA), and various cellbased techniques such as autologous chondrocyte implantation (ACI), matrix induced autologous chondrocyte implantation (MACI), and particulated juvenile allograft cartilage (PJAC) [3, 5]. For smaller lesions less than 2 cm2, debridement/ chondroplasty, microfracture, and OAT are the preferred treatment choices. OCA is preferable for larger lesions >2–4 cm2. Cell-based therapies like MACI and PJAC are also excellent for larger lesions, but are limited to lesions with minimal subchondral bone loss [14]. Deeper subchondral bone loss is better treated with OATs and OCAs, although bone grafting can be used with cellbased therapies in the setting of defects 8 mm at the time of cartilage restoration [15]. Patients younger than <55 generally qualify for cartilage restoration procedures versus total knee arthroplasty, but the primary criteria for this may depend upon how much healthy cartilage remains [16]. A person with several large lesions throughout the knee is more consistent with osteoarthritis and may fare better with a total knee or patellofemoral arthroplasty [5].
318 6 K. Credille et al. Debridement/Chondroplasty Chondroplasty is by definition a cartilage debridement and is one of the most commonly performed cartilage procedures [17]. In this procedure, a loose cartilage flap is debrided to a stable edge to reduce mechanical symptoms and prevent further propagation of the lesion from mechanical stress, as seen in Fig. 1. While this procedure is best suited for lesions smaller than 2 cm2, it can also be the first stage of cell-based cartilage procedures such as ACI, MACI, and PJAC [18]. While it is important to for debridement to create stable vertical walls, the negative effects of aggressively debriding tissue beyond areas of cartilage instability remains controversial [19], and it is crucial to avoid creating an uncontained lesions or exposing subchondral bone [20]. Clinical outcomes and proper characterization of cartilage debridement in the PFJ remain limited in the orthopedic literature. A case series performed by Anderson et al. in 2017 retrospectively identified 86 patients undergoing isolated cartilage debridement in the knee, with 58.5% of patients having lesions in the PFJ with Fig. 1 Arthroscopic image of a cartilage flap ICRS grades of 2–4 and mean size of 3.3 cm2. The authors found chondroplasty success was correlated with baseline presurgical PRO scores, male sex, and ICRS grade. On the other hand, lesion size, patient age, and obesity had no effect on surgical outcome [21]. In another retrospective case series performed by Federico and Ryder, 36 patients with patellar chondromalacia without a history of instability or malalignment who underwent patellar chondroplasty were examined and followed for an average of 59 months. Thirty-two (89%) of the patients reported the surgery had a beneficial effect and there was only a slight deterioration of results found at final follow up. Further, of the 29 patients playing sports preoperatively, 27 (93%) were able to return to play [22]. This indicates that chondroplasty has the potential to provide durable long term outcomes in the PFJ. 7 Bone Marrow Stimulation Bone marrow stimulation is achieved through a variety of techniques such as drilling, using K wires, and the microfracture technique which
Chondral and Osteochondral Lesions in the Patellofemoral Joint uses angulated awls. The goal of marrow stimulation is to promote fibrocartilage formation via migration of mesenchymal stem cells to the cartilage defect from subchondral bone [23, 24]. The threshold for performing bone marrow stimulation is restricted in the PFJ and should be 2 cm2 or less, due to the higher sheer stresses experienced in this joint compartment. It should be avoided in uncontained lesions altogether [25]. The authors advocate that bone marrow stimulation plays little to no role in the PFJ regardless of lesion size. Regardless of the marrow stimulation technique used, it is essential to perform a chondroplasty through the calcified cartilage to subchondral bone while creating stable vertical walls [19]. The bony perforations made with this technique must be perpendicular to the bone surface, which can be difficult to achieve for the patella via arthroscopy of the PFJ [3]. Sometimes a small arthrotomy is necessary for proper visualization, instrument angulation, and counter pressure that is necessary for lesions on the patella. For classic “micro fracture” each perforation must be at least 3 mm deep and spaced 3–4 mm apart from the others as seen in Fig. 2. Newer marrow stimulation techniques attempt as little bony injury as possible with very small (e.g., 1 mm) drill bits and drill to a depth of 6–10 mm to access more marrow derived cells. The injury to the bone surface will promote Fig. 2 Shows bony perforations spaced appropriately at approximately 3–4 mm apart from each other at the bed of a cartilage lesion 319 inflammation, bleeding, clot formation, and mesenchymal stem cell migration to the site of injury. It should be noted that while these cells will produce collagen and cartilage to repair the cartilage defect, it is fibrocartilage, which biomechanically inferior to the native hyaline cartilage typically found at the bone surfaces of joints [19]. Most of the outcome studies related to bone marrow stimulation combine data from both the tibiofemoral joint (femoral condyles) and PFJ, as there is limited data available on isolated patellar microfracture. The majority of these studies demonstrate low failures rates in the short-term at 2 years follow up in lower demand patients with smaller defects, with increases in long-term failure rates after 2–5 years of follow up [25–27]. Kreuz et al. evaluated full thickness cartilage lesions in 85 patients in different anatomic locations in the knee including the femoral condyle, tibia, trochlea, and patella. Patient reported outcomes were strong at 6-months and 18-months but started to deteriorate at the 2-year mark and MRI measured defect filling deteriorating at 36-months, with the trochlear and patellar patients declining more rapidly than the other groups [28]. Additionally, it has been shown that microfracture can negatively impact the success rates of subsequent cartilage restoration procedures. Minas et al. demonstrated an ACI failure rate of 26% after a prior marrow
320 K. Credille et al. stimulation procedure compared to a primary ACI failure rate of only 8%. The authors concluded that limiting bone marrow procedures in the PFJ to chondral lesions smaller than 2 cm2 and limiting it to the trochlea would maximize the chance of achieving a successful outcome if subsequent procedures were needed [29]. 8 Osteochondral Autograft Transplant (OAT)/Mosiacplasty Osteochondral autograft transplant is a cartilage restoration technique reserved for smaller osteochondral lesions <2–3 cm2 that involves harvesting 6–15 mm cylindrical cartilage plugs from non-weight-bearing portions of the ipsilateral knee such as the peripheral margins of the Fig. 3 Shows an OAT plug after harvest in the top part of the image and a smooth articular surface after plug implantation trochlea, posterior condyles, or intercondylar notch, and re-implanting them in the weight bearing chondral defect. For larger defects, numerous plugs are used in a mosaic pattern to provide lesion coverage [5, 19]. A harvested OAT plug is shown in Fig. 3. The plugs offer the advantage of transferring a native hyaline cartilage surface attached to underlying subchondral bone in a single-stage procedure, which facilitates healing. If any cartilage gaps are still present after autograft plug transfer, fibrocartilage will end up filling in the periphery of the autografts and augment the transferred native cartilage. The procedure is typically performed through an open arthrotomy, however newer techniques have evolved to allow this procedure to be performed arthroscopically [5]. Stable fixation is typically achieved without hardware as
Chondral and Osteochondral Lesions in the Patellofemoral Joint the autografts are often press fit after preparation of the cartilage defect [30]. While OAT is an autograft and avoids immunologic complication risks, there are still concerns for donor site morbidity, which limits the use of OAT in larger lesions >2–3 cm2 that may require mosaicplasty [31]. Additionally, creating a surface that matches the native cartilage contour is essential for achieving successful outcomes and is especially difficult with larger lesions [5]. It has been shown that autograft prominence as little as 1 mm can lead to catching and locking symptoms months after the procedure. For the PFJ, interface mismatch is more common and complicated by the unique anatomy of the trochlea and patella coupled with the patella having the thickest cartilage of any recipient site in the knee [19]. Outcomes studies for OAT in the PFJ report inconsistent success rates. Hongody et al. reported a 79% rate of good to excellent outcomes after mosaicplasty in the PFJ at long term 10-year follow up [32]. However, another prospective study by Baltzer et al. of 112 patients with chronic chondral lesions of the knee demonstrated retropatellar defect location (n = 25) as the strongest predictor of poor outcomes. However, this study failed to take into account the effects of PFJ malalignment [33]. Many authors believe that malalignment of the PFJ impacts the outcome in OAT. As an example, a study by Astur et al. found significantly improved clinical outcomes at 1 and 2-years follow up of <2.5 cm2 full-thickness cartilage lesions when PFJ malalignment patients were excluded [34]. This is further supported by recent research. For example, Emre et al. recently performed a study of isolated OAT in the PFJ with all 33 patients reporting improved outcomes at a mean followup of 19.3 month [35]. In another recent study, Yabumoto et al. examined isolated OAT in the PFJ with all patient reported outcomes showing improvement at a mean follow up of 46.9 months [36]. Both Emre et al. and Yabumoto et al. concluded that OAT is particularly effective even in the long-term when meticulous attention is paid to achieving a high surface congruity. 9 321 Osteochondral Allograft Transplantation (OCA) Osteochondral allograft transplantation (OCA) is indicated for large cartilage defects >2–4 cm2 with or without damage to underlying subchondral bone, as its use in pure chondral lesions is increasing [37]. It is arguably the most complex cartilage procedure of the PFJ. Indications include treatment of contained or uncontained cartilage lesions, meaning it can be used whether the lesion has surrounding articular cartilage or not [5]. Additionally, OCA can serve to treat bipolar lesions and as a salvage procedure after other cartilage restoration techniques have failed to provide pain relief and delay arthroplasty in younger patient populations [38, 39]. Relative contraindications include smoking, steroid use, and obesity as high failure rates have been demonstrated in these patients [5]. The surgical technique shares a lot of similar principles to OAT, being that it requires press fitting of a harvested implant and that surface topography matching is integral to procedure success. It is also a single-stage procedure but unlike OAT it does not carry any donor site morbidity as it is an allograft donor. However, a downside to OCA is the logistical constraints to matching a donor to the patient and scheduling surgery accordingly. Newer technologies such as cryopreserved OCAs have been invented to circumvent these constraints [40]. OCA requires an arthrotomy to place a size and topography matched donor allograft that press fits into a well-prepared defect that has been debrided down to a health stable rim as seen in Fig. 4. Its use in the PFJ is likewise complicated by the complex anatomy of the patella and trochlea and patellar cartilage thickness. Since this technique uses an allograft, fresh OCAs are harvested within 24 hours of a donor’s death and preserved for up to 28 days at 39° Fahrenheit [19]. Overall, the OCA failure rates have been demonstrated to be higher in the PFJ than the tibiofemoral joint space. A systematic review performed in 2016 by Assenmacher et al. showed success rates of 76% in the tibiofemoral joint
322 K. Credille et al. Fig. 4 Shows an OCA press fitted into a previously well prepared and debrided lesion with topography matching. space versus 50% in the PFJ at a mean follow-up of 12.3 years. In this study, the PFJ group had a reoperation rate of 83% compared to 34% for defects involving the tibial plateau or femoral condyles [41]. Unfortunately, there is a paucity of randomized control trials examining patellofemoral OCA. There are, however, several cohort studies reporting on patellofemoral outcomes for trochlear and patella OCA. A retrospective case series performed by Gracitelli et al. studied 28 knees with patellar lesions that underwent OCA with a mean follow up of 9.7 years and found 78.1% graft survivorship at 5 and 10 year follow up and 55.8% graft survivor ship at 15 years follow up. In another retrospective case series by Cameron et al. evaluating trochlear OCA on 29 knees with a mean follow up of 7 years, the authors found 100% graft survivor ship at 5 years and 91.7% graft survivorship at 10 years with improvement of all patient reported outcomes [42]. In addition, both studies showed an overall patient satisfaction rate of 89%. Thus, both studies demonstrate good 10-year outcomes for OCA in the PFJ and highlight its potential use as a salvage procedure prior to arthroplasty for large, isolated chondral defects. 10 Matrix Induced Autologous Chondrocyte Implantation (MACI) / Autologous Chondrocyte Implantation (ACI) Matrix induced autologous chondrocyte implantation (MACI) is a two-stage procedure that treats full thickness cartilage defects that are typically >2 cm2 without bony involvement. This procedure and its predecessor ACI allow for much easier topography matching in the PFJ than OAT or OCA [3]. Initially, healthy chondrocytes are typically harvested arthroscopically at the time of an initial staging and debridement procedure. The chondrocytes are then colony expanded in culture, and subsequently attached to a collagen membrane. Then, in a second procedure, the defect is debrided down to the calcified cartilage level and stable vertical walls are created typically and a mini parapatellar arthrotomy is used to enhance visualization. Then the membrane custom trim fitted into the debrided cartilage defect. This can be achieved by using a free hand technique by using pre-shaped cutting tools [43]. The implant is secured in the defect
Chondral and Osteochondral Lesions in the Patellofemoral Joint Fig. 5 Demonstrates a successful implant of the MACI membrane after fibrin glue has been applied and cured using a layer of fibrin glue in the defect bed and then another thin layer also placed above the membrane and given time to cure as seen in Fig. 5. One can also use sutures or suture anchors if needed for membrane fixation. Eventually, the goal is for the healthy autologous implanted chondrocytes to incorporate into the exposed bone and migrate/expand to fill the defect evenly. Due to the nature of this surgical technique, it has the advantage of fitting into lesions of a variety of different shapes and sizes, which is particularly useful in the PFJ [5]. The first-generation autologous chondrocyte implantation (ACI) was born out of the 1990s in the effort to supplant and improve upon the outcomes being achieved with microfracture and other cartilage restoration techniques. It grew in popularity due in large part to its ability to regenerate native hyaline cartilage and repair full thickness cartilage defects. Eventually, ACI was found to produce what researchers and clinicians alike desired: better long-term clinical outcomes with a more cost-effective technology than microfracture [44]. Since the inception of ACI, a second-generation technology has been developed using bi-layer collagen membranes and 323 MACI, the third-generation technology, was created by seeding chondrocytes onto matrices of collagen [45]. It should be noted that a common complication of MACI/ACI is graft hypertrophy given the cell-based nature of the technology [46]. As for MACI outcomes, Brittberg et al. performed a large scale prospective, multicenter, randomized trial comparing MACI and microfracture in lesions >3 cm2. The authors found improvements in patient reported outcomes at 2 and 5 years of follow up of MACI as compared to microfracture [47]. MACI/ACI has been well studied in the PFJ in contrast to many other cartilage restoration techniques and initially reports of ACI in this region were disappointing. However, with the emergence of better understanding of PFJ biomechanics and concomitant treatment of malalignment, ACI outcomes improved even in the mid to long term [48, 49]. A prospective cohort study by Keudell et al. examined patients with isolated patellar chondral lesions treated by ACI and found a 90% success rate at 15 years with 83% of patients reporting good to excellent outcomes at that time point [50]. A recent systematic review of 58 studies by Andriolo et al. found an overall failure rate of 14.9% for ACI/MACI mostly occurring within the first 5 years of follow up with no differences found between ACI and MACI [51]. In another systematic review by Schuette et al. of patients undergoing MACI of the knee joint, the authors found a 12.4% failure rate in the tibiofemoral joint versus 4.7% in the PFJ [52]. These results suggest that MACI/ACI are potentially better longer term treatments for chondral lesions in the PFJ, especially when PFJ malalignment is concomitantly treated. This is further supported by a recent meta-analysis by Hinckell et al. showing a success rate of 96.1% for 1274 cell-based cartilage restoration procedures, 1229 of which were MACI/ACI. Lastly, while MACI/ACI are both expensive, they may end up being similarly costeffective to other cartilage procedures given that they delay other costly procedures such as arthroplasty [19].
324 11 K. Credille et al. Particulated Juvenile Allograft Cartilage Particulated juvenile allograft cartilage (PJAC) is another cell-based cartilage restoration technique used for full-thickness chondral lesions 1–6 cm2 and ICRS grade 3 or higher without bony involvement [19]. PJAC is used preferentially in the PFJ but can still be utilized in the TFJ. Akin to MACI/ACI, this technique evolved from research efforts to expand the chondral lesion treatment arsenal for orthopedic surgeons and offers the same ease of surface contour matching. An additional benefit of PJAC compared to MACI/ACI is that it is a one-stage procedure. PJAC shares graft hypertrophy as a common complication with MACI/ACI as they are both cell-based techniques [46]. PJAC is initially harvested from the femoral condyles of pediatric donors, with a viable shelf life of 45 days. Each PJAC package contains 30–200 cubes of minced graft tissue and one package is capable of treating a full-thickness cartilage lesion up to 2.5 cm2, with larger lesions treated with multiple PJAC packages [2]. Mincing the graft allows chondrocytes to migrate from extracellular matrix and form native hyaline cartilage [53]. Furthermore, the advantage of using pediatric cartilage rather than adult tissue is that juvenile chondrocytes are capable of producing more extracellular matrix and proteoglycan content and thus have a more favorable cartilage gene expression profile [54, 55]. For implanting the graft, a similar defect preparation is used to that of MACI/ACI. The defect is debrided down to the calcified cartilage level and stable vertical walls are created typically via a mini arthrotomy similar to MACI/ACI. Once the defect is prepared, the minced PJAC cubes can be placed directly into the defect or prepared extra-articularly. Regardless of the method used, cubes should be spaced 1–2 mm apart in one layer and the top layer needs to be 1 mm below the periphery of the cartilage defect [2]. This ensures minimization of the shear stress and compressive biomechanical loading on the graft that might occur if the implant sits proud to the defect perimeter [56]. If the lesion is uncontained and there are concerns for excessive biomechanical sheer and compressive stresses, commercial collagen can be sutured or anchored to the cartilage wall defect extensions. This technique for treating uncontained lesions can also be applied to other cell-based techniques like MACI/ACI [57] (see Fig. 6). However, outcomes studies for PJAC remain sparse, are limited to case series or case reports and most of the PJAC research has been focused on lesions in the talus. Regardless, there is still some existing data. Recently, there was a prospective case series performed by Wang et al. of 27 patients treated for patellofemoral cartilage defects with an average of 3.84 years of followup. Patients in this study experienced statistically significant improvements in patient reported outcomes. Additionally, at the 2-year follow up MRI, nearly 70% of patients had more than twothirds of their defect filled [46]. Several other single arm studies have shown similarly favorable results for patients with patellar and trochlear cartilage lesions in the short-term and medium-term follow up [58–61]. Future studies will need to focus on long-term outcomes and head-to-head comparisons with other cartilage restoration techniques. 12 Post-operative Rehabilitation Cartilage restoration procedures have a variety of protocols aimed at protecting their repair. Range of motion exercises are usually started within the first week post-operatively to encourage cartilage healing and prevent stiffness. Weight bearing varies based on the procedure type and surgeon preference. Chondroplasty, for example, will be weight bearing as tolerated immediately while full weight bearing in extension is often the case for one or two weeks after patellofemoral cartilage procedures with the exception of marrow stimulation, MACI, and PJAC. The latter three procedures require six weeks of protected weight bearing before progression to full weight bearing to give time for a mature cartilage surface to
Chondral and Osteochondral Lesions in the Patellofemoral Joint 325 Fig. 6 Shows properly spaced minced PJAC cubes 1–2 mm apart sitting more than 1 mm below the periphery of the cartilage lesion form. For OCA, there is generally a slightly faster return to weight bearing before six weeks depending on physician preference [62]. 13 Conclusion As a patient is evaluated for a chondral defect in the PFJ, surgeons should comprehensively assess all factors that impact the etiology of a presenting lesion. Anatomic factors including PFJ alignment, concomitant meniscal or ligamentous injury, lesion size and depth, involvement of subchondral bone, and the amount of remaining cartilage in the PFJ overall should be evaluated. With the appropriate indications, good to excellent outcomes can be achieved. Chondroplasty and OAT can help treat patients with small lesions <2 cm2. Larger lesions will require OCA, MACI, or PJAC. Further head-to-head comparisons of these restoration procedures will be needed to fully determine the most cost-effective and efficacious procedures available for patients. 14 Key Message Treatment of chondral lesions in the PFJ requires a multifaceted approach as it involves management of the higher biomechanical stress of the PFJ, addressing malalignment issues concomitantly, anatomical differences such as thicker cartilage of the patella and complex anatomy of the patella and trochlea. Treatment choice requires careful consideration as differing outcomes studies exist between the PFJ compared to the tibiofemoral joint (TFJ). 15 Seven Take Home Messages 1. It is important to not immediately focus on the chondral lesion. The key to successful management is to first identify all the potential pain generators. As cartilage is aneural, “assigning the pain” to the cartilage lesion is a diagnosis by exclusion.
326 2. As a patient is evaluated for a chondral defect in the PFJ, surgeons should comprehensively assess all factors that impact the etiology of a presenting lesion: PFJ alignment, meniscal and ligamentous status, lesion size, depth, and location, involvement of subchondral bone, and amount of remaining cartilage in the PFJ. 3. Associated patellofemoral malalignment and instability can be addressed with concomitant mechanical procedures such as tibial tubercle osteotomy, medial patellofemoral ligament reconstruction, and lateral retinacular lengthening. 4. Small chondral lesions <2 cm2 that have failed nonsurgical management should be considered for chondroplasty, osteochondral autograft transplant (OAT), or particulated juvenile allograft cartilage (PJAC) 5. Larger chondral lesions >2–4 cm2 require osteochondral allografts (OCA), matrix induced autologous chondrocyte implantation (MACI/ACI) or even PJAC. 6. Larger lesions >2 cm2 with subchondral bone loss 6–10 cm2 = OAT or OCA and represent a strong opportunity to be a salvage procedure prior to the necessitation of arthroplasty. PJAC and MACI/ACI are contraindicated without addressing bony involvement. 7. MACI/ACI and PJAC provide easier topography matching than OCA or OAT. References 1. Heir S, Nerhus TK, Røtterud JH, et al. Focal cartilage defects in the knee impair quality of life as much as severe osteoarthritis: a comparison of knee injury and osteoarthritis outcome score in 4 patient categories scheduled for knee surgery. Am J Sports Med. 2010;38(2). https://doi.org/10.1177/0363546509352 157. 2. Riboh JC, Cole BJ, Farr J. Particulated articular cartilage for symptomatic chondral defects of the knee. Curr Rev Musculoskelet Med. 2015;8(4). https://doi.org/10.1007/s12178-015-9300-0. K. Credille et al. 3. Yanke AB, Cole BJ. Joint preservation of the knee: a clinical casebook. 2019. https://doi.org/10.1007/9783-030-01491-9. 4. Guermazi A, Hayashi D, Roemer FW, et al. Brief Report: Partial- and full-thickness focal cartilage defects contribute equally to development of new cartilage damage in knee osteoarthritis: the multicenter osteoarthritis study. Arthr Rheumatol 2017;69 (3). https://doi.org/10.1002/art.39970. 5. Krych AJ, Saris DBF, Stuart MJ, Hacken B. Cartilage injury in the knee: assessment and treatment options. J Am Acad Orthop Surg. 2020;28(22). https://doi.org/10.5435/JAAOS-D-20-00266. 6. Krych AJ, Hevesi M, Desai VS, Camp CL, Stuart MJ, Saris DBF. Learning from failure in cartilage repair surgery: an analysis of the mode of failure of primary procedures in consecutive cases at a tertiary referral center. Orthop J Sports Med. 2018;6(5). https://doi. org/10.1177/2325967118773041. 7. Dixit S, DiFiori JP, Burton M, Mines B. Management of patellofemoral pain syndrome. Am Fam Phys. 2007;75(2). 8. Caton J, Deschamps G, Chambat P, Lerat JL, Dejour H. [Patella infera. Apropos of 128 cases]. Revue de chirurgie orthopedique et reparatrice de l’appareil moteur. 1982;68(5). 9. Grelsamer RP, Bazos AN, Proctor CS. Radiographic analysis of patellar tilt. J Bone Joint Surg Ser B. 1993;75(5). https://doi.org/10.1302/0301-620x.75b5. 8376449. 10. Dejour H, Walch G, Neyret P, Adeleine P. [Dysplasia of the femoral trochlea]. Revue de chirurgie orthopedique et reparatrice de l’appareil moteur. 1990; 76(1). 11. Gomoll AH, Yoshioka H, Watanabe A, Dunn JC, Minas T. Preoperative measurement of cartilage defects by MRI underestimates lesion size. Cartilage. 2011;2(4). https://doi.org/10.1177/194760351039 7534. 12. Mehl J, Feucht MJ, Bode G, Dovi-Akue D, Südkamp NP, Niemeyer P. Association between patellar cartilage defects and patellofemoral geometry: a matched-pair MRI comparison of patients with and without isolated patellar cartilage defects. Knee Surg Sports Traumatol Arthrosc 2016;24(3). https://doi. org/10.1007/s00167-014-3385-7. 13. Johnston JD, Masri BA, Wilson DR. Computed tomography topographic mapping of subchondral density (CT-TOMASD) in osteoarthritic and normal knees: methodological development and preliminary findings. Osteoarthr Cartil. 2009;17(10). https://doi. org/10.1016/j.joca.2009.04.013. 14. Farr J, Cole BJ, Sherman S, Karas V. Particulated articular cartilage: CAIS and DeNovo NT. J Knee Surg. 2012;25(1). https://doi.org/10.1055/s-00311299652. 15. Jones KJ, Cash BM. Matrix-induced autologous chondrocyte implantation with autologous bone grafting for osteochondral lesions of the femoral
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Patellofemoral Arthritis Christopher S. Frey, Augustine W. Kang, Kenneth Lin, Doug W. Bartels, Jack Farr, and Seth L. Sherman 1 Background Patellofemoral arthritis (PF OA) is a common degenerative disease of the joint surface between the patella and trochlea that may exist in isolation or as part of a larger multi-compartmental disease-state. It is a common pathology with annual incidence between 0.6% to 3.1% [1]. About half of those with symptomatic knee osteoarthritis were found to have patellofemoral involvement [2]. Isolated disease is reportedly found in 9% of symptomatic knees in patient over 40 [3]. Rates were similar between women and men; however, in symptoms-based cohorts, females twice the prevalence compared to males (43% vs 23%) [2]. Considering the prevalence of patellofemoral arthritis, it is no surprise that the disease poses a significant burden on society. A 2018 systematic review of studies examining quality of life among patients with patellofemoral pain reported C. S. Frey K. Lin D. W. Bartels S. L. Sherman (&) Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA e-mail: shermans@stanford.edu A. W. Kang Stanford School of Medicine, Stanford, CA, USA J. Farr Knee Preservation and Cartilage Restoration Center, OrthoIndy, Indianapolis, IN, USA that relative to pain-free controls population norms, patients with patellofemoral pain had worse Knee Injury and Osteoarthritis Outcome Score-Quality of Life scores and physical and mental functioning scores [4]. There is also an economic impact. It is thought that knee osteoarthritis treatment costs well over $27 billion in annual healthcare costs alone. At 9% patellofemoral OA costs are not inconsequential. When surgery is indicated for PF OA, a recent study found that among younger patients, knee arthroplasty and subsequent procedures approach $50,000 [5]. It should be noted that patellofemoral arthroplasty has cheaper implants and was found to have better quality-adjusted life year gains Moreover, disability and time off work has financial repercussions as well. In fact, for generalized OA, there is an estimated $4,835 loss in productivity per year [6]. This can be attributed to reduced productivity, long-term sick leave, unemployment, and early retirement [7–9]. In those undergoing arthroplasty before 60 years of age, the cost of salvage procedures in the event of failure should also be taken into account. For this, patellofemoral arthroplasty proves easier as it can simply be easily converted to a primary total knee replacement. Although often overlooked, isolated patellofemoral arthritis is a significant healthcare issue. The goal of this chapter is to provide an overview of the common causes, workup, and treatment of PF OA. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_23 329
330 2 C. S. Frey et al. Anatomy The patellofemoral joint is a unique and morphologically complex structure involving the posterior surface of the patella and the trochlea. The posterior surface of the patella is typically covered by articular cartilage up to 7 mm thick [10]. It is made up of multiple facets, primarily the lateral, medial, and odd facets as well as a central ridge that has some variation in its position [11]. The trochlea consists of a groove surrounded by a medial and lateral facet which forms a concave trough for the patella to glide through. Normal trochlear morphology has a lateral facet that is higher than the medial facet allowing it to buffer against lateralization of the patella. The patella acts as a mechanical pulley for extensor mechanism, and is particularly critical in the last 30° of knee extension [12]. Passive alignment of the patella is maintained by both bony and soft features. The shape of the patella and trochlea guides the patella throughout much of the arc of motion. Passive soft tissue constraints consist of medial and lateral ligamentous and retinacular complexes [13]. Medially there is the medial patellar complex consisting of the medial patellofemoral ligament (MPFL), medial quadriceps tendon–femoral ligament (MQTFL), medial patellomeniscal ligament (MPML), and medial patellotibial ligament (MPTL) which collectively work to prevent lateralization throughout the full arc of patellar tracking [14]. On the lateral side, there are the superficial lateral retinaculum and deeper patellotibial and epicondylopatellar bands [11]. Dynamic alignment is largely dictated by the quadriceps, hip external rotators, and core [11]. Specifically, the vastus medialis oblique (VMO) is a primary restraint to lateral subluxation of the patella and its weakening may be a significant cause of “giving way”, if not frank instability. If the pull of the quadriceps vector is excessively lateral, this may increase the lateral PF contact pressure and contribute to instability [15]. The intricate balance of these factors keeps the patella centered through its excursion in a healthy knee. As the patella tracks, it is subject to a dynamic range of force vectors. In full extension, there is almost no posterior force and thus minimal joint reactive force. As flexion of the knee increases the patella begins to engage the trochlea. The force vectors of the patellar and quadriceps tendons become more posteriorly oriented and generate a cumulative posterior force [16]. Therefore, as the knee approaches 90° the joint reactive forces increase. At the same time, the contact area of the patella increases until about 60° of flexion, decreasing pressure [17]. It is associated with a general shift in contact from distal to proximal in the patella and from proximal to distal in the trochlea. 3 Pathophysiology and Risk Factors Patellar instability is the most common cause of cartilage injury and subsequent degenerative change in isolated PF OA, constituting about one in three cases [18]. Upon initial dislocation, up to 95% of knees may sustain articular cartilage damage to the patella [19]. Moreover, over ¾ of these injuries will involve an osteochondral defect. This highlights the importance of obtaining an MRI after patellar dislocations. After the initial dislocation, it appears that there is a significantly positive correlation between the number of dislocations and prevalence of PF OA on MRI [20]. In fact, nearly all (97%) of chronic dislocators were found to have cartilage lesions of the PF joint. Any significant alteration to the previously mentioned mechanisms of stability can result in maltracking or dislocation. For example, patients with trochlear dysplasia have a significantly higher risk of arthritis [18]. Patients with a trochlear boss (aka, spur, in which a proximal focal bony prominence is relatively anterior) have significantly greater risk of PF OA and the greater the dysplasia, the more risk for degeneration [18]. Another common mechanism of patellofemoral cartilage injury is blunt trauma. Excluding dislocations, traumatic etiology is thought to be responsible for about 9% of isolated PF arthritis
Patellofemoral Arthritis in some cohorts [18]. Injuries with fractures involving the articular surfaces of the patella or trochlea will likely pose the same risks of arthritis as most intra-articular fractures. In these cases, direct force transmission as well as chronic elevations in contact forces from joint incongruity leads to chondrocyte death [21]. For tibial plateau fractures, the incidence of secondary osteoarthritis may be nearly 50% [22]. Even without fractures, energy delivered is thought to manifest in delayed chondral damage. In other words, chondrocyte death occurs with impacts insufficient to cause bone fracture. In an in vitro rabbit model, cell death was detected at 20 Mpa impacts while frank matrix damage was found at 30 Mpa impacts [23]. With no living chondrocytes, the articular cartilage matrix deteriorates over time. Chondrocyte overload may also be a result of diminished trochlea-patella congruence or disturbed joint homeostasis. Ligamentous injuries are also associated with PF OA. A common association is with anterior cruciate ligament (ACL) injuries. One systematic review reported that PF OA is associated with ACL injury, especially in cases of reconstruction [24]. Bone-patellar tendon-bone graft, singlebundle reconstruction, and delayed operation time reported a higher prevalence of PF OA within this subset. In fact, the prevalence of PF OA at 15 years status post ACL reconstruction may be nearly 50% [25]. The mechanism is poorly understood, but loss of terminal extension and reduced patellar mobility may play a role. Quadriceps weakness and an overall inflammatory state may be additional contributing factors. Osteochondritis dissecans (OCD) is a condition involving focal subchondral bone impairment, necrosis, collapse, and destabilization of overlying articular cartilage. Although the vast majority occur in the medial femoral condyle and less commonly in the lateral femoral condyle, it sometimes occurs in the patellofemoral joint [26]. Most of these patients were competitive athletes at some point. One longitudinal study of skeletally immature patients reported that 2/42 331 nonoperatively treated and 4/53 operatively treated children with OCD lesions ultimately developed symptomatic arthritis [27]. Our knowledge of the genetic component of osteoarthritis is still limited and epigenetics is even more limited. It has been estimated that the heritability of osteoarthritis may be 50% or more [28]. Some genes reported to be associated include VDR, AGC1, IGF-1, ER alpha, TGF beta, CRTM, CRTL, and collagen II, IX, and XI. Genes that have been identified to lead to patellar anomalies when altered include TBX4 and LMX1B [29]. In general, these are associated with nail patella syndrome, small patella syndrome, and isolated patella aplasia. These conditions can lead to patellar dysplasia and instability which will ultimately contribute to PF OA. 4 Presentation It is crucial to understand the underlying pathology that links chondrosis to pain. Cartilage is considered an aneural tissue. Thus, the actual pain generator needs elucidation before planning treatment [30]. This can be from surrounding soft tissue, bone or rarely referred pain. Typically, the patient with PF OA will present with chronic anterior knee pain that is aggravated with flexion and activities such as lunges and stairs. [3] When isolated, they will often tolerate ambulating on level ground, but avoid stairs or squats. Patients may experience swelling and stiffness as well, especially with flares. In addition to pain, patients may also experience mechanical symptoms. This can consist of subjective sensations of grinding, popping, or clicking, likely from the increased friction between patella and trochlea. This should not be associated with frank locking, however, this can be associated with other pathology-like displaced meniscus tear or chondral flap [31]. The patient may also complain of patellar instability, which often, as discussed above, is a risk factor but not prerequisite for PF OA [18].
332 5 C. S. Frey et al. Examination It is helpful to examine the patient standing/ walking, sitting, and in supine. This allows for a thorough assessment of leg alignment, kinematics, patellar mechanics, and provocative testing. Observing the patient while standing offers much information about their limb alignment. Aberrations impacting patellar alignment such as genu valgum, femoral anteversion, external tibial torsion, or pes planus can be observed. Gait evaluation may yield characteristic stance abnormalities such as anterior pelvic tilt through stance phase on the affected side and lateral pelvic tilt on the contralateral side. There may also be increased hip adduction and lower hip extension during stance phase [32]. Having the patient sit with knees bent over the examination table makes it easy to assess patellar tracking. The patella should track more or less midline with active knee extension, but may track laterally. This is referred to as the “J” sign which may be associated with trochlear dysplasia or soft tissue conditions that are associated with instability [33]. The “jumping J” sign, an exaggerated form of the “J” sign, may be indicative of bony abnormality such as a supratrochlear spur implying soft tissue surgery alone may not be helpful [33]. In the supine position it is easy to inspect and palpate the knee and surrounding anatomy. Some commonly described findings include quadriceps atrophy, effusion, and patellofemoral crepitus [34]. Quadriceps atrophy seems to impact all components, not just the VMO [35]. Patellar tilt, patella alta, apprehension, and active instability tests have all been described. In brief, lateral patellar tilt is the angle the patella can be manipulated to by pressing on the medial patella and pulling on the lateral edge. This represents relative lateral tightness and loading. The patella alta test involves pressure over the inferior pole of the patella while the knee moves from extension to flexion and is positive with pain. Patellar apprehension involves a laterally directed force to the patella tested in an arc of knee flexion and extension. It is considered positive if painful or this is apprehension or guarding. Although it is often considered a test for instability, it may also be associated with PF OA. The active instability test involves assessing isometric quadriceps contraction in slight knee flexion (*15°) with the lower extremity in a neutral position. It is considered positive if there is lateral movement of the patella. Although specific, these tests may lack sensitivity in diagnosing PF OA [36]. In addition, the patellar grind test, or Clarke Test involves the patient contracting their quadriceps muscle while the provider resists proximal movement of the patella with counterforce. Pain is considered a positive finding. The Q angle can also be measured while supine to understand the direction of the force vector. It is measured as the angle between the line from the anterior superior iliac spine to the center of the patella and the line from the center of the patella to the tibial tubercle. The normal value is typically 10–15° for men and 15–20° for women There is some concern for poor intra and inter-observer reliability, but may have improved accuracy when performed using a goniometer in the clinic [37]. 6 Imaging Radiographs remain important in the evaluation of PF OA. Radiographic signs of arthritis include joint space narrowing, cyst development, subchondral sclerosis, and osteophyte formation. There are multiple views that allow for inspection of various aspects of the knee. The low flexion angle axial view (Merchant, Laurin, etc.) is helpful for directly assessing advanced degenerative change in the joint. If full thickness chondral defects are not present at this angle, the joint space may appear near normal. The most common grading system is the Iwano grade, which consists of four stages as follows [38]. Stage I involves a remodeling joint line, Stage II depicts joint narrowing less than 3 mm, Stage III is narrowing over 3 mm, but no bony contact, and Stage IV describes bone on bone contact. Some of the commonly implemented
Patellofemoral Arthritis parameters include: sulcus angle, congruence angle, and the lateral patellofemoral angle. Specifically, the sulcus angle measures trochlear depth. It is calculated as the angle between peaks of MFC and LFC and the nadir of the intracondylar sulcus. Greater values indicate trochlear dysplasia, with 145° often being cited as the cutoff [39]. The congruence angle, which uses the angle between the patellar articular ridge and apex of the sulcus angle, measures patellar subluxation. Normal subjects have an average angle of 16° (medial to the congruence line), and an angle over 16° is typically associated with subluxation [40]. Lastly, the lateral patellofemoral angle assesses patellar tilt. This parameter is measured as the angle between the line along the lateral facet and along the anterior condyles. If these lines are parallel or converge, it is indicative of increased tilt or subluxation and is associated with more severe chondromalacia [41, 42]. It is important to note that absolute values cannot be used in isolation. One should consider the whole picture when evaluating radiographs in PF OA. In the context of evaluating PF OA, the standing flexed PA, also known as the Rosenberg or skier view, as well as the classic AP, primarily aid in evaluation of the tibiofemoral joint. The PA view is considered to be more sensitive for catching medial/lateral compartment arthritis and may capture this before standard AP films [43]. However, a subset of patients with more anterior TF OA will have joint space narrowing only on the AP view. The true lateral view (femoral condyles are superimposed and confluent) allows for direct visualization of degenerative change in the patellofemoral joint as well as morphologic features that may predispose to arthritis there. While it visualizes the same hallmarks of PF OA as suggested by axial views, the lateral view has been found to have lower diagnostic accuracy [44]. Using these true lateral images, the classic signs of trochlear dysplasia may be detected as described by Dejour [39]. In short, the crossing sign appears when the line of the trochlear groove intersects the anterior border of the femoral condyle. The supratrochlear spur is seen 333 as a prominence just proximal to the trochlea and illustrates a prominence of the trochlea that works like a ramp to push off the patella. Lastly, the double contour consists of the radiographic line adjacent to the crossing sign and represents a hypoplastic medial condyle. 96% of patients with patellar instability were found to have these radiographic signs of dysplasia [39]. The Dejour classification was developed based upon various combinations of these findings and dysplasia is assigned to 4 main types to aid in operative planning. However, 3D reconstruction from MRI and/or CT have demonstrated a more nuanced continuum of dysplasia. Patellar height is another important factor measured on these lateral views. Patella alta may be associated with patellofemoral osteoarthritis [45]. This is related to multiple factors. Patients with this abnormal positioning of the patella have been found to have decreased contact surfaces of the patellofemoral joint, which increases the pressure on the cartilage interface and can directly lead to chondral injury [46]. Patella alta can also result in patellar instability, which can be a driving factor of degeneration [47]. On the other hand, patella baja is associated with anterior knee pain, decreased range of motion, and extensor tendon weakness [48]. This is less common and may be associated with prior intervention. Patella height factors into preoperative planning to decide whether or not the patellar component will be engaged in the trochlea component at full quad active extension. Although there may be some proponents of the Insall-Salvati, the most commonly used measurement by patellofemoral experts is the Caton-Deschamps Index (CDI) [49, 50]. It is calculated by dividing the distance from the anterosuperior articular margin of the tibia to the inferior articular margin of the patella/articular surface patella. Thus, it changes after tibial tubercle osteotomies, but stays constant with various degrees of knee flexion. This may be of value in corrective TTOs to assess for restoration of more “regular” parameters. Values over 1.2 are typically associated with patella alta. In addition, the patella overlap with the trochlea yields another assessment of patellar height.
334 The three compartments of the knee should not be viewed in isolation. For a complete picture of the knee, bilateral full hip to ankle radiographs are crucial to better characterize the anatomic and mechanical axes of the limb. This view will depict aberrations in contact forces and therefore, joint degeneration patterns. It will also assist in surgical planning. Knowledge of alignment will direct one to the most appropriate soft and/or bony intervention for a mechanically sound knee. Advanced imaging is particularly useful for patellofemoral joint evaluation. Computed tomography (CT) is an excellent tool for depicting bony morphology. It can be used to assess trochlear dysplasia, patellar height, and the tibial tubercle-trochlear groove (TT-TG) distance. TT-TG measurement captures malalignment in the axial plain, specifically the lateralization of the tibial tubercle relative to the trochlea. Values over 20 mm are often described as pathologic and an indication for intervention [39]. One should note the limitations of this measurement, however. It has been shown to positively vary with age and patient height. [51] This would need to be taken into consideration for patients at either end of the height spectrum. CT can also be used to evaluate the direct effects of degenerative change on the joint. Although cartilage is not best visualized with standard CT imaging, subchondral bone can easily be scrutinized. In fact, this imaging modality has superior resolution of underlying bony structure when compared to MRI [52]. Considering many patients will have an MRI and full XR series already, CT is not always worth the additional risk. Unlike CT, MRI is useful for directly evaluating articular cartilage. Considering how thin and structurally contoured this tissue is, high quality imaging is required. T1-weighted images are limited in delineating the boundary between joint effusion and cartilage surface [53]. This offers basic anatomic details but is not useful for focal defects or delamination. T2-weighted imaging provides better contrast resolution of this interface, but has the limitation of poor internal cartilage signal. For these reasons, C. S. Frey et al. proton density-weighted sequences are often most accurate in evaluating cartilage defects [54]. Findings can be classified with the modified Outerbridge classification, which has been adapted to MRI use. It consists of seven stages starting with mere signal heterogeneity and ending with full thickness cartilage loss. In addition to cartilage, MRI is useful for picking up changes in underlying bone. Common changes in subchondral bone include cyst formation, sclerosis, and marrow edema. Although fairly nonspecific, focal areas of edema may be indicative of overlying cartilage defects [55]. There may also be classic bone bruising patterns of patellofemoral instability at the medial patellar facet and lateral femoral condyle. These findings are helpful for guiding pre-operative planning; however, arthroscopy is still considered the gold standard [56]. After operative repair, MRI may be used for monitoring healing. There exist several detailed scoring systems such as MOCART and OCAMRISS, however, the data is mixed regarding correlation with clinical outcomes and at this time, this is largely applied in the setting of research [57]. Similar to CT, MRI offers evaluation of axial alignment. MRI is an accurate modality for measuring TT-TG, with good inter-rater reliability [58]. However, it appears to consistently yield higher values; 3.8 mm on average according to one study. Thus, the calculated values from CT and MRI are not interchangeable. With the ability to visualize soft tissue, MRI allows one to measure TT-PCL as well. Similarly, 20 mm may be used as a cutoff for pathologic lateralization [51]. However, there exist some key differences between TT-TG and TT-PCL that must be noted. By utilizing points in the femur and tibia, TT-TG measures gross femorotibial rotation as a result of factors such as femoral torsion, tibial torsion, lateralized tibial tubercle, and medialized groove. It is, therefore, more sensitive to knee flexion as well, through the “screw home mechanism”. By only using points on the tibia, TT-PCL isolates tibial pathology. By combining the two metrics, one can pinpoint the cause of the malalignment.
Patellofemoral Arthritis 7 Conservative Treatment Once PF OA is determined to be the cause of the patient’s symptoms, it is important to understand the driving force behind the pathology. For example, patellar instability due to malalignment or trochlear dysplasia may be treated with different methods than an isolated osteochondritis dissecans lesion or prior trauma. Regardless, a specific treatment plan must be developed to address their predisposing mechanical factors and corresponding chondral pathology. Conservative management is performed first and consists of many different techniques. Supervised physical therapy (PT) is an often implemented first line intervention. Benefits may be derived from general exercise and wellness or even weight loss. Much of the literature regarding PT and osteoarthritis comes from tricompartmental literature, but it has shown modest improvement in outcomes with little risk [59]. For these reasons, it is often recommended as a first line intervention. The most recent AAOS guidelines also strongly recommend selfmanagement and patient education programs to empower patients to best help themselves [60]. Regarding patellofemoral joint arthritis specifically, a “core to floor” program is often implemented. The addition of core and hip strengthening to standard therapy focusing on the afflicted extremity has been shown to have additive effects with pain and strength [61, 62]. McConnell tape was developed as a means of noninvasive restraint to prevent lateralization of the patella. By improving alignment, joint forces can be improved across the patellofemoral joint. MRI has shown that taping can significantly restore alignment in knees with PF OA [63]. Pain was also reduced with squatting. One small study found patellar taping to be associated with a 25% reduction in knee pain [64]. This may be attributed to the improved alignment, but it is difficult to parse out the impact of placebo. Bracing works in a similar fashion as taping to improve pain. Most patella stabilizing braces are designed to hold the patella medially. It was found that brace use during the day was 335 associated with decreased pain and bone marrow edema [65]. Moreover, it appears that bracing may also help to improve alignment and kinematics with walking, but not stairs [66, 67]. By increasing the contact area, stress is decreased which may alleviate the injury to underlying tissue. Interestingly one study found that the realigning strap may not provide additional value in decreasing the pain scores [68]. This may be because external alignment of the patella does not improve pain over the simple comfort of bracing despite adjusting the contact forces. This study also used one specific brace and these results may be more reflective of that particular brace. Offloading implements may be another option in relieving symptoms of PF OA. The most recent AAOS clinical practice guidelines recommends using canes to improve pain and function in patients with knee osteoarthritis with moderate strength [60]. Although not specific to the patellofemoral compartment, the concept of decreasing joint reactive forces across the joint is similar and likely transferable, especially with activities that bring the knee through flexion. There are even some companies with braces designed to decrease PF loading. Oral or topical medications to relieve the pain and/or inflammation are another first line intervention for primary OA. Although not specifically directed at PF OA, the most recent OARSI, AAOS, and ESCEO guidelines provide recommendations on nonoperative management of knee arthritis with pharmaceuticals [59]. There is a consensus between the three guidelines in recommending topical NSAIDs because of improved pain and function with use. Furthermore, this class benefits from a decreased side effect profile compared to oral NSAIDs. Interestingly, both ESCEO and OARSI strongly recommend against non-pharmaceutcal forms of glucosamine or chondroitin sulfate while the AAOS guidelines do not differentiate by preparation and offer a “limited” recommendation. ESCEO recommends their use when pharmaceutical grade. The committee claims that this formulation is stabilized and therefore has
336 physiologically relevant bioavailability which corresponds to clinical efficacy [69]. The OARSI and AAOS recommend paracetamol conditionally in the short and long term while the ESCEO only recommends short term use. Both groups cite low proof of clinical efficacy and mild hepatotoxicity risk. If this first-line of medical intervention is inadequate, both guidelines recommend short term use of oral NSAIDs [59]. Although effective in controlling symptoms, this medication class is limited by cardiovascular, renal, and gastric side effects. It is recommended to take PPIs with nonselective NSAIDs to mitigate the gastrointestinal effects. As a last resort pharmaceutical intervention, patients can also take opioids. The ESCEO guidelines recommend short term use of relatively weak narcotics such as tramadol [59]. This is attributed to efficacious pain relief. However, the OARSI and AAOS recommend against this class of medication, even in the short term because of unsavory side effects such as addiction, nausea, constipation, and falls. Alternatively, patients can take duloxetine, a serotonin-norepinephrine reuptake inhibitor, which is particularly suited for cases of central pain sensitization as well as other chronic pain disorders [70, 71]. The vast majority of injections currently in the orthopaedist’s armamentarium can be broken down into three groups: viscosupplementation, corticosteroids, and biologics. All three guidelines support the use of intra-articular corticosteroids, especially in the short term (<6 weeks) [59, 60]. This broad class of medications acts through glucocorticoid receptors to downregulate the inflammatory cascade. Although recently downgraded to moderate strength in the AAOS guidelines, it is still considered an integral component of the treatment algorithm for patients who do not respond to anti-inflammatories due to significant relief of symptoms. There is some concern that these injections may be cytotoxic. Indeed, there are studies that demonstrate both tenocyte, synoviocyte, and chondrocyte toxicity with combination injections, including local anesthetic and corticosteroids [72, 73]. It appears that bupivacaine and triamcinolone are the least C. S. Frey et al. noxious compounds, but it may be safest to avoid intra-articular anesthetics. This may be considered diagnostic in some sense, but this interpretation is limited in that injections are not sequestered to the PF compartment. Viscosupplementation is thought to work by augmenting the synovial fluid with additional glycosaminoglycans. This would have improved lubrication and shock absorbing qualities with ultimate mechanical and analgesic effects [74]. Typically, this involves hyaluronic acid with both high and low molecular weight options available. One small trial of hyaluronic acid used in patients with PF OA found significant improvements in pain with stairs and global assessments [75]. However, it was limited by an 18.6% adverse event rate, most of which were local site reactions such as joint effusion. In the context of general osteoarthritis, this treatment has had mixed outcomes with the AAOS recommending against hyaluronic acid with moderate strength and both OARSI and ESCEO recommending its use. The AAOS guidelines cite a lack of clinically relevant differences when compared to controls in more recent analysis, even with the use of high molecular cross-linked formulations. Lastly, there are various biologic formulations currently in use or on the horizon that are being applied to the degenerative joint. Of these, platelet rich plasma (PRP) is probably the most described. The technology relies on the concentration of a growth factor payload that is not completely understood and varies with formulation. In general, leukocyte poor (LP-PRP) is associated with less of an inflammatory effect as concentrations of the pro-inflammatory cells is lower than that of whole blood. This formulation is often favored out of concern for inflammation after the injection [76]. Additionally, LP-PRP has also been found to have a greater ability to preserve cartilage mouse models and functional outcomes in knee OA trials [76, 77]. Unfortunately, due to this variation, studies are fairly heterogenous. With respect to the patellofemoral joint, one publication found that LR-PRP was associated with an increase in volume of patellofemoral cartilage on 3D MRI analysis as well as several PROMs [78]. There is
Patellofemoral Arthritis 337 a vastly larger body of evidence for general OA. Overall, results are quite mixed with multiple large studies and meta-analyses showing no significant benefit. Subsequently, the AAOS guidelines downgraded the recommendation for its use to limited and OARSI recommends against its use for OA. The most recent ESCEO guideline does not delve much into the topic. Topical antiinflammatory AAOS ESCEO OARSI Strong for First line First line Oral anti-inflammatory Strong for First line First line Opioid Strong against Conditional short term Strong against Intra-articular corticosteroid Moderate short term Conditional short term Conditional short term Intra-articular viscosupplementation Moderate against Conditional Conditional Intra-articular PRP Limited for No comment Strong against Glucosamine/Chondroitin Limited for First line (Pharmaceutical grade) Strong against 8 Surgical Management of Patellofemoral Arthritis Once non-operative management fails, there are multiple surgical options. Several important factors should be considered when deciding on the best management. Patient factors include age, medical comorbidities, activity level, and symptomatology. The joint as a whole must be considered, and previous injuries, chondral wear pattern—both location and severity, and ligamentous pathology or instability should be incorporated into planning. Perhaps most importantly, lower limb alignment in both the coronal and axial or rotational planes is integral to the treatment algorithm for obtaining optimal outcome. In general, in more diffuse disease or older lower demand patients, arthroplasty with or without additional procedures would likely provide more predictable benefit than pure soft tissue work or restorative cartilage surgery. In the setting of malalignment, depending on the nature of the malalignment, corrective osteotomy may be warranted in order to correct aberrant force vectors and/or patellar instability. It should be noted that there is a very limited role for isolated arthroscopy in patellofemoral arthritis. Knee arthroscopy with debridement allows for direct evaluation of the cartilage as well as other intra-articular pathology such as meniscus injury to facilitate planning for definitive management. In essence, this serves more as a staging arthroscopy to take inventory of possible surgical targets. Chondroplasty can be performed on unstable lesions. Any loose bodies identified should be removed. Patients may have some initial symptomatic relief, especially if there are mechanical symptoms, but the underlying problem may require further definitive surgery. This technique may be used definitively in instances of acute pain, specific localized mechanical symptoms, and no malalignment or intra-articular pathology in low demand patients [79] One registry study found isolated large cartilage defects to respond well at one year post-operative follow-up, as long as there was no associated meniscus pathology requiring debridement. If there is isolated lateral trochlear or patellar disease, lateral retinacular lengthening or release can be used to decrease lateral retinacular forces on joint, yet the reduction of PF loading has been questioned. It may also have theoretical benefit from denervating the retinaculum to provide pain relief [80]. This can be done arthroscopically or open. In the setting of PF OA, lateral retinacular release had mixed results, with worse outcomes associated with cases of patellar instability [81, 82]. Typically, lateral lengthening is preferred over a complete release as the latter results in greater disruption of lateral stabilizing structures [83]. This can potentially result in iatrogenic medial patellar instability, especially in cases with patellar instability to begin with. Although there are no direct assessments of lengthening on isolated PF OA, it likely has a role as an adjunct, especially with tight lateral structures, or lateral osteophytes (Fig. 1). Similarly, lateral facetectomy can both decompress the tight lateral structures and remove focal lateral facet OA making up the
338 C. S. Frey et al. P R T Fig. 1 Lateral retinacular lengthening. After developing the plane superficial to the joint capsule, along the patellar tendon, a 2-cm lateral retinacular lengthening is performed, with closure of the lateral tissues at the retinaculum in a lengthened position to rebalance soft tissue tension while preventing iatrogenic instability. T: patellar tendon; P: patella; R: lateral retinaculum in lengthened position “kissing” osteophytes that may be contributing to pain [80]. When used to treat PF OA, often with lateral release, there were modest short term results with reoperation free survival of 85% at 5 years and 67.2% at 10 years in one study [84]. Another investigation utilizing lateral release combined with facetectomy for cases of PF OA with lateral patellar compression had overall good results with improved Kujala and satisfaction scores at 5 years out, but had similar reoperation rates [80]. measurement variability, as CT scan and MRI may produce differing measurements, and knee flexion angle may affect static measurement of the dynamic nature of axial malalignment [85]. Additionally, rotational malalignment is affected by femoral version, tibial torsion, tibiofemoral rotation through the knee joint and other factors [86]. While TTO is typically used in the setting of instability, by nature it alters force vectors across the patellofemoral joint, and thus, can be used to decrease contact pressures in areas of chondrosis. This method of relieving PF OA is most relevant for young, active patients who are not ready for arthroplasty. It is of less benefit in cases of more severe or diffuse disease. TTO can be performed in conjunction with soft tissue stabilization for patients with concomitant instability. The classic anteromedialization osteotomy of Fulkerson is best suited for cases with distal lateral patellar chondrosis related to maltracking refractory to conservative management. It helps realign the extensor mechanism and improve patellar contact with the trochlea earlier in the arc of motion. This shifts the contact area more proximal on the patella [87]. It serves to offload the joint and provide relief in patients with malalignment and lateral disease. In carefully selected patients, results are fairly promising with good satisfaction and improvements in Kujala 9 Osteotomy The tibial tubercle osteotomy (TTO) is the workhorse of bony alignment procedures for patellofemoral malalignment and can be used to manipulate contact forces. In patellofemoral OA, the optimal use of anteromedialization is distal and lateral OA of the patella. It is less effective for bipolar OA, medial, proximal and panpatellar presentations. Although a TT-TG > 20 mm is often cited as a threshold for this procedure in patella instability, indications are more nuanced for differing underlying pathologies and threshold values may be lower on case-by-case basis (i.e. TTTG > 15 mm). This is partially due to
Patellofemoral Arthritis scores [88]. However, failure rates are correlated with severity of arthritis and patients with arthritis have earlier deterioration of symptoms. Typically, it is indicated in younger patients under 50, however, active older patients may also benefit [89]. There is no consensus on the degree of correction. Some suggest a goal TT-TG of 10– 15 mm [90]. It is important not to over-medialize as this may cause increased medial tibiofemoral contact forces [91]. Pure anteriorization, known as the Maquet osteotomy, has been shown to decrease patellofemoral joint forces through changing the lever arm [92]. It unloads the patella without affecting alignment. This may be useful for medial patella cartilage lesions for when anteromedialization is contraindicated [90]. This technique, as originally described, was marred by infection and dehiscence, and carried the risk of overload of the superior pole. Direct medialization, often described as the Roux-Elmslie-Trillat procedure helps to address lateralized forces that lead to maltracking. Long term outcomes show around 54%-64% good or excellent results, with worse outcomes for patellofemoral pain than instability [93]. It is limited by bony contact needed for fixation and rarely indicated [90]. The TTO can be augmented with MPFL reconstruction to aid in patellar tracking and patellar contact area. This is typically indicated in cases of concomitant symptomatic instability and objective laxity remains after TTO. Although the MPFL cannot be used to “pull” the patella, it does offer soft tissue stabilization as a restraint to lateral subluxation with a native tensile strength of about 209 N [94]. When MPFL and TTO are combined for indicated cases, the recurrence rates of instability appear to be quite low, around 4%–6% [95, 96]. Rotational and coronal plane osteotomies are used to correct for malalignment in the axial plane malalignment through the tibia and femur, and while described, have not been extensively studied in the setting of PF arthritis. In cases of increased femoral anteversion, a femoral rotational osteotomy can be performed to redistribute pressure [97]. External derotation of the distal 339 femur can unload the lateral patella, but at the cost of increasing medial contact pressure. If the deformity is related to tibial torsion (typically external rotation of 40°), the corrective rotational osteotomy may be made through the proximal tibia [98]. Prior studies have reported improvement in patellofemoral pain and instability in patients who have failed prior extensor mechanism operations, but have not focused on treatment of PF arthritis. Pathologic genu valgum can lead to lateralization of force vectors acting on the patella and can be treated with varus producing distal femoral osteotomy [99]. It should be noted that prior reports of femoral varus producing or derotational osteotomies have not focused on PF arthritis, and although severe patellofemoral osteoarthritis is typically considered a contraindication, mild to moderate PF OA is not necessarily [99, 100]. 10 Cartilage Surgery Cartilage restoration is a powerful tool for treating symptomatic focal chondral defects in the setting of preserved joint space; thus, it is not considered for advanced or diffuse disease. Considering that hyaline cartilage is relatively avascular and hypocellular, its ability for spontaneous healing is limited [57]. The cartilage-based interventions can largely be broken down into palliative (arthroscopic debridement), reparative (marrow stimulating), or restorative (osteochondral or cartilaginous). Patients must be indicated carefully to optimize outcome, as it is accepted that in general, there is a limited role for these techniques in cases of patellofemoral arthritis. Osteochondral transfer is a useful tool for large defects and has been shown to be effective, even after failed bone marrow stimulation procedures [101]. However, several patient specific factors are worth consideration. While age and cause do not appear to have a significant impact, female gender, increasing size, patellar lesions, and bipolar lesions seem to be associated with worse outcomes [102]. Patients should not have severely diminished range of motion and
340 C. S. Frey et al. Fig. 2 Bipolar disease of the patellofemoral joint, focal, treated with bipolar osteochondral allograft. Top right—large but focal patellar defect; top right—focal central defect; bottom left—OCA to the patella showing good contour match with no step-off; bottom right—OCA to the trochlea showing restoration of trochlear surface geometry and no step-off typically recommended not to have end stage degenerative disease. As previously mentioned, maltracking and malalignment must be addressed as well to optimize outcomes. In general, the results of osteochondral allograft of the patellofemoral joint are positive, especially considering the lack of donor morbidity. A recent systematic review found significant improvements in IKDC as well as good 10 year survivorship of 77%, similar to femoral condyle lesions [103]. However, when applied to bipolar lesions in more severe disease the results are not quite as promising. One study found improvements in IKDC function and pain, but a five year survival of 64% [104]. However, another found that ultimately, 8 of 11 patients were able to delay arthroplasty and many grafts had survivorship over 10 years [105]. At this time there is limited applicability for patellofemoral arthritis. Arthroplasty is generally the more reliable option other than in very young and active patients (Fig. 2). There are some measures that can be taken to maximize outcomes. It is preferable to use grafts from the same location [102]. This improves surface congruency for smoother gliding. However, as long as the radius of curvature is similar, femoral grafts are likely to be of useful size [106]. Advanced imaging and sizing markers can be useful for templating. Another consideration when using allograft is maintaining chondrocyte viability. It is known that fresh allograft has better viability than cryopreserved counterparts and that sooner time implantation is generally better [107, 108]. It is also interesting to note that impaction can also lead to cell inviability [109]. The greater the impaction from tapping, the greater damage dealt. This is particularly salient for thick, mismatched plugs.
Patellofemoral Arthritis 11 Arthroplasty For cases of severe, isolated PF OA that has failed conservative management, patellofemoral arthroplasty is the most predictable and reliable treatment [110]. Traditionally, the ideal patient tended to be older than 50, but under 65, not excessively active, and not overweight. However, these boundaries continue to evolve. Recent literature has cited equivalent patient reported outcomes in obese and non-obese patients [111]. Contraindications include lack of conservative management, significant degenerative disease in the tibiofemoral joint, patellar malalignment or patellar instability, knee mechanical malalignment, inflammatory arthritis, infection, significant loss of ROM [112]. The senior authors now use PF arthroplasty in those over 40 and the elderly as they will likely enjoy the more natural kinematics compared to a TKA. Patellofemoral arthroplasty is a powerful tool that offers several advantages over other procedures for end stage disease. First of all, it resurfaces the patellofemoral joint to remove the arthritic articulation. Through implant position, moderate degrees of malalignment can be corrected, and properly centralizing the trochlear groove center effectively decreases TT-TG. Targeted placement of the patellar button can lower the patella and medialize the central ridge of the patella to effectively decrease Q-angle. PF arthroplasty also spares the medial and lateral compartment as well as cruciate ligaments, retaining more natural kinematics and proprioception than total knee replacements [113]. PF arthroplasty may be performed in conjunction with soft tissue stabilization for patients with concomitant instability. Historically, isolated patellofemoral arthroplasty did not compare favorably to total knee arthroplasty [114]. Revision was required in 1/3 of the patients and patient satisfaction was poor. At the time, design was limited by deviations from trochlear anatomy and susceptibility to maltracking and wear [115]. Second generation implants were developed with wider trochlear surfaces contoured to facilitate patellar tracking. 341 Some have lateralized and/or deepened trochlear grooves to further improve tracking. With more modern implants, many of these problems have been corrected and survivorship has improved. One recent systematic review cited 10 year survivorship of 83.3% and 20 year survivorship of 66.6% [116]. When used for isolated PF OA, patellofemoral arthroplasty and total knee arthroplasty have yielded similar results in recent studies. In one randomized controlled trial, 1-year WOMAC functional scores was not significantly different between the two [117]. Moreover, long term outcomes for Oxford Knee Score (OKS) and EQ5D quality of life scores were not significantly different. Complications were similar, yielding a similar number of superficial infections, but more secondary interventions in the TKA group. This was replicated in a recent systematic review [112]. Although patients did well in both groups with improvements in PROMs after surgery, patellofemoral arthroplasty patients had better functional results and physical activity scores throughout the first two years postoperatively. Complications and revision rates were in total, not significantly different. PF arthroplasty has been associated with lower blood loss, decreased tourniquet time, and decreased hospital stay [118]. Some studies have found higher revision rates than TKA. PFA may be intentionally used as a bridge to TKA in younger patients, with a greater likelihood of higher post-op activity level, greater implant wear, and more rapid progression of arthritis in the tibiofemoral compartments, which would warrant earlier revision. Exact techniques for PFA vary based on surgeon preference, patient factors, and implant system, but the general concepts should be emphasized. A tourniquet can be placed at the surgeon’s discretion. The typical skin incision will be longitudinal from the patella down to the tibial tubercle, carried through the skin and subcutaneous tissue. Sometimes the patient will have scars from prior operations that can be incorporated into the incision. Several approaches to the knee are viable, including medial and lateral arthrotomies. The senior author, SS,
342 prefers a medial parapatellar arthrotomy. Next, a limited synovectomy can be performed to mobilize the patella. Once adequately mobile, the patella can be prepared and sized. Patellar and quadriceps tendon attachments can be used as reference and a minimum of 12–14 mm of patella should be left after cutting—in younger patients, the risk of “stuffing” the joint is overridden by the reward of better bone stock if revision is needed in the distant future. Rotational alignment of the trochlea can be established with an intra- or extra-medullary system to prepare for femoral cuts. The native trochlea can be used to determine varus/valgus orientation. However, if there is dysplasia one can align the proximal trochlea groove just lateral to the mid sagittal plane of the femur [110]. When performing the anterior femoral cut, steps should be taken to ensure that there will be no notching. The anterior cut should yield a “modified grand piano” sign. PFA is a resurfacing. The lateral facet is normally higher than the medial facet, therefore, PFA orientation may appear neutral rather than the external rotation. One can use direct visualization as well as fluoroscopy to ensure that there is no notching. The rest of the femur can be prepared and trochlea sized according to the system used. Implant position and patellar tracking should be checked with trial implants. The patella should engage throughout its entire excursion. After thorough cleansing and drying, final implants are cemented in place. Following final implantation, if there is maltracking, instability, or lateral retinaculum tightness, these can be addressed at this time (Fig. 3). There are several complications that can result from incorrect procedural technique. For example, component malpositioning in the sagittal, coronal, and/or axial planes can lead to maltracking and instability [119]. Excessive external rotation has been associated with subluxation while internal rotation leads to impingement. Patellar fracture has also been known to occur, up to rates of 9% in some cases [120]. Risk C. S. Frey et al. factors for this include low BMI, larger resections, thinner patellas, and large trochlear components. Sometimes, the procedure may be executed well, but the patient may just have progression of disease due to activity level, genetics, or other factors. Notching has the potential to yield stress concentration and possibly fracture, similarly to TKA. Though not a “complication”, it is important to have a thorough discussion with those patients who have a remote history of patellar instability. In the more recent years, the instability has resolved secondary to the high coefficient of friction (CoF) of PFA implants and soft tissue contractures associated with OA. With low CoF PFA, the old, contracted scar of prior MPFL tearing may progressively loosen and lead to functional subluxation or rarer, dislocation. While this is easily addressed with MPFL reconstruction, a preoperative discussion is important for patient trust and satisfaction. Alternatively, an MPFL reconstruction may be performed at the index PFA. However, if the patella is stable intra-operatively, the risk/reward ratio supports only performing the PFA to avoid problems with ROM with the “prophylactic” addition of MPFLR as only a subset will develop this instability. Procedure Indications Outcomes Palliative Arthroscopy Mechanical symptoms, diagnostic workup, loose body, unstable chondral lesion Short term symptomatic relief of mechanical symptoms Lateral Lengthening/Lateral Facetectomy Lateral tightness Short to medium term pain relief in select patients Tibial Tubercle Osteotomy Malalignment, lateral wear pattern, young/active, mild disease Short to medium term improvement in select patients Patellofemoral Arthroplasty Isolated patellofemoral degenerative disease and pain Good medium to long term results in select patients Total Knee Arthroplasty Multicompartmental degenerative disease and pain Good long term results
Patellofemoral Arthritis Fig. 3 Intraoperative photographs of patellofemoral arthroplasty, through a medial parapatellar arthrotomy. Top—diffuse chondrosis of the patella and 12 Conclusion PF OA is a degenerative condition resulting from multiple etiologies. It is largely a clinical diagnosis confirmed with imaging. Treatment 343 trochlea. Bottom—final placement of patellar and femoral trochlea components. consists of initial nonoperative modalities such as therapy, oral medications and injections. For refractory cases, operative management should be customized to each patient’s presentation, demands, mechanics and pathology. Orthopaedic surgeons have multiple tools at their disposal to
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Fresh Osteochondral Allografts in Patellofemoral Surgery Suhas P. Dasari, Enzo S. Mameri, Bhargavi Maheshwer, Safa Gursoy, Jorge Chahla, and William Bugbee 1 Introduction Patellofemoral chondral lesions of the knee are a particularly challenging subset of chondral lesions to manage. In addition to difficulties related to physiological healing, anatomical and biomechanical derangements that are unique to the patellofemoral joint must also be addressed [1]. The morphology of the patella and trochlea between patients is widely variable, making each procedure intrinsically challenging for any operative technique [2]. Biomechanically, the anterior compartment of the knee experiences very high loads during daily function that can exacerbate symptoms and impair healing processes. Concomitant abnormalities, such as coronal and rotational limb malalignment, patellofemoral maltracking, patella alta, excessive lateral tilt, and trochlear dysplasia can all contribute to the challenge of managing patellofemoral chondral lesions and must be adequately addressed to ensure a satisfactory clinical outcome [1]. S. P. Dasari E. S. Mameri B. Maheshwer S. Gursoy J. Chahla (&) Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA e-mail: Jorge.chahla@rushortho.com Despite their difficult nature, these lesions are not rare occurrences, and the optimal management of these defects must be understood when implementing a joint-preserving procedure. Among patients undergoing knee arthroscopy, a study by Widuchowski et al. examined 25,124 patients and reported 60% of them had chondral lesions of the knee with patellar lesions being the most common [3]. Furthermore, a recent 2017 meta-analysis by Hart et al. demonstrated that up to 52% of patients with knee pain are diagnosed with cartilage lesions in the patellofemoral joint [4]. Thus, the relative incidence of these debilitating lesions, the complex biomechanical environment, and high stress forces experienced in the PFJ make it critical for surgeons to understand the anatomy, biomechanics, pathophysiology, and treatment modalities available for appropriately addressing osteochondral lesions of the PFJ. The purpose of this chapter is to describe the key anatomical and biomechanical principles, pathophysiology, basic science principles, advantages and disadvantages, indications and contraindications, operative planning, surgical techniques, and clinical outcomes of patellofemoral chondral lesions managed with a fresh osteochondral allograft (OCA) technique. W. Bugbee Department of Orthopaedic Surgery, Scripps Clinic, La Jolla, CA, USA © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_24 349
350 2 S. P. Dasari et al. Anatomical and Biomechanical Considerations Articular cartilage in the PFJ is the thickest in the human body and is up to 7.5 mm thick on the patella [5]. The proximal posterior surface of the patella is covered by thick hyaline articular cartilage and has a midline ridge that is congruous with the femoral trochlear groove, while the distal aspect of the patella’s posterior surface is nonarticulating [6]. The patellar bone is composed of two major articular facets and several subfacets that vary considerably from patient to patient. The facets are broadly classified by the Wiberg scheme into 3 different groups [7, 8]. A type 1 patella will have concave medial and lateral facets that are approximately equal in size; this is the rarest phenotype. Type 2 facets will have a flat or convex medial facet that is much smaller in size than the lateral facet; this is the most common subtype in the general population. A type 3 patella will have a convex medial facet that is only slightly smaller than the lateral facet and accounts for 25% of patellae. The femoral trochlea articulates with the patella to form the patellofemoral joint. It is a 5.5 mm deep groove in the distal aspect of the femur that is lined with articular cartilage [6]. It has a larger lateral facet that extends more proximally and anteriorly relative to its smaller medial facet [6]. The articular cartilage at the body of the trochlea has an average depth of 4 mm [9]. The remainder of the trochlea has a 2 to 3 mm thick cartilage cap that is thinner medially [6]. The trochlea plays a critical role in PFJ biomechanics as it provides a lateral buttress to prevent subluxation of the patella during knee flexion [7, 8, 10]. It also facilitates painless, friction-free articulation over a full range of motion in healthy knees. Biomechanical forces, contact area, and contact pressure at the PFJ change with varying degrees of knee flexion. During knee range of motion, the greatest forces are experienced between 60° to 90° of flexion [11]. These forces move proximally along the patella as the angle of knee flexion increases [11]. Contact area also reaches a maximum at 90° of flexion, at which point the proximal patella will come into contact with the trochlea [6]. Beyond 90° of flexion, the contact area decreases [6]. Contact pressure is defined by the ratio of force across the joint and contact area at a given angle of knee flexion. Because force increases at a rate that is greater than the increase in contact area during knee flexion, the maximum compressive pressures will occur between 60° to 90° of knee flexion [11]. Clinically, this manifests with patients describing anterior knee pain during flexion related activities though they can also complain of intermittent sharp pain if their lesion is unstable. This increased strain at the PFJ was quantified in a study by Flynn and Soutas-Little [12]. The authors demonstrated that the patellofemoral joint (PFJ) experienced 1.3 times body weight (BW) while ambulating, 3.3 times BW when climbing stairs, and 5.6 times BW when running due to strain associated with increased flexion angles. 3 Pathophysiology The pathophysiology of chondral lesions within the PFJ is multifactorial. Lesions develop from traumatic or instability events as well as secondary injuries in the setting of aberrant joint loading [6]. More specifically, common mechanisms that contribute to injury include chronic repetitive microtrauma from suboptimal extensor mechanism alignment and acute microtrauma [13]. Maltracking of the patella can be caused by a number of conditions and leads to an altered distribution of pressure, can cause chronic repetitive stress, and/or contribute to treatment failures [14]. Increased lateral patellar maltracking, a greatly increased Q angle (or tibial tuberosity-trochlear groove [TT-TG] index), abnormal femoral torsion, trochlear dysplasia, and patellar instability all contribute to abnormal contact pressures in the PFJ [14, 15]. An acute dislocation frequently damages the medial soft tissue constraints and predisposes the patient to further episodic patellar dislocations, which
Fresh Osteochondral Allografts in Patellofemoral Surgery eventually lead to chondral damage in the vast majority of patients [5]. Furthermore, acute injuries can occur in up to 95% of dislocation events and lead to osteochondral or chondral fractures and fissures that occur either at the time of the injury/dislocation or during the reduction [5]. Subsequent ongoing chondral damage occurs via chondroptosis, which is a chondrocyte specific apoptotic pathway, and via degradation of the extracellular matrix due to elevated matrix metalloproteinase expression [5]. Chronic patellar instability is associated with underlying trochlear dysplasia, increased Q angles, insufficient medial stabilization, and increased TT-TG distances [16]. Patellar maltracking is defined as instances where the patella fails to engage or subsequently disengages from the trochlear groove [17]. The medial patellofemoral ligament (MPFL), the lateral trochlea, and the deep sulcus work in a synergistic effect to maintain normal patellar tracking during the full range of knee motion [16]. The MPFL is the primary restraint during the first 70° of knee flexion; however, the trochlea serves as the primary restraint for the remainder of knee flexion. Deficiency in either mechanism can lead to chronic patellar instability, and trochlear dysplasia has been reported to be present in 85% of patients with recurrent lateral patellar instability [18]. Joint instability has demonstrated increased in-vitro peak contact stresses and has correlated with cartilage degeneration in an animal model [5, 19, 20]. Furthermore, a study by Jungmann et al. has reported an association between trochlear dysplasia and severe patellofemoral joint degradation [21]. This is reflected by the results of a separate study by Noehren et al., where the authors identified common risk factors of patellar instability like trochlear dysplasia, patella alta, and increased TT-TG distance and reported the correlation between these risk factors and advanced early onset degenerative disease in young patient populations [22]. When addressing PFJ pathology, trochlear morphology is critical to surgical planning. A systematic review by Cregar et al. demonstrated that MPFL reconstruction, while effective in patellar instability cases, was at an increased 351 risk to fail in cases with high grade trochlear dysplasia [23]. Furthermore, a shallow, dysplastic trochlear groove creates a knee with instability that is comparable to a knee with an incompetent MPFL. A dysplastic trochlea is defined as a trochlea with a sulcus angle greater than 145° on sunrise views of a knee flexed at 30° [17]. The Dejour classification is used to grade the level of trochlear dysplasia [17]. Dejour outlined radiographic parameters that define trochlear dysplasia [24]. This included a trochlear depth less than 4 mm, a patellar tilt over 20°, a spur height greater than 5 mm, and a trochlear sulcus angle over 145°. Using these criteria, the Dejour dysplasia classification was described with four overarching dysplastic phenotypes (A-D). This was further subclassified into low-grade dysplasia (type A dysplasia) and high-grade dysplasia (types B-D dysplasia) [17]. Clinically, this is reflected in the treatment options recommended as low-grade trochlear dysplasia does not typically require operative intervention as these patients are unlikely to benefit from a trochleoplasty procedure [17]. The complex strain and stress environment at the PFJ articular surface has made chondral lesions of the PFJ a notoriously difficult pathological challenge to surgeons [25]. Focal defects of the patellar cartilage lead to altered biomechanics, debilitating pain, and rapid acceleration of osteoarthritis when mismanaged [25]. An understanding of the pathophysiology of patellofemoral osteochondral lesions can guide a surgeon in determining which combination of procedures will provide the best long term pain relief, provide substantial functional improvement, and adequately address the etiology of aberrant joint loading and instability when present. 4 Treatment Modalities Cartilage lesions of the knee can be debilitating conditions that can worsen overtime and progress to a diffuse arthritis if left untreated [26, 27]. When managing these lesions, the first-line goals are conservative modalities that aim to relieve
352 inflammation, control pain, and restore functional capacity [13]. Typically, nonsteroidal antiinflammatory medications, intra-articular corticosteroids, and hyaluronic acid viscosupplementation are utilized as first-line therapeutic interventions to manage inflammatory symptoms [13]. Physical therapy can also play a crucial role in the early nonoperative management of these lesions as there is a high incidence of functional impairment and kinematic derangement in individuals with PFJ cartilage lesions. Muscle strengthening can improve absorption of physiological loads across the knee, while weight loss and activity modification can avoid aggravation of painful symptoms [28, 29]. In general, nonoperative treatment should be trialed prior to pursuing surgical intervention as many patients will achieve substantial relief through these conservative measures, allowing them to potentially avoid a complicated subsequent surgical procedure [30, 31]. Surgical management is pursued for patients with persistent, functionally limiting symptoms that have failed to adequately respond to initial nonoperative treatment [6]. There are several effective cartilage repair modalities that have been described for the management of patellofemoral chondral defects, including bone marrow stimulation techniques, autologous chondrocyte implantation (ACI), osteochondral autograft transplantation (OAT), and osteochondral allograft transplantation (OCA) [1]. When determining the optimal treatment modality, the lesion size, depth, location, subchondral bone, and patient demand must be assessed. Due to the relatively challenging anatomy and increased biomechanical forces experienced at the PFJ, these cartilage procedures have consistently demonstrated inferior clinical outcomes when implemented at the PFJ relative to other locations within the knee, regardless of the technique used [1, 27, 32]. Bone marrow-stimulation techniques, such as microfracture or subchondral drilling attempt to stimulate bone marrow to allow cell migration into the defect area to promote healing [33]. These procedures are limited as they create fibrocartilage that is physiologically and S. P. Dasari et al. biomechanically inferior to hyaline cartilage [34]. These techniques are also unable to adequately manage larger osteochondral lesions [35, 36]. Additionally, the unique anatomy of the PFJ makes marrow stimulation techniques challenging and leads to difficulty in creating stable vertical walls [37]. These factors, combined with the challenging biomechanical environment, limit the utility and popularity of marrow stimulation techniques in the PFJ. Autologous chondrocyte implantation (ACI) utilizes tissue engineering techniques to regenerate cartilage using cell-based therapy. While effective, it is a two-stage procedure that requires harvesting donor cartilage from a nonweightbearing portion of the knee in addition to an expensive culturing phase. The modality has been shown to be effective in treating large chondral lesions and can be implemented using a sandwich technique, when there is subchondral bone involvement [38]. Many proponents of ACI recommend routine use of patellofemoral unloading and realignment procedures when using this technique [2, 39, 40]. Osteochondral autograft transfer (OAT) is a procedure that is effective at managing smaller symptomatic osteochondral lesions regardless of underlying subchondral bone involvement [41]. Typically, autografts are harvested from nonweight bearing portions of the knee like the intercondylar notch before being prepared and press-fit in a single stage procedure [6]. OATs have several inherent advantages including the transfer of mature, physiologic hyaline cartilage and viable chondrocytes over an intact osseous bed. Additionally, the technique has no risk of immunologic reaction [28]. While effective for smaller lesions, this technique is not without limitations. For example, the morbidity associated with a donor site of an OAT procedure can make it an undesirable therapeutic intervention for patients with defects that are larger than 2.5 cm2 [42]. Additionally, this technique is particularly limited in the management of patellofemoral chondral lesions due to the challenging anatomy of the PFJ. There is difficulty matching the surface concavity and convexity of the patellofemoral articulation when transplanting
Fresh Osteochondral Allografts in Patellofemoral Surgery autograft plugs from a non-weightbearing portion of the knee [6]. Moreover, donor grafts from non-weight-bearing portions of the knee tend to have thinner articular cartilage than that of the native patella, which further limits the applicability of this technique for patellofemoral chondral lesions [43]. Finally, the typical donor sites for graft harvest are often within the same patellofemoral articulation that is being treated for symptomatic cartilage disease, which may compromise the clinical situation. These inherent limitations suggest that OAT procedures can be viable modalities for small patellofemoral chondral lesions with subchondral bone involvement but are limited in their applicability for larger lesions in the PFJ. 5 Osteochondral Allografts (OCA) OCAs have numerous advantages relative to many of the other cartilage repair modalities when managing lesions of the PFJ (Table 1). This includes the presence of mature, metabolically active chondrocytes in the graft, 353 immunoprivileged properties, no donor site morbidity, management of underlying subchondral pathology, and efficacy in large lesions, unconstrained lesions, and bipolar lesions [44, 45]. Unlike an OAT, the OCA is able to provide viable cells without the associated concomitant donor site morbidity that is intrinsic to an autograft technique [27]. This lack of donor site morbidity can also make an OCA a more viable treatment option for larger defects, where an OAT procedure would not be feasible. Thus, the OCA procedure allows for the management of a large osteochondral defect using a single procedure without concomitant donor site morbidity [13, 46]. An additional benefit of the OCA procedure is that it facilitates the replacement of a defect with hyaline cartilage overlying an intact osseous bed [47]. This creates an architecturally stable articular surface with mature hyaline cartilage in the setting of a large, full-thickness osteochondral defect [27]. This property allows the graft to accept full loading as soon as the bone base has healed, which can expedite the rehabilitation and recovery process; this is particularly beneficial Table 1 Advantages and Disadvantages of the Fresh Osteochondral Allograft Technique for Patellofemoral Osteochondral Lesions Advantages Disadvantages Mature, metabolically active chondrocytes transplanted in the graft Graft availability and challenges related to morphology matching the donor graft with the recipient’s knee anatomy No donor site morbidity Expensive procedure Relatively immunoprivileged A risk of disease transmission Management of underlying subchondral bone pathology Technically demanding procedure Effective option for large lesions, unconstrained lesions, bipolar lesions Logistical demands to minimize chondrocyte death Effective for trochlear dysplasia with high grade chondromalacia Can be used as a primary procedure or a secondary salvage procedure after a failed prior surgical intervention Graft survivorship not impacted by prior procedures to the lesion Return to weight bearing can begin when bone base has healed and integrated
354 when managing the lesion in athletes as it can accelerate their return to activity and weight bearing [41, 48, 49]. Furthermore, the OCA technique for PFJ lesions offers a wide range of applicability. The technique can be implemented in large chondral lesions with or without subchondral bone involvement. Additionally, transplantation necessitates removal of the underlying native subchondral bone, so prior microfracture surgery does not affect graft survivorship [26]. Another benefit is that OCAs can be used to treat unconstrained lesions as they do not need a continuous border of healthy articular cartilage for successful repair [41, 50]. The technique can also be successfully implemented in bipolar lesions, as a salvage procedure after failed prior treatment, and in young patients with posttraumatic osteochondral defects after fractures around the knee joint [13]. For trochlear defects, an OCA procedure can be implemented as both a primary and salvage procedure, while it is typically utilized as a salvage procedure for large patellar lesions to delay arthroplasty in young patients [13]. Though trochleoplasty is able to address high grade trochlear dysplasia and provide an osseous restraint to patellar instability, it does not adequately address any symptomatic trochlear chondral lesions and is contraindicated in cases of high grade trochlear chondromalacia [17, 18]. As a result, in chronic instability cases with a large chondral lesion and high-grade trochlear dysplasia, a trochlear shell OCA technique may be a viable surgical option to adequately address both trochlear pathologies [18]. In cases of severe dysplasia of both the patella and trochlea, large plug or shell allografts have the unique ability among cartilage repair techniques to change structural pathoanatomy. Disadvantages of an OCA are related to availability, cost, infection risk, disease transmission, and challenging surgical technique (Table 1). Cost is a major limitation of the OCA technique. In 2016, it had been reported that the average cost of a fresh OCA in the United States S. P. Dasari et al. was approximately 11,000 dollars [27]. Part of this cost is reflected in the rigorous testing that grafts undergo to minimize the risk of disease transmission [41]. Despite this testing, there is still some small risk of communicable disease transmission associated with OCA transplants [27]. Graft availability is another relative disadvantage of the OCA technique. Variability between patellar and trochlear anatomy in the population can make it difficult to find an appropriate donor graft [2]. Graft matching is made further challenging by the unique bony shape, chondral thickness, and sliding articulation intrinsic to the PFJ [51]. Challenges related to complex morphology matching are most pronounced when lesions involve the central trochlear groove or median patellar ridge [2]. As a result, graft availability can be a significant limitation as the ideal graft should be from a donor of similar or younger age at death and have similar knee dimensions to the recipient [41]. Location matching and size matching are strategies implemented to offset this challenge, but graft availability still remains a limiting factor in the effective implementation of this transplant technique [2]. To offset this limitation, it is crucial for scheduling flexibility. When a wellmatched donor graft becomes available, the surgeon and patient should agree to perform the procedure in a time frame that minimizes chondrocyte death (*28 days). While the goal should be to find a donor graft that matches the morphology of the host joint architecture, a slight mismatch has been shown to lead to acceptable clinical results [51]. Another drawback to OCA transplants within the PFJ is that they are technically challenging procedures. Precise fitting of the plug and creating a smooth transition between the donor and recipient is crucial to success with this technique [13]. The complex topography and variation in anatomy of the patella and the trochlea contribute to the challenges associated with the OCA transplantation procedure [2].
Fresh Osteochondral Allografts in Patellofemoral Surgery 6 Osteochondral Allograft Storage and Preparation Chondrocyte viability is critical for graft survival and resulting mid-to-long term clinical outcomes [2]. Chondrocyte viability is important for graft survivorship as these cells maintain the extracellular matrix (ECM) to prevent deterioration [52]. Viability is dependent on a variety of factors, including preservation technique, timing from graft harvesting to implantation, and the technique of implantation. Fresh allografts are typically harvested within 24 h of the donor’s death and stored at 4° Celsius until the procedure [53]. The shelf life of a fresh graft has remained controversial with current recommendations suggesting a storage time of up to 28 days [54, 55]. These recommendations have demonstrated adequate chondrocyte viability for current transplant practices [13]. Storage media and methods have varied greatly over the past 50 years since the technique was initially described [52]. As grafts have become commercially supplied under Food and Drug Administration (FDA) oversight, they have become subjected to a prolonged storage interval to allow for rigorous testing protocols [52]. Under ideal conditions, grafts should be recovered from donors between the age of 15–35 years of age with macroscopically healthy cartilage and harvested within 12 to 24 h after a donor’s death [52]. This period can be extended by approximately 12 h if the donor’s body is cooled within the first 6 h of death [56]. Prior to storage, the tissue is subjected to high pressure pulsatile lavage irrigation, decontamination, dry centrifugation, and centrifugation with sterile phosphatebuffered saline before microbiological tests can be performed [56]. Stricter guidelines imposed by the FDA have decreased the risk of disease transmission allowing OCA transplants to become an increasingly popular primary or salvage procedure [13]. Because the procedure is heavily dependent on chondrocyte viability within the graft, there have been several studies dedicated to optimizing temperature and storage media conditions [57– 355 61]. Broadly speaking, grafts can be stored as frozen, cryopreserved, or fresh. Each technique has variable effects on chondrocyte viability, graft immunogenicity, and duration of time where the graft is viable for a transplantation [52]. Frozen grafts demonstrate a chondrocyte survivorship of less than 5% but also demonstrate decreased immunogenicity due to the freezing process [62, 63]. Cryopreservation has been proposed as a solution to maintain chondrocyte viability during the freezing process by preventing intracellular ice formation [52]. While sound in theory, cryopreservation only allows for viable chondrocytes at the surface of the articular cartilage layer as the dense extracellular matrix limits penetration of the cryopreservant to deeper cellular layers [56, 64]. Additionally, the freezing process can cause fissures and delamination of the cartilage [65]. Fresh OCAs have the highest chondrocyte viability and are placed in tissue culture medium at 4° Celsius [52]. A study by Ranawat et al. demonstrated superior histological and biomechanical properties of fresh allografts relative to frozen/cryopreserved porcine specimens [66]. A subsequent study by Pallante et al. demonstrated similar findings in a goat animal model [67]. In addition to the storage medium and conditions, the time from harvesting to implantation is critical for maximizing chondrocyte viability at the time of the procedure. For properly stored fresh grafts, there is little loss in viability during the first week after harvesting [68, 69]. Studies have demonstrated a time dependent decrease in chondrocyte viability and mechanical properties of fresh grafts after storage beyond 14 days [44, 70, 71]. By 3 weeks, chondrocyte viability declines to roughly 70% and is approximately 67% by 7 weeks [44, 57, 60, 61]. While prolonged storage decreases viability, cell density, and tissue metabolism, it has minimal effects on the ECM or osseous components [65]. Expedited implantation is made challenging by the need for tissue banks to store the transplant grafts for a minimum of 7–10 days to ensure proper microbiologic and serologic testing [65, 72]. Furthermore, delays for size matching
356 grafts can also prolong the time from harvesting to implantation. While it is important to perform the procedure in a timely manner, studies that have investigated the implantation of fresh OCAs after prolonged storage demonstrated good efficacy in grafts stored up to 42 days after harvest despite the corresponding decline in chondrocyte viability [73, 74]. Based on these findings, current recommendations would suggest that the transplant procedure be performed within 42 days of graft harvesting [65]. Higher impact loads also adversely affect cell viability. Prior studies have demonstrated that less than 50% of cells in the graft survive high force loads during impaction [75, 76]. It has also been demonstrated that the load of the impact plays a larger role in chondrocyte death than the number of impacts, so multiple low-load taps are preferred over a single high-load tap if impaction cannot be avoided [2]. Ideally, impaction should not be needed and the graft can be press fit into position such that it is flush and in contact with the base of the recipient hole regardless of subchondral bone matching [2]. Using this method allows the surgeon to decrease the subsidence of the graft, leading to a better restoration of the contact pressure in that knee compartment [77]. Another potential drawback to an allograft technique is the risk of potential immunogenicity. Intact hyaline cartilage is a relatively immunoprivileged tissue because it is avascular and the chondrocytes of the tissue are embedded in a dense ECM that is inaccessible to the host immune system [52]. Despite this, marrow elements in the osseous portion of the graft have some degree of immunogenicity as the subchondral bone component of the graft is laden with potentially immunogenic cells and proteins [65]. Routine pulse lavage of the graft has been implemented to decrease the concentration of these marrow elements, mechanically remove proteins that may trigger a reaction, and thus reduce immunogenicity of the allograft [78–80]. Studies have demonstrated that larger grafts were more likely to elicit a systemic immune response [81]. Because the immunogenicity of the graft is directly related to the osseous portion of the graft, reducing the thickness of the subchondral S. P. Dasari et al. bone component of an OCA is thought to minimize the risk of potential immunogenicity [13]. Despite this potential risk, larger grafts have not demonstrated inferior overall survival rates relative to smaller grafts [82]. Graft integration occurs over a gradual process termed creeping substitution. Overtime, the osseous portion of the graft is gradually replaced by host bone. This slow process is mediated on the cellular level by osteoblastic bone formation and osteoclastic resorption; minimizing the amount of transplanted bone may reduce the healing process associated with bone incorporation [83]. The cartilage component is transplanted at a mature stage, does not undergo interactions with the host, and does not undergo further healing [65]. When performed appropriately, transplanted OCAs have good survivorship and retrieved specimens have demonstrated high donor chondrocyte viability [57, 69]. 7 Indications and Contraindications As a high load joint, symptomatic patellofemoral osteochondral lesions often require an intervention. When nonoperative treatment measures fail, surgical intervention should be considered. OCA is a valid treatment modality for large patellar and trochlear chondral defects except in patients with end-stage osteoarthritis [2]. Cases with subtotal loss or bipolar lesions without significant joint space narrowing can be adequately addressed by this modality in younger patient populations [2]. OCA is indicated as a primary procedure in patients who have large, full thickness cartilage lesions with abnormal subchondral bone, though it is gaining increasing implementation in the treatment of pure chondral lesions as well [13]. OCA is suitable for a wide range of disease pathologies due to its inherent osseous structure and multishaping possibilities: this includes complex reconstruction procedures, massive osteochondral defects, osteonecrosis, diseases affecting the subchondral bone, primary large chondral lesions, and lesions that have failed a prior cartilage repair technique [52].
Fresh Osteochondral Allografts in Patellofemoral Surgery Surgical candidates for an OCA transplant procedure are young active patients with full thickness, symptomatic focal lesions that are greater than 2 cm2 in size [41]. Typically, these patients cannot undergo another restorative procedure like arthroplasty due to their age or an OAT or ACI procedure due to defect size, depth, and location [41]. For these younger patients with cartilage defects, arthroplasty is not an ideal treatment modality as it leads to functional limitations and a higher rate of revision joint replacement [84–86]. Unlike joint replacement procedures, OCA transplantations give this subset of patients the best possibility to return to athletic activity, especially in those younger than 24 years old with symptoms that are less than a year old [41]. Another major benefit of OCA transplants for larger lesions and for patellofemoral lesions is the ability to construct an optimized allograft that matches the size, shape, and depth of the lesion [53, 65]. This allows it to be a suitable modality for posttraumatic osteochondral defects, osteonecrosis, and osteochondritis dissecans, where large lesions that are unamenable to adequate repair by OAT can be managed [41]. Additionally, unlike ACI, OCA transplants are single stage procedures that replace hyaline cartilage and the underlying subchondral bone without the need for an additional intervention [53, 65, 87]. Another advantage of OCA transplants is that prior treatment failures do not limit its utilization and it can be successfully used as a salvage procedure [53]. For bipolar patellofemoral lesions, there is some controversy over the efficacy of OCA transplants, with some authors proposing it as an effective surgical option for large defects, defects with extensive subchondral bone involvement, or as a salvage procedure for extensive degenerative changes in younger patient populations [84]. OCA can be performed in cases of contained lesions, with the use of the dowel-plug technique, as well as larger uncontained defects, with the use of the shell technique [25, 37, 56]. Knee alignment and patellar tracking should be evaluated to determine the need for any concomitant 357 procedures when pursuing an OCA transplant. General indications for the procedure include young, active patients (typically less than 50 years old) with severe discomfort from a focal chondral or osteochondral lesion (Table 2) [6]. There are several absolute contraindications where a fresh patellofemoral OCA should not be pursued (Table 2). These include advanced osteoarthritis, where patellofemoral arthroplasty may be a superior treatment option; cases with a chronic posttraumatic defect; or any patient who is a poor surgical candidate [41]. Advanced osteoarthritis and inflammatory arthritis are contraindications for OCA transplant as the failure rate for the procedure and need for subsequent total knee arthroplasty in a short span make this patient population unlikely to benefit from the intervention [41]. Relative contraindications to the procedure include obese patients (BMI > 35 kg/m2), concomitant meniscal/ligamentous injuries in the ipsilateral knee, uncorrectable malalignment of the knee joint, smoking, or corticosteroid use (Table 2) [41]. Irreversible damage can occur to allografts in obese patients, patients who smoke, and those who chronically use corticosteroids, due to impaired bone metabolism [41]. For cases with osteonecrosis, it is recommended that chronic corticosteroid use is stopped prior to pursuing the OCA transplant. It is believed that continued corticosteroid use will interfere with revascularization of the allograft leading to collapse [53, 88]. Higher body mass leads to an increased risk of failure in obese patients due to aberrant loading of the graft and the resulting death of viable chondrocytes [89–91]. Normal joint alignment is critical for a successful OCA transplant, and uncorrectable malalignment can lead to decreased viability of transplanted chondrocytes [41]. It is also critical to restore normal intraarticular biomechanics via addressing any concomitant meniscal insufficiency or ligamentous instability during the OCA procedure [41]. Patients with posterior cruciate ligament deficiency will place increased stress on the PFJ and are not ideal candidates for this procedure in isolation [25].
358 S. P. Dasari et al. Table 2 Indications, Absolute Contraindications, and Relative Contraindications of the Fresh Osteochondral Allograft Technique for Patellofemoral Osteochondral Lesions Indications Large chondral/osteochondral lesions (greater than 2 cm2) of the patellofemoral joint that have failed nonoperative management [41] Patellar defects, trochlear defects, bipolar defects, and subtotal defects without significant joint space narrowing [2] Patients with associated subchondral bone pathology [13] Salvage procedure after failing a prior cartilage repair technique [53] Young active patients (less than 50 years old) who desire to return to a relatively high level of activity and are willing to follow postoperative recovery and rehabilitation protocols [41, 84–86] Absolute Contraindications End stage osteoarthritis [41] Chronic post traumatic defects [41] Poor surgical candidates [41] Inflammatory arthritis [41] Relative Contraindications Obese patients (BMI over 35 kg/m2) [41, 89–91] Concomitant ligamentous or meniscal injuries (must be addressed before or during the procedure in order to purse an OCA of the PFJ) [41] Uncorrected malalignment of the joint (must be addressed before or during the procedure in order to purse an OCA of the PFJ) [41] Smoking [41] Chronic corticosteroid use [53, 88] 8 Pre-Operative Planning 8.1 Imaging Preoperative imaging of chondral and osteochondral lesions usually begins with plain radiographs consisting of standing anteroposterior views, lateral views, patellofemoral (sunrise) views, and long axis weight-bearing [25, 50, 56, 92]. The common standing views are often paired with a 45° flexion posteroanterior weightbearing (Rosenberg) view and should be inspected for pathological changes in all knee compartments. Bearing in mind the possible anatomical underlying causes for patellofemoral disorders, the lateral view also provides information regarding patellar height or trochlear dysplasia. Further assessment of trochlear morphology, as well as patellar morphology and additional maltracking features can be noted in sunrise views. Long axis radiographs should be inspected for coronal plane mechanical malalignment. Advanced imaging studies, including magnetic resonance imaging (MRI) and computed tomography (CT) should also be conducted (Fig. 1). MRI is a highly sensitive and specific modality for the detection of chondral pathology, with similar accuracy reported for patellar and trochlear defects [93]. Aside from lesion size and location, MRI is able to detect subchondral bone edema or sclerosis [94]. Additionally, MRI is valuable for assessing associated intra-articular disorders that would require intervention, such as meniscal status, ligament status, or the presence of loose bodies. CT can be useful as an additional means of quantifying bone involvement, and bone stock in the context of massive chondral defects or OCD patients [50]. TT-TG distance, patellar tilt, and rotational deformities can also be assessed.
Fresh Osteochondral Allografts in Patellofemoral Surgery 359 Fig. 1 Focal patellar chondral lesion with an uncontained trochlear lesion, disrupted medial patellofemoral ligament, and concomitant severe trochlear dysplasia seen on an axial T2 MRI (A, B) 8.2 Concomitant Procedures It is crucial to address any associated knee disorders that could jeopardize cartilage restoration, either beforehand in a staged approach or concomitant to the OCA [1, 2, 13]. A tibial tuberosity osteotomy (TTO) is a distal realignment procedure that allows for adjustments in the coronal, sagittal, and axial planes in order to redistribute patellar contact pressures and improve patellar tracking [95]. Anteriorization of the tibial tubercle will shift contact forces proximally, and medialization of the tubercle will decrease the lateral force vector [95]. The Fulkerson anteromedialization (AMZ) TTO combines both mechanisms and was developed to address patellofemoral pain with concomitant patellar maltracking [96]. The procedure improves contact mechanics and unloads the patellofemoral joint, so it is often performed alongside patellofemoral cartilage restoration procedures as it has been shown to improve the clinical outcomes of these restoration techniques [95, 97, 98]. The AMZ TTO transfers contact forces from distal and lateral to proximal and medial on the patellar articular surface to unload the PFJ and minimize strain on an OCA. This makes it particularly useful when managing lesions on the inferior pole or lateral facet [13]. The AMZ TTO is designed to decrease the Q angle to a more central position and correct the TT-TG distance for cases of patellar instability, allowing for adequate unloading of the patellofemoral compartment during cartilage restoration surgery [6]. This has been shown to significantly decrease patellofemoral contact pressure [99]. Furthermore, a study by Pidoriano et al. has demonstrated superior outcomes for managing lesions at the lateral facet or distal pole of the patella relative to patients who did not undergo AMZ TTO [100]. In the setting of cartilage restoration procedures, the AMZ TTO can be performed as a concomitant procedure to minimize contact pressures on the OCA and optimize the biomechanical environment [95]. An unloading osteotomy is also strongly considered when an OCA is performed in the setting of bipolar patellofemoral lesions [2]. Unloading osteotomies can reduce joint surface pressures by up to 30%, making them crucial for success in this situation. Varus or valgus osteotomies for coronal plane malalignment, lateral retinacular release or lengthening, vastus medialis advancement, medial—and rarely lateral—patellofemoral ligament reconstruction, distalization of the patella, and de-rotation osteotomies should be performed when necessary [1, 2, 50]. While unloading osteotomies improve clinical outcomes related to OCA, they are not without complications and carry a risk of nonunion, painful hardware, or iatrogenic overloading of a separate site within
360 the patellofemoral joint [6]. Lastly, bone marrow aspirate concentrate (BMAC) is also often used in conjunction with an OCA to enhance graft integration [13]. 8.3 Graft-Matching Allograft size-matching is a critical step of preoperative planning as creating a smooth articular surface is key to the success of the procedure [101]. The traditional prevailing parameter for donor matching is based on anteroposterior and lateral radiographs of the recipient corrected for magnification [102, 103]. Previous studies using computer modeling and cadaveric specimens have demonstrated that contact pressures can significantly increase when there is a graft mismatch leading to a 0.5–1 mm protuberance relative to the neighboring cartilage [77, 104]. MRI can also be useful in presurgical matching and is employed by 93% of members of the Metrics of Osteochondral Allografts (MOCA) expert group in addition to standard radiography with a sizing marker for patellofemoral OCA [2, 105]. Previous studies have shown a potential for underestimating defect size when using MRI in comparison to surgical findings [106, 107]. However, modern equipment and cartilagespecific MRI sequences tend to allow for more detailed evaluation [25]. Other reported parameters are preoperative CT scan, anthropometric agreement between donor and recipient, and Wiberg’s classification for the shape of the patella [56]. The anatomic complexity of the patellofemoral joint, combined with wide variability for articular geometry and cartilage thickness, make donor-matching even more challenging than OCA procedures for the tibiofemoral compartments. To create a matching system specific to OCA procedures of the PFJ, Determann et al. proposed the use of radiographic patellar measurements [108]. The authors demonstrated a strong correlation for ex vivo patellar angle and articular length and moderate correlation for lateral facet width, total width and central ridge S. P. Dasari et al. height using their technique. While potentially beneficial, this method still lacks sufficient clinical validation. As a result, to help with surgical planning, a diagnostic arthroscopy is recommended to further evaluate for the size, location, and severity of the cartilage defect, and to further verify patient eligibility for OCA. 9 Surgical Technique and Case Presentation 9.1 Patient Positioning and Anesthesia The patient is placed in the supine position on the operating table and placed under general anesthesia. The senior author prefers a technique, where a well-padded high-thigh tourniquet is placed on the operative side and a bump is placed under the knee so that it rests at approximately 30° of flexion. The contralateral leg is secured to the table in full extension with a pneumatic compression device to help prevent DVT. Preliminary arthroscopy and eventual concomitant procedures should be performed before the OCA. An adductor canal block combined with local infiltration is an effective and safe option for pain management, without the loss of quadriceps motor function associated with femoral nerve blocks. 9.2 Surgical Exposure A small medial or lateral parapatellar arthrotomy is performed depending on the location of the cartilage defect. A medial arthrotomy is generally preferred as it facilitates patellar mobilization and exposure of both the patella and trochlea, which makes it far superior to lateral approaches for this. Furthermore, the lateral trochlea surface is directed medially and thus instruments are more easily positioned from the medial side with the patella subluxed laterally. Medial subluxation of the patella for exposure is significantly more difficult. Full exposure of the patella
Fresh Osteochondral Allografts in Patellofemoral Surgery and trochlea—particularly in cases of bipolar lesions or large defects requiring the shell technique—may require a sizeable arthrotomy. 9.3 Dowel-Plug OCA Technique The defect should be identified and templated. Next, a guide pin is placed in the center of the defect and the edges of the defect are scored. It is essential that the guide pin be placed as perpendicular as possible to the joint surface. The defect is then reamed until bleeding, healthy bone is encountered, with care not to exceed a maximum of 7 to 8 mm of overall bone depth. This can be achieved by frequently checking the calibrated coring reamer (Arthrex, Inc. Naples, Florida), along with a final measurement. The recipient site is then dilated with a smooth cylinder (Arthrex, Inc. Naples, Florida) several times to ensure the donor plug can be inserted without the need to apply too much pressure. In order to accomplish a perfect fit between the donor graft and the host socket, a compass reference is created on the prepared defect and measures are taken from each main coordinate (North/South/East/West). These measurements will be used later at the time of graft trimming. The whole donor specimen is then secured within an allograft workstation (Arthrex, Inc. Naples, Florida) to ensure precision during harvest. The osteochondral donor plug is then harvested from the allograft with use of a coring reamer. The direction of this reamer relative to the surface of the allograft should be identical to the direction that the recipient site was prepared. This fundamental technique can be challenging in the complex surface topography of the patella and trochlea. The subchondral bone of the donor plug is then trimmed according to previous measurements to match the corresponding depths of the host location, and the surfaces are smoothed with a rasp. The depth of the recipient site and donor plug is measured several times to make sure there are no areas that will be too proud. Copious irrigation should be used while reaming the receiving site and graft in order to 361 prevent heat necrosis. Prior to implantation of the donor bone plug, the subchondral bone is subjected to pulse lavage with an antibiotic solution to eradicate any remaining bone-marrow elements to minimize the chance of immune reaction [79]. Bone marrow aspirate concentrate is often used in an effort to augment allograft integration [109]. The bone plug is then gently press-fit into the socket to match the exact height of the surrounding articular cartilage. Rotation of the plug is checked to ensure “best fit.” Impaction of the graft should be avoided when possible. Consensus among the MOCA expert group points to an ideal depth of the allograft that is limited to 6 to 10 mm [76]. If proud, the surgeon should consider removal of the plug with a small blunt elevator and smoothing off the small, elevated area with a rasp. If the recipient site is too deep, then remove the allograft and add a deeper layer of bone graft first. Preference should be given to matching cartilage surface topography and minimizing peripheral step-off over osseous mismatching [2]. The dowel-plug technique is the preferred method of patellofemoral OCA when working with focal, contained chondral defects (Figs. 2 and 3) [2, 37]. The dowel or press-fit technique fashions a 15–35 mm diameter plug that allows for press-fit implantation on the recipient site and obviates the need for implant-fixation. Defects that are entirely on the medial or lateral facets of the patella can be addressed with small dowelplugs. Central defects can be treated with a dowel OCA but are technically more challenging to match perfectly owing to the complex geometry of the trochlear groove and patellar median ridge. Although there is no consensus on the ideal approach for these cases, options include ACI, a “mega-OAT” dowel technique, where one uses a single large plug to resurface almost the entire patella, or a shell technique [2, 110, 111]. 9.4 Shell Technique for the Patella Common indications for a patellar shell OCA technique include extensive damage to both
362 S. P. Dasari et al. A B C D Fig. 2 Patellar osteochondral lesion treated with a fresh osteochondral allograft (OCA) using the dowel-plug technique. A Osteochondral lesion of the patella, B patellar lesion after removal of the lesion by reaming, C shaped osteochondral allograft plug, D OCA press-fit using the dowel-plug technique patellar facets, damage to the median ridge, and uncontained lesions [37]. The technique is typically indicated for cartilage defects that are not eligible for a dowel-plug OCA procedure. In the clinical setting, other frequent indications include post-traumatic arthritis (post-patellar fracture) and osteonecrosis [16, 56]. For patellar shell grafting, a patellar cut is performed using principles comparable to those of resurfacing during total knee arthroplasty. A caliper can be used to obtain the patellar thickness measurement, in addition to superiorinferior and medial–lateral widths for donor sizematching. The patellar cut is performed either free-hand or using a “lobster-claw” patellar clamp. At least 12 mm of the native patellar thickness should be preserved in order to limit fracture risk, and no more than about 15 mm should be preserved in order to avoid overstuffing, which would increase patellofemoral contact forces and limit flexion [112, 113]. Any resulting sclerotic bone should be drilled. Donor graft
Fresh Osteochondral Allografts in Patellofemoral Surgery 363 9.5 Shell Technique for the Trochlea Fig. 3 A focal, contained trochlear osteochondral lesion treated with a press-fit OCA using the dowel-plug technique preparation is carried out in similar fashion. It is wise to avoid shell grafts that are beyond 10 mm of subchondral bone thickness as this is the known threshold for a theoretically higher risk of immune reaction, although large trochlea graft often are up to 15 mm at their highest point to accommodate a minimum thickness (5–6 mm) at their lowest point [114]. Oversized graft or native bone margins can be trimmed for ideal matching. The allograft is placed and temporarily fixed to the receiving site with Kirschner wires, positioned on the extra-articular dorsal aspect of the patella. If placement, size, and tracking are deemed satisfactory, definitive fixation canthen be performed. Retrograde fixation from the dorsal aspect to the subchondral bone as well as countersunk headless fixation from the margins of the articular surface have been described as typical fixation techniques [37, 56, 111]. Possible fixation implants include metal screws, bioabsorbable screws or pins. The trochlear shell OCA technique is typically indicated for uncontained trochlear lesions as well as cases with trochlear dysplasia and concomitant high grade chondromalacia [17, 18, 41]. In a recently published technical note, the senior author described a trochlear shell allograft technique combined with MPFL reconstruction and a TTO to treat trochlear dysplasia in the setting of chondral damage and chronic patellar instability (Fig. 4) [16]. After performing a medial parapatellar incision and dissecting to the joint capsule, a medial patellar arthrotomy is performed. During this initial stage, it is important that the incision is large enough to allow complete visualization and exposure of the trochlea, patellar surfaces, and tibial tubercle, if a TTO is indicated. While the knee is positioned in 60° of flexion, three 2.0 mm Kirschner wires are placed in parallel in a distal to proximal fashion to serve as a guide for the oscillating saw when removing the existing native dysplastic trochlea. Copious irrigation is utilized during this step to minimize the risk of thermal necrosis. The remaining bony surface is then homogenized to facilitate anatomic fixation of the allograft. The donor femur allograft is prepared on the back table. Three Kirschner wires are placed: one is central and superior to the notch while the other two pins are parallel and just lateral to either side of the central pin. These are used to guide the oscillating saw. After making the cut, the undersurface of the graft is shaved and osteophytes are removed to facilitate anatomic reconstruction of the trochlea. Pulsatile irrigation is performed on the graft followed by pressurized carbon dioxide once the curvature of the graft match is confirmed. This is followed by application of bone marrow aspirate concentrate to the osseous portion of the graft, which is done to maximize healing and integration of the graft (Fig. 5). The graft is then placed in its optimal anatomic position on the patient’s femur and four
364 Fig. 4 Trochlear osteochondral allograft (OCA) shell technique. A Three Kirschner wires are used to guide an oscillating saw, which is cutting the trochlea under constant irrigation. B The cut surface after the trochlear cap was removed and C the placement of the Fig. 5 Bone marrow aspirate concentrate (BMAC) applied to the osseous portion of the trochlear OCA. A Aspiration of bone marrow from the iliac crest. B Using pressurized carbon dioxide on the osseous portion of the graft. C, D Application of BMAC to the OCA S. P. Dasari et al. osteochondral allograft to ensure an anatomic reconstruction. D Securing the trochlear OCA using four headless screws. E A lateral fluoroscopic view after the fixation. F Final view of the anatomically reconstructed trochlea with an OCA secured using four headless screws
Fresh Osteochondral Allografts in Patellofemoral Surgery 365 Fig. 6 Preoperative (A) and postoperative (B) axial views of CT scans demonstrating the trochlear shell allograft for trochlear dysplasia with concomitant trochlear chondromalacia in a left knee Table 3 Pearls and Pitfalls of the Fresh Osteochondral Allograft Technique for Patellofemoral Osteochondral Lesions Pearls For contained lesions, a dowel-plug technique should be used, while a shell technique should be used for uncontained lesions alone or when correcting a trochlear lesion in the setting of trochlear dysplasia Knee alignment and patellar tracking should be evaluated to determine the need for a concomitant procedure like an anteromedialization tibial tubercle osteotomy, medial patellofemoral ligament reconstruction etc Preoperative matching of the donor to the recipient in terms of size, shape, curvature, and overall knee morphology is critical to ensuring a successful outcome Donor cartilage should be from young patients without obvious chondral disease. The donor should ideally be similar in age or younger than the recipient Surgeon and patient schedules must be flexible to facilitate timing of the surgery when a size and shape matched donor graft becomes available For the plug technique, bleeding healthy bone should be encountered while reaming the defect. However, the recipient site should not exceed 7–8 mm of depth. Frequently check the calibrated coring reamer to avoid over-reaming. Using a graft that is thicker than 8 mm may increase the immunogenicity of the transplanted tissue For the plug technique, using a smooth dilator after reaming the defect facilitates further insertion of the donor plug For the plug technique, reduce the size of the original allograft in order to facilitate its manipulation during osteochondral plug preparation For the plug technique, use a clockface reference (12/3/6/9) for measuring the depth of the recipient’s bed and have an assistant outside the surgical field taking notes to precisely prepare the donor plug. This allows the surgeon to ensure an accurate donor-host curvature match Multiple trials of shaving the undersurface of the graft should be done to facilitate anatomic reconstruction Pulsed lavage the osseous component of the graft to minimize the risk of an immunogenic reaction Bone marrow aspirate concentrate (BMAC) can be used to biologically enhance and expedite graft integration BMAC should be applied to the osseous component of the graft after pulsed lavage of the graft and after applying pressurized carbon dioxide to the osseous component of the graft. Pressurized carbon dioxide helps to clean the bone microarchitecture Pitfalls Heat necrosis can occur from high-speed reamers in the edges of the receptor’s bed as well as in the donor plug. It can also occur when using the oscillating saw for the shell technique. Copiously irrigate cutting surfaces with roomtemperature saline while using reamers and saws to minimize this risk Failure to address concomitant underlying pathology such as instability related to an insufficient MPFL or a dysplastic trochlea can ultimately lead to failure of the procedure (continued)
366 S. P. Dasari et al. Table 3 (continued) Inaccurate curvature match can lead to inferior outcomes of the OCA procedure Ensure a flush fit of the graft; a graft that is too proud will lead to aberrant joint mechanics Reaming too deep increases the risk of a fracture and also requires the use of an OCA with a thicker osseous component that could increase the risk of immunogenicity For the plug technique, minimize impaction of the osteochondral graft while press-fitting it into the receptor’s bed (use a sponge to cushion the chondral surface and frequent low-force impaction if necessary) Non-compliance with postoperative rehabilitation can lead to poor results. Do not pursue an osteochondral allograft in a patient who is unwilling or unable to follow the postoperative rehabilitation and recovery protocol Kirschner wires are drilled to hold the graft in place, while four headless screws are used to secure the graft. The screws are placed either perpendicularly through the center of the graft or obliquely from the graft margins. For this case, the trochlear shell technique (Fig. 6) was followed by a TTO, MPFL reconstruction, and a dowel-plug technique OCA for a contained patellar chondral lesion. A list of pearls and pitfalls of the fresh OCA technique for patellofemoral osteochondral lesions is outlined in Table 3. encouraged after 6 weeks [37]. From 6 to 12 weeks the patient should be able to regain the ability to perform functional activities of daily life. Avoidance of high-impact activities during the first 6 to 12 months is advised to allow for complete graft healing and incorporation. A preference for low-impact over high-impact activities after this period is also encouraged. Athletes should follow rigorous criteria for return to play, at the discretion of the treating surgeon [50]. 11 10 Rehabilitation Patients should customarily follow an initial period of non-weight-bearing during the first eight weeks for graft protection. Progressive weightbearing with a knee brace locked in full extension, has not been shown to excessively load the patellofemoral joint, and, as a result, it is safe for patients and often implemented assuming no associated osteotomy was performed [2, 115]. Supervised rehabilitation should start immediately postoperatively, with a focused emphasis on quadriceps activation. Early range of motion exercises are widely considered safe in order to avoid arthrofibrosis, and a continuous passive motion (CPM) machine should be implemented whenever possible [2]. Some authors advocate limiting knee flexion during the early postoperative phase and allowing for 30° flexion increments biweekly until a full range of motion is Patient Outcomes 11.1 Clinical Outcomes The current literature has consistently demonstrated good to excellent outcomes in terms of survival and function for generalized knee OCA procedures [50, 52]. However, when compared to OCAs in the tibiofemoral compartment, patellofemoral OCA has often been associated with inferior results, higher failure rates, and higher reoperation rates [27, 32, 116]. Cameron et al. retrospectively evaluated patient outcomes and satisfaction in 28 patients who had OCA to the femoral trochlea [117]. They found significant improvement in modified d’Aubigné-Postel score, International Knee Documentation Committee (IKDC) subscores, and Knee Society Score-Function (KS-F). Furthermore, 89% of patients were extremely satisfied or satisfied with their surgical outcome. This was determined using the OCA patient satisfaction score.
Fresh Osteochondral Allografts in Patellofemoral Surgery However, these results must be interpreted with caution due to the small sample size and lack of comparison with other treatment options. In 2020, Chahla et al. performed a systematic review of clinical outcomes after PF OCA with at least 1.5 years follow up [1]. One hundred and twenty nine patients were evaluated from eight clinical studies. The etiologies of the osteochondral lesions included trauma, osteochondritis dissecans, patellar instability, degenerative chondral lesions, and osteoarthritis. A total of 16 outcome measures were utilized across these studies. Significant improvement in at least one of the following primary clinical outcome measures was reported in seven of the eight studies. These primary outcome measures were the IKDC, Knee Society Score-Function, Lysholm Knee score, and modified d’Aubigné-Postel score. However, the apparent heterogeneity in studies’ reporting of subjective and objective outcomes, as well as the influence of concomitant pathologies and procedures alongside PF OCA limit the generalizability of these findings. Additionally, the design of the included studies precluded the authors from performing a formal meta-analysis of the data. 11.2 Imaging Outcomes Similar to the clinical outcomes for PFJ OCA, the imaging outcomes are supportive of the technique but limited thus far. Spak and Teitge evaluated radiographs at final follow-up for graft incorporation, resorption, collapse, cyst formation, and osteophyte formation [1, 118]. At final follow up, all patients demonstrated an intact allograft with radiographs exhibiting mild degenerative changes for six of eight patients, and no degenerative changes in the remaining two patients. Jamali et al. also evaluated radiographs of 12 patients for visibility of allografthost junctions, allograft radiodensity, and presence of subchondral cysts [119]. Four patients did not show signs of PF arthrosis, six had mild arthrosis, and two patients developed advanced arthrosis. The allograft-host interface was visible in three patients. Graft radiodensity was found to be increased in four patients. Subchondral lysis 367 was seen in four patients; however, three of these four grafts had good to excellent clinical scores. Given the limited radiographic analyses performed for PF OCA outcomes, future studies should focus on imaging outcomes to aid in validating the success of OCA to treat patellofemoral chondral lesions. 11.3 Survivorship In the systematic review by Chahla et al., seven included studies performed Kaplan–Meier survival analysis for PF OCA [1]. Cameron et al. reported 100% allograft survivorship at 5 years and 91.7% at 10 years post-operatively [117]. The lowest survivorship was reported by Gracitelli et al. with 55.8% at 15 years follow up [26]. When combining data from all studies, the weighted mean 5 year survival rate was 87.9%, the average 10-year survivorship was 77.2%, and survival rate at 15 years was 55.8%; however, this 15 year outcome was only reported in one single study [1]. Amongst these seven clinical studies included in the systematic review by Chahla et al., graft failure was not uniformly defined [1]. Three studies defined graft failure as necessitating graft revision or conversion to total knee arthroplasty (TKA) [117, 120, 121]. Another study defined failure as any reoperation resulting in allograft removal [26]. Frank et al. defined failure to be conversion to TKA, revision OCA, or graft failure as observed on second-look arthroscopy [89]. One study included clinical outcome measures as part of their definition of failure, with clinical ratings less than 70 points on KSS-F and Lysholm Knee Score scales [118]. A recent 2019 study by Cotter et al. performed a survivorship analysis of 50 patients treated with PF OCA (using either plug or shell technique) and identified variables associated with graft failure [37]. In the plug technique group, two patients (out of 16 patients) failed at an average of 9.17 years post-operatively. In the shell technique group, 13 patients (out of 34 patients) failed at an average of approximately 3.81 years post-operatively. In addition, Kaplan–Meier
368 survival analyses was performed for each group. The plug technique group was found to have survival rates of 100% and 66% at 5 and 9.8 years after PF OCA, respectively. The shell technique group had survival rates of 65.8% at 5 years and 37% at 10.6 years. In this study, logistic regression analysis was performed to identify variables associated with PF OCA failure within the entire cohort of patients and within the shell group specifically (37]. Increased BMI was found to be associated with graft failure in the entire cohort as well as within the shell technique group. Furthermore, a traumatic etiology of the chondral pathology was protective against graft failure in the entire cohort analysis. An additional study by Meric et al. reported on the results from a total of 48 subjects with bipolar reciprocal osteochondral lesions. Survivorship of the bipolar OCA was 64.1% at 5 years. High reoperation (62%) and failure rates (46%) were observed, but patients with surviving allografts showed significant clinical improvement (18-point score, IKDC pain, IKDC function, KS-F). Interestingly, bipolar OCA transplants in the PFJ have displayed lower failure rates when compared to bipolar tibiofemoral transplants [111]. S. P. Dasari et al. 11.4 Complications Complications following PF OCA are relatively uncommon, and studies reporting on this data are limited. No intraoperative complications were identified by Chahla et al.’s systematic review [1]. In a 2006 study by Spak and Teitge, the authors reported five minor complications: four patients developed postoperative anterior knee pain that was managed conservatively and one patient developed a post-operative skin rash that resolved with prednisone [118]. In addition, all patients had mild synovitis that resolved spontaneously. Cameron et al.’s study of 28 patients found one patient to have persistent pain, possibly attributed to complex regional pain syndrome, ultimately requiring a total knee arthroplasty (TKA) (117]. Bakay et al. reported on one patient developing hyperpressure of the patellofemoral joint, which did not require reoperation [122]. Cotter et al. reported no intraoperative complications, but three patients developed postoperative complications [37]. One patient developed a deep infection requiring arthroscopic irrigation and debridement followed by intravenous antibiotics. One patient experienced a superficial skin infection that resolved Table 4 Key Points to “Take-Home” “Take-Home” Points Osteochondral lesions of the patellofemoral joint are challenging to treat due to the complex, variable anatomy and high biomechanical strain experienced at the joint. Despite this, osteochondral allografts can effectively treat patellar lesions, trochlear lesions, large lesions, unconstrainted lesions, and bipolar lesions at this joint as both a primary and salvage treatment option Osteochondral allografts combine mature hyaline cartilage with metabolically active chondrocytes over a stable, structural osseous base allowing them to address chondral and subchondral pathology Location matching, size matching, expedition of time from harvest to transplantation, and minimization of impaction are all critical components to optimizing clinical outcomes with the fresh osteochondral allograft procedure Concomitant procedures including the Fulkerson anteromedialization tibial tubercle osteotomy, patellofemoral ligament reconstruction, varus/valgus osteotomies, de-rotation osteotomies, lateral reticular release/lengthening, and the application of bone marrow aspirate concentrate can all be critical towards satisfactory clinical outcomes for the application of osteochondral allografts when treating patellofemoral pathology The dowel plug technique is ideal for focal, contained lesions while shell techniques are preferred for large, unconstrained lesions or lesions with concomitant trochlear dysplasia The initial literature has demonstrated inferior outcomes of patellofemoral osteochondral allografts relative to tibiofemoral osteochondral allografts; however, several studies have reported promising initial clinical improvement and patient satisfaction with fresh osteochondral allografts at this joint. Additionally, a recent systematic review has demonstrated good survivorship of the transplanted graft at five- and ten-years follow-up
Fresh Osteochondral Allografts in Patellofemoral Surgery with oral antibiotic treatment only. One patient developed pain and stiffness secondary to intraarticular adhesions requiring arthroscopic lysis of adhesions. Wang et al. reported on three patients who developed arthrofibrosis post-operatively, but all were successfully treated with arthroscopic lysis of adhesions and scar excision [120]. Unfortunately, one of these patients subsequently developed septic arthritis after lysis of adhesions, which was treated with arthroscopic irrigation and debridement. This same patient later went on to undergo TKA nearly four years later. 11.5 Reoperation Rates The most common reoperation reported after PF OCA was hardware removal [1, 26, 118–120]. However, it is not clear if this was secondary to the index PF OCA procedure or due to concomitant procedures performed during PF OCA (e.g., realignment surgeries or osteotomies). Reoperations were also performed for patients who were deemed to have a failed allograft, subsequently requiring TKA. Cotter et al. reported five of 16 patients (31.3%) that underwent plug technique required reoperation approximately 1–2 years following primary PF OCA [37]. Reasons for reoperation in this group included medial femoral condyle chondroplasty, post-operative pain necessitating second-look arthroscopy, hardware removal for concomitant high tibial osteotomy, and irrigation and debridement secondary to infection. In contrast, 28 of 34 patients (82.4%) that underwent shell technique PF OCA required reoperation. The most common reoperation was patellofemoral arthroplasty and second-look arthroscopy with chondral debridement (grafts intact). Six patients required TKA, and four patients required hardware removal from concomitant osteotomy procedures. 369 12 Conclusion and Key Message Patellofemoral osteochondral allograft is an effective procedure used to treat patellofemoral osteochondral lesions unamenable to conservative measures (Table 4). It can be used as both a primary procedure or a secondary salvage procedure to treat large lesions, unconstrained lesions, lesions involving the underlying subchondral bone, and bipolar lesions. Current clinical literature shows promise in the widespread implementation of this technique. Future studies should continue to investigate possible graft-matching parameters specifically tailored for the patellofemoral joint as well as the longterm outcomes and complications associated with the patellofemoral OCA surgical technique. References 1. Chahla J, Sweet MC, Okoroha KR, Nwachukwu BU, Hinckel B, Farr J, et al. Osteochondral allograft transplantation in the patellofemoral joint: a systematic review. Am J Sports Med. 2019;47(12):3009–18. 2. Chahla J, Hinckel BB, Yanke AB, Farr J, Bugbee WD, Carey JL, et al. An Expert consensus statement on the management of large chondral and osteochondral defects in the patellofemoral joint. Orthop J Sports Med. 2020;8(3):2325967120907343. 3. Widuchowski W, Widuchowski J, Trzaska T. Articular cartilage defects: study of 25,124 knee arthroscopies. Knee. 2007;14(3):177–82. 4. Hart HF, Stefanik JJ, Wyndow N, Machotka Z, Crossley KM. The prevalence of radiographic and MRI-defined patellofemoral osteoarthritis and structural pathology: a systematic review and metaanalysis. Br J Sports Med. 2017;51(16):1195–208. 5. Lording T, Lustig S, Servien E, Neyret P. Chondral Injury in patellofemoral instability. CARTILAGE. 2014;5(3):136–44. 6. Strauss EJ, Galos DK. The evaluation and management of cartilage lesions affecting the patellofemoral joint. Curr Rev Musculoskelet Med. 2013;6 (2):141–9.
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Extensor Mechanism Complications After Total Knee Arthroplasty Jobe Shatrov, Cécile Batailler, Gaspard Fournier, Elvire Servien, and Sebastien Lustig 1 Introduction Extensor mechanism problems in total knee arthroplasty account for 12% of complications [41]. Manifestations are broad both in terms of etiology and impact on the patient. The most commonly encountered complications are patellar tendon rupture, quadriceps tendon injury, periprosthetic patella fracture, patellofemoral instability, soft tissue impingement and osteonecrosis of the patella. The purpose of this chapter is to review the incidence, risk factors and surgical management of the aforementioned complications. 2 Commonly it is diagnosed on plain imaging by the presence of sclerotic bone which may appear smaller than the contralateral side and may have the appearance of being fractured or fragmented. In latter stages remodelling may occur characterised by a periosteal reaction. Interestingly, the superior pole tends to demonstrate increased radiodensity, and the inferior pole increased radiolucency [47]. CT imaging typically features a focal area of bone sclerosis surrounded by a sclerotic demarcation line. Radionuclide studies can show either decreased accumulation of the bone-seeking radiopharmaceutical agent or focal increased uptake of the radionuclide depending on the phase of the disease. Avascular Necrosis of the Patella 2.1 Definition and Epidemiology The rate of patella osteonecrosis after TKA is reported to be 1.4% [25]. However many patients are asymptomatic and the actual incidence is unknown. J. Shatrov C. Batailler G. Fournier E. Servien S. Lustig Albert Trillat Center, Lyon North University Hospital, Lyon, France J. Shatrov (&) Sydney Orthopedic Research Institute, St. Leonard’s, Sydney, NSW, Australia e-mail: sebastien.lustig@gmail.com 2.2 Anatomical Considerations The blood supply to the extensor mechanism is provided by an anastomotic ring created by 6 branches; descending geniculate artery superior and inferior medial and lateral geniculate arteries and a branch from the anterior recurrent tibial artery. On a left knee the first two arteries join and enter the ring at 1 o’clock, with the remaining vessels entering the ring at 3, 5 7 o’clock respectively [30]. It is disrupted as part of routine exposure to the knee joint [42]. During a medial parapatellar arthrotomy the descending, superior and inferior genicular arteries are disrupted. During excision of the lateral meniscus © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_25 375
376 and the infrapatellar fat pad the lateral supply is disrupted by cutting the recurrent branch of the anterior tibial artery and inferior lateral geniculate artery. A lateral arthrotomy will disrupt the superior and inferior lateral geniculate arteries as well as the anterior tibial recurrent artery leaving only the superior lateral geniculate artery intact [36]. Exposure and release of the medial meniscus and plateau will disrupt the inferior medial geniculate artery, leaving only the superior medial geniculate artery intact. 2.3 Risk Factors 2.3.1 Surgical Approach Whilst a medial parapatellar approach reduces blood flow to the patella by 53% it is generally considered safe and no difference has been demonstrated with a sub-vastus approach [38]. If a lateral release is performed the sole remaining blood-supply to the patella may be from the recurrent branch of the anterior tibial artery. However AVN has been reported in case reports following isolated medial parapatellar arthrotomy as well [39]. Given lateral releases are typically performed to improve patella tracking, the need to perform such a release may be avoided through careful component sizing and positioning which have been shown to improve patella tracking. These include avoiding over-stuffing, dome shaped patella button, lateralised and externally rotated femoral component and a lateral arthrotomy in valgus osteoarthritis. In difficult exposures we prefer a tibial tubercle osteotomy (TTO) as this avoids injury to quadriceps and the superior geniculate vessels which can occur with a V–Y turn-down or quadriceps snip. 2.4 Surgical Management Asymptomatic cases can be managed nonoperatively with a period of activity modification, monitoring with serial clinical examination for the presence of an extensor lag and x-rays for J. Shatrov et al. fragmentation or fracture. However in the case of unbearable symptoms, extensor lag, component loosening or fragmentation surgical intervention is indicated. 2.4.1 Allograft In cases of discontinuity of the extensor apparatus, extensor mechanism allograft replacement is required. Our preference is to perform a complete extensor mechanism replacement including a tibial tuberosity bone block, patellar tendon, patella and quadriceps tendon. Brown et al. have reported outcomes following complete extensor mechanism allograft at 10 years, reporting a failure rate of 38% [8]. For patients not meeting the criteria for extensor mechanism allograft, bracing, knee arthrodesis or patellectomy with muscle transfer are alternative options. A surgical technique for extensor mechanism allograft reconstruction in TKA is described at the end of this section. 2.4.2 Muscle Transfer Transfer of the vastus medialis, vastus lateralis, and medial head of the gastrocnemius muscle can be used to fill the defect caused by loss of the patella and extensor tendon mechanism after failure and removal of allograft material. However only short—term results have been reported with this technique and it is generally considered a salvage procedure after failed reconstruction [50]. 2.4.3 Patellectomy Patellectomy may be indicated in such cases where reconstruction of allograft is not possible (infection, inability to adhere to post-operative protocol) however it must be recognised that this reduces the quadriceps strength by 50%, requires at least 15% more force to straighten the knee and may result in a progressive recurvatum in a nonconstrained prosthetic knee [49]. Change et al. followed up 8 patients with unsalvageable patella fractures with TKA up at 49 months who were treated with patellectomy. Whilst pain relief was achieved, 2 could not use stairs, two had quadriceps failure and 50% had an extensor lag [13].
Extensor Mechanism Complications After Total Knee Arthroplasty 2.5 Extensor Mechanism Allograft Replacement Contraindications 1. Active infection or repeated unsuccessful staged re-implantation surgeries with infection 2. Inability to comply with post-operative immobilisation (3 months leg in extension) and rehabilitation Pre-operative planning • Fresh frozen, non-irradiated extensor mechanism allograft is available which matches the affected side • 10 cm’s of quadriceps tendon is necessary for sufficient soft tissue fixation and overlap with the host tissue • If the allograft tibia is not delivered in its entirety, a minimum 6 cm of tuberosity bone length must be available for sufficient distal fixation • The allograft should be inspected and deemed appropriate prior to the patient entering the operating room • A constrained prosthesis may be required to avoid delayed recurvatum and graft failure 377 • Allograft is made slightly larger than the host insertion site since it can be easily trimmed down to obtain a press-fit at the time of insertion. The patellar tendon must be carefully protected during harvest, so it is not damaged by the oscillating saw • The host tibial tubercle trough is sized appropriately and outlined on the anterior tibial cortex. • Proximal portion of the tubercle is dovetailed in a distal/anterior to proximal posterior fashion, just proximal to the patellar tendon insertion. The dovetail is outlined with a pen in a 30–40° angle with a 20–25 mm length. The allograft is securely stored until ready for implantation (Fig. 1). • We recommend a graft that has the following dimensions • Quadriceps tendon −10 cm • Patella—minimum 40 mm in diameter and 25 mm in thickness • Patellar tendon minimum 50 mm in length • Tibial tuberosity • Minimum 6 cm in length, minimum 2 cm in diameter proximally and distally with 15 mm thickness The graft is cleared of any remnant muscle fibres leaving the quadriceps tendon, patella tendon, patella and tibial tuberosity intact. The graft is than fashioned to create two long strips of quads tendon with a whip stitch (Fig. 2). The critical step of the trough preparation is to leave a 1.5 cm bridge proximally to prevent graft escape, with a so called dove-tail technique. This is measured and then a small sagittal saw and lombotte are used to create the desired dimensions to receive the graft. A small medialization or change in length may be achieved by manipulating placement of the trough. The patella height should be checked prior to completion of the trough (Fig. 3). The tibial tuberosity is first fixed with two large fragment screws. Each limb of the graft is then pulvertaft weaved into the quads tendon and then stitched in extension (Fig. 4). The patient is managed for minimum 12 weeks locked in extension followed by graduated flexion. It is critical not to bend the knee once final fixation and tensioning of the graft has been achieved. Graft Preparation Take home messages • The tibial tubercle of the allograft is carefully measured to dimensions of approximately 56 cm of length, 2 cm wide, and 2 cm depth • Patella osteonecrosis following TKA is a rare complication Graft sizing
378 Fig. 1 Whole extensor mechanism allograft preparation Fig. 2 Tibial preparation for extensor mechanism allograft placement J. Shatrov et al.
Extensor Mechanism Complications After Total Knee Arthroplasty 379 Fig. 3 Fixation of the extensor mechanism • Etiology related to multiple incisions disrupting the blood supply as well as remnant thickness of the patella • Management is usually non-surgical • Surgical options vary and are considered salvage options. 3 Patella Clunk Syndrome 3.2 Anatomical Considerations Patella clunk occurs when a discrete fibrosynovial nodule forms between the superior pole of the patella and the undersurface of the quadriceps tendon and becomes entrapped within the intercondylar box of the PS femoral component during knee flexion. Subsequently, when the knee is extended within 30–45° of full extension, the nodule dislodges resulting in an audible and often painful clunk [28]. 3.1 Definition and Epidemiology Patella clunk is a palpable sound which may range from a painless subtle crepitation to a painful, catching or audible clunk of the patella that occurs typically in the range of 20°–45° flexion [17]. Diagnosis is clinical and it typically presents 3–12 months post-surgery. Patella clunk syndrome has been reported in both CR and PS designed prosthesis and has an incidence of 0%–18 [17, 28]. 3.3 Risk Factors 3.3.1 Prosthesis Type Most reports are with the use of a PS constrained implant and this is the greatest risk-factor. PS femoral prosthesis have a relatively higher trochlear transition zone from the groove of the prosthesis to the intercondylar box that is hypothesised to result in increased contact of the
380 J. Shatrov et al. Fig. 4 Post operatively distal quadriceps tendon compared to other prosthesis designs. This is believed the subsequent soft tissue irritation, fibrous hyperplasia and subsequent clunk [15]. 3.3.4 Elevation of the Joint Line Joint line elevation of more than 8 mm has been shown to create patella baja that can produce patella clunk syndrome [21]. 3.3.2 Prosthesis Design PS prosthesis with an intercondylar box ratio of less than 0.7 have been reported to have no incidence of patellar clunk [23]. 3.3.5 Surgical Technique Inadequate synovial tissue removal at the junction between the quadriceps tendon and the superior pole of the patella may also be associated with patella clunk syndrome [26]. 3.3.3 Prosthesis Placement A proximal placement of the patella button, causing impingement on the quadriceps tendon [26]. 3.4 Surgical Management Management is ideally non-surgical. In approximately 20–50% of cases resolution occurs with
Extensor Mechanism Complications After Total Knee Arthroplasty conservative treatment, reassurance and occasionally targeted corticosteroid injection [28]. Arthroscopic debridement of the fibrous nodule has a success rate of over 80% [32]. In refractory cases, or cases where arthroscopy is not possible open peripatellar synovectomy has been shown to successfully treat clunk syndrome although is a more morbid procedure than arthroscopic resection [41]. Take home messages • Patella clunk syndrome is a clinical diagnosis • Syndrome is strongly associated with PS design femoral implants • 20–50% will management resolve with non-surgical • Arthroscopic removal of the fibrous nodule has a high success rate. 4 Patella Tendon Rupture in Total Knee Arthroplasty 4.1 Definition and Epidemiology Patella tendon rupture following TKA is a rare but devastating complication, occurring in less than 1% of primary knee arthroplasties. Rupture can occur intra-operatively or post-operatively. 4.2 Anatomical Considerations Patella tendon rupture most commonly occurs as an avulsion from its insertion at the tibial tubercle. A mid-substance tear is less common. The majority of the patellar tendon fascicles attach to the distal two thirds of the anterior surface of the patella, with 60% of their fibres inserting lateral to the apex of the inferior pole of the patella. It is thin and flat, tapering slightly distally and being an average of 6.5 cm in length [4]. 381 4.3 Risk Factors 4.3.1 Difficult Exposure Difficult exposure is the most commonly sited reason for patella tendon injury intra-operatively [44]. Situations associated with difficult exposure include obesity, revision surgery, pre-operative stiffness and heterotopic ossification and patella baja. 4.3.2 Previous Tibial Tubercle Osteotomy In an early series of patients suffering patellar tendon injury intra-operatively, nearly half had a history of previous tibial-tubercle-osteotomy[44]. 4.3.3 Joint Line Elevation Joint line elevation beyond 4 mm is associated with increased patellofemoral joint contact forces in walking and during stair climbing [31]. Joint line elevation typically occurs in revision knee arthroplasty where there has been distal femoral bone loss. 4.4 Surgical Management Surgery should consist of repair with augmentation, reconstruction or replacement. A number of techniques have been described for augmentation and reconstruction of patellar tendon ruptures in TKA. A suggested algorithm[37] that summarises when these techniques may be used is presented below (Fig. 5). 4.4.1 Achilles Tendon Allograft Burnette et al. compared an Achilles tendon bone-block to a complete extensor mechanism allograft in 19 patients following TKA and suggested the use of a total extensor mechanism replacement when the inferior pole of the patella could not be mobilised to within 2–3 cm of the joint line [9]. This technique also requires a stable component and an intact patella in order to attach the bone block to the tuberosity.
382 J. Shatrov et al. Fig. 5 Patella tendon rupture in total knee arthroplasty surgical management algorithm 4.4.2 Partial Extensor Mechanism Allograft Using the ‘HourGlass Technique’ The hourglass variant of the partial allograft technique is a useful treatment option that can be used even after patellar resurfacing. An hourglass-shaped patellar bone block is press-fit into the native patella. The graft is fixed to both the patella and the tibia then sutured with the knee fully extended. Outcomes of this technique have been reported previously in 5 patients after at least 24 months’ follow-up. The mean knee and function Knee Society Scores values were 77.8 and 64.0, respectively. Extension lag was less than 10 in all 5 patients [22]. The technique is described later in this section. 4.4.3 Whole Extensor Mechanism Allograft Whole extensor mechanism allograft may be required in cases of chronic patellar tendon rupture when the patella is retracted and cannot be mobilised to within 1-2 cm of the joint line, or when bone stock is poor. Both of these situations are common in this setting. The technique and outcomes for whole extensor mechanism allograft has been highlighted in an earlier section. 4.4.4 Surgical Technique—Acute Patellar Tendon Rupture— Repair with Semitendinosus Augmentation A surgical technique is demonstrated in a cadaveric dissection below (Figs. 6, 7, 8). Several descriptions of this technique with variations have been described and published previously [10, 29]. A mid-substance patellar tendon disruption is seen (Fig. 6). The patella can be reduced to its natural position. The semitendinosus tendon is harvested and detached (Fig. 7). Both free ends are subsequently whip stitched to facilitate passing through tunnels. Two transverse tunnels are created using a 4.5 mm drill. The length of the tendon should be
Extensor Mechanism Complications After Total Knee Arthroplasty 383 Fig. 6 Patellar tendon repair with semtitendinosus autograft augmentation Fig. 7 Tunnel creation for graft checked prior to creation of the tibial tunnel to ensure it is long enough. The graft is shuttled through the tunnels and sutured to itself once the tendon has been repaired end-to-end. Alternative options include leaving the tendon attached to its insertion medially and fixing it with an anchor fixation on the lateral tuberosity, or fixation of both free ends with the use of anchors.
384 J. Shatrov et al. Fig. 8 Graft passage and tendon repair 4.4.5 Surgical Technique for Chronic Patellar Tendon Rupture— Reconstruction with a PartialExtensor Mechanism Allograft—The “Hour-Glass” Technique (Fig. 9) The allograft patella is cut in the coronal plane to remove the cartilage-covered aspect. The remaining bone is then cut into an hourglass shape and press-fit into a groove fashioned in the native patella (see below). An hourglass shape that is identical to the shape of the groove in the patella is critical to ensure primary stability. A metallic wire 1.2 mm in diameter is threaded distally through the tibial bone block, which measures about 6 cm (Fig. 10). A partial extensor mechanism is fashioned in the shape of an hour glass being 12 mm wide at its thinnest point in the patella trough. The tibial tuberosity bone block is 2 cm wide proximally and 12 mm wide distally, with a length of 6 cm. Troughs are created in the patella and tibial tuberosity to receive the allograft. The patellar bone block is press-fit into the patellar groove and firmly fixed using the metallic wire. Primary stability is enhanced by the hourglass shape of the bone block, and most of the tendon attachments are preserved. In addition to primary stability, the metallic wires and proximal fixation to the quadricipital tendon combine to prevent migration of the patellar bone block (Fig. 11). The graft is fixed distally with 2–3 cortical screws and the quadriceps tendon end of the graft is then pulvertaft weaved through the native quadriceps tendon with the leg held in extension. Post operatively the patient is managed with the knee locked in strict extension for a minimum of 8 weeks followed by a period graduated flexion
Extensor Mechanism Complications After Total Knee Arthroplasty 385 Fig. 9 Chronic patellar tendon rupture reconstruction using partial extensor mechanism allograft—‘Hourglass’ technique with monitoring via serial x-rays and clinical examination. 5 Take home messages 5.1 Definition and Epidemiology • Patellar tendon rupture following TKA is difficult problem to treat • Usually occurs as a result of difficult exposure and revision surgery • Acute rupture may be repairable, however we advise augmentation due to high rates of failure with primary repair • Chronic ruptures require salvage reconstructive procedures, with allograft options providing the most reliable results in our institution´s experience. The rate of quadriceps tendon rupture following TKA is low, being reported to be 1- 0.1%, with partial tears being more common than complete disruption [20, 33]. Quadriceps Tendon Rupture 5.2 Risk Factors Systemic disorders, that weaken soft tissues, excessive resection of the patella, lateral release and a prior quadriceps snip or V–Y turndown have all been associated with quadriceps tendon
386 J. Shatrov et al. Fig. 10 Graft and host preparation rupture in TKA suggesting the aetiology is likely multifactorial [20, 33, 41]. 5.3 Surgical Management A management algorithm adapted from one suggested by Nam et al. is presented below that summarises management of quadriceps tendon injury in TKA (Fig. 12) [36]. Partial tears can be managed successfully with non-operative management [20]. When surgery is indicated, primary repair is associated with a high failure rate (30–100%) thus augmentation with a biological or synthetic augment is recommended. Augmentation for repairs or quads tendon injuries has similarly been described using fascia lata and Achilles tendon allograft, muscle transfer using sartorius, allograft, hamstring reconstruction and synthetic material. Take home messages • A similar approach for patellar tendon ruptures can be followed for Quadriceps tendon ruptures • Non-surgical management for partial injuries with a minimal lag have good results • Primary repair should be augmented. 6 Periprosthetic Patella Fracture 6.1 Definition and Epidemiology The rate of periprosthetic patellar fracture following total knee arthroplasty ranges from 0.68% to 5.2%, however the rate in unresurfaced patella is 0.05% [11].
Extensor Mechanism Complications After Total Knee Arthroplasty 387 • II—intact implant but extensor mechanism disruption • IIIa—loose implant, with good patellar bone stock • IIIb—loose implant, with poor patellar bone stock. 6.3 Risk Factors Patient factors • BMI greater than 30 6.3-fold and 1.7-fold increases in the risk of loosening and fracture [35]. • Pre-operative thickness of <18 mm has been shown to be a risk factor for fracture [24]. • Osteoporosis [36]. • Loosening − 50% of patella fractures have loosening of the component [37]. Surgical technique factors • Resurfacing the patella—Unresurfaced patella have a rate of fracture that is 0.05% (significantly lower than resurfaced patella) • Lateral release increases 2.7 times the risk for patella fracture [35]. Fig. 11 Graft fixation and post-operative management 6.2 Anatomical Considerations Rather than considering the fractured region of the patella, it is more useful to consider the stability of the implant, the continuity of the extensor mechanism and the remaining bone stock. Patella fractures can be classified in multiple ways. The most commonly quoted system was reported by Ortiguera and Berry [40]. • I—a stable implant and intact extensor mechanism • Residual remnant bone thickness for the patella is recommended to be at least 12 mm of initial thickness. However results are inconclusive with some studies showing a higher rate of fracture < 12 mm [35], and others no difference [24]. Patella design • In a study of cementless implants with a porous tantalum anchoring surface a 20% 2year fracture rate was observed in a study of 30 patients [12]. • Fixation with a single central peg has been suggested to increase the risk of fracture [35].
388 J. Shatrov et al. Fig. 12 Algorithm for surgical management of quadriceps tendon rupture following total knee arthroplasty Fig. 13 Treatment algorithm outlining the management of periprosthetic patellar fracture following total knee arthroplasty. (Reproduced from: Parker DA, Dunbar MJ, Rorabeck CH. Extensor mechanism failure associated with total knee arthroplasty: prevention and management. J Am Acad Orthop Surg. 2003 Jul–Aug;11(4):238–47) 6.4 Surgical Management A management algorithm [41] that is commonly quoted in the management of periprosthetic patella fractures is shown above (Fig. 13). Regardless of management options, complications rate is high when the extensor mechanism is disrupted. We present a case where the extensor mechanism has been augmented with a biological semitendinosus autograft. Case details are provided below. Type 1—Non-operative management. Good results [40].
Extensor Mechanism Complications After Total Knee Arthroplasty 389 Fig. 14 Pre-operative x-rays demonstrating malunited patella fracture with severe tricompartmental arthrosis Type 2–42% reoperation rate, 50% complication rate, and 58%prevalence of extensor lag postoperatively [11]. Type 3—reoperation rate of 20% and an overall complication rate of 45% [11]. 6.5 Case Example Images and x-rays of an 82 year old gentleman who initially presented to our service with a painful stiff knee after a previous patella fracture (Fig. 14). Pre-operatively he had a total range of 20°, with a 20° fixed-flexion deformity and only able to flex to a maximum of 40°. He subsequently underwent a TKA (Fig. 15) with a rotating hinge prosthesis with a TTO for exposure which was uneventful. 3 months following the surgery he fell and these are his radiographs (Fig. 16). X-ray following a fall demonstrating a transverse periprosthetic patella fracture and the post for the hinge mechanism can be seen dislodged on the lateral view indicating that the post mechanism was ‘jumped’ during the hyperflexion of the knee during the fall (Fig. 16). Intra-operative images demonstrating the prosthesis dislocated in deep flexion as the piston has ‘jumped’ out of the polyethelene. The patella
390 J. Shatrov et al. Fig. 15 Post-operative xrays showing an all-cemented hinge-prosthesis with a resurfaced patella. Note a TTO has been performed to facilitate exposure post fixation with tension band wire. Note the extensor mechanism has been augmented with a semi-tendinosus autograft which has been left attached to its insertion at the pes anserinus, tunnel through the patella using a 6 mm transverse tunnel in the superior half and fixed back to the tibia using the screw from the TTO and a suture anchor (Fig. 17). Post op-operative x-rays (Fig. 18) demonstrating patella fracture fixation with a tension band wire. Note the post of the rotating hinge is now reduced in the correct position and an anchor can be seen just below the tibial plateau on the lateral view. Intra-operatively the patella prosthesis was noted to be stable and well fixed. Take home messages • The critical factors determining management of patella fractures are the stability of the implant, the integrity of the extensor mechanism and the quality of the bone-stock • Surgical management has a high complication rate • Augmentation of the extensor mechanism is a good option to protect internal fixation.
Extensor Mechanism Complications After Total Knee Arthroplasty 391 Fig. 16 Periprosthetic patella fracture with a dislocated hinge 7 Patellar Instability in Total Knee Arthroplasty 7.1 Definition and Epidemiology Patellofemoral instability (PFI) following TKA is an uncommon but devastating complication with incidence ranging from 0.5 to 0.8% [43, 45]. It is defined as either subluxation or dislocation of the patella on the femoral component (Fig. 19). 7.2 Risk Factors Aetiology of PFI following TKA is either implant, soft tissue related or a combination of both. The most frequently cited cause is femoral or tibial component internal rotation [1, 2, 48], and when present, revision arthroplasty is recommended [34, 48]. What defines the threshold for malrotation has not been clearly defined. 7.2.1 Femoral Component Rotation Determining the threshold for femoral and tibial malrotation is difficult. Post-operatively, the PCA is no longer available for femoral referencing and therefore most studies have described using the TEA as a landmark to measure femoral component positioning on CT scans [6, 14]. We set a threshold to define malrotation of the femoral component TEA as more than 6° of IR. This is based on the observation that the PCA is 3.5° to 0.3° IR to the TEA in a normal population [6]. 7.2.2 Tibial Rotation Tibial rotation malrotation is also not well defined, with variations in definitions and thresholds varying. Typically the most prominent
392 J. Shatrov et al. Fig. 17 Intra-operative findings and extensor mechanism augmentation point or medial third of the tibial tuberosity is used as a reference point, however it has previously been shown that the interobserver measurement disagreement is more than 3° in 70% of cases [27]. We set a threshold for tibial rotation of 20° according to the technique described by Berger et al. which utilises the most prominent point of the tibial tuberosity. Using this technique a range of 18° ± _2.6° was described as a limit. An inherent issue with measuring tibial rotation however is the wide variation in the position of the tibial tuberosity which has previously been described [16]. 7.3 Surgical Management 7.2.3 Femoral-Tibial Rotation For combined femoral-tibial mal-rotation we set a limit no more than 3º. Previously it has been observed that 3°–8° of combined internal rotation was associated with PFI in TKA [5]. Tibial Tubercle Osteotomy When implant position is satisfactory, addressing the soft tissue imbalance is required. The medial patellofemoral ligament (MPFL) prevents the patella from subluxing laterally and keeps it within the trochlear groove in early flexion [18]. Reconstruction of the MPFL has been used successfully in the treatment of lateral patella instability in the native knee [3, 7, 19]. A management algorithm is described below (Fig. 20) and a surgical technique for MPFLr and TTO at the end of this section. • TTO should be performed in the following situations: • Grade 3 J-sign
Extensor Mechanism Complications After Total Knee Arthroplasty 393 Fig. 18 Post-operatively • Chronic patella dislocation • Severe quadriceps shortening or severe patella baja. 7.3.1 Technique The TTO is performed using an oscillating saw to create an osteotomy that is 6 cm in length, 1.5cm deep proximally, tapered distally and hinged open leaving the lateral side attached to soft tissues. TTO is fixed using two 3.5 mm cortical screws, or in cases of thin bone, transosseous cerclage wires can be utilised. Medialisation is performed up to 10 mm, or until correction of the J-sign and proximalisation in cases of quadriceps shortening or severe patella baja. 1.5 cm bone bridge is preserved proximally to avoid conflict with the tibial tray. 7.3.2 Medial Patellofemoral Ligament Reconstruction A medial sub-vastus approach is performed and extended if necessary for a TTO. The MPFLr is performed using a quadriceps tendon autograft taken from the medial 1/3 of the quadriceps tendon, leaving the patella attachment undisturbed (Fig. 21). The graft is whip stitched and passed beneath the vastus medialis muscle. Next, a femoral tunnel is drilled starting from the femoral footprint of the MPFL [46] aiming for the metadiaphyseal junction laterally. Due to the observation of poor bone quality in the supracondylar region of the femur, an additional cortical fixation is added with the use of an endobutton. The graft is tensioned with the knee flexed to approximately 30°- 45° and fixed with an interference screw but a cortical button is added laterally to avoid graft slippage (Figs. 22 and 23). Post operatively the patient is placed into a range-of-motion knee brace that allows a range of movement from 0 to 90 degrees flexion. The patient can fully-weight bear with the brace locked in full extension. Follow-up consultation at 6 and 12 weeks is performed with x -rays to look at patella height, tilt and translation. If a
394 J. Shatrov et al. A C B Fig. 19 Patellar instability post total knee arthroplasty. Patient with dislocated patella post TKA. A. AP image, B, skyline view and C lateral view Fig. 20 Suggested management algorithm for patella instability post total knee arthroplasty
Extensor Mechanism Complications After Total Knee Arthroplasty Fig. 21 Graft harvest and passage Fig. 22 Tunnel placement and graft double-fixation 395
396 J. Shatrov et al. A B C Fig. 23 Post MPFLr using double fixation with tibialtubercle-osteotomy. Post-operative x-rays of the patient from Fig. 19 taken at 12 post-surgery. A. Sky-line view demonstrating the patella now centered with a patellar tilt of 6°. B. AP x-ray, the endobutton can be seen sitting flush on the lateral cortex. C. Lateral profile demonstrating the tibial-tubercle osteotomy and tunnel position. The osteotomy is united at 3 months post surgery
Extensor Mechanism Complications After Total Knee Arthroplasty TTO is performed, x-rays are taken until radiographic union is achieved which is usually 12 weeks after surgery. 4. Take home messages • Surgery for patellar instability post TKA either requires revision of components or a soft tissue procedure, plus or minus a TTO. • MPFL reconstruction in this population should utilise a quadriceps tendon autograft. • Double fixation of the graft that is reinforced with a cortical button should be used due to the typically poor bone quality in this region post TKA. 5. 8 8. Summary Extensor mechanism complications following TKA are common. Fortunately, those with the most severe impact on the patient are rare, however their management is difficult and in many circumstances is considered salvage surgery. Knowledge regarding the relevant anatomy and risk factors for these main complications will assist surgeons in avoiding them. Algorithms to guide management decisions and inform treatment thresholds are presented based on our institution’s experience and the best available literature. Furthermore, several surgical techniques are described for various extensor mechanism complications. 6. 7. 9. 10. 11. 12. 13. References 14. 1. Akagi M, Matsusue Y, Mata T, Asada Y, Horiguchi M, Iida H, et al. Effect of rotational alignment on patellar tracking in total knee arthroplasty. Clin Orthop Relat Res. 1999. https://doi.org/ 10.1097/00003086-199909000-00019155-163. 2. Anouchi YS, Whiteside LA, Kaiser AD, Milliano MT. The effects of axial rotational alignment of the femoral component on knee stability and patellar tracking in total knee arthroplasty demonstrated on autopsy specimens. Clin Orthop Relat Res. 1993:170–177. 3. Astur DC, Gouveia GB, Borges JH, Astur N, Arliani GG, Kaleka CC, et al. Medial patellofemoral 15. 16. 397 ligament reconstruction: a longitudinal study comparison of 2 techniques with 2 and 5-years follow-up. Open Orthop J. 2015;9:198–203. Basso O, Johnson DP, Amis AA. The anatomy of the patellar tendon. Knee Surg Sports Traumatol Arthrosc. 2001;9:2–5. Berger RA, Crossett LS, Jacobs JJ, Rubash HE. Malrotation causing patellofemoral complications after total knee arthroplasty. Clin Orthop Relat Res. 1998. https://doi.org/10.1097/00003086-19981100000021144-153. Berger RA, Rubash HE, Seel MJ, Thompson WH, Crossett LS. Determining the rotational alignment of the femoral component in total knee arthroplasty using the epicondylar axis. Clin Orthop Relat Res. 1993:40–47. Bouras TUE, Brown A, Gallacher P, Barnett A. Isolated medial patellofemoral ligament reconstruction significantly improved quality of life in patients with recurrent patella dislocation. Knee Surg Sports Traumatol Arthrosc. 2019;27:3513–3517. Brown NM, Murray T, Sporer SM, Wetters N, Berger RA, Della Valle CJ. Extensor mechanism allograft reconstruction for extensor mechanism failure following total knee arthroplasty. J Bone Joint Surg Am. 2015;97:279–83. Burnett RS, Butler RA, Barrack RL. Extensor mechanism allograft reconstruction in TKA at a mean of 56 months. Clin Orthop Relat Res. 2006;452:159–65. Cadambi A, Engh GA. Use of a semitendinosus tendon autogenous graft for rupture of the patellar ligament after total knee arthroplasty. A report of seven cases. J Bone Joint Surg Am. 1992;74:974–9. Chalidis BE, Tsiridis E, Tragas AA, Stavrou Z, Giannoudis PV. Management of periprosthetic patellar fractures. A systematic review of literature Injury. 2007;38:714–24. Chan JY, Giori NJ. Uncemented metal-backed tantalum patellar components in total knee arthroplasty have a high fracture rate at midterm follow-up. J Arthroplasty. 2017;32:2427–30. Chang MA, Rand JA, Trousdale RT. Patellectomy after total knee arthroplasty. Clin Orthop Relat Res. 2005;440:175–7. Chauhan SK, Clark GW, Lloyd S, Scott RG, Breidahl W, Sikorski JM. Computer-assisted total knee replacement. A controlled cadaver study using a multi-parameter quantitative CT assessment of alignment (the Perth CT Protocol). J Bone Joint Surg Br. 2004;86:818–23. Clarke HD, Fuchs R, Scuderi GR, Mills EL, Scott WN, Insall JN. The influence of femoral component design in the elimination of patellar clunk in posterior-stabilized total knee arthroplasty. J Arthroplasty. 2006;21:167–71. Cobb JP, Dixon H, Dandachli W, Iranpour F. The anatomical tibial axis: reliable rotational orientation in knee replacement. J Bone Joint Surg Br. 2008;90:1032–8.
398 17. Conrad DN, Dennis DA. Patellofemoral crepitus after total knee arthroplasty: etiology and preventive measures. Clin Orthop Surg. 2014;6:9–19. 18. Dandy DJ. Chronic patellofemoral instability. J Bone Joint Surg Br. 1996;78:328–35. 19. Deie M, Ochi M, Sumen Y, Adachi N, Kobayashi K, Yasumoto M. A long-term follow-up study after medial patellofemoral ligament reconstruction using the transferred semitendinosus tendon for patellar dislocation. Knee Surg Sports Traumatol Arthrosc. 2005;13:522–8. 20. Dobbs RE, Hanssen AD, Lewallen DG, Pagnano MW. Quadriceps tendon rupture after total knee arthroplasty. Prevalence, complications, and outcomes. J Bone Joint Surg Am. 2005;87:37–45. 21. Figgie HE 3rd, Goldberg VM, Heiple KG, Moller HS 3rd, Gordon NH. The influence of tibialpatellofemoral location on function of the knee in patients with the posterior stabilized condylar knee prosthesis. J Bone Joint Surg Am. 1986;68:1035–40. 22. 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Surgical Techniques: Why, When and How I Do It
Sonosurgery Ultrasound-Guided Arthroscopic Shaving for the Treatment of Patellar Tendinopathy When Conservative Treatment Fails Ferran Abat and Håkan Alfredson 1 Background Proximal patellar Tendinopathy, commonly denominated as Jumper´s Knee, is widely considered to be a challenge to treat [1]. The treatment of patellar tendinopathy focuses on reducing if not eliminating the pain and improving function. At present, there are a several distinct treatments oriented to that end, and a “gold-standard” treatment might be in sight [2]. Conservative treatment of chronic patellar tendinopathy by means of eccentric quadriceps training has shown good results [3, 4]. The authors put forward the following treatment protocol for patellar tendinopathy (Fig. 1). It starts from the correct diagnostic positioning (Fig. 2) and moves on to physiotherapy, rehabilitation as well as biomechanical and behavioral modification. If that approach fails, we begin with ultrasound-guided procedures outside the injured region in the tendon, and sometimes F. Abat (&) ReSport Clinic Barcelona. Blanquerna-Ramon Llull University School of Health Science. Rosselló, 102. 08034 Barcelona, Spain e-mail: abat@resportclinic.com H. Alfredson Department of Community Medicine and Rehabilitation, Sports Medicine, Umeå University, 901 87 Umeå, Sweden e-mail: hakan.alfredson@umu.se end with an ultrasound-guided arthroscopic shaving procedure (Fig. 3). Conservative treatment should initially consist of physiotherapy and rehabilitation that progresses with inertial eccentric exercises. Other functional rehabilitation processes should also be relied upon [5]. The key for the correct analysis of the patients will be the biomechanical study of the patient [6]. Ultrasound-guided electrolysis or USGET (Ultrasound-Guided Galvanic Electrolysis Technique) is considered when the tendon is in the chronic phase and physiotherapy treatment has not been sufficient [1, 2]. This technique makes use of 0.3 mm acupuncture needles through which a galvanic current is directed to the injured area of the tendon (Fig. 4). This technique should always be utilized under strict ultrasound control and with the help of local anesthesia to control pain. USGET acts on the biology of the tendon that is damaged and that does not heal on its own. It destroys the degenerating tissue and triggers the biological response necessary for repair. In other words, it causes a key inflammatory response in the biological process of tendon collagen repair [7]. However, causing inflammation and a biological process to repair collagen is pointless if it is not done in combination with the application of active work that correctly directs tendon repair. Therefore, it is essential that this technique be partnered with good mechanical stimulus planning. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_26 403
404 F. Abat and H. Alfredson Fig. 1 Treatment algorithm proposed by the authors according to the ReSport Clinic methodology for patellar tendinopathy. Initially, the diagnosis is made by ultrasound, which can be supported by magnetic resonance imaging (MRI). The conservative physiotherapy protocol is started as well as the modification of sports and biomechanical habits. If the result is not satisfactory, treatment proceeds with ultrasound-guided galvanic electrolysis (USGET) under local anesthesia with or without platelet-rich plasma support. In the case of hypervascularization, high-volume infiltrations or polidocanol can be used (the latter is the authors’ preferred option). If this does not improve the patient's symptoms, sonosurgery is performed USGET is non-thermal electrochemical ablation with a cathodic flow to the clinical focus of tendon degeneration. The treatment brings on a dissociation of the H2O, salts and amino acid components, those elements that create new molecules through ionic instability, of the extracellular matrix. The organic reaction that is induced in the tissue encircling the cathodic needle gives rise to a localized inflammation in the area to be treated [7]. An immediate activation of an inflammatory response and overexpression of the activated gamma receptor for peroxisome proliferation (PPAR-gamma) is produced. Moreover, the action of IL-1, TNF and COX-2, which are mechanisms of tendon degeneration, are affected by USGET through its direct inhibitory effect and thereby facilitates phagocytosis and tendon regeneration [7]. The application of USGET stimulates the production of new immature collagen fibers that come to maturity through eccentric stimulus (Abat et al. 2015). With that application, excellent results are obtained in the short- and long-term in terms of pain and function. It must be said that using this technique without mechanical stimuli results in a significant loss of the biological effect. The introduction of Platelet Rich Plasma (PRP) is another adjunct to USGET in conservative treatment. It is applied by means of ultrasound-guided infiltrations in the area of
Sonosurgery Ultrasound-Guided Arthroscopic Shaving … Fig. 2 High-definition ultrasound image of a proximal patellar tendinopathy. Longitudinal sect with linear probe. Note the thickened tendon in its proximal portion in contact with the patella (double arrow) as well as cortical 405 rarefaction of the patella at the insertion of the tendon. An important intrasubstance rupture (arrow) and the fibrosis of Hoffa's fat pad stand out Fig. 3 Positioning in the operating room for sonosurgery on the patellar tendon. The main surgeon handles the arthroscopic instruments while the assistant shows the ultrasound image. It is important that the arthroscopic and ultrasound screens be viewed simultaneously during the procedure tendon injury. To carry it out, blood must be drawn from the patient and centrifuged to separate the blood components. Then, the Platelet Rich Plasma (high concentration of platelets) is collected from it. The PRP is later pushed into the injured area to try to bring about a stimulatory response. This response helps to reduce pain and increase function [2, 8, 9]. Although pain during treatment and in the days immediately following it seems to increase considerably, it is
406 F. Abat and H. Alfredson Fig. 4 Ultrasound-guided galvanic electrolysis (USGET) procedure under local anesthesia. The ultrasound shows the lesion area within the patellar tendon and the 0.3 mm needle of the USGET handpiece applies the galvanic current directly to the focus of the lesion one of the most valid options among the nonsurgical ones to improve function and alleviate pain in the long-term. it is advisable to rely on other treatments such as radiofrequency to address the intermediate pain, but the administration of anti-inflammatories should be avoided. Thought must be given to the surgical approach when the conservative options fail. The open patellar tenotomy and excision of the region with tendon changes is quite often included in traditional surgical treatment. On occasion, ultrasound-guided percutaneous longitudinal tenotomy, curettage, multiple drilling of the inferior patellar pole, or excision of the distal patellar tip are also employed [10–12]. The aftermath of these treatments is always a relatively long rehabilitation period. The clinical results of classical surgery vary, and the outcomes are often unsatisfactory [13]. In a randomized study in which treatment with eccentric quadriceps training was compared to traditional open tenotomy in combination with excision, similar results were seen. However, there was only 50% of good clinical results in both groups [14]. Over recent years, the question as to where the pain originates in this case and other chronic painful tendinopathies has been debated [15]. In some studies that used Color Doppler Ultrasound in surgery along with immuno-histochemical analyses of tendon biopsies, high blood flow [16] and nerves outside the tendon (on the dorsal side of the proximal patellar tendon) [17, 18] have been documented. Very few nerves were seen inside the tendons if any. A temporary cure for the pain was observed by injecting a local anesthetic that targeted the region with high blood flow and nerves outside the tendon. Those findings were at the root of the push to develop new treatment methods like sclerosing polidocanol injections [19] and ultrasound-guided arthroscopic shaving [20]. They put a focus on treatment outside the dorsal patellar tendon where high blood flow and nerves have been detected. Herein, we describe the newly invented surgical treatment method. 2 Classification and Preoperative Evaluation The deep portion of the proximal insertion of the patellar tendon supports most of the traction forces that the tendon must withstand. When the patient has lived with the patellar tendon injury for a long time, they generally present with hypotonic atrophy of the quadriceps muscles. The pain typical of patellar tendinosis can be triggered by a sudden and rapid contraction of the quadriceps.
Sonosurgery Ultrasound-Guided Arthroscopic Shaving … Historically, the Blazina scale [21] of 1973 is used to classify the degree of injury. It provides a qualitative description of the injury. Four injury gradations can be defined: • Grade I: Pain during sport • Grade II: Pain at the start of sports activities that disappears after warming up and reappears when fatigue comes on. • Grade III: Pain during and after activity, making the subject unable to participate further in sports activities. • Grade IV: Complete tendon rupture. As regards the duration of symptoms, authors like Kaux [22] characterize the phases of tendinopathy as: • Acute (0–6 weeks) • Sub-Acute (6–12 weeks) • Chronic (>3 months) A diagnosis is necessarily acquired by means of a thorough clinical examination as well as supplementary musculoskeletal ultrasound (Echo-MSK) and magnetic resonance imaging (MRI). The ultrasound image of an injured tendon will show a pattern of fibrillar irregularity with hypoechoic areas. There may even be intratendinous lesions. The tendon will be thickened. Moreover, hypervascularizations that have their origin in Hoffa’s fat pad may be present. In the insertional portion of the patella, cortical irregularities can be seen. 3 Indications It is indicated for patients that have lived with proximal patellar tendon pain during patellar tendon loading activity for more than 3 months. They would have also been diagnosed, both clinically and with ultra–sound and Doppler or MRI, with patellar tendinopathy/Jumper’s knee. Furthermore, conservative treatment would have failed for them. 407 4 Contraindications The contraindications include chronic inflammatory diseases, other systematic diseases that affect the joints and/or connective tissue as well as concomitant knee injuries (ACL, menisci, cartilage, fractures). 5 Surgical Technique Using Ultrasound-Guided Arthroscopy Sonosurgery [2, 20, 23] has shown good clinical results. It has few complications and makes for a decrease in tendon thickness along with better tendon structure over time. The technique is based on the use of ultrasound simultaneously with arthroscopy (Fig. 5), thus making it possible to work on the injured tendon with total security by combining the two approaches. Treatment is currently focused mainly on the exterior of the patellar tendon, that is, its dorsal part (Fig. 6). It has been demonstrated that it is where there is the greatest blood flow and new nerves are being generated over the course of tendinopathy. To start, a thorough ultrasound with Color Doppler examination is performed (Fig. 7). Then, the main damaged area of the tendon is analyzed to determine whether there is a patella tip causing an imprint on the tendon, a rupture or involvement of the bursa. Later, an arthroscopic review of the knee will detect possible associated injuries. Although some surgeons prefer to use spinal anesthesia, surgery can be performed under local anesthesia. Either option is correct. However, not tightening the ischemia cuff so that hypervascularizations can be seen with ultrasound during surgery is imperative. Put the patient in a supine position with the knee straight and the quadriceps relaxed. The procedure is started on the ventral/deep part of the tendon. A standard antero-medial and anterolateral portal and a controlled pressure pump are used (Fig. 8).
408 F. Abat and H. Alfredson Fig. 5 Starting position for sonosurgery on the patellar tendon. Direct view of the tendon under ultrasound and arthroscopy simultaneously Fig. 6 Longitudinal view with linear probe and highdefinition ultrasound of a proximal patellar tendinopathy. The shaver can be visualized in the external dorsal portion of the tendon, the starting point of the arthroscopic procedure Afterwards, the insertion of the patellar tendon in the patella is identified to initiate debridement using a synoviotome with a 4.5 mm full radius. Simultaneous longitudinal and crosssectional ultrasound views guide the entire procedure (Fig. 9). Debridement is carefully performed. The goal being the destruction of only the high blood flow (neovessels) region and the nerves adjacent to the tendinosis changes on the dorsal side of the tendon (i.e., separating the Hoffa fat pad from the patellar tendon). Healthy tendon tissue is not resected, and the Hoffa fat pad should be left untouched as much as possible. Should a prominent patella peak be encountered (Fig. 10), the recommendation is to resect it with caution. The tendon must be well explored in search of intratendinous tears (Fig. 11). When a lesion is been detected at the level of the superficial bursa of the patellar prior to surgery, a longitudinal incision in the skin and resection of the bursa should be carried out (Fig. 12). The portals are closed with sutures or tape and a bandage is kept in place for 24 h.
Sonosurgery Ultrasound-Guided Arthroscopic Shaving … Fig. 7 Pre-surgery ultrasound image with high-definition ultrasound and linear probe in transverse (left) and longitudinal (right) views. Note the hypervascularization 409 (single arrow) entering the tendon from Hoffa's fat pad. Tendon thickening (double-headed arrow) and hypoechoic tendon injury areas (asterisk) are highlighted Fig. 8 Arthroscopic and ultrasound positioning during patellar tendon sonosurgery. The arthroscope and shaver will alternately be used through a standard anteromedial and an anterolateral portal 6 Rehabilitation Protocol Walking with full weightbearing immediately after treatment is allowed. As intratendinous surgery is not performed, rehabilitation can begin immediately and be relatively aggressive and rapid. Range-of-motion exercises, standing and walking, cycling, and low-load strength training begin within the first 3 weeks. Then, there is a gradual increase in load and the initiation of more sport-specific training. It depends on the degree of swelling and pain. Isometric, concentric, and eccentric exercises (Fig. 13) should be tolerated before starting up plyometric training. Required rehabilitation periods vary from 2 to 4 months before a return to full tendon loading sports activity. Day 1: Here, partial weightbearing with crutches is the start. Then, the patients are given instructions to begin full non-weightbearing range-of-motion exercises. Day 2–7: The next step is to start walking and do light bicycling. Light concentric as well as
410 Fig. 9 Ultrasound images in transverse (left) and longitudinal (right) views with a linear probe where the insertion of the patellar tendon in the patella is identified Fig. 10 Arthroscopic image where a patella with a prominent beak can be seen. By means of debridement with the shaver, this prominence is lowered so that it does not imprint on the tendon eccentric strength training for the quadriceps muscles are brought into play. Day 8–14: In the 2nd week after treatment, the patients are instructed to increase their tendon loading activity step-by-step with more sportspecific training. Extreme jumping, running or weight training activity is strongly discouraged, or better yet, disallowed for the first 2 weeks. Maximum patellar tendon loading activity (return to sport) could be started two weeks postoperatively if there are no signs of marked muscle atrophy. F. Abat and H. Alfredson for debridement by means of a 4.5 mm full radius arthroscopic shaver. Simultaneous transverse and longitudinal ultrasound views guide the entire procedure Fig. 11 Arthroscopic image where, after careful debridement of the injured patellar tendon and removal of the patellar beak, an intratendinous tear is observed in the deep portion of the tendon in its contact with the patella 7 Complications In general, this procedure is free of serious complications but, of course, attention must be paid to the risks that are native to knee arthroscopy. When tendon debridement is not done with sufficient precision and ultrasound control, the thickness of the tendon can be excessively compromised. This circumstance possibly sets the stage for a subsequent rupture.
Sonosurgery Ultrasound-Guided Arthroscopic Shaving … Fig. 12 Debridement of the superficial bursa of the patella as the last step in the sonosurgery of the injured tendon in those cases in which a bursal pathology 411 accompanying the tendon injury had previously been confirmed. A longitudinal incision is made in the skin and the bursa is resected Fig. 13 Progression of exercises after surgery for patellar tendinopathy. From elastic exercises with one and two legs to the use of inertial devices such as the yoyo multigym or leg extensions in protocolized loading programs 8 Conclusions (Take Home Message) Intra-tendinous surgical revision treatment of proximal patellar tendinopathy seems questionable to us. This assertion is grounded in the poor clinical results seen with intra-tendinous surgical approaches and the new research findings gained from looking at the innervation patterns. Surgical treatment around the tendon with US and DP-guided arthroscopic shaving has shown a great potential to make for a pain-free return, after a relatively short rehabilitation period, to sports activities that place a high demand on the patellar tendon.
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Medial Patellofemoral Ligament Reconstruction: Anatomical Versus Quasi-anatomical Femoral Fixation Vicente Sanchis-Alfonso, Maximiliano Ibañez, Cristina Ramirez-Fuentes, and Joan Carles Monllau 1 Introduction Chronic lateral patellar instability (CLPI) is a common finding in the orthopedic knee surgeon´ s daily clinical practice. First-time lateral patellar dislocation has an incidence rate of 23 per 100,000 person-year [1]. After a first episode, patellar dislocation recurrence follows in more than 50% of patients [2]. As likely as not, the etiology of CLPI is multifactorial. However, the deficiency of the medial patellofemoral ligament (MPFL) seems to be the most important factor in the genesis of instability [3] Over recent years, MPFL recon- V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com M. Ibañez ICATME, Hospital Universitari Dexeus, UAB, Barcelona, Spain C. Ramirez-Fuentes Medical Imaging Department, Hospital Universitario y Politecnico La Fe, Valencia, Spain J. C. Monllau Hospital del Mar, Barcelona, Spain Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain Universitat Autònoma de Barcelona (UAB), Barcelona, Spain struction (MPFLr) has come to be recognized as crucial in its treatment. Resultingly, MPFLr is the most routinely used surgical intervention for CLPI. It is possible to carry out MPFLr along with other surgical techniques that are directed toward correcting some predisposing factors that frequently go hand-in-hand with CLPI. They are anteromedialization of the tibial tubercle, rotational osteotomy or trochleoplasty [4–6]. The first publications on MPFLr date from the early 1990s [7–9]. Ellera-Gomes [7] published in 1992 in Arthroscopy 58 cases of MPFL reconstructions operated on from September 1986 to March 1998. One year later Avikainen and colleagues [8] published in Clin Orthop 14 adductor magnus tenodesis associated to MPFL repair performed from 1982 to 1984. We could considered this technique as a non-anatomic MPFLr. Robert A. Teitge began doing MPFL reconstructions in the early 1980s as a consequence of the good results he had obtained with reconstructions of the lateral patellofemoral ligament in patients with iatrogenic medial patellar instability. In 1994 Robert Teitge published a paper in which he described both LPFL and MPFL reconstructions [9]. But if we dig a little deeper into this topic we find a 1924 publication by Gallie and Le Mesurier [10], which seems prophetic, describing not only the reconstruction of the MPFL (in older literature called “proximal transverse retinaculum”), but also highlighting the importance of alignment and bone deformities in the genesis and treatment of © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_27 415
416 V. Sanchis-Alfonso et al. patellofemoral instability. But as often happens, this technique fell into oblivion. In the last 30 years, many variations of these pioneer techniques in which multiple graft types and fixation strategies were used have been published. Overall, the MPFLr techniques can be grouped in two main types, the static and the dynamic. The current gold standard seems to favor the static MPFLr with anatomical bone attachments at both the femoral and patellar insertion points. More recently a dynamic nonanatomical MPFLr using the adductor magnus tendon (AMT) as a pulley, has been again advocated [11]. This technique may be particularly useful in children as it avoids the risk of injuring the distal femur growth plate and so a limb deformity overtime [12]. The objective of this chapter is to describe, in detail, both static and dynamic MPFL reconstructive techniques as well as the authors’ rational for the treatment used in patients with CLPI. 2 Aim The objective of MPFLr is only to stabilize the patella in the early degrees of knee flexion (i.e., the first 30°), but not to correct the patellofemoral maltracking (J-sign). Isolated MPFLr does not correct patellar shift and tilt. Therefore, an MPFLr should be done only after patellofemoral maltracking has been corrected. 3 Indications For a successful MPFLr it is crucial to have the proper selection of the patient. The ideal patients for an isolated MPFLr would be those with at least two documented episodes of lateral dislocation with otherwise no advanced signs of malalignment on any plane (namely, a TT-TG distance of less than 20 mm, a patellar CatonDeschamps index of less than 1.2 and grade A trochlear dysplasia) [13]. Patellar dislocation should be confirmed with physical examination under anesthesia (Fig. 1). Fig. 1 Physical examination of the right knee under anaesthesia. Note the lateral dislocation of the patella. (“Republished with permission of Elsevier Science & Technology Journals, from Medial Patellofemoral Ligament Reconstruction, V Sanchis-Alfonso & JC Monllau, Operative Techniques in Sports Medicine, Vol 27, 4, 2019; permission conveyed through Copyright Clearance Center, Inc.”) 4 The Bases for a Successful MPFLr The most important points for a successful MPFLr are (1) the accurate location and placement of the graft, particularly at its femoral attachment, and (2) its adequate tensioning. The MPFL is more like a checkrein that should not be too tense. For that reason, getting the correct tension is key to a successful reconstruction. In general, an overly tight graft is believed to cause overtensioning in the medial patellofemoral joint (PFJ) and probably patellofemoral osteoarthritis (PFOA) in the long run. In this chapter, this problem will be further addressed. Lateral retinacular release (LRR) that has been used extensively over several years for the treatment of various extensor mechanism abnormalities and associated to MPFLr is no longer recommended as a rule. 4.1 The Femoral Attachment Point As happens in other ligament reconstructions, poor graft placement of the MPFLr can cause severe complications and even disability [13]. The femoral attachment point will determine the
Medial Patellofemoral Ligament Reconstruction … length change behavior of the graft and therefore the graft tension at different angles of knee flexion [14]. Proximal and anterior femoral attachments points will result in an excessive stretching of the MPFL-graft at deeper knee flexion angles as shown by Wang and colleagues [15]. This will over-constrain the medial PFJ and increase the cartilage pressures at this level. In that way, PFOA may be the consequence of femoral tunnel malposition after MPFLr. Interestingly, the patellar attachment point seems not to be so important as the femoral attachment point [14]. It has been demonstrated that MPFL length changes during knee flexion depend on the femoral attachment site more than on the patellar attachment one [14]. In this section, we will focus on the femoral attachment point. The current trend in MPFLr is oriented towards drilling the femoral attachment in the most anatomic point. An anatomic femoral fixation is the easiest and most reproducible way to achieve the optimal length-change behavior of the graft during knee flexion—extension, and therefore, a satisfactory long-term clinical result [13, 14]. Yet a strict anatomic femoral attachment point might not be that critical for a successful reconstruction, as has been demonstrated by Sanchis-Alfonso and colleagues [14]. A nonanatomic MPFL graft that replicates the isometry and length change pattern of a native MPFL will also provide satisfactory results [14]. This concept is of paramount importance in children because of the close anatomical relationship between the distal femoral physis and the area where the anatomic tunnel should be drilled. The actual risk of iatrogenic physeal damage is the reason the first author performs a quasianatomical MPFLr with gracilis tendon autograft, using the AMT as a pulley for femoral fixation in skeletically immature patients with good clinical results. Using this technique, the kinematic behavior exhibited by the graft is like that of the native MPFL [16]. In 2007, Schoettle and colleagues [17] published a technique that demonstrated how to find a reproducible anatomic femoral attachment point. They used intra-operative fluoroscopy to determine some radiological coordinates that 417 help the surgeon to reach the right spot. According to this investigation, an exact lateral image is needed to locate the anatomic femoral attachment point. This is currently the most common technique to determine the femoral fixation point. The technique permits drilling the femoral tunnel through a very small and cosmetic skin approach. However, one may wonder how accurate this method is insofar as replicating the anatomic femoral attachment point? In terms of accuracy, it largely depends on getting a true lateral knee image with a perfect superposition of both femoral condyles. Nevertheless, several authors have questioned the precision of this radiological method [18–21]. The femoral MPFL attachment site is located approximately one centimeter distal to the tip of the adductor tubercle (AT) [22]. However, the great interindividual anatomical variability in the location of the AT probably explains the unpredictability relative to the location of the femoral insertion of the MPFL. This means that the MPFL is unique for every single individual and so the optimal femoral position is patient specific. More recently, new technologies like 3D-CT scan (Fig. 2) appeared to help the surgeon in locating the right spot for femoral MPFL attachment. Sanchis-Alfonso and colleagues [19] evaluated 100 patients with CLPI by means of 3D-CT. For each knee, two virtual 7 mm diameter femoral tunnels were created. One tunnel was shaped based on the AT landmark (the anatomic tunnel). The second one was created according to Schoettle’s radiological method [17]. The ratio of overlapping between the two tunnels was calculated. An overlapping area superior to 50% was considered as reasonable. The goal was achieved in only 38% of cases with a good intra- and inter-observer reliability values [19]. Therefore, it was concluded that the radiological method is only an approximation and should not be the sole basis for safely and reproducibly drilling an anatomic femoral tunnel in MPFLr. Some drawbacks in Schoettle[17] investigation may contribute to understanding this paradox. They analyzed only 8 frozen cadaver knees
418 V. Sanchis-Alfonso et al. Fig. 2 Location of the AT (red arrow) by means of 3DCT. Medial supracondylar line (white arrow). Medial femoral epicondyle (blue arrow). Non-anatomical femoral tunnel placement (black arrow). (“Republished with permission of Springer Nature BV, from Does radiographic location ensure precise anatomic location of the femoral fixation site in medial patellofemoral ligament surgery?, Sanchis-Alfonso V, et al., 24, 2838– 2844, 2016; permission conveyed through Copyright Clearance Center, Inc.”) of unknown age and gender. Additionally, the presence of trochlear dysplasia was not mentioned or considered. However, CLPI is more frequent in young females with bony variances such as trochlear dysplasia. Therefore, the use of female knees with trochlear dysplasia would be reasonable in this type of studies. To further illustrate this concept, in the Sanchis-Alfonso [19] investigation, 7 out of 12 male patients without severe trochlear dysplasia showed an overlap area greater than 50% when using the method described by Schöettle. Conversely, this occurred in only 12 out of 40 female patients with severe trochlear dysplasia [19]. Thus, severe trochlear dysplasia associated with the female gender was predictive of overlap of less than 50 in 70% of the cases [19]. In conclusion, in female knees with a severe trochlear dysplasia, the radiographic method used to recognise the femoral anatomic fixation point showed a nonnegligible number of inaccuracies. Since CLPI is more frequent in females with a severe trochlear dysplasia, this finding is relevant from the clinical standpoint. Fluoroscopy is a method that can be very helpful for the casual surgeon to determine the femoral attachment point. However, to avoid mistakes, the fluoroscopic findings should not be relied upon too greatly due to extreme interindividual anatomical variability. For that reason, it is wise to recommend an incision large enough to permit the correct identification of the anatomy of the area, including the AMT and the apex of the AT. The femoral MPFL attachment is located 10 mm distal to the AT and proximal and a bit posterior from the medial femoral epicondyle (ME) in a groove midway between the MFE and the AT (Fig. 3). And so, the AT has been suggested as a consistent landmark for a proper location of the femoral tunnel during MPFLr because the distances between the AT and the femoral attachment of the MPFL are uniform, approximately 10 mm distally [22–25]. However, a good option would be to use the 3D-
Medial Patellofemoral Ligament Reconstruction … 419 A Fig. 3 Anatomic dissection of the left knee showing medial restraints to lateral patellar translation: medial patellotibial ligament (MPTL), medial patellomeniscal ligament (MPML), medial patellofemoral ligamemt (MPFL). Adductor tubercle (AT) and the medial femoral epicondyle (ME). Superficial medial collateral ligament (sMCL), medial meniscus (MM), semimembranosus tendon (SM), and medial gastrocnemius tendon attachment site (MGT). (“Republished with permission of Springer Nature BV, from Recognition of evolving medial patellofemoral anatomy provides insight for recognition, Tanaka MJ, et al., 27, 2537–2550, 2019; permission conveyed through Copyright Clearance Center, Inc.”) CT scan to locate the anatomic femoral attachment point if a minimally invasive and most cosmetic surgery is considered. This technology makes for locating the MPFL femoral attachment point based on the position of the AT. Software translates the 3D-CT calculated point into 2D images (Fig. 4). In conclusion, determination of femoral attachment point location must be based on anatomy. Just like anterior cruciate ligament (ACL). The vital thing is to know the anatomy. As Jack Hughston said, orthopaedic surgery is above all anatomy plus a bit of common sense. Once the anatomic femoral attachment point has been determined, normal isometry of the graft is automatically expected. The MPFL shows isometric behaviour in 80% of the cases from 0° to 60° and in 20% of the cases from 0° to 30° [14]. This is called “favourable anisometry”. B Fig. 4 The AT is an important landmark to determine the location of the MPFL femoral attachment point. Using software analyses, the point calculated in the 3D-CT (A) can be translated to a regular 2D x-ray image (B). Tunnel created using the AT as a landmark—anatomic tunnel (red circle). Tunnel created in accordance with Schöttle’s radiological method (yellow circle). Like in our study, Ishikawa and colleagues [26] demonstrated, on a virtual true lateral radiograph reconstruction from a threedimensional computed tomography (3D-CT) image, that in patients with recurrent patellar dislocation the femoral attachment point of the MPFL is more posterior and distal to the Schöttle point. (Reused from SAGE JOURNALS. Sanchis-Alfonso V, RamirezFuentes C, Montesinos-Berry E, et al. Radiographic location does not ensure a precise anatomic location of the femoral fixation site in medial patellofemoral ligament reconstructions. The Orthopaedic Journal of Sports Medicine, 5(11), 2,325,967,117,739,252. https://doi.org/ 10.1177/2325967117739252. ©The Author(s) 2017) Beyond these degrees of flexion, the graft slackens. Nevertheless, the idea of ligament isometry is based on a knee with regular anatomy should be remembered and the patients with CLPI are know to have many anatomical knee abnormalities. 4.2 Graft Tensioning The MPFL is considered a checkrein, more than a constraint, that it is not under constant tension in its native state. It only comes under tension when a lateral or medial force pushes the patella either laterally or medially. Schoettle brilliantlly compared its function to that of a dog leash, which is loose most of the time. However, when the dog (namely, the patella) runs away (meaning, dislocates), the leash tightens. Therefore,
420 there is no need to tension the MPFL graft during its reconstruction. If the graft were tight all the time, it would bring on an increase in patellofemoral pressure that could lead to PFOA over time. 4.3 Role of Lateral Retinacular Release Lateral retinacular release (LRR) of the patella has been used extensevely for knee surgeries, particularly in disorders of the extensor mechanism. However, its current usefulness is under scrutiny due to its complications and doubtful outcomes. In the first author’s opinion, LRR or lengthening has no role in primary CLPI surgery. In a series of 33 patients evaluated with a minimum of 12 months, Malatray and colleagues [27] demonstrated that isolated MPFLr was not inferior to MPFLr associated with arthroscopic LRR in terms of the IKDC subjective score and patellar tilt. They conclude that there is no indication for LRR associated to MPFLr in the treatment of CLPI. Furthermore, Merican and colleagues [28] conducted a biomechanical investigation showing that the lateral retinaculum actually contributes to resisting lateral patellar displacement. Consequently, lateral patellar instability will increase after LRR. To guide the patella towards the trochlear sulcus during the first degrees of knee flexion, both the MPFL and the lateral retinaculum must interplay in a harmonious way. Christian Lattermann states that both ligaments behave similarly to the reins of a horse. Both reins must have some degree of tension. They are not very tense but they are not loose either. If one of the reins is completely loose the horse is inclined towards the opposite direction as it occurs in the patella. This will provoke a patellofemoral imbalance that could be responsible for iatrogenic anterior knee pain (AKP). The most usual indication for LRR or lengthening is severe patellar tilt. However, in this case, severe trochlear dysplasia is also a V. Sanchis-Alfonso et al. common finding that can be addressed by means of trochleoplasty. This last procedure relaxes the deep layer of the lateral retinaculum and so LRR is unnecessary. Additionally, LRR in cases of trochlear dysplasia might provoke medial patellar instability. Only in the rare cases of fixed lateral dislocation in flexion must we consider LRR or lengthening since in these cases there is a shortening of the lateral structures. In these exceptional cases the advice of the first author (V.S-A) is not to perform a LRR but a lenghthening (Fig. 5). It has the same effect regarding the elimination of hypercompression and hypertension on the lateral side as the LRR. Moreover, lateral retinaculum lenghthening is a tecnnique individually adapted. Finally, it avoids the secondary complications of LRR such as medial patellar instability. 5 Surgical Technique Step-By-Step. Pearls and Tips 5.1 Static and Anatomic MPFLr The first author’s preferred surgical technique is the anatomic double-bundle static MPFLr using a semitendinosus autograft. MPFLr can be done either with single-bundle (SB) or double-bundle (DB) graft configuration. According to current evidence, the use of a double-bundle pattern seems more advisable to better reproduce the native MPFL function. Better outcomes (i.e., Kujala, IKDC, and VAS) and fewer complications, reoperations and re-dislocation rates have been found in a recent revision of primary isolated DB MPFLr for recurrent patellofemoral instability [29]. Furthermore, Migliorini and colleagues [30] have shown that isolated MPFLr with semitendinosus tendon graft performed better than the gracilis. All the scores of interests (Kujala, Tegner, Lysholm) and range of motion scored better in the semitendinosus group. Moreover, in favour of the semitendinosus group, a statistically significant reduction of the revision surgeries and re-dislocations were evidenced.
Medial Patellofemoral Ligament Reconstruction … 421 A B C D Fig. 5 Lateral retinaculum lengthening. Technical note according to RM Biedert, MD. The lateral retinaculum consists of a superficial oblique and a deep transverse part (A). Lengthening is started incising longitudinally the superficial oblique retinaculum about 5 mm from its attachment to the lateral border of the patella. Then it is separated from the deep transverse retinaculum (B). The deep transverse ligament is incised also longitudinally from its attachment to the iliotibial band and the synovial layer opened (C). This releases the increased tension of the lateral structures. The two parts of the lateral retinaculum are sutured together in 90º of knee flexion (D). This makes it impossible that the retinaculum is too tight. The mobility of the patella should be 1–2 quadrants to the medial and the lateral side in full extension, guaranteeing a normal balance of the patella in the trochlea The patient is placed in the supine position on a standard table. After induction of anesthesia lateral patellar dislocation must be confirmed (Fig. 1). Fathalla and colleagues [31] have assessed the prognostic value of examination under anesthesia (EUA) prior to MPFLr. They retrospectively evaluated the outcome of 23 patients who had undergone an isolated MPFLr for CLPI. Of the 23, 9 failed (39%), all of them had a dislocating patella at more than 30º of knee flexion. They concluded that patients in whom the patella can be dislocated beyond 30º on EUA are unlikely to benefit from isolated MPFLr. The leg to be operated on is prepared in the standard fashion. The use of a tourniquet is optional. A sterile bump is placed under the knee to keep it slightly flexed. Although the benefit of a diagnostic arthroscopy has been questioned [32], it is routinely performed prior to MPFLr in the author’s practice (Fig. 6). The main objectives being (1) full evaluation of the status of the cartilage and (2) to rule out any intraarticular damage not seen on the preoperative magnetic resonance imaging. Then, the semitendinosus tendon is harvested following the standard technique, prepared and wrapped in gauze previously soaked in a solution of 100 ml of saline mixed with 500 mg of vancomycin powder. This last step has been suggested to avoid microbiological contamination of the graft [33]. Next, an incision is made in the anterior aspect of the knee, centered over the junction of the medial and middle thirds of the patella. The
422 V. Sanchis-Alfonso et al. Fig. 6 Diagnostic arthroscopy previous to MPFLr. Note (A) a chondropathy in the medial facet of the patella, (B) a loose body in the subquad area (axial CT view), (C) arthroscopic view, an (D) after its excision. (“Republished with permission of Elsevier Science & Technology Journals, from Medial Patellofemoral Ligament Reconstruction, V SanchisAlfonso & JC Monllau, Operative Techniques in Sports Medicine, Vol 27, 4, 2019; permission conveyed through Copyright Clearance Center, Inc.”) medial third of the patella is exposed and subperiosteally dissected with a scalpel. The dissection is carried through medially between layers 2 and 3. Two 4.5 mm diameter tunnels are drilled in the anterior cortex of the patella near its medial aspect (Fig. 7). Special care should be taken when drilling to avoid penetrating the subchondral bone and damaging the articular cartilage. Attention should be paid to leaving at least 10 mm of bone-bridge between the tunnels to avoid intraoperative fractures. Then, a small incision is made over the medial epicondyle. 3D-CT technology is used to locate the anatomic femoral attachment point as explained earlier on. The image intensifier is used to further check the femoral attachment point (regularly located 10 mm distal to the AT). Once the anatomic femoral attachment point is determined using the 3D-CT method, there is no need to further check the graft isometry. After that, the medial patellar and medial femoral incisions are connected by blunt dissection by means of a hemostat. Firstly, the graft is passed through the patellar tunnels (Figs. 7 and 8) and then between layers 2 and 3 until the femoral attachment point is reached. Correct ligament tension is crucial to the success of MPFLr surgery. Enough tension to put the graft taut is sufficient. Do not pull the graft tight at the time of fixation. If done so, it leads to elevated medial contact pressures and medial patellar tracking. To avoid excessive graft tension, the graft is fixed at 30° of knee flexion as the distance between the femoral and patellar attachments points is greatest at this angle [14]. Graft fixation on the femoral side can be done with bioabsorbable interference screws or suture anchors, which is the author’s preferred technique. A biomechanical cadaveric study demonstrated that suture anchor femoral fixation was not significantly different from interference screw fixation in terms of load-to-failure [34]. Likewise, the mean load-to-failure values for both fixation techniques in MPFLr were greater than the values reported in the medical literature for the native MPFL [34]. The effect of interference
Medial Patellofemoral Ligament Reconstruction … Fig. 7 Intraoperative views of the patellar steps of the surgical procedure. (A) the dissected anterior and medial sides of the patella. (B) drilling two 4.5 v-shaped tunnels. (C) and (D) the graft being passed through the tunnels. (“Republished with permission of Elsevier Science & 423 Technology Journals, from Medial Patellofemoral Ligament Reconstruction, V Sanchis-Alfonso & JC Monllau, Operative Techniques in Sports Medicine, Vol 27, 4, 2019; permission conveyed through Copyright Clearance Center, Inc.”) significantly increases graft tension. If the difference between the diameter of the femoral tunnel and the graft is 0 or 1 mm, the tension of the graft increased significantly compared to when the difference between the diameters is equal to or greater than 2 mm. Therefore, the casual surgeon should be aware of the inadvertent increases in graft tension even in low preloading conditions to palliate the risk of graft overtensioning. Fig. 8 Double-bundle MPFLr screw femoral fixation on MPFL graft tension has been analyzed by Ackermann and colleagues [35]. They demonstrated that this type of fixation 5.2 Quasi-Anatonical (Elastic) MPFLr For this technique (Fig. 9), the homolateral gracilis tendon (GT) autograft is the author’s (JCM) preferred choice. The harvesting technique consists of a 2 cm long vertical skin
424 Fig. 9 Operative images of a left knee showing the 3 surgical approaches needed and the fundamental steps of the technique. A V-shaped tunnel is drilled in the medial aspect of the patella A; the GT is introduced in the patellar tunnel B; a traction suture looped around the adductor magnus (AM) C; the GT is then looped around the AM tendon D. (“Republished with permission of Springer Nature BV, from Clinical and radiological outcomes after a quasi-anatomical reconstruction of medial patellofemoral ligament with gracilis tendon autografty, Monllau JC, et al., 25, 2453– 2459, 2017; permission conveyed through Copyright Clearance Center, Inc.”) V. Sanchis-Alfonso et al. A B C D incision centered in the upper medial aspect of the tibia and some 3-fingerbreadths down the joint line. After dissecting the soft tissue, the Sartorius fascia is incised horizontally, releasing the distal attachment of the GT. From there on, the graft is harvested using a tendon stripper. When harvesting the tendon, care should be taken so as not to amputate it before full dissection is made. The graft must be at least 90 mm in length (total graft length 180 mm) to properly reconstruct the MPFL in a doublebundle pattern. The 2 ends of the graft are prepared with #2 high-strength Krackow mattress sutures. The prepared graft is then sized and kept wrapped in vancomycin-soaked gauze to prevent bacterial contamination [32]. The native MPFL was found to have a mean tensile strength of 208 N and the mean maximum load for 1 strand of a GT was found to be 837 ± 138 N [36, 37]. Therefore, the author’s (JCM) opinion is that the GT is enough in terms of both length and strength to reconstruct the MPFL. A second 2 to 3 cm vertical skin approach is then made over the superior medial border of the patella to expose its proximal third where the anatomical footprint of the MPFL is located. Two convergent 4.5 mm holes are drilled at the edges of the footprint. The tunnels are made in a convergent V-shape from the medial cortex to the cancellous bone of the patella. Attention should be paid to leaving at least 15 mm of bonebridge between the tunnels to avoid intraoperative fractures or locus minor resistentiae where a stress fracture could be produced postoperatively. The edges of both drill holes and the inner angle of the V-shaped tunnels obtained are smoothed out to avoid any “killer turn”. A third 2 to 3 cm skin incision is then made slightly proximal to the ME along the AMT. The approach is deepened in line with the medial
Medial Patellofemoral Ligament Reconstruction … intermuscular septum and the AMT is easily identified, by means of finger palpation under the crural fascia. The AMT is carefully dissected as distally as possible in order to reach the closest point possible to the native MPFL footprint. A looped suture is placed around the AMT to later aid in graft passage. The same suture helps in a proper distal dissection of the AMT with a pulling and “sawing” movement toward the femoral insertion. The graft is then passed through the patellar tunnels and then through the interval between layers 2 and 3. Attention should be paid to avoid an intra-articular graft. This is of particular relevance when the MPFL is reconstructed in combination with other intraarticular procedures. Finally, the graft is looped around the AMT, used like a pulley, and back to the patella. While maintaining the graft under a slight tension, the knee is cycled several times to find the correct physiometry and to check patellofemoral tracking. Before proceeding to the last step, it is important to verify that the patella can still be manually lateralized some 10 mm to avoid any over-constraint. Lastly, both graft ends are tied together at 30° of flexion with highresistance irresorbible #2 sutures. The remaining tendon end can be cut, or it can also be tied under the pre-patellar periosteum if it is long enough. This kind of MPFLr at the femoral side permits securing the graft without any bone drilling, without hardware, and with an elastic fixation of the new ligament. Therefore, the procedure is inexpensive, safe in skeletally immature patients and less likely to develop the medial patellofemoral over-constraint that is eventually produced by static femoral fixation [38, 39]. The author’s accumulated experience as well as a previous finite element investigation supports this concept [40]. In addition, the current procedure does not require the use of an image intensifier. Although the AMT femoral insertion is not completely anatomic, as the MPFL anatomically inserts some 10 mm distally to the AT, it is assumed that this kind of elastic attachment might compensate for the mismatching. 425 6 Addressing the Associated Predisposing Factors to Patellar Dislocation Patellar chondropathy is a common finding in cases of CLPI. In general, the authors only remove unstable cartilage flaps and loose bodies, other cartilage lesions are not addressed. Although patellar chondropathy could be responsible for AKP in patients with CLPI, the pain disappears even though the eventual chondral lesion is left alone once the patella has been stabilized. Medialization of the tibial tuberosity (TT) is commonly recommended when the TT-TG distance is greater than 20 mm. However, there is no consensus as to the threshold value of TT-TG distance for indicating TT osteotomy (TTO) associated with MPFLr for the treatment of recurrent patellar instability. In a retrospective analysis of 81 patients who underwent either isolated MPFLr or MPFLr combined with TTO for recurrent patellar instability with a TT-TG distance of 15 to 25 mm, Kim and colleagues [41] observed that both groups had similar satisfactory clinical results with a similar incidence of MPFLr failure. Interestingly, no differences in clinical outcomes were observed between the isolated MPFLr and TTO subgroups (TT-TG 15– 20 versus TT-TG 20–25). The conclusion was that an isolated MPFLr is a safe and reliable treatment for patients with recurrent patellar instability with a TT-TG distance of 15 to 25 mm. Some reasons may contribute to explain these findings. Firstly, the TT-TG distance depends on knee flexion, weightbearing, tibiofemoral rotation, and joint size [42]. Secondly, the intra and interobserver reliability for TT-TG distance measurements is less in patients with severe trochlear dysplasia compared to low-grade trochlear dysplasia [42]. Thirdly, there are no differences in the TT-TG distance between the stable and the unstable knee in patients with unilateral patellar instability [43]. Finally, some studies have not found differences in the
426 outcomes of isolated MPFLr in the setting of a TT-TG index>20 mm compared to those with a TT-TG distance<20 mm [44]. Therefore, it seems wise to use these measurements with care when designing the treatment for each individual. A much more comprehensive approach that includes the patient’s medical history and physical examination, the etiology of dislocation (traumatic versus atraumatic), the uni or bilaterality of the process as well as the activity level and expectations of the patient is advised. Patellofemoral tracking (J-sign) should also be taken into consideration. In conclusion, TTO should be considered in extremely selected cases when a less invasive alternative is insufficient. Similarly, there is no consensus on a threshold value for the Caton-Deschamps index to indicate TT distalization associated with MPFLr for the treatment of recurrent patellar instability. In a recent publication, isolated MPFLr in patients with patella alta (Caton-Deschamps index 1.2) and CLPI results in a significant decrease in the patellar height ratio with the effect size being greatest in patients with higher pre-operative Caton-Deschamps index values [45]. In patients with patella alta, defined as a Caton-Deschamps index 1.2, normalization of the patellar height ratio occurred in 59.6% of the cases [45]. Additionally, no differences in clinical outcomes were encountered in patients with and without patella alta using de Banff Patellofemoral Instability Instrument score [45]. Consequently, distalization may not be necessary in most CLPI associated with patella alta if MPFLr provokes a descent of the patella, at least in those with Caton-Deschamps Index values between 1.2–1.4 [46]. On the other hand, patients with mild patella alta report similar outcomes after isolated MPFLr than patients with normal patella height [46]. In conclusion, the value of adding TT distalization in patients with patella alta is not clear. Moreover, TT distalization is not a panacea. TT distalization always implies some degree of medialization. Additionally, it may be risky in patients with chondral lesions of the distal pole of the patella because the procedure causes an overload of this area upon initial flexion. V. Sanchis-Alfonso et al. Furthermore, the detachment of the TT might potentially cause a tibial fracture and non-union. Regarding sulcus deepening trochleoplasty, it is not a routine surgical procedure. It is a valuable tool only in a small subset of patients, mostly in revision surgeries. They include severe trochlear dysplasia, when the patella dislocates not only during the first 30º of knee flexion but also at high degrees of knee flexion, and when there is patellofemoral maltracking (positive Jsign). The first author (V.S-A) recommends never performing a trochleoplasty, a femoral osteotomy or a tibial tubercle osteotomy if there is no maltraking (J-sign) as isolated MPFLr is likely to work. 7 Postoperative Management Pain control is important after surgery; a femoral nerve block and endovenous analgesics are our preferred options. A knee brace is recommended for 4 weeks until the quadriceps is fully activated. Immediate full weightbearing, as tolerated, with the help of two crutches is encouraged from the beginning. The principles of MPFLr rehabilitation stress early complete range-of-motion (ROM) exercises, with the emphasis on extension to prevent scar formation and capsular retractions, quadriceps strengthening and proximal control of the lower limb (hip abductors and external rotators strengthening). As knee rotation places lateral stress on the patella, it is necessary to refrain from knee rotation until three months after the operation [47]. In recent years, several investigations have analyzed the return to sports after ACL reconstruction. Conversely, there is scarce information on when to start sports after MPFLr. As in the ACL reconstruction, the timing to return to sports is not just a matter of time but rather a matter of meeting some clinical and functional requirements. Ménétrey and colleagues [48] proposed six clinical criteria for returning to sport after MPFLr: absence of pain, no effusion, no patellar instability, full range of motion, symmetrical
Medial Patellofemoral Ligament Reconstruction … strength (85–90%) in both legs, and excellent dynamic stability assessed with the use of several functional tests such as the single-leg squat and the star excursion balance test (SEBT). Many sports activities call for changes in direction and landing from jumps. It is therefore important to assess these parameters before returning to sports. Drop and jump test and side hop-test provide valuable information about those sports gestures. 8 Clinical Outcomes. Scientific Evidence Medial patellofemoral ligament (MPFL) reconstruction is being performed more frequently each time with good clinical outcomes. SappeyMarinier and colleagues [49] have reported the clinical outcomes of isolated MPFLr. They conclude that isolated MPFLr is a safe and efficient surgical procedure with a low failure rate. They evaluated 211 MPFL reconstructions with a mean follow-up of 5.8 years (range, 3– 9.3 years). Twenty-seven percent of patients had a preoperative positive J-sign, and 93% of patients had trochlear dysplasia (A, 47%; B, 25%; C, 15%; D, 6%). The mean CDI was 1.2 (range, 1.0−1.7); mean tibial tubercle-trochlear groove distance, 15 mm (range, 5−30 mm); and mean patellar tilt, 23° (range, 9°-47°). The mean Kujala score improved from 56.1 preoperatively to 88.8 in the postop. Recurrent patellar instability requiring surgical revision was reported in 10 cases (4.7%). Preoperative predictive factors for failure were patella alta (CDI 1.3) and a preoperative positive J-sign. These results are in accordance with a recent systematic review with a meta-analysis to evaluate outcomes after isolated MPFLr for the treatment of recurrent patellar dislocations. The pooled estimated mean postoperative Kujala score was 85.8 (95% CI, 81.6–90.0), with 84.1% (95% CI, 71.1–97.1%) of the patients returning to sports after surgery. The pooled total risk of recurrent instability after surgery was 1.2% (95% CI, 0.3–2.1%) with a positive apprehension sign risk of 3.6% (95% CI, 427 0–7.2%) and a reoperation risk of 3.1% (95% CI, 1.1–5.0%) [50]. Platt and colleagues [51] also meta-analyzed the overall rate of return to sports after MPFLr. In their revision, the rate of return to sport was higher (92.8%) even though only 71.3% return to their preoperative level of performance. Return to sport after MPFLr does not differ significantly in patients with or without an osteotomy (95.4 vs. 86.9%). Moreover, the time to return to play was seen at approximately 7 months after index surgery. Complications occurred at an overall rate of 8.8%, being the most common recurrence of instability (1.9%). Another interesting issue is the characteristics of patients who were unable to return to play after MPFLr. This subject was addressed by Hurley and colleagues [52]. They evaluated the psychological readiness to return to sport using the MPFL-RSI score. It was concluded that patients that do not return to play exhibit poor psychological readiness with the most common reason being fear of re-injury. Interestingly, only 42.4% of US military servicemembers undergoing primary MPFLr were able to fully return to unrestricted impact activity after surgery, bilateral instability being a factor of poor prognosis [53]. In summary, a high percentage of patients with CLPI undergoing MPFLr have good clinical outcomes with a return to sports and a low incidence of recurrent instability, postoperative apprehension, and reoperations. 9 Anatomical MPFLr Versus Quasianatomical MPFLr Marot and colleagues [54] performed a multicenter longitudinal prospective study to compare the functional outcomes after an isolated MPFLr using either a quasi-anatomical technique (elastic femoral fixation) or an anatomical (static femoral fixation) MPFLr. Patients with trochlear dysplasia types C and D were excluded. The main evaluation criterion was the Kujala functional score. The secondary objectives were to compare the rates of redislocation, range-of-motion and
428 V. Sanchis-Alfonso et al. subjective patellar instability (Smillie test). The mean postoperative Kujala was 90.4 (89.4 in group A and 92.1 in group B). Upon comparing the mean difference between pre- and postoperative values, no differences were detected between the two groups. They concluded that an isolated quasi-anatomical MPFLr using a gracilis tendon autograft provides outcomes as good as the isolated anatomical MPFLr at the 2–5 years follow-up in the selected subgroup of patients with CLPI. 6. 7. 8. 9. 10 Take Home Messages – MPFLr has proven to be a safe, reliable and reproducible technique for the treatment of CLPI. – The paramount requirement for a successful MPFLr is the proper selection of the patient as well as correct presurgical planning and a meticulous surgical technique. – An MPFL reconstruction should not be performed if the patella cannot be laterally dislocated. 10. 11. 12. 13. 14. References 1. Sanders TL, Pareek A, Hewett TE, et al. Incidence of first-time lateral patellar dislocation: a 21-year population-based study. Sports Health. 2018;10 (2):146–51. 2. Huntington LS, Webster KE, Devitt BM, et al. Factors associated with an increased risk of recurrence after a first-time patellar dislocation: a systematic review and meta-analysis. Am J Sports Med. 2020;48(10):2552–62. 3. Nomura E. Classification of lesions of the medial patello-femoral ligament in patellar dislocation. Int Orthop. 1999;23(5):260–3. 4. Allen MM, Krych AJ, Johnson NR, et al. Combined tibial tubercle osteotomy and medial patellofemoral ligament reconstruction for recurrent lateral patellar instability in patients with multiple anatomic risk factors. Arthroscopy. 2018;34(8):2420–6. 5. Nelitz M, Dreyhaupt J, Robert S, et al. Combined supracondylar femoral derotation osteotomy and patellofemoral ligament reconstruction for recurrent 15. 16. 17. 18. 19. patellar dislocation and severe femoral anteversion syndrome: surgical technique and clinical outcome. Int Orthop. 2015;39(12):2355–62. Nelitz M, Williams SR. [Combined trochleoplasty and medial patellofemoral ligament reconstruction for patellofemoral instability]. [Article in German] Oper Orthop Traumatol. 2015;27(6):495–504. Ellera Gomes JL. Medial patellofemoral ligament reconstruction for recurrent dislocation of the patella: a preliminary report. Arthroscopy. 1992;8(3):335–40. Avikainen VJ, Nikku RK, Seppanen-Lehmonen TK. Adductor magnus tenodesis for patellar dislocation. Technique and preliminary results. Clin Orthop Relat Re. 1993;(297):12–16. Teitge RA. Treatment of complications of patellofemoral joint surgery. Oper Tech Sports Med. 1994;4:317–33. Gallie WE, Lemesurier AB. Habitual dislocation of the patella. J Bone J Surg. 1924;6(3):575–82. Monllau JC, Masferrer-Pino A, Ginovart G, et al. Clinical and radiological outcomes after a quasianatomical reconstruction of medial patellofemoral ligament with gracilis tendon autograft. Knee Surg Sports Traumatol Arthrosc. 2017;25(8):2453–9. Seitlinger G, Moroder P, Fink C, et al. Acquired femoral flexion deformity due to physeal injury during medial patellofemoral ligament reconstruction. Knee. 2017;24(3):680–5. Sanchis-Alfonso V. Guidelines for medial patellofemoral ligament reconstruction in chronic lateral patellar instability. J Am Acad Orthop Surg. 2014;22:175–82. Sanchis-Alfonso V, Ramírez-Fuentes C, MontesinosBerry E, et al. Femoral insertion site of the graft used to replace the medial patellofemoral ligament influences the ligament dynamic changes during knee flexion and the clinical outcome. Knee Surg Sports Traumatol Arthrosc. 2017;25(8):2433–41. Wang C, Kernkamp WA, Li C, et al. Elongation and orientation pattern of the medial patellofemoral ligament during lunging. J Orthop Res. 2021;39 (9):2036–47. Pérez-Prieto D, Capurro B, Gelber PE, et al. The anatomy and isometry of a quasi-anatomical reconstruction of the medial patellofemoral ligament. Knee Surg Sports Traumatol Arthrosc. 2017;25(8):2420–3. Schöttle PB, Schmeling A, Rosenstiel N, et al. Radiographic landmarks for femoral tunnel placement in medial patellofemoral ligament reconstruction. Am J Sports Med. 2007;35(5):801–4. Ziegler CG, Fulkerson JP, Edgar C. Radiographic reference points are inaccurate with and without a true lateral radiograph: The importance of anatomy in medial patellofemoral ligament reconstruction. Am J Sports Med. 2016;44(1):133–42. Sanchis-Alfonso V, Ramirez-Fuentes C, MontesinosBerry E, et al. Radiographic location does not ensure a precise anatomic location of the femoral fixation
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430 45. Hiemstra LA, Kerslake S, Lafave MR, et al. Patella alta is reduced following MPFL reconstruction but has no effect on quality-of-life outcomes in patients with patellofemoral instability. Knee Surg Sports Traumatol Arthrosc. 2021;29(2):546–52. 46. Bartsch A, Lubberts B, Mumme M, et al. Does patella alta lead to worse clinical outcome in patients who undergo isolated medial patellofemoral ligament reconstruction? A systematic review. Arch Orthop Trauma Surg. 2018;138(11):1563–73. 47. Fujii Y, Nakagawa S, Arai Y, et al. Clinical outcomes after medial patellofemoral ligament reconstruction: an analysis of changes in the patellofemoral joint alignment. Int Orthop. 2021;45(5):1215– 22. 48. Menetrey J, Putman S, Gard S. Return to sport after patellar dislocation or following surgery for patellofemoral instability. Knee Surg Sports Traumatol Arthrosc. 2014;22(10):2320–6. 49. Sappey-Marinier E, Sonnery-Cottet B, O´Loughlin P, et al. Clinical outcomes and predictive factors for failure with isolated MPFL reconstruction for recurrent patellar instability: a series of 211 reconstructions with a minimum follow-up of 3 years. Am J Sports Med. 2019;47(6):1323–30. 50. Schneider DK, Grawe B, Magnussen RA, et al. Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent V. Sanchis-Alfonso et al. 51. 52. 53. 54. lateral patellar dislocations: a systematic review and meta-analysis. Am J Sports Med. 2016;44(11):2993– 3005. Platt BN, Bowers LC, Magnuson JA, et al. Return to sport after medial patellofemoral ligament reconstruction: a systematic review and meta-analysis. Am J Sports Med. 2021. https://doi.org/10.1177/ 0363546521990004. Hurley ET, Markus DH, Mannino BJ, et al. Patients unable to return to play following medial patellofemoral ligament reconstructions demonstrate poor psychological readiness. Knee Surg Sports Traumatol Arthrosc. 2021. https://doi.org/10.1007/s00167021-06440-y. Moreland CM, SZhaw KA, Burks R, et al. Primary medial patellofemoral ligament reconstruction in military service members: can we reliably restore preinjury function and stability?. Orthop J Sports Med. 2021. https://doi.org/10.1177/23259671211 013334. Marot V, Sanchis-Alfonso V, Perelli S, et al. Isolated reconstruction of medial patellofemoral ligament with an elastic femoral fixation leads to excellent clinical results. Knee Surg Sports Traumatol Arthrosc. 2021;29(3):800–5.
Minimal Invasive MPFL Reconstruction Using Quadriceps Tendon Christian Fink 1 Historical Perspective In 2011, as president of the German speaking Arthroscopy Association (AGA) I was invited as a guest speaker to the 2nd Balkan Congress of Arthroscopy, Sport Traumatology, and Knee Surgery in Ohrid, Macedonia. In a busy period of my practice, I was not particular keen to go there initially, but in the end this trip changed the way of treating my patellofemoral patients up to now. As one of the first speaker of the meeting Prof. Matthias Veselko from Ljubljana presented his technique of MPFL reconstruction using a strip of quadriceps tendon (QT) [1]. At this time MPFL reconstruction in general had just become more and more popular replacing the retinacular repairs and duplications as well as the tibial tubercle transfers, which one or the other (or both) we have been doing for almost all the patellar dislocations at that time. Most of the MPFL reconstruction techniques at this time used hamstring grafts (HS), commonly the gracilis tendon [2, 3]. This was exactly what I was doing at this stage. C. Fink (&) Gelenkpunkt Sport and Joint Surgery, Innsbruck, Austria e-mail: C.fink@gelenkpunkt.com Research Unit for Orthopedic Sports Medicine and Injury Prevention, UMIT Hall, Tirol, Austria However, at the same time I was very interested in the QT for ACL reconstruction. In order to reduce the morbidity of open tendon harvest I was working on the development a new instrumentation to allow for a more precise and easier QT graft harvest. Following the presentation of Prof. Veselko my head kept spinning. This strip of QT he used for his technique looked just so much more like the natural flat and thin MPFL (Fig. 1) than the hamstring graft I was currently using. Most of all, this technique avoided anchors or drill holes a common worry not only to me, but many of my surgeons friends. I was wondering why this technique was not used more commonly around the globe. Looking at this presentation (I took a lot of pictures) again and again on my way back from Macedonia I thought I discovered a possible reason. Conventional QT harvest for ACL or PCL reconstruction requires a fairly extended longitudinal incision over the thigh. This was sometimes associated with some ugly scar formation and a possible reason why QT as a primary ACL graft was also not really popular at this stage (Fig. 2). Competing with a 2 cm incision necessary for HS harvest this was not exactly making you a popular surgeon especially within a female patient community. So, I was convinced about the technique the first minute I saw it but I realized in order to make this technique more popular a minimal invasive harvesting technique for the QT just like © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_28 431
432 C. Fink A B Fig. 1 Anatomical dissection of the native MPFL (A) compared to a reconstructed one using a QT strip (B) Fig. 2 Example of a scar following conventional quadriceps tendon harvest for reconstruction of the anterior (ACL) or posterior (PCL) cruciate ligament would be helpful. In the next few months, I went to the anatomy lab to do some anatomical dissections and also talked to the engineer I was working with at the KARL STORZ company to make some modification on the ACL harvesting instruments we were developing. All we really needed was to define a new tendon separator of 3 mm thickness instead of the 5 mm used for ACL/PCL graft harvest. After a few trials in the lab the new minimal invasive technique for quadriceps MPFL reconstruction was born [4]. Parallel to these developments I went through the literature and realized that this technique with some modification has been around for a few years already and that very encouraging clinical results had been published. The first description of partial-thickness QT graft MPFL reconstruction was by Burks and Luker in 1997 [5]. This was a free graft technique, harvesting a strip of QT with a patella bone block, which was placed into a recessed bony bed in the femoral epicondyle and secured with a screw/washer. The QT end of the graft was secured through a bone tunnel on the patella side.
Minimal Invasive MPFL Reconstruction Using Quadriceps Tendon Steensen et al. in 2005 [6] were the first to describe leaving the quadriceps tendon attached on the patella side. Harvesting a partial thickness quadriceps tendon graft, they extended dissection distally over the anterior patella elevating the thick periosteum. By dissecting further distal laterally than medially they created a diagonal hinge point, allowing the graft to fold into position medially on an intact periosteal pedicle. A 5 cm midline longitudinal incision was made extending proximally from the superior pole of the patella. A partial thickness quadriceps tendon graft, 10–12 mm wide, was harvested from the central third of the quadriceps tendon. Shortly after Steensen et al. [6], in 2005 Noyes and Albright [7] published a technique, also based on an intact graft pedicle on the patella side. They harvested an 8 70 mm fullthickness graft from the medial (rather than central) aspect of the QT. This was left attached at the superomedial border of the patella, passed medially beneath the medial retinaculum and sutured to the medial intermuscular septum. Due to non-anatomical femoral fixation, this is technically not an MPFL reconstruction, but a medial reinforcement. On one of the following international Knee meetings I got to know Prof. Deepak Goyal from India, who was using a QT MPFL technique for several years. He published his clinical results and the technique with bony femoral fixation in 2013 [8]. He harvests the central 10–12 mm of the QT superficial lamina, via a 7–8 cm longitudinal incision starting at the superior pole of the patella. The proximal free end of the graft was tunneled medially between the capsule and medial retinaculum. No.2 Ethibond® stay sutures were placed at junction of the medial edge of the patella and the graft to stabilize the graft-patella anatomic attachment and finally, the graft is secured in the distal femur with a biointerference screw rather than transosseus sutures as described by Steenson et al.[6]. Proudly I presented my “discoveries” and my technique to friends who I knew being involved with patellofemoral surgeries for years. They all used hamstring MPFL techniques at this time. 433 However, there was not only interest but a lot of skepticisms, most of all questioning the strength of the patellar graft fixation. Was fixation of a detached and diverged periosteum strip only with sutures at the medial edge of the patella really strong enough to withstand the forces? There was nothing in the literature about this topic. So again, I knew if this technique was about to get more popular, we needed both biomechanical as well as clinical data. I knew that a group in Münster Germany had just published on the biomechanical characteristics of different MPFL fixation methods for hamstring graft on the patella [9]. This setup seemed perfect for testing the QT construct and would also allow for direct comparisons not only to the characteristics of the natural MPFL but also in comparison to the commonly used hamstring techniques. I contacted one of the authors (Prof. Mirco Herbort) of the paper whom I knew and presented my ideas. He was immediately interested and soon afterwards we started the biomechanical project. I flew to Münster in order to demonstrate and train them in the surgical technique. I did not want to be part of the further procedures and the testing itself in order to avoid bias. A few weeks later I got a phone call from Prof. Herbort late at night. He sounded really excited. Not only was the maximum pullout strength equivalent or higher than the natural MPFL but the stiffness of the construct also closely resembled that of the natural MPFL. The biomechanical results and the good clinical impression we got from the first patients encouraged us to push this technique forward [10]. 2 Anatomy and Considerations for QT Graft Harvest The native MPFL is a broad flat structure approximately 1 mm thick arising from a broad origin on the femur approximately 9–17 mm in width and located within a triangle formed by the
434 C. Fink adductor tubercle, medial femoral epicondyle and gastrocnemius tubercle [11–14]. It has a similarly broad insertion on the patella (24 mm ±5 mm), occupying approximately the upper half of the length of the patella articular surface. Hence the native MPFL is morphologically more similar to a broad flat QT graft, than a tubular HS graft. Interestingly, embryologically, the MPFL and QT are both formed from the same origin, ventral mesenchyme, whilst the HT originates in the dorsal mesenchyme [8]. Given the native QT width (44 mm), harvesting a 10–12 mm wide graft will usually constitute 20–30% of the QT width. QT thickness increases steadily as aponeurotic layers of the extensor apparatus join, reaching a maximal thickness of 7.9 mm distally (range 6.5 to 9.5 mm)[15]. Therefore, a 3 mm deep graft will constitute less than half the depth distally. Due to proximal tendon narrowing and thinning, the graft constitutes a relatively larger proportion of the volume proximally. However, volumetric MRI studies have shown that a full thickness 10 mm 80 mm graft constitutes 39% by volume [16]. A 3 mm deep graft therefore is likely to constitute only around 20% by volume and no donor site problems have been reported in any published studies. 3 Biomechanics Herbort et al. [17], found that in a human cadaveric model the biomechanical characteristics of a 3 mm thick by 10 mm wide QT strip [stiffness 33.6 N/mm (±6.8), yield load 147.1 N (±65.1),maximum load to failure 205 N (±77.8)] were very similar to that of the native MPFL [stiffness 29.4 N/mm (±9.8), yield load 167.8 N (±80), maximum load to failure 190.7 N (±82.8)], whilst Lenschow et al. [9] found that HT constructs are about 3stiffer (87– 100 N/mm). Therefore, QT grafts may more closely restore native MPFL kinematics and may be more forgiving of variations in position and tension. Stiffer HT grafts may be more sensitive to over-tensioning or malpositioning, which can lead to increased patellofemoral joint stress compression forces and lead to restricted motion. 4 Surgical Technique 4.1 Patient Positioning and Arthroscopy Patient positioning has to allow free knee motion between 0° and 120°. The intraoperative access for the fluoroscope is important to be kept in mind and ideally checked prior to draping. We prefer fixation of the operative leg in an electric leg holder (Fig. 3A). An arthroscopy is performed initially, to inspect the articular cartilage in the patellofemoral joint and to evaluate patella tracking (Fig. 3B). The latter is best visualized through a superolateral portal for the arthroscope. 4.2 Graft Harvest In 90° of knee flexion a 3 cm transverse skin incision is placed over the superomedial margin of the patella (Fig. 4A). The prepatellar bursa is incised longitudinally and the quadriceps tendon is then carefully exposed. A long Langenbeck retractor (Fig. 4B) is then introduced and the quadriceps tendon subcutaneously exposed proximal to the patella. Step 1: A double knife (Karl Storz, Tuttlingen) in 10 or 12 mm width is then introduced. It is pushed proximally to a minimum of 9 cm (mark on the instrument) (Fig. 5A and B). Step 2: The thickness of the graft is then determined with 3 mm by a tendon separator (Karl Storz, Tuttlingen). The separator is angled about 30 degree and pushed proximally to the same mark (minimum 9 cm) (Fig. 6A and B). Step 3: Finally, the tendon strip is subcutaneously cut using a special tendon cutter (Karl Storz, Tuttlingen) (Fig. 7A and B).
Minimal Invasive MPFL Reconstruction Using Quadriceps Tendon A 435 B Fig. 3 Positioning of the patient. A The operated knee is placed in an electric leg holder. B Arthroscopy is performed prior to graft harvest A B Fig. 4 A Placement of the skin incision at the superomedial aspect of the patella. B A long Langenbeck retractor is inserted to allow proper visualization of the quadriceps tendon
436 C. Fink B A Fig. 5 Graft harvest—Step I: Double knife of 10 or 12 mm (KARL STORZ, Tuttlingen) pushed proximally 8—10 cm above the superior patella boarder (A schematic drawing, B operative procedure) Fig. 6 Graft harvest—Step 2: Tendon Separator (3 mm) (KARL STORZ, Tuttlingen) pushed proximally to the same length (8–10 cm) (A schematic drawing, B. operative procedure) A 4.3 Patella Preparation The free proximal end is sheathed with resorbable sutures (Fig. 8A) in a web-stitch technique (Fig. 8B). The diameter of the free tendon end is measured using an ACL graft sizer (Fig. 8C). Distally the longitudinal cuts are continued in the same width (10 or 12 mm) with a surgical knife towards the patella and over the patellar surface (2 cm-lateral and 1 cm-medial). The quadriceps tendon strip is than subperiostally elevated from the surface of the patella (Fig. 9A B and B). The proximal 1.5 cm of the medial patellar border is then exposed. Using a periosteal elevator the prepatellar tissue is lifted from the medial patella border (Fig. 10A) creating a subperiosteal tunnel (Fig. 10B). A surgical clamp is introduced into the tunnel from medial to lateral and by grasping the sutures the graft is passed through. The graft diverged 90° and left attached to the periosteum (Fig. 11A and B). It is then secured at the medial boarder of the medial patellar (equivalent to the attachment of the natural MPFL) by resorbable No. 1 sutures.
Minimal Invasive MPFL Reconstruction Using Quadriceps Tendon A 437 B Fig. 7 Graft harvest—Step 3: The tendon strip is cut at the desired length (8–10 cm) using a special Tendon cutter (KARL STORZ, Tuttlingen) (A schematic drawing, B operative procedure) A B C Fig. 8 A The free proximal end is sheathed with resorbable sutures in a B locked web-stitch technique. C the tendon diameter is measured
438 C. Fink * ° A B Fig. 9 The preparation of the tendon strip is extended distally on the patella (°lateral 1.5 to 2 cm and *medial 0.5 to 1 cm (A schematic drawing, B operative procedure) A B Fig. 10 The prepatellar tissue is lifted from the medial patella border (Fig. 10A) using a periosteal elevator creating a subperiosteal tunnel (Fig. 10B) 4.4 Femoral Preparation A 1.5 cm skin incision is then made over the adductor tubercle. Under fluoroscopic guidance a 2.4 mm guide pin is drilled into the insertion of the MPFL (Fig. 12) [3]. It is directed anterolaterally to exit the femur on the lateral cortex well proximal to the lateral epicondyle. If found accurate by fluoroscopy the guide pin is over reamed with a cannulated reamer according to the diameter of the graft (most commonly 6– 8 mm) to a depth of 30 mm. Starting at the medial boarder of the patella a long curved clamp is used to create a tunnel in the space between the vastus medialis and the joint capsule (Layer 2 and 3). A suture loop is
Minimal Invasive MPFL Reconstruction Using Quadriceps Tendon A 439 B Fig. 11 The QT strip diverged 90° and left attached at the periosteum. (A schematic drawing, B operative procedure) then pulled through the tunnel. This loop is used later to pull the graft towards the femoral insertion (Fig. 13A and B). The graft is then pulled into the tunnel. The knee is cycled 5 times with moderate tension on the graft. Fixation is performed with a bioabsorbale interference screw (with a equivalent diameter to the tunnel diameter) at 40–60 degrees of knee flexion (Fig. 14A). The lateral border of the patella should be flush with the lateral border of the trochlear groove. Alternatively, and generally in children with open physis the graft is fixed with a bone anchor and additional sutures (Fig. 14B). 5 Pearls and Pitfalls 5.1 Pearls • Careful dissection is necessary to expose the QT (including removal of all the bursal and superficial layers). • The QT is longest when starting slightly lateral over the center of the patella. • The QT can be inspected using the arthroscope before harvesting. • Be sure you have enough graft length (minimum 9 cm in an average patient). 5.2 Pitfalls • The QT strip could peel off the bony surface of the patella. – To avoid a “peel off,” dissection must be performed carefully. If “peel off” occurs and the graft is amputated from the patella, bone anchors may be used to fix the QT strip to the medial aspect of the patella (free QT graft) or if the graft is long enough it can be looped through the prepatellar tissue and sutured on to itself. • The QT strip could be too short. – It is important to angle the tendon separator 30° down, in order to avoid “cutting out” anteriorly leading to premature graft
440 C. Fink Fig. 12 Fluoroscopic control of the guide wire placement [according to Schöttle et al. [3]] amputation. We had one case in our clinical series where the QT strip was cut too short (5 cm). In this case a second 3 cm strip was harvested and sutured to the primary one. Alternatively, a strip of adductor tendon could have been harvested, left attached to the femur and sutured to the QT graft. • As the MPFL functions as a check-rein, it is important to avoid over tightening. – Graft fixation at the desired length should be performed in 40–60 degrees flexion with just enough tension to align the patella with the lateral trochlea. 6 Postoperative Treatment We use a hinged knee brace with ROM 0–90° for the first 2 postoperative weeks. The patient is mobilized immediately following surgery with 20 kg partial weight bearing for 3 weeks. Full weight bearing is started thereafter. Passive ROM exercises are initiated immediately postoperatively. Stationary cycling is started around 6 weeks postop. Full return to pivoting sports is between 4 and 5 months after the operation [18].
Minimal Invasive MPFL Reconstruction Using Quadriceps Tendon 441 B A Fig. 13 A, B The graft is pulled in between layer 2 and 3 towards the femoral incision using a long clamp Fig. 14 A The QT graft is fixed in 20° of knee flexion with a bioabsorbable screw in the same diameter as the bone tunnel. B Alternatively or in children the graft is fixed with a bone anchor and sutures A 7 Clinical Outcome In a study published by Gföller et al. [19] we included a consecutive series of 36 Patients (38 knees). All of these patients had>2patella dislocations, a TT-TG<20 mm, and no patellofemoral chondromalacia<ICRS grade IIIB. MPFL reconstruction was performed by our minimal invasive QT technique described above. All patients were evaluated clinically and with patient reported B outcome questionnaires including the Tegner-[20], Lysholm-[21] and Kujala–[22] Scores as well as the Visual Analogue Scale (VAS) for pain preoperatively and at 6, 12 and 24 months postoperatively. A functional Back-in-Action (BIA) test battery, including a total of seven different stability, agility and jumping tests, was performed on 19 (50%) patients at final follow-up. One Patient was lost to follow-up at 24 months. The mean age at time of operation was 25.2 ± 6.1 years. No re-dislocations occurred during the
442 C. Fink period of investigation. The mean Lysholm Score improved significantly (p < 0.05) from 79.3 ± 16.1 pre-operatively to 83.2 ± 14.4 at 6 m, 88.1 ± 11.3 at 12 m and to 90.0 ± 9.6 at 24 months follow-up. No change throughout the study period was observed for the median Tegner Activity Score (median = 6). The mean Kujala Score increased from a pre-operative value of 82.0 ± 12.4, to 84.5 ± 8.4 at 6 m, 88.2 ± 5.8 at 12 months up to 88.7 ± 4.5 at 24 months followup. 77.8% of the performed functional BIA tests were equal or above of the norm for patients of the corresponding age and activity level. 8 Discussion QT MPFL reconstruction has been shown to be a safe technique with high success at preventing recurrent dislocations and fewer complications than HT techniques [23, 24]. QT grafts provide a thin, broad strip of tissue with a continuous anatomic attachment along the superior half of the medial border of the patella that is anatomically and biomechanically more similar to the native MPFL than HT grafts [17, 23]. Maintaining an intact graft pedicle on the patella means that patella bone tunnel drilling or suture anchor placement is not necessary, reducing fracture risk. Long incisions described for open QT graft harvesting may have deterred surgeons from using this technique, however a minimal invasive QT harvesting techniques offer potentially better cosmetic results than both open QT and HT techniques. On the other hand, the option to harvest QT via a midline incision means that QT MPFL reconstruction combines well with trochleaplasty via the same incision. Overall, QT is a valuable alternative to common HT grafts for primary MPFL reconstruction in children [25] and adults, and is an important revision surgery option. References 1. Macura M, Veselko M. Simultaneous reconstruction of ruptured anterior cruciate ligament and medial patellofemoral ligament with ipsilateral quadriceps grafts. Arthroscopy. 2010;26(9):1258–62. 2. Christiansen SE, Jacobsen BW, Lund B, Lind M. Reconstruction of the medial patellofemoral ligament with gracilis tendon autograft in transverse patellar drill holes. Arthroscopy. 2008;24(1):82–7. 3. Schoettle PB, Schmeling A, Romero J, Weiler A. Anatomical reconstruction of the medial patellofemoral ligament using a free gracilis autograft. Arch Orthop Trauma Surg. 2009;129(3):305–9. 4. Fink C, Veselko M, Herbort M, Hoser C. Minimally invasive reconstruction of the medial patellofemoral ligament using quadriceps tendon. Arthrosc Tech. 2014;12;3(3): e325—9 5. Burks RT, Luker MG. Medial patellofemoral ligament reconstruction techniques in orthopaedics. 1997. 6. Steensen RN, Dopirak RM, Maurus PB. A simple technique for reconstruction of the medial patellofemoral ligament using a quadriceps tendon graft. Arthroscopy. 2005;21(3):365–70. 7. Noyes FR, Albright JC. Reconstruction of the medial patellofemoral ligament with autologous quadriceps tendon. Arthroscopy. 2006;22(8):904 e901–907. 8. Goyal D. Medial patellofemoral ligament reconstruction: The superficial quad technique. Am J Sports Med. 2013;41:1022–9. 9. Lenschow S, Schliemann B, Gestring J, Herbort M, Schulze M, Kösters C. Medial patellofemoral ligament reconstruction: fixation strength of 5 different techniques for graft fixation at the patella. Arthroscopy. 2013;29(4):766–73. 10. Fink C, Veselko M, Herbort M, Hoser C. MPFL reconstruction using a quadriceps tendon graft: Part 2: operative technique and short term clinical results Knee. 2014;21(6):1175–9. 11. Aframian A, Smith TO, Tennent TD, Cobb JP, Hing CB. Origin and insertion of the medial patellofemoral ligament: a systematic review of anatomy. Knee Surg Sports Traumatol Arthrosc. 2017;25:3755–72. 12. Amis AA, Firer P, Mountney J, Senavongse W, Thomas NP. Anatomy and biomechanics of the medial patellofemoral ligament. Knee. 2003;10 (3):215–20. 13. Andrikoula S, Tokis A, Vasiliadis H, Georgoulis A. The extensor mechanism of the knee joint: an anatomical study. Knee Surgery, Sport. Traumatol. Arthrosc. J Article. 2006;14:214–220. Springer, Berlin.
Minimal Invasive MPFL Reconstruction Using Quadriceps Tendon 14. Dirim B, Haghighi P, Trudell D, Portes G, Resnick D. Medial patellofemoral ligament: cadaveric investigation of anatomy with MRI, MR arthrography, and histologic correlation. AJR Am J Roentgenol. 2008;191(2):490–8. 15. Grob K, Manestar M, Filgueira L, Ackland T, Gilbey H, Kuster MS. New insight in the architecture of the quadriceps tendon. J Exp Orthop. 2016;3(1):32 16. Xerogeanes JW, Mitchell PM, Karasev PA, Kolesov IA, Romine SE. Anatomic and morphological evaluation of the quadriceps tendon using 3dimensional magnetic resonance imaging reconstruction: applications for anterior cruciate ligament autograft choice and procurement. Am J Sports Med. 2013;41(10): 2392–9. 17. Herbort M, Hoser C, Domnick C, Raschke MJ, Lenschow S, Weimann A, Kösters C, Fink C. MPFL reconstruction using a quadriceps tendon graft. Part 1: Biomechanical properties of quadriceps tendon MPFL Reconstruction in comparison to the Intact MPFL. A Human Cadaveric Study. Knee. 2014;21(6):1169—74. 18. Fisher B, Nyland J, Brand E, Curtin B. Medial patellofemoral ligament reconstruction for recurrent patellar dislocation: a systematic review including rehabilitation and return-to-sports efficacy. Arthroscopy. 2010;26(10):1384–94. 19. Gföller P, Hoser C, Runer A, Abermann E, Wierer G, Fink C. Medial patellofemoral ligament (MPFL) 20. 21. 22. 23. 24. 25. 443 reconstruction using quadriceps tendon autograft provides good clinical, functional and patientreported outcome measurements (PROM): a 2-year prospective study. Knee Surg Sports Traumatol Arthrosc. 2019;27(8):2426–32. Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligament injuries. Clin Orthop Relat Res. 1985;198:43–9. Lysholm J, Gillquist J. Evaluation of knee ligament surgery results with special emphasis on use of a scoring scale. Am J Sports Med. 1982;10:150–4. Kujala UM, Jaakkola LH, Koskinen SK, Taimela S, Hurme M. Nelimarkka O. Scoring of patellofemoral disorders. Arthroscopy. 1993;9:159–63. Fink C, Steensen R, Gföller P, Lawton R. Quadriceps tendon autograft medial patellofemoral ligament reconstruction. Curr Rev Musculoskelet Med. 2018;11(2):209–20. Shah JN, Howard JS, Flanigan DC, Brophy RH, Carey JL, Lattermann C. A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med. 2012;40 (08):1916–23. Nelitz M, Williams SR. Anatomic reconstruction of the medial patellofemoral ligament in children and adolescents using a pedicled quadriceps tendon graft. Arthrosc Tech. 2014;3(2):e303–8.
Combined Medial Patellofemoral Ligament and Medial Patellotibial Ligament Reconstruction Robert S. Dean, Betina B. Hinckel, and Elizabeth A. Arendt 1 Introduction Lateral patellar dislocations (LPD) have a reported incidence of 23.2 per 100,000 adolescents each year [1], with nearly equal sex distribution [2]. Recurrence is common; a recent systematic review found the overall rate of recurrent dislocation following first-time LPD was 33.6% [3]. There are multiple anatomical considerations that are risk factors for LPD, both primary and recurrent [3–5] (ref C). Important anatomic risk factors include open physis, patellar alta, and trochlear dysplasia, e.g., Generalized hyperlaxity including Ehlers-Danlos can increase the risk for instability/dislocation [6]. The medial patellar ligaments are responsible for the lateral stability of the patellofemoral joint. They include three primary structures, the medial patellofemoral ligament (MPFL), the medial patellotibial ligament (MPTL) and the medial patellomeniscal ligament (MPML) [7]. Injuries to any of these structures can lead to lateral instability events which can incite lack of knee confidence, pain and at times cartilage degeneration R. S. Dean B. B. Hinckel (&) Beaumont Health, Royal Oak, MI, USA e-mail: betinahinckel@gmail.com E. A. Arendt University of Minnesota, Minneapolis, MN, USA [8]. While the MPFL has been the focus of the majority of biomechanical and clinical studies, the MPTL and MPML both play an integral role in patellofemoral stability and warrant further consideration for patients presenting with lateral instability [9, 10]. Many surgical techniques and subsequent outcomes studies have described MPFL reconstruction in detail, but this book chapter aims to demonstrate the importance of the MPTL and MPML which collectively are referred as the distal medial patellar constraints. The anatomy and biomechanics, clinical work-up, and surgical techniques will be described, and outcomes of prior surgical studies. 2 Anatomy and Biomechanics In 1974, Slocum et al. first described an analogous structure to the MPTL and the MPML which they described as a single structure. These authors described it as a single reinforcing band that arises from the lower margin of the articular segment of the patella and passed in an oblique fashion, inferiorly and medially, before inserting at the anteromedial aspect of the tibia; they also reported that the band had some attachment to the medial meniscus [11]. An anatomic study by the current authors described the MPTL originating 3.6 mm proximal to the distal border of the patella. The course is 28° relative to the patellar tendon. The average © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_29 445
446 length of the MPTL is 36.4 mm and the width is 7.1. Radiographic evidence demonstrates that the tibial attachment is 9.4 mm from the joint line and in line with the medial border of the medial tibial spine [12]. The MPML is encountered as three distinct layers. They originate from the inferomedial patella (5.7 mm proximal to the distal border of the patella), just proximal to the MPTL and insert at the anterior meniscus, at the anterior horn or transition from the anterior horn to the body of the meniscus. The angulation of the ligament relative to the patellar tendon is 22–42° when the knee is at 90° of flexion [13]. The histological samples of both the MPTL and the MPML demonstrated dense connective tissue with oriented collagen fibers uniformly in parallel and intermingled, elongated fibroblasts consistent with ligamentous tissue [13]. The mean failure loads of the MPTL and MPML were 147 and 105 N, respectively. It is important to put the strength of these ligaments in relation to the MPFL which has a reported load to failure of 178 N [14]. In one cadaveric study, 90% of MPTLs failed by mid-substance rupture and 100% of MPMLs failed by midsubstance rupture. It is important to note that the MPTL was significantly stiffer and showed less deformation in maximum tensile strength compared to the MPFL [13]. Biomechanical cutting studies have reported that the MPFL accounts for 50–60% of restraint against lateral patellar instability, whereas the MPTL and MPML combined to provide 20–40% of the resistance in extension [15–17]. The medial retinaculum accounts for the remaining 3–25% of restraint [15–18]. Individually, the MPTL may provide up to 24% of restraint and the MPML provided up to 38% of restraint near full extension [15, 17–19]. Ebied and El-Kholy performed a sequential sectioning study of the medial patellar stabilizers followed by sequential repair of the sectioned ligaments. After cutting the MPFL and leaving the MPTL intact, lateral subluxation of the patella was possible between 0 and 30° of knee R. S. Dean et al. flexion. Next, the MPTL was sacrificed in addition to the MPFL and full dislocation was observed between 0 and 60° of knee flexion. When reattaching only the MPFL, lateral dislocation was not possible, but subluxation was observed between 0 and 10° of knee flexion. After reattaching only the MPTL, some stability was restored but frank dislocation was still observed at full flexion and subluxation of the patella was noted between 0 and 15°. Thus, these authors concluded that the MPTL provided a less significant stabilizing force than the MPFL, but the rupture or dysfunction of the MPTL may result in increased lateral patellar laxity which can result in lateral patellar instability [20]. A biomechanical study by Phillippot et al. determined that the MPTL and MPML combined to provide approximately 46% of the restraint forces against lateral patellar subluxation when the knee was at 90° of flexion. Additionally, the MPTL and MPML were responsible for 72% of patellar tilt and 92% of patellar rotation. Unfortunately, this study did not study the MPTL and MPML separately, but rather examined them as a combined entity [21]. These previous conclusions were called into question by Grantham et al. who examined the role of the MPFL and MPTL through a sectioning biomechanical model. These authors found that when the MPTL was sectioned the patella tracking was similar to the native state. They described the role of the MPTL as “complementary” to the MPFL and reported that MPTL reconstruction in a MPFL deficient knee did not improve knee stability. Additionally, they concluded that the MPTL provided a more significant contribution to medial stability at greater than 30° of knee flexion [22]. Based upon these studies the distal medial patellar complex (MPTL and MPML) is most important during two knee motions: active terminal extension of the knee where it directly counteracts the quadriceps contraction, and deeper knee flexion when the distal ligament complex tightens increasing its contribution to resistant lateral patellar translation [21] (Fig. 1).
Combined Medial Patellofemoral Ligament and Medial Patellotibial … Fig. 1 This image depicts a cadaveric dissection of a left knee from an anterior viewpoint. It’s important to appreciate the medial patellotibial ligament (MPTL) and medial patellomeniscal (MPML) ligament as unique structures. Medial meniscus (MM), medial femoral condyle (MFC), medial patellofemoral ligament (MPFL), lateral femoral condyle (LFC), iliotibial band (ITB) 3 447 A traditional glide test is performed by applying a medial or lateral force to the patella, displacement of greater than or equal to 3 quadrants with this test is considered a positive result. Similarly, the patellar apprehension sign is observed when forced lateral displacement of the patella produces anxiety and/or forced resistance from the patient contracting their quadriceps. A modified technique can be performed with the quadriceps completely relaxed and knee at full extension with the examiner applying an equal force to both extremities, if one side has a soft endpoint with increased translation, which can be identified when the medial femoral trochlea is greater than one half uncovered and can be palpated, suspicion for a medial patellar stabilizers insufficiency should be raised [23]. A patellar tilt test can be used to assess for tightness of the lateral. The J sign signifies patellar mal-tracking [19]. Additionally, increased lateral patellar translation in deep flexion suggests increased dependency on the distal medial patellar stabilizers—MPTL and MPML, due to insufficient support from the trochlear groove and/or lack of engagement due to patellar alta [24]. Tenderness over the anteromedial proximal tibia in addition to focal tenderness over the inferior aspect of the patella, at the insertion of the MPTL or MPML can heighten the suspicion for lesions to the distal medial patellar structures. Diagnosis 3.2 Imaging 3.1 Presentation and Physical Exam It is crucial to perform a thorough physical examination in order to identify any concomitant pathologies including ligamentous, muscular, osseous or cartilaginous pathologies which can contribute to various findings during the workup phase of management. Exam features pertinent to this discussion will be detailed. Several physical exam maneuvers can be suggestive of medial patellar stabilizers injury, however it is essential compare all findings to the contralateral, healthy, limb for reference. Imaging of these injuries typically begins with standard AP and lateral radiographs along with a low flexion axial view. These images allow clinicians the opportunity to appreciate any frank dislocations, increased lateral translations or avulsion fractures. Additionally, the lateral radiograph is used evaluate for trochlear dysplasia as well as patellar height. Low flexion axial views allow one to assess for sulcus depth, patellar tilt and translation, as well as patellar morphology. Finally, in some circumstances full length weight bearing films can be used to
448 R. S. Dean et al. evaluate limb alignment and are helpful because valgus tibiofemoral alignment places more strain on the inferomedial patellofemoral complex susceptible [25]. MRI should be obtained to evaluate for injury to the local soft tissues, cartilage and bone bruising patterns. MRI has been shown to be a reliable modality for diagnosis of MPFL tears with a sensitivity of 85% and an accuracy of 80% when using open exploration of the medial knee as the “gold standard”. This same study reported that MRI was a more accurate diagnostic modality than arthroscopy [26]. While there are no known studies that report on the accuracy of advanced imaging for MPTL and MPML, injuries there are several known studies that describe the visualization of these ligaments on MRI. These studies reported accurate anatomical identification of the structures as unique entities [7, 27, 28]. As such, one can surmise that a trained eye would likely be able to identify lesions along the visualized structures. Thawait et al. reported several cases with isolated injuries to the inferior pole of the medial retinaculum, corresponding to the MPTL and MPML, without lateral patella dislocation or noted MPFL lesions. They reported that these ligaments can be injured in isolation through twisting injuries and are likely associated with medial meniscal or meniscocapsular lesions [28]. Tompkins et al. reviewed MRI of primary LPD and a majority (61%) of patellar chondral lesions were at its inferomedial aspect; all medial patellar retinacular partial injuries involved the inferomedial aspect of the patella, consistent with the insertion of the medial patellotibial ligament [29] (Fig. 2). 4 Treatment Options The indications for distal medial patella-tibial reconstruction are evolving. Although we recognize the contribution of both MPML and MPTL, most surgeons focus on the reconstruction of the MPTL due to the technical challenges and risk to meniscal stability with reconstruction of the MPML. Fig. 2 This image depicts an axial A and sagittal B slice of an MRI with disruption of the medial patellar retinaculum. Increased signal intensity in this region is highly suggestive of a medial patellotibial complex injury The current authors consider performing MPTL reconstruction in adjunct to MPFL reconstruction when there is lateral patellar subluxation with quadriceps contraction with the knee fully extended, flexion instability (obligate dislocation in flexion), knee hyperextension associated to generalized laxity, and/or increased quadriceps vector due to rotational deformities [24]. Additionally, it can be used and as adjuvant procedure in children with significant risk factors for recurrence of dislocation when bony surgery
Combined Medial Patellofemoral Ligament and Medial Patellotibial … is limited due to open physes [24]. It should also be noted that the utilization of MPTL reconstruction in combination with MPFL reconstruction may limit the need for bony procedures such as tibial tuberosity osteotomy and/or trochleoplasty in certain patients. Though historically there have been studies utilizing emphasize an isolated MPTL reconstruction for surgical patellar stabilization, current practice supports MPFL reconstruction as primary, and MPTL as an adjuvant ligament restraint. The MPTL reconstruction is performed first and the MPFL second. 5 Isolated Procedures 5.1 Hamstrings Tenodesis In isolation, MPTL reconstructions can be performed as a hamstring (either gracilis or semitendinosus) tenodesis. The technique was originally described in 1972 by Baker et al. They recommended harvesting the semitendinosus and then mobilizing the patella by releasing the lateral capsule and fascial band. Next, an oblique hole was drilled across the patella in the line of the tenodesis and the tendon was tied back on itself [30]. Several articles proposed a similar strategy to the aforementioned technique in children [31, 32]. 5.2 Isolated MPTL Reconstruction Zaffagnini et al. proposed a non-anatomic technique which began with a midline incision when the knee was at 20° of flexion. The authors then harvest the patellar tendon, with its associated bone plug, from the medial third of the tendon. They recommend repeated dynamic analysis of patellar tracking in order to identify a reinsertion point that ensured stability without excessively tensioning the ligament or patellofemoral joint. The quality of fixation is assessed subjectively using direct palpation and observation. When the correct point is established, a socket is created and the bone plug is fixed using a cortical screw [33]. 449 5.3 Combined “3 or 4 in 1” Procedures Myers et al. utilize a patellar tendon autograft in addition to a lateral release and VMO advancement. After the medial retinaculum is elevated from the tibia, the medial third of the patellar tendon is harvested from its tibial attachment. The graft is then transferred to the superficial medial collateral ligament (sMCL) so that the graft has a 40–45° angle with the remaining patellar tendon. The graft is fixed with the knee flexed to 30°. At the end of this technique the VMO is advanced 5–10 mm distally and laterally [34]. A similar technique was described in a pediatric population by Oliva et al. A difference between this newer technique is the fixation modality; Oliva et al. utilizes 2 metallic suture anchors to suture the patellar tendon graft to the medial aspect of the tibia in addition to the sMCL [35]. In 2007 Joo et al. proposed an adaptation of the hamstring tenodesis where they avoided using bone tunnels through the patella by directly fixing the tendon to the patella using a screw. This technique was a “4-in-1” that also involved a lateral release, proximal “tube” realignment of the patella, and patellar tendon transfer in addition to the hamstring tenodesis. The tendon is pulled across the surface of the patella and the portion that was abutting the superolateral corner of the patella is sutured under tension using a non-absorbable anchoring screw. The remaining tendon is sutured to the periosteum with a running suture, in the line of the tenodesis. This construct is fixed with the knee at 30° of flexion [36]. 5.4 Combined MPFL and MPTL Reconstruction The authors’ preferred MPTL technique utilizes a soft tissue allograft. When using an anterior tibialis allograft there is often enough width to divide the graft into 2 parts (Fig. 3). The larger portion can be used for the MPFL reconstruction
450 R. S. Dean et al. Fig. 3 Two hamstring autografts are prepared. Each graft should be a minimum of 28 cm in length and whipstitched at both ends while the smaller graft can be used for the medial patellotibial complex graft. The surgeon can identify the inferior-medial border of the patella at the distal end of the cartilage border, C-arm can be used as needed. Careful dissection through each layer of the medical capsule ensures (Fig. 4). The anatomic landmarks of the MPTL are identified on the patella (Figs. 5 and 6). Fixation can be established using a small anchor such as 1.8 mm QFix (Smith and Nephew). If the patella is small or if there are concerns about bone quality, one can undermine the periosteum on the dorsal surface of the patella. Using fluoroscopic guidance, the appropriate fixation point for the distal medial patellotibial complex can be identified on the anteromedial tibia approximately 5–10 mm distal to the joint line and just medial to the medial edge of the medial tibial spine [13]. The reconstructed ligament is typically placed at a 25–30° angle relative to the medial aspect of the patellar tendon. This angle is equal to a diagonal line from the inferior medial to superolateral corners of the patella, which helps resist superolateral migration of the patella throughout knee range of motion [13]. Fixation can be established using a small anchor such as 2.8 mm Q-Fix (Smith and Nephew) (Fig. 7). The graft is then sutured to the
Combined Medial Patellofemoral Ligament and Medial Patellotibial … Fig. 4 This figure depicts the medial capsule of the knee with the layer reflected medially Fig. 5 This image shows the anatomic placement of the patellar attachment of the medial patellofemoral ligament, between the proximal and middle thirst of the patella Fig. 6 The medial patellofemoral tunnel is drilled 1 cm directly lateral to the previously identified medial most patellar attachment 451
452 R. S. Dean et al. Fig. 7 This image demonstrates the anatomical location of the medial patellotibial ligament, just medial and proximal to the distal pole of the patella. A suture anchor is placed here for future fixation periosteum and back upon itself using a free needle for additional fixation (Fig. 8 and 9). It is easier to tension the graft in the patellar attachment. Therefore, the graft is fixed first on the tibia, passed deep to the retinaculum and then fixed in the patella. The final fixation and tension should be done with the knee in 90° of flexion. During fixation the surgeon should confirm that the tension through the MPTL is similar to that of the patellar tendon. This is important as to ensure that there isn’t excessive pressure on the medial compartment. The knee is then observed through complete range of motion as well as medial and lateral forces on the patella as to assess for the degree of translation [19]. Grantham et al. proposes a slight variation of the MPTL reconstruction aspect of the technique using their anatomic studies. They start by preparing a gracilis graft. From there, they establish the MPTL patellar attachment 9.1 mm proximal to the inferior pull with a suture anchor. Next, they identify the tibial attachment 5 mm distal to the joint line and 23 mm medial to the tibial tubercle. The allograft is then tensioned with the knee at 70° [22]. An additional non-anatomic technique was described by Maffulli et al. who utilizes a semitendinosus autograft to reconstruct both the MPFL and MPTL. The authors propose maintaining the native semitendinosus attachment site and passing the graft through two bone tunnels on the patella. The fixation is achieved by looping the graft around the adductor magnus tendon at 30° of flexion [37]. Concerns over this technique were raised by outside authors who questioned the specific distances of the patellar tunnels, the fixation method of the graft after being looped around the adductor magnus tendon, in addition to the non-anatomic location of the semitendinosus on the tibia compared to the attachment site of the MPTL [38]. Recently, Abdelrahman et al. reports on a combined MPFL and MPTL reconstruction in which the MPTL reconstruction is performed based upon a central approximation of the MPTL and the MPML. These authors reported that it is fundamental to identify the individual anatomic footprint of both the MPTL and the MPML in the tibia and the meniscus so that to place their reconstruction with hamstring autograft at the
Combined Medial Patellofemoral Ligament and Medial Patellotibial … Fig. 8 The graft is passed and both ends are fixed with the knee at 90° of flexion Fig. 9 In the patellar side the graft is sutured to the periosteum for additional fixation 453
454 R. S. Dean et al. Medial Patellotibial Ligament Reconstruction Techniques By Studies That Reported on Combined MPFL and MPTL Reconstruction Author Graft choice Fixation modality Fixation location Fixation angle Combined with MPFL (Y/N) Hughston [41] Direct repair (39/65) IT band autograft (12/65) Patellar Tendon autograft (12/65) Suture anchors vs bone tunnels N/A 60° Yes Drez [42] Semitendinosus, Gracilis or Fascia Lata Suture anchors “1.5 cm distal to the joint line” 0° flexion Yes Brown and Ahmad [43] Semitendonosis or Gracilis Bone tunnel with suture Pes Anserine 60° Yes Ebied [20] Semitendinosus or Gracilis Interference screws? N/A 30° Yes Giordano [44] Semitendinosus and gracilis Suture a nchors N/A 35–40° Yes Sobhy [45] Semitendinosus autograft Bone tunnels? N/A 45° Yes Hinckel [46] Patellar tendon autograft Suture anchor Tibial: 1.5–2.5 cm below the joint line and 15–25 mm medial to the patellar tendon 90° Yes Grantham [22] Gracilis allograft Suture anchors Patellar: 9.1 mm proximal to the inferior pole Tibial: 5 mm distal to joint and 23 mm medial to the tubercle 70° Yes Maffulli et al. [37] Semitendinosus autograft “looped around the AMT” Patella: bone bunnel, looped around the AML Tibia: native attachment site of the semitendinosus 30° Yes Abdelrahman [39] Semitendinosus autograft Suture anchor Tibia: the midway point in between the anatomic insertion of the patellotibial and patellomeniscal insertion 90° Yes midpoint between these distinct anatomic points. They also propose fixing the graft with the knee is at 90°, where they report the ligament is at maximal tension [39]. 5.5 MPML Repair Garth et al. reports on 2 MPML reconstruction techniques using either an open or arthroscopic technique [23]. The open procedure begins by creating a 3 cm incision approximately 1 cm medial from and parallel to the inferomedial margin of the patella. Careful dissection ensues down to the third layer of the capsule. The MPML fibers are identified and advanced proximally and laterally to the inferomedial border of the patella using suture augmentation. The sutures are then secured and the capsular layers of the MPML are closed. These authors also described an arthroscopic technique. The procedure begins with a diagnostic arthroscopy
Combined Medial Patellofemoral Ligament and Medial Patellotibial … followed by a debridement of <1 cm of fatty tissue in the gutter adjacent to the inferomedial patella. A PDS suture is then passed from the inferomedial periosteal border of the patella into the arthroscopic visual field. A second suture is passed through the MPML, approximately 1.5 cm distal and medial to the initial needle. After the suture is passed with the use of this initial needle placement a second set of needles was inserted in parallel to the initial set, approximately 10–15 mm more proximally, near the proximal margin of the MPML. A 10 mm incision is then made between the entrance and exit sites of the respective sutures. An extracapsular tract is created using a hemostat, deep to the subcutaneous tissue through each incision, extending to the site at which each suture exited the capsule. The hemostat is then used to pull them through the tract to exit the incision. The sutures are then tied down. In both the open and arthroscopic technique the authors note that by advancing the MPML 1 cm, they are able to prevent pathologic displacement of the central patellar ridge over the lateral trochlea without excessive restriction of the patella [23]. There is one known case report that describes isolated MPTL and MPML avulsion fractures without evidence of MPFL pathology. On exam, they stated that the patella rested in a subluxed position, but wouldn’t dislocate when the knee was in full extension but dislocated easily when the knee was flexed to 30°. They reported a successful repair using nonabsorbable transosseous sutures through the MPTL/MPML to the insertion on the patella to the medial/inferior patellar border [40]. 5.6 Post-operative Protocol Depending on concomitant pathology and/or additional surgeries, patients can be weightbearing as tolerated in a knee brace locked in extension immediately after surgery. Passively, patients can focus on early range of motion as tolerated, and they can also work on isometric quadriceps exercises [22, 39]. After 1–2 weeks patients can begin 455 kinetic closed chain strengthening programs. By 4–6 weeks post-operatively, patients are typically allowed to start progressive strengthening of muscles with ultimate return to full activity by approximately 12 weeks post-op [33]. 6 Outcomes 6.1 MPTL Repair/Reconstruction Without MPFL Hughston et al. reported on MPTL repair or reconstruction at mean 54-month follow-up and showed that 68% reported improvement in their functional levels and 75% reported subjective improvements. Eighty percent stated they had a good/excellent outcome and only 6/65 knees required a secondary surgery by the latest available follow-up [41]. Using a combination of open and arthroscopic techniques Zaffagini et al. reported encouraging clinical and radiographic results at 6.1 years following MPTL reconstructions. Eighty-three percent of knees were normal or nearly normal by IKDC scoring, and only 1 knee (3%) was found to have patellar osteoarthritis. They also reported that only 14% of patients suffered surgical failure, 7% had further dislocation and 7% required a revision surgery [33]. One study reported on outcomes following semitendinosus tenodesis in a pediatric population and found that at an average of 3.17 year follow-up, 88% of patients were asymptomatic, 5% developed recurrent subluxations and 5% had recurrent dislocations, while 14% complained of recurrent patellofemoral syndrome [31]. Similarly, in a study from 1972 that included 53 patients with mean 5 year follow-up, Baker et al. reported 3.8% of patients had re-dislocation and 9.4% underwent reoperation following MPTL reconstruction using a semitendinosus tenodesis. They also reported that 80.1% of patients reported good or excellent outcomes [30]. Conversely to these successful reports, Grannatt et al. reported a less optimistic longer-term follow-up study on 34 pediatric patients that underwent semitendinosus tenodesis. They reported 35% reoperation
456 secondary to instability, with 82% reporting recurrent subluxations or dislocations and 41% with an IKDC score of less than 70 [32]. Several other studies have reported successful outcomes with MPTL reconstruction using a patellar tendon transfer with lateral retinaculum release and vastus medialis advancement [34, 35, 47]. Myers et al. reported on 42 knees with minimum 2 year follow-up and reported that 76% had good or excellent results with 12% reporting poor results; two had recurrent dislocations [34]. Oliva et al. included 25 patients and 8 year follow-up with only 1 patient suffering a re-dislocation which occurred following a motor vehicle accident [35]. 6.2 MPTL with MPFL Reconstruction Ebied and Kholy was the first known study that reported outcomes following combined MPFL and MPTL reconstruction in 25 knees. They reported significant improvement in IKDC scores with no reports of subsequent dislocation events [20]. Additionally, Drez et al. published and early report of 15 patients with minimum 2-year follow-up after combined MPFL/MPTL reconstructions using either semitendinosis, gracilis or IT band autografts. They reported 93% had good or excellent outcomes, no rates of re-dislocation and high patient reported outcome scores [42]. Hetsroni et al. reported on outcomes of combined MPFL and MPTL reconstructions in 23 knees with a minimum of 2-year follow-up. They demonstrated significant improvements in Kujala score (86.4 vs 54.9), however activity scores were not consistently restored compared to preinjury levels [48]. Similarly, Sobhy et al. reported on 33 patients that underwent combined MPFL and MPTL reconstruction with semitendinosus autograft and reported improved pain scores (VAS 6.3 vs 1.8) and patient reported outcomes (Kujala score, 37 vs 91; Lysholm score, 52 vs 90) [45]. Recently, Hinckel et al. reported on 7 patients that underwent a combined MPTL and MPFL reconstruction and reported high rates of satisfaction with 100% of patients R. S. Dean et al. stating they would undergo the procedure again at a mean of 5.5 months post-operatively [46]. 6.3 MPTL with Concomitant Realignment Procedures Several studies reported on MPTL reconstruction with Roux-Goldthwait procedures [36, 49, 50]. Most recently, Niedzielski et al. included 11 patients at 8-year follow-up and had only 1 dislocation, with 10 having normal patellar tracking. Of note, this study reported a decrease in the maximum quadriceps muscle torque between 60 and 180° compared to the healthy contralateral limb [49]. Additionally. Joo et al. reported no redislocations and all patients with a Kujala score greater than 88 at 4.5-year follow-up [36]. Marcacci et al. performed a tibial tuberosity osteotomy in addition to MPTL reconstruction with a patellar tendon autograft. In their 18-person study with 5 year follow-up, they reported no re-disclocations with 83.3% of patients having IKDC A or B scores, and a mean Kujala score of 88.9% [51]. 6.4 Systematic Reviews Finally, Baumann et al. performed a systematic review of previous outcome studies describing MPTL reconstruction which included 403 knees from 19 studies. Their review included primarily studies that utilized hamstrings tenodesis (n = 9), medial transfers of the patellar tendon (n = 5), and combined MPFL and MPTL reconstructions using either hamstring autograft or allograft (n = 5). They showed that despite a variable degree of study qualities, most studies reported favorable patient reported outcomes with low rates of dislocation [52]. 7 Conclusions The distal medial patellar ligamentous complex (MPTL and MPML) are integral stabilizers of the patella. Additionally, they have a consistent
Combined Medial Patellofemoral Ligament and Medial Patellotibial … anatomical and biomechanical profile in preclinical studies. While typically performed in conjunction with MPFL reconstruction, there are several described surgical procedures designed to repair or reconstruct these structures which have demonstrated reproducible and encouraging outcomes. Understanding the anatomy and surgical options for managing distal medial patellar ligamentous complex injuries can offer a promising option for managing the complexities of lateral patellar instability in the at risk patient population. 8 Key Message While the long-term outcomes are scarcely described in the literature, the available data suggests that the addition of a medial patellotibial ligament reconstruction to a medial patellofemoral ligament reconstruction is effective at preventing subsequent dislocations or instability events in select high risk situations, while also providing pain and functional relief to a young and active patient population. References 1. Sanders TL, Pareek A, Hewett TE, Stuart MJ, Dahm DL, Krych AJ. Incidence of first-time lateral patellar dislocation: a 21-year population-based study. Sports Health. 2018;10(2):146–51. 2. Stefancin JJ, Parker RD. First-time traumatic patellar dislocation: a systematic review. Clin Orthop Relat Res. 2007;455:93–101. 3. Huntington LS, Webster KE, Devitt BM, Scanlon JP, Feller JA. Factors associated with an increased risk of recurrence after a first-time patellar dislocation: a systematic review and meta-analysis. Am J Sports Med. 2020;48(10):2552–62. 4. Askenberger M, Arendt EA, Ekström W, Voss U, Finnbogason T, Janarv PM. Medial patellofemoral ligament injuries in children with first-time lateral patellar dislocations: a magnetic resonance imaging and arthroscopic study. Am J Sports Med. 2016;44 (1):152–8. 5. Arendt EA, England K, Agel J, Tompkins MA. An analysis of knee anatomic imaging factors associated with primary lateral patellar dislocations. Knee Surg Sports Traumatol Arthrosc. 2017;25(10):3099–107. 457 6. Parikh SN, Lykissas MG, Gkiatas I. Predicting risk of recurrent patellar dislocation. Curr Rev Musculoskelet Med. 2018;11(2):253–60. 7. Hinckel BB, Gobbi RG, Kaleka CC, Camanho GL, Arendt EA. Medial patellotibial ligament and medial patellomeniscal ligament: anatomy, imaging, biomechanics, and clinical review. Knee Surg Sports Traumatol Arthrosc. 2018;26(3):685–96. 8. Salonen EE, Magga T, Sillanpää PJ, Kiekara T, Mäenpää H, Mattila VM. Traumatic patellar dislocation and cartilage injury: a follow-up study of longterm cartilage deterioration. Am J Sports Med. 2017;45(6):1376–82. 9. Stupay KL, Swart E, Shubin Stein BE. Widespread implementation of medial patellofemoral ligament reconstruction for recurrent patellar instability maintains functional outcomes at midterm to long-term follow-up while decreasing complication rates: a systematic review. Arthroscopy. 2015;31(7):1372–80. 10. Tanaka MJ, Chahla J, Farr J 2nd, LaPrade RF, Arendt EA, Sanchis-Alfonso V, et al. Correction to: recognition of evolving medial patellofemoral anatomy provides insight for reconstruction. Knee Surg Sports Traumatol Arthrosc. 2019;27(8):2551. 11. Slocum DB, Larson RL, James SL. Late reconstruction of ligamentous injuries of the medial compartment of the knee. Clin Orthop Relat Res. 1974;100:23–55. 12. Gali JC, Junior CA, Nogueira F, Yuri, Nakamichi, Santos NBd, et al., editors. Medial patellotibial ligament anatomy and histology. 2017. 13. Hinckel BB, Gobbi RG, Demange MK, Pereira CAM, Pécora JR, Natalino RJM, et al. Medial patellofemoral ligament, medial patellotibial ligament, and medial patellomeniscal ligament: anatomic, histologic, radiographic, and biomechanical study. Arthroscopy. 2017;33(10):1862–73. 14. LaPrade MD, Kallenbach SL, Aman ZS, Moatshe G, Storaci HW, Turnbull TL, et al. Biomechanical evaluation of the medial stabilizers of the patella. Am J Sports Med. 2018;46(7):1575–82. 15. Panagiotopoulos E, Strzelczyk P, Herrmann M, Scuderi G. Cadaveric study on static medial patellar stabilizers: the dynamizing role of the vastus medialis obliquus on medial patellofemoral ligament. Knee Surg Sports Traumatol Arthrosc. 2006;14(1):7–12. 16. Hautamaa PV, Fithian DC, Kaufman KR, Daniel DM, Pohlmeyer AM. Medial soft tissue restraints in lateral patellar instability and repair. Clin Orthop Relat Res. 1998;349:174–82. 17. Desio SM, Burks RT, Bachus KN. Soft tissue restraints to lateral patellar translation in the human knee. Am J Sports Med. 1998;26(1):59–65. 18. Conlan T, Garth WP, Lemons JE. Evaluation of the medial soft-tissue restraints of the extensor mechanism of the knee. J Bone Joint Surg Am. 1993;75 (5):682–93. 19. Hinckel BB, Gobbi RG, Demange MK, Bonadio MB, Pécora JR, Camanho GL. Combined reconstruction
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Warning: Lateral Retinacular Release Can Cause Medial Patellar Dislocation—Lateral Patellofemoral Ligament Reconstruction Robert A. Teitge 1 Historic Evolution of Diagnosis and Treatment It should be obvious that a joint will not dislocate without being acted upon by a dislocating force. An unstable and dislocatable joint when at rest often resides in a position of normal alignment and radiographs often show no subluxation and almost never dislocation. For me, it was perhaps hearing Losee et al. [1] describe the pivot shift and Slocum and Larson [2] describe Rotatory Instability of the Knee which made me appreciate such maneuvers provide the force required to displace the tibia from femur. Unfortunately, neither of these tests can be quantified. Beginning in 1980, I began seeing many referred patients with failed patellofemoral surgery. Examining medial and lateral displacement of the patella, later referred to as glide, was part of the examination, but it was obvious the neutral starting position could not be determined. It was the rule in the 1970’s at Los Angeles County General Hospital that no patient could have surgery for an unstable joint unless radiographs provided proof of dislocation. Stress radiographs when compared with the contralateral stable joint provided an opportunity to objectively measure R. A. Teitge (&) Wayne State University, Detroit, Michigan, USA e-mail: rteitge@med.wayne.edu the amount of instability. Likewise, any improvement resulting from surgery could also be quantified with stress radiographs. Stress radiography was the obvious solution to the problem of determining if an excess patellar displacement was medial or lateral. Many of these “failed” patients had had a lateral retinacular release as part of their surgery. Many were severely disabled much worse than before surgery. In many the PFJ was so sensitive with patients so apprehensive that meaningful examination was not possible. Routine PF radiographs were most often not revealing. 2 Stress Radiographs Stress radiographs proved to be the key to diagnosis. Trial and error led to a reliable technique. Using positioning for the standard Merchant axial view and an adjustable frame at the end of the x-ray table, radiographs were repeated with stress applied in both the medial and lateral direction of both knees. (Fig. 1). Since the height of the patella and patellar flexion is different in different patients, the angle of the x-ray beam to the table often needs adjustment so the beam is perpendicular to the tangent point of PF contact on the trochlea. Following the recommendation of Laurin et al. [3] we attempted to minimize knee flexion but were generally unable to obtain axial radiographs at less than 30° flexion. Initially I used my fingers gripping both sides of the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_30 461
462 R. A. Teitge A Fig. 1 Stress Radiographs A In clinic, the knee is extended to the maximum and still be able to obtain an axial view. The knee is supported on one side to prevent rotation while stress is applied to the opposite side of the patella B Patient positioning in the operating theater for stress radiographs C Medial stress being applied patella to apply the displacement force, before moving to a padded curved wooden block and later to a device produced for me by the Medmetric Corporation in San Diego. This Patella Pusher (Fig. 2) had a gauge to measure force so an equal force would be applied with each test. It was obvious that an absolute displacement value could not be used for all patients because of differences in generalized soft tissue laxity, trochlear geometry, and patellar height. Therefore, comparison with the asymptomatic side needed to be the reference. For those with bilateral symptomatic knees, the comparison meant little, but we felt confident the finding of complete dislocation represented instability. The presence of complete dislocation on the symptomatic side contrasted with minimal medial translation on the asymptomatic side was dramatic evidence of medial instability. (Fig. 3). It became clear that many patients worse after lateral release (LR) had patellae which would dislocate outside the trochlea with medial stress (Figs. 3 and 4). We then realized we had two groups of patients with medial dislocation. There were patients who had a lateral release for pain but not instability and those who had LR for instability. Those with LR for pain with medial dislocation on stress often had lateral displacements slightly greater than normal but would not dislocate laterally. Those with LR for lateral
Warning: Lateral Retinacular Release … 463 Fig. 2 Patella pusher instability would often dislocate in both the medial and lateral direction. These were referred to as multi-directional instability. It was also clear that patients with medial dislocation often were more anxious, depressed, afraid of being examined, and afraid of pain far in excess of the presentation of lateral instability patients. In 1987 I presented a scientific exhibit at the annual AAOS meeting. Jack Hughston was quite excited and spent considerable time studying the cases. In 1991 I presented at AAOS a case series of 68 patients all worse after LRR, all with increased medial excursion, all with medial excursion apprehension and all with a stress radiographs demonstrating a patella dislocated medially. The moderator requested I remove this paper from the program because he did not believe that radiographs showing medial patellar dislocation represented true pathology but rather represented an adequate and appropriate release and that stress radiographs were not a valid testing method.
464 R. A. Teitge A Fig. 3 Radiographs of a 40-year-old women who had a lateral release 1 year after a dashboard injury of the left knee sustained in a minor automobile accident. (A) static axial patellar view post-lateral release shows no pathology. B and C are medial stress radiographs taken 1 year after lateral release. (B) A complete medial patellar dislocation is obvious. Medial displacement on the left patella measures 40 mm from the Laurin reference line. (C) Medial displacement of the normal right patella measures 16 mm. The increase in medial displacement is 24 mm. D and E are lateral stress radiographs. (D) Lateral stress of the operated knee shows lateral patellar displacement of 15 mm and medial tilt of 44°. (E) Lateral stress of the normal patella shows lateral displacement of 10 mm and medial tilt of 26°. In this patient lateral release produced a pathologic increase in lateral displacement of 5 mm. and increased medial tilt of 18° In 1996 we reported [4] that stress radiographs were the only radiographic choice for the diagnosis of medial patellar instability (Figs. 3 and 4). No other measure of axial radiographs gave a hint of medial subluxation or dislocation. It was also the strongest test to diagnose lateral instability. In the control group the mean difference in lateral and medial displacement (glide) between the right and left normal knees was 1.3 and 1.2 mm respectively. In the lateral instability group the mean difference in lateral and medial displacement between the asymptomatic side and the symptomatic side was 7.5 and 0.2 mm. In the medial instability group the difference in lateral displacement between the symptomatic (L.R.) and asymptomatic side was 0.5 mm while the mean difference in medial displacement between the symptomatic (L.R.) and asymptomatic knees was 10.3 mm. In the multi-instability group the difference in lateral and medial displacement
Warning: Lateral Retinacular Release … Fig. 4 24 year old athlete post lateral release and lateral facet chondroplasty for anterior knee pain. Pain was unresolved and she underwent a second chondroplasty and lateral release. A CT arthrogram shows complete removal of lateral facet articular cartilage with intact between the asymptomatic and symptomatic side was 9.5 and 10.6 mm respectively. We calculated that the threshold for instability was 4 mm more excursion in the potential instability side compared with the asymptomatic side. The mean increase in medial displacement on the symptomatic side in patients with medial dislocation was 10.3 mm. The incidence of medial subluxation/dislocation is unknown because no studies measuring medial displacement increase after lateral release have been reported. Pagenstert et al. [5] made a most important observation that 36% of patients in a prospective randomized study of lateral release vs lateral retinacular lengthening demonstrated signs and symptoms of medial instability compared with none in the lateral lengthening group. I suspect, without evidence, medial stress radiographs would show an even higher incidence. 465 medial cartilage. B the patella was unstable enough to stay in the dislocated position for CT which shows complete medial dislocation and contact of the lateral facet with the medial trochlear edge 3 Lateral Patellofemoral Ligament Reconstruction Initially medial dislocation was treated with repair of the lateral retinacular defect. The defect often contained a very thin lax areolar tissue but careful dissection anterior and posterior to the defect often could identify stout tissue felt to represent the released retinacular edges. Direct repair was attempted. Over time, 6 months-3 years symptoms and increased laxity with increased medial displacement on stress radiographs began to appear frequently, perhaps in ½ of the cases, so I discontinued this secondary repair and realized ligament reconstruction was necessary. I am aware that there are many reports of successful secondary repair today, but my experience is that Lateral PatelloFemoral
466 Ligament Reconstruction (LPFLR) is unpredictable and often unreliable, even though the repairs at surgery look strong. The principles of ligament reconstruction are well known. Ligaments attach to bones with a unique and complex geometry which prevents excess displacement. Ligament reconstruction requires selection of an adequate graft, proper location of the graft, proper tension, adequate fixation and avoidance of local mechanical damage. There is much literature on each of these requirements. Adequate graft material requires a strength to withstand displacement forces, but also the laxity required to prevent overconstraint. Tendons used for grafting do not have the same materials property as ligaments but are stiffer. They do not have the same geometrical fiber arrangement. Thus, ligament reconstructions run a risk of over-constraint of patellar motion in some joint positions and excess laxity in others. The location of the graft on both the femur and patella should be such that changes in distance between these two attachment points does not change with knee flexion −extension. This so-called isometric location is a weak compensation for our lack of reproducing ligament geometry and normal ligament laxity. Isometers measure distances between points. Measurement of the change in length with knee motion allows estimating tension changes between points on the patella and femur. With the isometer placed into a 2.5 mm hole in the medial patella a k-wire with an attached string may be “walked” around potential attachment sites for graft attachment to the lateral femur. I have used since the mid 1980’s a “tension isometer” developed by Synthes. By using a constant pneumatic pressure, the piston applies a constant tension to the test string and length change can be read within 0.5 mm. Charles Henning, M.D. compared accuracy of this with various commercial isometers and concluded the pneumatic gave consistent almost perfect measurements as opposed to spring isometers. The graft will occupy an area larger than the isometric point and will typically migrate away from the isometric point to one side of a tunnel opening, so the graft tunnels need to be shifted behind the R. A. Teitge isometric points. Secure fixation of the graft which is not lost over time is essential. Mountney et al. [6] compared fixation of an MPFL graft fixation with suture repair of the ruptured ligament, and with the failure load of the intact ligament. Three fixation methods for a tendon graft included suturing the graft to the bone edges with suture anchors, interference screws anchoring grafts at the tunnel entrances, interference screws anchoring the graft on the lateral edge of tunnels after crossing the femur and patella. Normal MPFL ruptured at 208 N, ligament suture repair failed at 37 N as the suture cut through the ligament tissue, suture anchor fixation failed at 142 N usually by the anchors pulling out of the bone, interference screw (8 mm dia.) fixation at the entrance to tunnels failed at 126 N with the grafts pulling past the femoral screws, and passing the graft through the patella and femur and fixing on the lateral side with interference screws failed at 195 N with the grafts pulling past the screws. This study should be applicable to LPFL fixation. In 1982 I did the first LPFL reconstruction for a failed repair of a lateral retinacular release. I have followed this patient for 30 years. The patella has remained stable. The first series of reconstructions used a 1 cm square patellar bone block from the proximal edge of the patella and partial thickness quadriceps tendon graft (Figs. 5 and 6). The square bone block was countersunk into the lateral femoral condyle at the isometric point. Thin bone chisels cut a square recess into the femoral condyle and the patellar bone block was held in place with a lag screw. This allowed the quadriceps tendon to run straight from its bone block without bending over sharp corners. A transverse hole was placed across the upper 1/3 of the patella. Obviously and unfortunately removing a bone block from the upper 1 cm of the patella and placing a transverse tunnel at the same level created a stress riser and a few patellar fractures were not surprising. Additionally, a 1 cm wide quadriceps tendon graft was far larger than was probably necessary for a LPFL graft. Roger Torga-Spak’s [7] description of the technique reported that 60 of these operations had been performed before his 2004 publication.
Warning: Lateral Retinacular Release … 467 Fig. 5 Lateral patellofemoral ligament reconstruction. The technique is not important as long as the objectives outlined are met. Patellar bone quadriceps graft. The bone block was countersunk into the lateral femoral condyle at the isometric point, the quadriceps graft was passed through a transverse tunnel in the patella. Drawing of the isometer in the medial patella and the k-wire on the lateral epicondylar region. Drawing of the quadriceps graft attached to the lateral femur and then passed through the patellar tunnel and back onto the anterior surface of the patella Fig. 6 Left knee approach for lateral PF ligament reconstruction. To locate the isometric site on the lateral femoral epicondyle, the tip of a pneumatic driven piston isometer is inserted into a 2.5 mm drill hole in the medial patella; a #2 suture runs from the piston, through the transpatellar hole to a k-wire which is walked around the epicondyle until an isometric position or a position which allows the string to become 1-3 mm looser with flexion is located. The graft will be positioned immediately posterior to this isometric location Gradually I have shifted to hamstring allografts, largely because of the risk of patellar fracture and the complexity of countersinking a bone block with lag screw fixation. I have not studied the tension behavior of a double bundle graft. Obviously tension would be different in the two limbs I have not used ITB graft because of the observation reported in 1980 [8] that 53% of patients in which a portion of the ITB was used for a lateral extra-articular reconstruction of ACL
468 instability demonstrated medial tilting of the patella on post-op axial radiographs. Lateral PF Ligament Reconstruction is a salvage procedure to improve the complication of medial instability. It cannot be considered a cure for whatever reason the lateral release was supposed to improve. Since the lateral retinaculum does provide a resistance to lateral patellar displacement it was observed early that patients with lateral instability often noted improvement in their lateral instability with LPFL reconstruction. Results have held up and I am unaware of any recurrence of medial dislocation. Lag screws used for fixation often had to be removed because of the irritation to the overlying ITB. The clinical outcome cannot be assessed beyond the patients report of improvement because of the multiple variables of their underlying disease. Residual symptoms may arise from the original undiagnosed cause of pain or from an imbalance between medial and lateral retinacular tightness. It is generally impossible to diagnose this imbalance. As Pagenstert [5] reported the group difference between < 1 quadrant, 1−2 quadrants and 3 quadrants of medial glide was Kujala scores of 57.7, 90.3 and 75.3 (significantly different). This reflects the potential extreme sensitivity of retinacular imbalance. It must also be acknowledged the agreement between 5 examiners in the PatelloFemoral Study Group was only 11% for assessment of patellar glide and 8% for assessment of patellar tilt (kappa = 0.11 and 0.08) [9]. Clearly, assessment of retinacular tension balance R. A. Teitge is poor and the decision to improve balance with lateral release is likely a poor choice. Case examples shown in Figs. 3 and 4. References 1. Losee RE, Johnson TR, Southwick WO. Anterior subluxation of the lateral tibial plateau. A diagnostic test and operative repair. J Bone Joint Surg Am. 1978;60(8):1015−30. 2. Slocum DB, Larson RL. Pes anserinus transplantation. A surgical procedure for control of rotatory instability of the knee. J Bone Joint Surg Am. 1968;50(2): 226−42. 3. Laurin CA, et al. The abnormal lateral patellofemoral angle: a diagnostic roentgenographic sign of recurrent patellar subluxation. J Bone Joint Surg Am. 1978;60 (1):55–60. 4. Teitge RA, et al. Stress radiographs of the patellofemoral joint. J Bone Joint Surg Am. 1996;78(2):193– 203. 5. Pagenstert G, et al. Open lateral patellar retinacular lengthening versus open retinacular release in lateral patellar hypercompression syndrome: a prospective double-blinded comparative study on complications and outcome. Arthroscopy. 2012;28(6):788–97. 6. Mountney J, et al. Tensile strength of the medial patellofemoral ligament before and after repair or reconstruction. J Bone Joint Surg Br. 2005;87(1):36–40. 7. Teitge RA, Torga Spak R. Lateral patellofemoral ligament reconstruction. Arthroscopy. 2004;20(9): 998 −1002. 8. Teitge RA, et al. Iliotibial band transfer for anterolateral rotatory instability of the knee. Summary of 54 cases. Am J Sports Med. 1980; 8(4): 223−7. 9. Smith TO, et al. The intra- and inter-observer reliability of the physical examination methods used to assess patients with patellofemoral joint instability. Knee. 2012;19(4):404–10.
Reconstruction of the Lateral Patellofemoral Ligament David S. Zhu and Lutul D. Farrow 1 Introduction Reconstruction of the lateral patellofemoral ligament (LPFL) is primarily utilized for the treatment of medial subluxation and dislocation of the patella. Medial patellar instability is very rare and is classically considered to be iatrogenic, typically occurring following extensive lateral release when performed in the setting of patellofemoral instability and/or patellofemoral pain. Recently, primary medial instability has been recognized as a clinical entity that may warrant LPFL reconstruction. The lateral patellofemoral ligament is an important anatomic structure and has secondary role in stability of the patellofemoral joint, resisting lateral displacement of the patella. A tight LPFL has also been implicated as a contributor to increased patellofemoral contact pressures in the setting of patellofemoral pain Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/978-3-031-09767-6_31. D. S. Zhu L. D. Farrow (&) Cleveland Clinic Orthopaedic and Rheumatologic Institute, Cleveland, OH, USA e-mail: farrowl@ccf.org L. D. Farrow Cleveland Clinic Lerner College of Medicine, Cleveland Clinic Sports Health Center, 5555 Transportation Blvd, Garfield Heights, Ohio, USA and chondrosis [1, 2]. Over the past few decades several studies have helped to describe the function of the lateral patellofemoral ligament [3–5]. In a biomechanical study, Desio et al. demonstrated that the lateral retinaculum contributes ten percent of the total restraining force opposing lateral displacement of the patella [4]. Another biomechanics study demonstrated that while lateral release can decrease contact pressures on the lateral patellar facet of the patella, it also results in increased lateral tracking of the patella [5]. Finally, Bedi and Marzo showed that adding a lateral release following medial patellofemoral (MPFL) repair actually decreases the force necessary to laterally displace the patella when compared to the MPFL repair without lateral retinacular release [3]. These biomechanical studies helped to support the LPFL’s contribution to stability of the patellofemoral joint. Although it is now known that isolated lateral retinacular release is contraindicated in the treatment of patellar instability, the procedure has long been utilized as a standalone procedure for patellofemoral instability and also in conjunction with other procedures for patellofemoral instability such as tibial tubercle osteotomy and medial patellofemoral ligament reconstruction. The first description of lateral retinacular release in the English literature dates back to 1891 when Pollard described this technique for treatment of a patient with obligatory dislocation of the patella [6]. In this report, lateral retinacular release was utilized in conjunction with a medial retinacular © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_31 469
470 D. S. Zhu and L. D. Farrow reefing and trochleoplasty to successfully treat this condition [6]. Since this first report lateral retinacular release has been utilized for the treatment of patellar instability but became increasingly popular following a preliminary report on its use by Merchant and Mercer and subsequent positive reports on its use [7, 8]. Lateral release was touted as an effective, simple and less invasive procedure for the treatment of lateral patellofemoral instability. Chen and Ramanathan described a percutaneous approach to lateral retinacular lengthening that was felt to eliminate the need for larger open instability surgeries in most patients [7]. In addition to its use for the treatment of lateral patellar instability lateral release has also been utilized for the treatment of patellofemoral pain. In lateral patellar hypercompression syndrome (LHPS) patellofemoral pain was thought to be caused by a tight lateral retinaculum leading to patellofemoral joint overload, chondral degeneration and resultant pain [1, 2]. Being relatively quick and less technically demanding this procedure has been used by many for the treatment of patellofemoral instability and pain. Following the widespread adoption and use of this procedure in the 70’s and 80’s, Hughston and Deese provided the first report of medial patellar subluxation as a result of lateral retinacular release [9]. In their series, 50% of knees referred to the senior author with complications following lateral release were found to have developed medial subluxation [9]. This study demonstrated for the first time that overzealous lateral retinacular release can result in symptomatic medial subluxation of the patella. Following this initial report, several other authors have reported on complications following lateral retinacular release [10–12]. 2 Indications (Table 1) The primary indication for lateral patellofemoral ligament reconstruction is in cases of medial patellofemoral ligament instability, both primary and iatrogenic. Medial instability (subluxation and dislocation) of the patella has long been Table 1 Indications 1. Iatrogenic medial patellar instability following prior lateral release 2. Primary medial patellar instability 3. Refractory lateral parapatellar pain following prior lateral release 4. During revision patellofemoral stabilization following prior lateral release thought to be iatrogenic, only occurring following extensive release of the lateral patellofemoral ligament. Recently, primary medial instability of the patella has been described. Loeb et al. reported on a series of 6 patients with primary medial patellofemoral instability [13]. Of the 6 patients in this series only one patient required LPFL reconstruction [13]. Although medial patellar instability is uncommon, LPFL reconstruction can be important in management of patients with medial subluxation/dislocation. 3 Contraindications (Table 2) Lateral patellofemoral ligament reconstruction is contraindicated in cases with a competent lateral patellofemoral ligament and in cases without medial instability. Although rare, LPFL reconstruction should be avoided in cases of prior IT band surgery. Procedures utilizing IT band (i.e., physeal-sparing anterior cruciate ligament surgery in the skeletally immature patient) or excising IT band (lateral friction syndrome) might make it difficult or impossible to use the iliotibial band for LPFL reconstruction. In patients with end-stage patellofemoral Table 2 Contraindications 1. Intact and competent lateral patellofemoral ligament/lateral retinaculum 2. Absence of medial patellar instability 3. Prior IT band surgery (i.e. lateral friction syndrome, physeal-sparing ACLR, etc.) 4. End-stage patellofemoral osteoarthritis 5. Inflammatory arthropathy 6. Unmanaged complex regional pain syndrome
Reconstruction of the Lateral Patellofemoral Ligament 471 osteoarthritis or inflammatory arthropathy arthroplasty options should be considered rather than soft tissue stabilization techniques. anchor placement and graft healing. The trough should be placed at the mid-portion of the patella. The incision for the iliotibial band harvest is made along the lateral aspect of the thigh. This incision is started at the lateral epicondyle and taken proximally 7–8 cm. With mobilization of the subcutaneous tissues a smaller incision can be utilized. Sharp dissection is carried down to expose the iliotibial band. The subcutaneous are then lifted bluntly to allow for wide visualization of the iliotibial band. Next, the subcutaneous tissues at the level of the patella are tunneled proximally in order to form a subcutaneous tunnel between the anterior incision and the lateral incision for later passage of our graft. At this point in time a 10 mm wide 80 mm long strip of iliotibial band is created. (Fig. 1) The proximal strip is released sharply but the distal base is maintained. The free end of the graft is whipstitched with a #2 non-absorbable braided suture. A large, blunt forcep is then tunneled under the soft tissues just lateral to the patella and passed to the distal aspect of the opening in the iliotibial band. The tag sutures are then used to pull the strip of the iliotibial band anteriorly, bringing the graft perpendicularly under the iliotibial band. (Fig. 2) While suture fixation can be utilized to attach the iliotibial band strip to the lateral patella, we prefer suture anchor fixation. We utilize and all suture anchor placed into the groove we previously made at the mid-point of the patella. This anchor is placed at the hemisphere of the patella. Typically, only a single anchor is necessary for fixation. The knee is now placed over a bolster in order to position it at 20–30°. The patella is placed in the center of the groove and the suture from our suture anchor is passed in order to fix the iliotibial band strip to the lateral aspect of the patella. (Fig. 2) Any excess iliotibial band strip is then sutured to the anterior patellar periosteum with an absorbable #0 suture. Stability of the patella is then checked in full extension and at 30 degrees of flexion. The knee is taken through a full arc of motion to assess patellar tracking. The goal is 1 quadrant of medial glide of the patella and the patella should be able to be everted to neutral when the patella is centered over the trochlear groove with the 4 Procedure We perform the procedure under general anesthesia with a regional nerve block. The patient is positioned supine on an operative table with the contralateral extremity padded free from pressure. A non-sterile tourniquet is applied high on the thigh. If we are performing arthroscopy, a lateral stress post is utilized in order to aid with application of valgus stress when viewing the medial compartment. Some authors prefer the use of a leg holder. We prefer to position the operative leg free in order to allow full range of motion of both the hip and knee during surgery to better assess stability of the patellofemoral joint. Once positioning is complete, the entire lower extremity is prepped and draped. The limb is exsanguinated and the procedure is performed under tourniquet control. When addressing iatrogenic medial instability, preexisting incisions may dictate approach for reconstruction of the lateral patellofemoral ligament. In the absence of prior surgery and in most cases of revision surgery we utilize a two incision approach. The goal is to adequately visualize the mid-portion of the iliotibial band and also visualize the lateral border of the patella. We first utilize an anterior midline incision to expose the patella. This incision is typically 5–7 cm in length. This is taken down through the subcutaneous tissues until the prepatellar fascia is identified. The prepatellar fascia is then incised longitudinally and lifted laterally in order to expose the lateral retinaculum. In cases of extensive iatrogenic medial instability the lateral retinaculum may be completely absent and the joint may be open to the subcutaneous tissues. In most cases the lateral joint is covered by a sheet of scar tissue. The lateral patellar border is identified and a cautery knife is utilized to clear the lateral border of soft tissue. A small rongeur is then utilized to decorticate the lateral patellar border and create shallow trough to aid with
472 D. S. Zhu and L. D. Farrow Fig. 1 A 10 mm wide 80 mm long strip of iliotibial band is created. Reprinted with permission, Cleveland Clinic Foundation ©2022. All Rights Reserved knee in full extension. Lateral tilt of the patella is indicative of over tensioning and should be avoided. If happy with stability and patellar tracking the defect in the iliotibial band is then closed side to side with a running absorbable #0 suture. (Fig. 3) Closing this defect will help to further tension the iliotibial band reconstruction of the lateral patellofemoral ligament. At this time we will typically place the arthroscope back into the knee in order to confirm proper patellofemoral tracking through the range of motion, specifically confirming that there is not abnormal lateral tracking. At this point in time the tourniquet is deflated and meticulous hemostasis is obtained prior to closure. All wounds are closed in layers and the patient is placed into a sterile compressive bandage. We utilize a motion-control hinged knee brace. Disposable ice packs or a cryotherapy device is placed in the operating room. 5 Pearls and Pitfalls The greatest pearl with respect to management of the medial patellofemoral dislocator/subluxator is prevention. Lateral release should be avoided whenever possible in treatment of lateral patellar instability, especially in patients with underlying significant ligamentous laxity. When the lateral retinaculum is tight and in need of management, the surgeon should utilize lateral retinacular lengthening whenever possible. Lateral retincular lengthening helps to avoid symptomatic medial instability. Proper diagnosis is also of utmost importance. Apprehension with medial patellar glide is often seen with these patients. On occasion, a clunk can also be felt with this maneuver. This maneuver should be performed on all patients presenting with complaints of patellofemoral instability.
Reconstruction of the Lateral Patellofemoral Ligament 473 Fig. 2 The iliotibial band strip is passed under the anterior iliotibial band in order to fix it to the lateral aspect of the patella. Reprinted with permission, Cleveland Clinic Foundation ©2022. All Rights Reserved This procedure is fairly straightforward but taking an IT band strip which is too short could make it difficult or impossible to pass the strip to the lateral aspect of the patella. Generally a 60– 70 mm long strip (as measured from a plumb line at the level of the mid-patella) will be long enough to reconstruct the LPFL. Suture irritation in the IT band has been seen on occasion. Nonabsorbable sutures used to close the harvest defect can possibly rub on the lateral condyle and cause pain from friction. Alternatively, thinner patients may feel the suture in the IT band. In order to prevent this I utilize an absorbable #0 suture to close the IT band defect. We have seen no complications with this approach. 6 Postoperative Rehabilitation Following surgery, the patient is touch-down weight-bearing until seen by the Physical Therapist. Once properly instructed, the patient may progress to weight-bearing as tolerated with the brace locked in full extension. Once the patient is confident with ambulation while the brace is unlocked he/she may progress off crutches. When non-weight-bearing the brace may be unlocked and motion is allowed. For the first 4 weeks following surgery, the patient is allowed motion from 0 to 90°. After 4 weeks, range of motion can be progressed as tolerated. The brace
474 D. S. Zhu and L. D. Farrow Fig. 3 The defect in the iliotibial band is closed side to side. Reprinted with permission, Cleveland Clinic Foundation ©2022. All Rights Reserved may be unlocked for weight bearing at 4 weeks post-surgery if quadriceps function and gait mechanics allow. The brace is discontinued at 6 weeks post-surgery. Expectations are that patients may begin a running program at 3 months post-surgery. Return to sport may commence as soon as 4 months post-surgery if pain and effusion has resolved, range of motion has fully returned and when the patient has met return to play criteria as determined by the Physical Therapist. 7 Outcomes Due to the rare occurrence of medial patellar instability there have not been many large studies evaluating outcomes following lateral patellofemoral ligament reconstruction. Most of the evidence describing lateral techniques to address medial patellar instability exists as isolated case reports or case series [13–21]. One of the first studies evaluating outcomes came from Hughston et al. who evaluated direct repair or reconstruction of the LPFL in 63 patients with symptomatic patellofemoral instability [9]. At final follow-up 80% of patients reported good to excellent results and 6 knees required additional surgery due to failure to improve [9]. The authors found this technique was effective in relieving painful medial subluxation of the patella [9]. In addition to improved functional status following LPFL reconstruction, Sanchis-Alfonso et al. also evaluated resolution of psychological variables following reconstruction [18]. As mentioned previously, patients with medial subluxation of the patella following overzealous lateral release can present not only with apprehension and instability but also patellofemoral pain. In the study by Sanchis-Alfonso et al. 24%
Reconstruction of the Lateral Patellofemoral Ligament 475 of patients had signs of depression, 59% had anxiety, 41% exhibited catastrophizing with respect to patellofemoral pain and 100% exhibited kinesiophobia [18]. Following LPFL reconstruction depression, anxiety and catastrophizing was completely resolved in this cohort and only 53% experienced kinesiophobia [18]. This study outlined the importance of LPFL reconstruction not only for relieving painful medial subluxation but also for improving psychological findings in these patients. Our own greater than 10-year anecdotal experience with lateral patellofemoral ligament reconstruction mirrors the clinical outcomes discussed above. Careful diagnosis is critical to insure that medial subluxation is the true cause of patient symptoms. When present, medial patellar instability can be quite unsettling and even mentally and physically debilitating for the patient. Lateral patellofemoral ligament reconstruction is a simple yet extremely effective procedure for correction of medial patellar instability, both iatrogenic and primary. Owing to the large width of the iliotibial band, when proper surgical technique is utilized, there is low risk for morbidity with this technique. Lateral patellofemoral ligament reconstruction should be in the armamentarium of any surgeon routinely managing patients with complex patellofemoral pathology. 5. Ostermeier S, Holst M, Hurschler C, Windhagen H, Stukenborg-Colsman C. Dynamic measurement of patellofemoral kinematics and contact pressure after lateral retinacular release: an in vitro study. Knee Surg Sports Traumatol Arthrosc. 2007;15(5):547–54. https://doi.org/10.1007/s00167-006-0261-0 Epub 2007 Jan 16 PMID: 17225178. 6. Pollard B. Old dislocation of patella by intra-articular operation. Lancet. 1891;30(2):1203–4. 7. Chen SC, Ramanathan EB. The treatment of patellar instability by lateral release. J Bone Joint Surg Br. 1984;66(3):344–8. https://doi.org/10.1302/0301620X.66B3.6725343 PMID: 6725343. 8. Merchant AC, Mercer RL. Lateral release of the patella. A preliminary report. Clin Orthop Relat Res. 1974;(103):40–5. https://doi.org/10.1097/00003086197409000-00027. PMID: 4414065. 9. Hughston JC, Deese M. Medial subluxation of the patella as a complication of lateral retinacular release. Am J Sports Med. 1988;16(4):383–8. https://doi.org/ 10.1177/036354658801600413. PMID: 3189663. 10. Jackson RW, Kunkel SS, Taylor GJ. Lateral retinacular release for patellofemoral pain in the older patient. Arthroscopy. 1991;7(3):283–6. https://doi.org/10. 1016/0749-8063(91)90128-k PMID: 1750937. 11. Kolowich PA, Paulos LE, Rosenberg TD, Farnsworth S. Lateral release of the patella: indications and contraindications. Am J Sports Med. 1990;18(4):359–65. https://doi.org/10.1177/036354 659001800405. PMID: 2403183. 12. Miller PR, Klein RM, Teitge RA. Medial dislocation of the patella. Skeletal Radiol. 1991;20(6):429–31. https://doi.org/10.1007/BF00191085 PMID: 1925 675. 13. Loeb AE, Farr J, Parikh SN, Cosgarea AJ. Noniatrogenic medial patellar dislocations: case series and international patellofemoral study group experience Orthop J Sports Med. 2021;9(2):2325967120985530. https://doi.org/10.1177/2325967120985530. PMID:33748301;PMCID:PMC7938389. 14. Ahmad CS, Sinicropi SM, Su B, Puffinbarger WR. Congenital medial dislocation of the patella. Orthopedics. 2003;26(2):189–90. https://doi.org/10.3928/ 0147-7447-20030201-25 PMID: 12597226. 15. Johnson DP, Wakeley C. Reconstruction of the lateral patellar retinaculum following lateral release: a case report. Knee Surg Sports Traumatol Arthrosc. 2002;10(6):361–3. https://doi.org/10.1007/s00167002-0309-8 Epub 2002 Sep 11 PMID: 12444515. 16. Nonweiler DE, DeLee JC. The diagnosis and treatment of medial subluxation of the patella after lateral retinacular release. Am J Sports Med. 1994;22 (5):680–6. https://doi.org/10.1177/0363546594022 00517. PMID: 7810793. 17. Richman NM, Scheller AD Jr. Medial subluxation of the patella without previous lateral retinacular release. Orthopedics. 1998;21(7):810–3. https://doi.org/10. 3928/0147-7447-19980701-12 PMID: 9672920. References 1. Johnson RP. Lateral facet syndrome of the patella. Lateral restraint analysis and use of lateral resection. Clin Orthop Relat Res. 1989;148–58. PMID: 2910595. 2. Krompinger WJ, Fulkerson JP. Lateral retinacular release for intractable lateral retinacular pain. Clin Orthop Relat Res. 1983;179:191–3 PMID: 6617015. 3. Bedi H, Marzo J. The biomechanics of medial patellofemoral ligament repair followed by lateral retinacular release. Am J Sports Med. 2010;38 (7):1462–7. https://doi.org/10.1177/0363546510373 581. PMID:20601605.(B,1891). 4. Desio SM, Burks RT, Bachus KN. Soft tissue restraints to lateral patellar translation in the human knee. Am J Sports Med. 1998;26(1):59–65. https:// doi.org/10.1177/03635465980260012701. PMID: 9474403.
476 18. Sanchis-Alfonso V, Montesinos-Berry E, Monllau JC, Merchant AC. Results of isolated lateral retinacular reconstruction for iatrogenic medial patellar instability. Arthroscopy. 2015;31(3):422–7. https://doi.org/10.1016/j.arthro.2014.09.005 Epub 2014 Nov 4 PMID: 25450418. 19. Yazdi H, Monshizadeh S, Bozorgi Z. Congenital medial dislocation of the patella with multiple congenital anomalies: case report and method of treatment. J Pediatr Orthop B. 2014;23(2):126–9. https://doi.org/10.1097/BPB.0b013e32836330c6 PMID: 24296651. D. S. Zhu and L. D. Farrow 20. Saper MG, Shneider DA. Medial patellar subluxation without previous lateral release: a case report. J Pediatr Orthop B. 2014;23(4):350–3. https://doi. org/10.1097/BPB.0000000000000054 PMID: 247 55851. 21. Akşahin E, Yumrukçal F, Yüksel HY, Doğruyol D, Celebi L. Role of pathophysiology of patellofemoral instability in the treatment of spontaneous medial patellofemoral subluxation: a case report. J Med Case Rep. 2010;22(4):148. https://doi.org/10.1186/17521947-4-148. PMID:20492715;PMCID:PMC28 83992.
Patellar Tendon Imbrication Ronak M. Patel, Sneh Patel, and Jack Andrish 1 Introduction Lateral patellar dislocations are not uncommon, with a reported incidence of 30 to 43 per 100,000 [1]. Furthermore, the recurrence rate of patellar dislocations is reported to be 20 to 80% [1–4]. An increasingly common surgery used to treat patellofemoral instability is a medial patellofemoral ligament (MPFL) reconstruction [5–7]. Patel et al. analyzed the ABOS Part II database and reported that the number of MPFL reconstructions performed increased an average of 3% annually from 2003–2017 [8]. However, in their systematic review, Shah et al. reported a complication rate of 26.1% for MPFL reconstructions [5]. The increased percentage of MPFL reconstructions and relatively high complication rate highlight the need to evaluate for other anatomic risk factors for recurrent patellar instability. R. M. Patel (&) Illinois Center for Orthopaedic Research and Education, 550 W. Ogden Ave, Hinsdale, IL 60521, USA e-mail: r-patel7@md.northwestern.edu S. Patel University of Illinois College of Medicine at Chicago, Chicago, IL, USA J. Andrish The Cleveland Clinic Foundation, Cleveland, OH, USA One of the most common risk factors for recurrent patellar instability is patella alta. Review of radiographic findings in patients with recurrent patellar instability found patella alta to be one of the most common underlying pathoanatomic findings related to the recurrence of patellar disclocations [9]. The exact definition of patella alta has been up to debate but recently the patellar articular surface contact with the articular surface of the trochlea has been used to relate normal vs abnormal patellar tendon lengths [10]. In patella alta, the increased distance between the patella and the trochlea leads to delayed engagement of the patella and trochlea during flexion, which has been associated with increased patellofemoral contact forces and greater vulnerability to patellar dislocation [11–14]. A common approach to surgically correcting patella alta is to perform a tibial tuberosity osteotomy with a distalization [15]. However, a tibial tuberosity osteotomy cannot be performed in a skeletally immature patient because of the presence of the open tibial tuberosity apophysis. Additionally, tibial tuberosity osteotomy has been associated with problems of delayed union and non-union and hardware irritation and damage [16, 17]. A novel method to treat patella alta was described in 2007 by the senior author, and it involves shortening the patellar tendon via imbrication [18]. Since the imbrication procedure does not involve the tibial tuberosity, it can be used in skeletally immature and mature patients. This chapter discusses the surgical technique for © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_32 477
478 R. M. Patel et al. the imbrication procedure in the treatment of patella alta as well as recent results from a radiographic study. 2 Surgical Indications Patella alta is typically measured via a validated height index, including Blackburne-Peele, InsallSalvati, and Caton Deschamps ratios. Patients who present with radiographically confirmed patella alta and recurrent patellar dislocations are candidates for the imbrication procedure [10, 19–22]. Since the pathoanatomies are usually multifactorial, the procedure often includes other patellar stabilization techniques including MPFL reconstruction vs medial retinacular imbrication and lateral lengthening. Furthermore, if medialization of the tibial tuberosity is needed, the imbrication can be combined with a Trillat osteotomy of the tibial tuberosity, instead of performing a distalmedial transfer of the tuberosity [23]. The imbrication procedure can also be used for management of anterior knee pain in a patient with patella alta and patella chondrosis that involves the distal articular surface. This procedure allows the load to be transferred to the more proximal articular cartilage, which will result in the lessening of contact stresses due to a broader distribution of the load. 3 Surgical Technique The amount of shortening of the patellar tendon is first determined by creating a patella tendon length that will normalize the Insall-Salvati (IS) Index. An IS ratio of 1:1 is the intended goal of the imbrication procedure. An exception to this method is when the patella has a long nonarticular nose. In this case, the amount of shortening is determined by normalizing the modified IS index or the Canton-Deschamps Index. If a MPFL reconstruction needs to be completed, perform the imbrication technique before the MPFL reconstruction. However, if a medialization osteotomy of the tibial tuberosity is required, perform the osteotomy before performing the imbrication technique. A video of the imbrication procedure is provided in Yalcin et al. [24]. The surgical technique (Fig. 1) is described below. Step 1: The amount of shortening is determined preoperatively through radiographic measurements and marked with a marking pen (a). A third line is drawn proximally to the dissection that is one-half the distance of the patella tendon shortening (b = 1/2a). Step 2: At the location of the distal marking, the anterior half of the tendon is elevated by sharp dissection using a fresh No. 15 blade proximal to the predetermined level. The dissection follows the parallel fibers of the tendon. Throughout the dissection, it is important to stay uniform in thickness. Step 3: After detaching the infra-patella fat pad from the posterior aspect of the patella tendon, three #1 PDS are placed from the proximal marking and passed deep to the tendon and brought midway through the dissected portion of the tendon. After a locking stitch has been made, the sutures are again passed deep to the tendon and returned to the original entry site and left untied. These sutures will be used to fasten the redundant flap on the posterior side that results from the imbrication. Step 4: Three #2 FiberWire (Arthrex, Naples, FL) sutures are placed at the proximal apex of the flap created in Step 2 and passed through the flap and secured to the original start of the dissection. Locking stitches are made distally and returned to the original entry site. Step 5: The FiberWire sutures are tied, and it is sometimes helpful to distract the patella distally as the sutures are tied to facilitate the imbrication.
Patellar Tendon Imbrication Step 6: The sutures placed in Step 3 are tied, which imbricates the redundant posterior side of the tendon. The distal end of the anterior section of the tendon is repaired in a pants-over-vest fashion using #0 absorbable sutures. Step 7: The knee is flexed to 90° to assess for competence of the sutures. Additionally, the flexion is used to assess for the need for a quadriceps lengthening in cases of severe patella alta or fixed congenital lateral patellar dislocation. Full flexion is usually obtained after rehabilitation. 4 Postoperative Care The initial phase of the postoperative care involves a motion-control brace set at zero to 30 degrees of flexion and touchdown nonweightbearing is allowed. Starting at 2–3 weeks after surgery, flexion is increased in the brace by 10–20° per week until week 6. At 6 weeks, the brace can be completely removed. If full weightbearing is needed prior to 6 weeks after surgery, the brace can be locked in 0° of extension during ambulation. Starting at 3 weeks, the brace can be removed to perform heel-slide range of motion exercises. However, except for performing the exercises, the brace should be worn full time when ambulating or sleeping. Patients are encouraged to perform hourly repetitions of quadriceps isometric exercises as well as focus on ‘pelvifemoral’ conditioning and core stability. After 6 weeks, weightbearing can be increased gradually and patients can be slowly weaned off of crutches. Closed chain resistance exercises can also be started around this time. However, open chain resistance exercises are deferred until 4 months. Full weightbearing is usually achieved by 8–12 weeks. Return to full rehabilitation and sport level activity generally is seen after 6 months but can vary depending on factors such as age and elimination of strength deficits. 479 5 Discussion Patellar instability is not uncommon in the skeletally immature population. The rate of patellar dislocation was found to be 29% to 43% in the age range of 10 to 17 years [1, 3, 4]. These patellar dislocations have been highly associated with patella alta. However, the most common procedure to treat patella alta is a tibial tuberosity osteotomy with distalization, and this procedure cannot be performed on this patient population due to an open apophysis. Because of this issue, the senior author developed the imbrication method to correct patella alta in skeletally immature patients that has now been expanded to adults. A recent study conducted by Patel et al. assessed the postoperative radiographic results of the imbrication procedure [25]. The study evaluated 27 patients (32 knees) with a mean age of 19.8 years (range, 12–35 years) and a mean follow-up of 4.1 years (range, 2–8.25 years). The mean patellar length preoperatively was 6.1 cm (range, 5.0–8.0 cm). The mean patellar length 3 weeks and a minimum of 2 years postoperatively was 5.1 cm (range, 3.4–8.0 cm) and 5.2 cm (range, 3.7–7.1 cm), respectively. On average there was no significant loss of the corrected length of the patellar tendon postoperatively at a minimum of 2 years. Additionally, the complications involved in this procedure were minimal. Parvaresh et al. also described an imbrication technique that was similar to one described in this chapter [26]. However, the paper did not assess the clinical outcomes of their technique. In conclusion, the patellar tendon imbrication is a viable and effective technique in treating patella alta with recurring patellar instability in skeletally immature and mature patients.
480 R. M. Patel et al. Fig. 1 Stepwise patellar tendon imbrication procedure. See text for details. Adapted from Andrish [18]. Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography ©2022. All Rights Reserved Take Home Messages • Patella alta is a common underlying cause of recurrent patellar instability • Tibial tuberosity osteotomy has been historically performed to correct patella alta, but this procedure cannot be used on skeletally immature patients due to an open apophysis • Patellar tendon imbrication can be performed on skeletally immature and mature patients to correct patella alta • Careful dissection of the patellar tendon at 50% depth throughout ensures appropriate integrity • Performing locking stitches prevents migration of the imbrication/reduction • A clinical study evaluating patellar tendon imbrication demonstrated that there was no significant loss of the corrected length of the patellar tendon after a minimum of 2 years postoperatively Key Message: In both skeletally immature and mature patients, patellar tendon imbrication is an effective procedure in treating patella alta with recurring patellar instability References 1. Fithian DC, Paxton EW, Stone ML, Silva P, Davis DK, Elias DA, et al. Epidemiology and natural history of acute patellar dislocation. Am J Sports Med. 2004;32(5):1114–21. 2. Amin NH, Lynch TS, Patel RM, Patel N, Saluan P. Medial patellofemoral ligament reconstruction. JBJS Rev. 2015;3(7):1–9. 3. Atkin DM, Fithian DC, Marangi KS, Stone ML, Dobson BE, Mendelsohn C. Characteristics of patients with primary acute lateral patellar dislocation and their recovery within the first 6 months of injury. Am J Sports Med. 2000;28(4):472–9. 4. Quirbach S, Smekal V, Rosenberger RE, El Attal R. Scho¨ ttle PB. Anatomical double-bundle reconstruction of the medial patellofemoral ligament with a gracilis autograft [in German]. Oper Orthop Traumatol. 2012;24:131–9. 5. Shah JN, Howard JS, Flanigan DC, Brophy RH, Carey JL, Lattermann C. A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med. 2012;40:1916–23. 6. Gao G, Liu P, Xu Y. Treatment of patellar dislocation with arthroscopic medial patellofemoral ligament reconstruction using gracilis tendon autograft and modified double-patellar tunnel technique: Minimum 5-year patient-reported outcomes. J Orthopaed Surg Res. 2020;15(1). https://doi.org/10.1186/ s13018-020-1556-4. 7. McNeilan RJ, Everhart JS, Mescher PK, Abouljoud M, Magnussen RA, Flanigan DC. Graft choice in isolated medial patellofemoral ligament reconstruction: a systematic review with metaanalysis of rates of recurrent instability and patientreported outcomes for autograft, allograft, and synthetic options. Arthroscopy. 2018;34:1340–54. 8. Chilelli B, Patel R, Bhatia S, Das V. Surgical trends and reported complications of medial patellofemoral
Patellar Tendon Imbrication 9. 10. 11. 12. 13. 14. 15. 16. ligament reconstruction among board eligible orthopaedic surgeons: analysis of data over a 15 year period. Am J Sports Med. Forthcoming. Dejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994;2:19–26. Biedert RM, Albrecht S. The patellotrochlear index: a new index for assessing patellar height. Knee Surg Sports Traumatol Arthrosc. 2006;14:707–12. https:// doi.org/10.1007/s00167-005-0015-4. Luyckx T, Didden K, Vandenneucker H, Labey L, Innocenti B, Bellemans J. Is there a biomechanical explanation for anterior knee pain in patients with patella alta? Influence of patellar height on patellofemoral contact force, contact area and contact pressure. J Bone Joint Surg Br. 2009;91:344–50. Singerman R, Davy DT, Goldberg VM. Effects of patella alta and patella infera on patellofemoral contact forces. J Biomech. 1994;27:1059–65. Stefanik JJ, Zhu Y, Zumwalt AC, et al. Association between patella alta and the prevalence and worsening of structural features of patellofemoral joint osteoarthritis: the multicenter osteoarthritis study. Arthritis Care Res. 2010;62:1258–65. Ward SR, Terk MR, Powers CM. Patella alta: association with patellofemoral alignment and changes in contact area during weight-bearing. J Bone Joint Surg Am. 2007;89:1749–55. Mayer C, Magnussen RA, Servien E, Demey G, Jacobi M, Neyret P, et al. Patellar tendon tenodesis in association with tibial tubercle distalization for the treatment of episodic patellar dislocation with patella alta. Am J Sports Med. 2012;40:346–51. https://doi. org/10.1177/0363546511427117. Payne J, Rimmke N, Schmitt LC, Flanigan DC, Magnussen RA. The incidence of complications of tibial tubercle osteotomy: a systematic review. Arthroscopy. 2015;31:1819–25. https://doi.org/10. 1016/j.arthro.2015.03.028. 481 17. Sherman SL. Tibial tubercle osteotomy that includes distalization has higher reoperation and revision rates. Healio Medblog; 2018. https://www.healio. com/news/blogs/%7Bd0aa44d3-00d3-4b42-beef660d11561766%7D/patellofemoral-update/blogtibial-tubercle-osteotomy-that-includesdistalizationhas-higher-reoperation-and-revision-rates. 18. Andrish J. Surgical options for patellar stabilization in the skeletally immature patient. Sports Med Arthrosc Rev. 2007;15(2):82–8. https://doi.org/10. 1097/jsa.0b013e31805752d0. 19. Neyret P, Robinson AHN, Le Coultre B, Lapra C, Chambat P. Patellar tendon length—the factor in patellar instability? Knee. 2002;9:3–6. 20. Caton J, Deschamps G, Chambat P, Lerat JL, Dejour H. Patella infera. Apropos of 128 cases. Rev Chir Orthop Reparatrice Appar Mot. 1982;68:317–25. 21. Blackburne JS, Peel TE. A new method of measuring patellar height. J Bone Joint Surg Br. 1977;59:241–2. 22. Insall J, Salvati E. Patella position in the normal knee joint. Radiology. 1971;101:101–4. https://doi.org/10. 1148/101.1.101. 23. Andrish J. Patellar tendon shortening. In: Dejour D, Zaffagnini S, Arendt E, Sillanpää P, Dirisamer F, editors. Patellofemoral pain, instability, and arthritis. 2nd ed. Springer; 2020. p. 551–6. 24. Yalcin S, Patel RM, Andrish J, Farrow LD. Patellar tendon imbrication. Video J Sports Med. 2021;1 (3):263502542110066. https://doi.org/10.1177/ 26350254211006699. 25. Patel RM, Gombosh M, Polster J, Andrish J. Patellar tendon imbrication is a safe and efficacious technique to shorten the patellar tendon in patients with patella alta. Orthop J Sports Med. 2020;8 (10):232596712095931. https://doi.org/10.1177/ 2325967120959318. 26. Parvaresh KC, Huddleston HP, Yanke AB. Patellar tendon shortening for treatment of patella alta in skeletally immature patients with patellar instability. Arthrosc Techniq. 2021;10(8). https://doi.org/10. 1016/j.eats.2021.04.025.
Quadricepsplasty Jason Koh 1 Introduction Quadricepsplasty in the context of anterior knee pain and instability is primarily required in patients with congenital or obligate patella dislocation who have a tight or excessively contracted extensor mechanism [1]. In these patients in order to obtain knee flexion, the contracted extensor mechanism will seek the shortest distance between the femoral attachment and the tibial tubercle, and the patella dislocates laterally rather than remaining on the trochlea (Fig. 1) [2, 3]. Treating these instability patients without recognition and treatment of these contractures will lead to either loss of motion, recurrent dislocation, or both [3–5]. In severe cases, quadricepsplasty to lengthen the tight extensor mechanism is required to successfully maintain patella stability [6, 7]. Quadricepsplasty may be also required for such conditions such as congenital dislocation of the knee [2], arthrogryposis [2], and congenital or acquired arthrofibrosis or quadriceps scarring [8–10]. Historically, a number of procedures such as the Thompson [11] or Judet [12] quadricep- J. Koh (&) Department of Orthopaedic Surgery, NorthShore University HealthSystem, Skokie, IL, USA e-mail: drjasonkoh@gmail.com splasty have been described for the treatment of acquired quadriceps contractures. Typically these have been related to quadriceps contracture or adhesions that can occur after trauma [13], but with the changes in management of femur fractures with internal fixation and rapid mobilization this has become less commonly required. When these types of more extensive quadricepsplasties need to be performed it is more commonly in those patients who have prolonged use of external fixation and/or immobilization [14]. Key to those procedures are the progressive release of intra- and extra-articular adhesions, resection of fibrous tissue and scar, and sometimes resection or release of fibrotic or contracted muscle [14, 15]. The results are typically successful in achieving improvement of range of motion, but these extensive procedures may have a relatively high complication rate and a significant rate of residual quadriceps weakness [2, 9, 13, 16]. In the context of obligate dislocation in flexion, these types of extensive procedures are not usually necessary. Several authors have proposed either Z step cut lengthening [6, 7, 18] or V–Y lengthening [18, 19] of the quadriceps tendon to allow increased excursion. These reports have been very small series or case reports in patients with significant congenital dislocations and often syndromic conditions. The patients have typically improved range of motion but there have been a relatively significant number of complications, residual quadriceps weakness or recurrences. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_33 483
484 J. Koh Fig. 1 Contracted and laterally displaced extensor mechanism resulting in patella dislocation in flexion. (Reproduction with permission from the Cleveland Clinic Foundation) [1] In these patients the lateral structures are tight and contracted, and the quadriceps tendon is usually shortened. Conversely, the medial structures, including the vastus medialis obliquus and the medial retinacular tissues are often deficient and stretched out from being pulled over the distal femur [1, 20]. The pathophysiologic combination of these factors guides the recommendations for treatment of these patients. Medial structures are to be preserved and reinforced; while lateral structures (including potentially the iliotibial band) are to be lengthened appropriately. 2 Evaluation The evaluation of the patient should consist of several components. Importantly, it should be identified if these patients are symptomatic. Some patients with congenital or obligate patella dislocation have good knee function for daily activity [21], and are able to walk, work, and perform household functions with little or no pain [21, 22]. It is not uncommon for these patients to appear to have some syndromic appearance or abnormality [23–25], which can be associated with cognitive impairment. Understanding patient functional goals and symptoms is important, along with an evaluation of the potential impact and risks of a major surgical procedure and ability to comply with a fairly demanding postoperative regimen. A careful assessment of the alignment is also critical. Obligate dislocation may be in part related to valgus malalignment, tibial tubercle malalignment, or rotational malalignment of the femur and/or tibia. As part of the physical examination there should be evaluation of limb alignment and rotation, including extended and seated Q angle, foot progression angle and hip rotation. Radiographic assessment should include long leg standing alignment films and a true lateral to assess patella height and trochlear dysplasia. If there is concern from the physical examination, axial CT imaging is helpful to assess femoral and tibial version as well as tibial tubercle to trochlear groove distance. These patients often have trochlear dysplasia and hypoplastic femoral condyles [25]. Significant bony malalignment will need to be addressed, and in some cases appropriate osteotomy may confer significant stability and obviate the need for quadricepsplasty [26]. Additional components of the physical examination should include assessment of patella tracking, evaluation of the ability of the patella to maintain stability through the range of motion, lateral tightness, apprehension, crepitus, tenderness and effusion. The quadriceps should be inspected for atrophy and orientation. MRI imaging is often helpful in evaluating soft tissues and cartilage. The medial structures are often deficient, and the medial patellofemoral ligament (MPFL) if present is often attenuated. MRI can provide an alternative method of evaluating TT-TG and trochlear dysplasia.
Quadricepsplasty 485 Table 1 Indications 1. 2. 3. 4. 5. 3 Contracture of extensor mechanism resulting in obligate lateral patella dislocation and poor function Congenital dislocation of the patella Given “normal” alignment, failure of lateral lengthening to permit relocation of patella Arthrofibrosis/arthrogryposis with quadriceps contracture Significant patella alta requiring distalization that would result in loss of knee flexion Indications The primary indication for quadricepsplasty is significant lateral side and extensor mechanism tightness that prevents the patella from being [1] located with the knee in flexion. Medial patellofemoral ligament reconstruction and lateral lengthening are often sufficient for many patients with lateral patella dislocation; however, if lateral lengthening alone is insufficient to permit reduction in knee flexion quadricepsplasty may need to be performed (Table 1). 4 Contraindications Contraindications to quadricepsplasty include the absence of significant quadriceps contracture. In many cases, lateral side tightness can be addressed with lateral retinacular lengthening rather than quadriceps lengthening. Another significant contraindication is lack of significant functional impairment or pain. As noted, some patients are relatively functional for their activities of daily living; or have limited mobility or limb function so that addressing the dislocation or contracture may not provide significant improvement in quality of life. An inability to comply with the postoperative regimen is also a contraindication to quadricepsplasty. Finally, Table 2 Contraindications 1. 2. 3. 4. 5. Lack of quadriceps contracture Minimal symptoms or impact on daily activities Inability to comply with postoperative management Poor or absent quadriceps function Inadequate soft tissue coverage patients with preexisting significant quadriceps weakness or lack of function may have a higher risk of poor function since there is often a period of postoperative quadriceps weakness that may become permanent (Table 2). 5 Surgical Technique 5.1 Preoperatively A tourniquet is applied on the thigh for potential use but is generally not immediately inflated since this may affect quadriceps excursion. To limit blood loss and improve hemostasis, 1000 mg of intravenous tranexamic acid is infused preoperatively. Perioperative antibiotics are also used. Patella tracking and mobility are assessed. 5.2 Incision and Exposure Typically, an anterior incision is made that extends from the tibial tubercle to 6–10 cm proximal to the patella with the knee in extension. The patella, patella tendon, 6–10 cm of quadriceps tendon, vastus lateralis, rectus, and vastus medius insertion are exposed. The medial side is often noted to be stretched out and deficient.
486 J. Koh 5.3 Lateral Side Releases Stepwise progression of lateral releases and lengthening is performed. If the patella cannot be easily relocated, a lateral retinacular lengthening is performed similar to that described by Larson [27] (following Slocum’s description). (Figure 2) Initially, the more superficial lateral retinacular tissue (the superficial oblique lateral retinacular tissue) is divided along the lateral patella, carefully separating it from the deep transverse lateral retinaculum. This split is developed posteriorly until reaching the iliotibial band and then released off the band. The deep capsule can also be released. Patella tracking and the ability of the patella to remain reduced with the knee at 90 degrees of flexion is assessed. If this is not possible, additional releases need to be performed. Repair is performed at the conclusion of the overall lengthening and stabilization procedure. The two layers (superficial oblique and deep transverse) can be repaired edge to edge (Fig. 2). This is performed with the patella located and the knee flexed 90 degrees, since otherwise the tissue if repaired in extension or less flexion may fail with knee flexion since it will be under greater tension. Typically, up to 1.5–2 cm of lengthening can be achieved. Lengthening is preferred to release since the lateral retinaculum confers additional stability to the patella. Additionally, a lateral retinacular defect can be painful and unsightly. If there already has been some type of lateral release leaving deficient or absent tissue, sometimes retinacular flaps can be raised or a graft performed. The lateral capsule is then released, including adjacent to the lateral edge of the patella tendon. The lateral patellomeniscal ligaments and the lateral retinaculum adjacent to the patella tendon can act as a tether to limit medial translation of the extensor mechanism [1]. The lateral infrapatellar fat pad is where the lateral patellofemoral ligaments are located. The use of electrocautery is helpful since the fat pad is quite vascular. The vastus lateralis tendon insertion to the patella is then divided at the patella and sharply Fig. 2 Lateral retinacular lengthening. The superficial layer is divided adjacent to the patella, and separated from the deep transverse lateral retinaculum. The step-cut is then repaired at the conclusion of the case with the knee in flexion. (Reproduced with permission from Ellsworth et al.) [20] separated from the central quadriceps tendon (Fig. 3). Proximally, the posterior undersurface attachments of the vastus lateralis are then released off the lateral intermuscular septum using sharp and blunt dissection. Care should be taken since there are some small perforating vessels. This mobilization is key to allowing increased excursion of the vastus lateralis.
Quadricepsplasty Fig. 3 Mobilization of the vastus lateralis oblique. The tendon is divided from the patella and proximally to the musculotendinous junction. The muscle belly is elevated from the intramuscular septum. Reproduced with permission from the Cleveland Clinic Foundation) [1] 5.4 Quadriceps Lengthening If following the lateral releases and mobilization, the patella is unable to remain reduced in the trochlea with the knee at 90 degrees of flexion, quadriceps lengthening will need to be performed. The initial step of quadriceps lengthening is to release the vastus lateralis from the patella and quadriceps tendon 6–10 cm proximal to the quadriceps insertion. Undersurface synovial adhesions and attachments of the quadriceps to the femur should also be released since they can also tether the extensor mechanism. Again, patella tracking is assessed. If the patella is able to remain reduced to 90 degrees of knee flexion, the vastus lateralis is repaired to the quadriceps tendon with the knee flexed. Conversely, if obligate dislocation is seen, then the main quadriceps tendon will need to be lengthened. 487 Several techniques to lengthen the quadriceps tendon exist, including V–Y lengthening and step-cut (Z) lengthening in the coronal plane. The author’s preference is a step cut (Z) lengthening beginning on the superolateral quadriceps insertion to the patella, extending transversely 50%, and then proximally 6–8 cm before exiting medially. This is similar to that described by Green but with a longer central split to allow side to side tendon repair (Fig. 4). This preserves the VMO attachment to the patella and quadriceps tendon while applying a relatively greater medial force to the proximal pole of the patella. Given that the medial structures are already relatively lengthened and attenuated, and the vastus medialis obliquus is already often stretched and weakened, the medial structures are unlikely to be the source of excessive tightness. Additionally, cutting or detaching the VMO will contribute further to temporary and perhaps permanent weakness of this important muscle for knee function and patella stability. The appropriate length of the extensor mechanism can then be determined by flexing the knee to 90 degrees and seeing where the appropriate cut ends of the central quadriceps tendon are located. This is marked and the side-to-side repair of the quadriceps tendon at the appropriate length is performed with the knee in extension to avoid distraction on the repair site. Typically the central tendon lengthening is 1–2 cm. Multiple high strength suture or tapes are used in a locking stitch fashion to provide a robust repair between the split tendon. The longer split allows for a greater number of crossing sutures spanning the repair site. This can be further oversewn with interrupted sutures for reinforcement. The vastus lateralis is similarly sutured at the appropriate location onto the lateral quadriceps tendon. This is often significantly more proximal (4–6 cm) to the patella than the central quadriceps tendon lengthening and is consistent with the differential contracture of the lateral, central, and medial sides. If there is concern that the tendon is deficient, allograft tissue can be incorporated as a patch onto the repair. Tension on the repair should be assessed and the knee should just be
488 J. Koh Given that the medial structures remain deficient, at this point a medial patellofemoral ligament reconstruction is performed. As usual, great care should be taken to avoid excessive tension on the graft in flexion. For further reinforcement, the VMO insertion can be sutured to the superior limb of a two-tailed MPFL graft. Notably, the graft should not have to “pull” the patella into the trochlea and should be without tension with the knee in deeper flexion. 6 Fig. 4 Step-cut quadriceps lengthening. After detachment of the vastus lateralis, a transverse step-cut is made in the central quadriceps tendon. The vastus medialis obliquus insertion is preserved, and the medial cut is proximal to the bulk of the VMO attachment. The knee is flexed and the amount of lengthening is determined followed by side-to-side repair of the central quadriceps tendon and the vastus lateralis tendon. (Modified with permission from Ellsworth et al.) [20] able to flex to 90 degrees with the patella located and good tension without gapping. The lateral retinacular tissues can be then repaired with the knee flexed as previously described. Associated Procedures and Order of Correction In general, if an osteotomy to correct bony malalignment needs to be performed, this would be done prior to addressing the soft tissue. A tibial tubercle osteotomy can be done at this point through the anterior incision. If a varus or rotational osteotomy needs to be performed, the appropriate incisions are made and the osteotomy performed prior to the extensor lengthening, but care should be taken to plan the exposure to avoid incisions too close together. If there is a significant concern the procedure can be staged. If autologous soft tissue is used for the MPFL reconstruction, it is preferred to use a hamstring graft rather than a segment of the quadriceps tendon since the central quadriceps tendon is already being divided and should not be further weakened. The hamstring graft harvest should be performed at the beginning of the case since otherwise the knee flexion that is commonly used during harvest will put strain on the repaired extensor mechanism. MPFL reconstruction should be performed after the quadricepsplasty since the patella and femur relative positions may have changed. 7 Postoperative Management The intraoperative evaluation should demonstrate adequate stability of the repair up to 90 degrees of flexion. Initially the patient is kept in a hinged
Quadricepsplasty knee brace locked in extension for 2 weeks, and then progression by allowing 30 degrees additional range of motion every 2 weeks in the brace until 90 degrees of knee flexion is achieved. With the brace locked in extension, touch down weightbearing is permitted with the brace for the first 2 weeks, then progressed to 50% at 4 weeks and full at 6 weeks. The brace can be discontinued when quadriceps function allows a straight leg raise. The initial goal range of motion is 110 degrees of knee flexion by 3 months. Progression is slow to allow tissues to heal without excessive lengthening or stretching out. 489 mechanism, meticulous and strong repair techniques, and rehabilitation that respects the biology of healing. Recurrent instability is related to improper tensioning and the lack of strong medial structures to restrain the patella. Reconstruction of the MPFL helps decrease the risk of instability. In either case, if patients remain symptomatic, revision repair and reconstruction would be appropriate. Other potential issues include wound complications or failure of range of motion. 10 8 Results of Quadricepsplasty Early results of quadricepsplasty for congenital or obligate dislocation utilized different techniques of quadriceps lengthening and had relatively good results in terms of keeping the patella reduced. These procedures did not differentially lengthen the vastus lateralis compared to the central and medial quadriceps tendon, and it was not uncommon to see patients who had an extensor lag [2, 28]. More recently, Andrish described repairing the vastus lateralis to the side of a coronal split central quadriceps tendon. He was able to achieve good range of motion and patella stability, and good quadriceps function. He did note that the restoration of quadriceps strength took up to a year [1]. Green has also described differential repair of the vastus lateralis to a split quadriceps tendon. The split cut is similar to that described here with preservation of the VMO and medial quadriceps tendon attachment. No extensor lag was noted in 24 patients [20]. 9 Complications Complications of quadricepsplasty are primarily related to either failure of extensor mechanism repair resulting in extensor lag, or recurrent instability. Prevention of failure of the repair is related to appropriate tensioning of the extensor Take Home Message Obligate lateral patella dislocation is primarily contracture of the lateral more than central or medial tissues. Lateral release should be meticulous and complete, and begin with retinacular tissues, the lateral patellotibial ligaments, and then the vastus lateralis. A step-cut lengthening of the quadriceps tendon preserving the medial quadriceps tendon and VMO attachments may allow for improved quadriceps strength and differential tensioning of the less contracted medial structures [20]. The repair should be tested intraoperatively to demonstrate appropriate patella tracking. Lateral structures should be repaired at the appropriate tension and the medial patellofemoral ligament reconstructed to increase patella stability. With appropriate technique and rehabilitation, excellent results can be expected. References 1. Andrish J. Quadricepsplasty for congenital dislocation of the patella and patellar tendon shortening for patella alta. In: Parikh S, editor. Patella Instability. Philadelphia: Wolters Kluwer; 2020. p. 353–61. 2. Tercier S, Shah H, Joseph B. Quadricepsplasty for congenital dislocation of the knee and congenital quadriceps contracture. J Child Orthop. 2012;6 (5):397–410. 3. Bose K, Chong KC. The clinical manifestations and pathomechanics of contracture of the extensor mechanism of the knee. J Bone Joint Surg Br. 1976;58-B (4):478–84. 4. Zeier FG, Dissanayake C. Congenital dislocation of the patella. Clin Orthop Relat Res. 1980;148:140–6.
490 5. Bergman NR, Williams PF. Habitual dislocation of the patella in flexion. J Bone Joint Surg Br. 1988;70 (3):415–9. 6. Gao GX, Lee EH, Bose K. Surgical management of congenital and habitual dislocation of the patella. J Pediatr Orthop. 1990;10(2):255–60. 7. Ghanem I, Wattincourt L, Seringe R. Congenital dislocation of the patella. Part II: orthopaedic management. J Pediatr Orthop. 2000;20(6):817–22. 8. Dos Santos CF. GA TAM, Rocha de Faria JL, Perez da Motta D, Dos Santos Cerqueira F, Adolphson F. Minimally Invasive Quadricepsplasty Arthrosc Tech. 2019;8(3):e343–7. 9. Oliveira VG, D’Elia LF, Tirico LE, Gobbi RG, Pecora JR, Camanho GL, et al. Judet quadricepsplasty in the treatment of posttraumatic knee rigidity: long-term outcomes of 45 cases. J Trauma Acute Care Surg. 2012;72(2):E77-80. 10. Hung NN, Tan D, Do Ngoc Hien N. Patellar dislocation due to iatrogenic quadriceps fibrosis: results of operative treatment in 54 cases. J Child Orthop. 2014;8(1):49–59. 11. Thompson TC. Quadricepsplasty. Ann Surg. 1945;121(5):751–4. 12. Masse A, Biasibetti A, Demangos J, Dutto E, Pazzano S, Gallinaro P. The judet quadricepsplasty: long-term outcome of 21 cases. J Trauma. 2006;61 (2):358–62. 13. Merchan EC, Myong C. Quadricepsplasty: the Judet technique and results of 21 posttraumatic cases. Orthopedics. 1992;15(9):1081–5. 14. Ali AM, Villafuerte J, Hashmi M, Saleh M. Judet’s quadricepsplasty, surgical technique, and results in limb reconstruction. Clin Orthop Relat Res. 2003;415:214–20. 15. Daoud H, O'Farrell T, Cruess RL. Quadricepsplasty. The Judet technique and results of six cases. J Bone Joint Surg Br. 1982;64(2):194–7. 16. Bidolegui F, Pereira SP, Pires RE. Safety and efficacy of the modified Judet quadricepsplasty in patients with post-traumatic knee stiffness. Eur J Orthop Surg Traumatol. 2021;31(3):549–55. J. Koh 17. Marumo K, Fujii K, Tanaka T, Takeuchi H, Saito H, Koyano Y. Surgical management of congenital permanent dislocation of the patella in nail patella syndrome by Stanisavljevic procedure. J Orthop Sci. 1999;4(6):446–9. 18. Wada A, Fujii T, Takamura K, Yanagida H, Surijamorn P. Congenital dislocation of the patella. J Child Orthop. 2008;2(2):119–23. 19. Jones RD, Fisher RL, Curtis BH. Congenital dislocation of the patella. Clin Orthop Relat Res. 1976;119:177–83. 20. Ellsworth B, Hidalgo Perea S, Green DW. Stepwise lengthening of the quadriceps extensor mechanism for severe obligatory and fixed patella dislocators. Arthrosc Tech. 2021;10(5):e1327–31. 21. Eilert RE. Congenital dislocation of the patella. Clin Orthop Relat Res. 2001;389:22–9. 22. Drennan JC. Congenital dislocation of the knee and patella. Instr Course Lect. 1993;42:517–24. 23. Ferrone JD Jr. Congenital deformities about the knee. Orthop Clin North Am. 1976;7(2):323–30. 24. Sever R, Fishkin M, Hemo Y, Wientroub S, Yaniv M. Surgical treatment of congenital and obligatory dislocation of the patella in children. J Pediatr Orthop. 2019;39(8):436–40. 25. Grisdela PT, Paschos N, Tanaka MJ. Fixed (congenital) patellar dislocation. Clin Sports Med. 2022;41 (1):123–36. 26. Ramaswamy R, Kosashvili Y, Murnaghan JJ, Yau CK, Cameron JC. Bilateral rotational osteotomies of the proximal tibiae and tibial tuberosity distal transfers for the treatment of congenital lateral dislocations of patellae: a case report and literature review. Knee. 2009;16(6):507–11. 27. Ceder LC, Larson RL. Z-plasty lateral retinacular release for the treatment of patellar compression syndrome. Clin Orthop Relat Res. 1979;144:110–3. 28. Mo Y, Jing Y, Wang D, Paley D, Ning B. Modified Langenskiold procedure for congenital patella dislocations in pediatric patients. BMC Musculoskelet Disord. 2022;23(1):241.
Sulcus Deepening Trochleoplasty Edoardo Giovannetti de Sanctis and David H. Dejour 1 Introduction Trochlear dysplasia refers to a genetic pathologic alteration of the trochlear shape, becoming shallow, flat or even convex sometimes with a superolateral prominence (Fig. 1). The trochlear dysplasia, and therefore an incongruency between trochlear and patellar surfaces, has a high influence on patellar tilt, subluxation and lateral displacement, failing to provide an adequate constraint to the normal patellar tracking. Trochlear dysplasia is the main factor in patellar dislocation and is found in 96% of the population with objective patellar dislocation OPI (at least one true dislocation) [1]. The higher the degree of trochlear dysplasia, the higher the risk of instability. We found in the old literature the Disclosure Statement E. G. d. S. has nothing to disclose. D. D.: Royalties ARTHREX. E. Giovannetti de Sanctis (&) D. H. Dejour Lyon-Ortho-Clinic: Clinique de La Sauvegarde, Ramsay Santé, 8, avenue Ben Gourion, 69009 Lyon, France e-mail: edoardo.giovannettids@gmail.com D. H. Dejour e-mail: corolyon@wanadoo.fr E. Giovannetti de Sanctis Lyon Ortho Clinic, 29 Av. des Sources, 69009 Lyon, France description of trochleoplasty by Bilton Polar in 1890, but since then it has undergone different changes. Another publication done by Masse in 1978 [2] describes a sort of trochleoplasty but was Henri Dejour in 1987 [3] who popularized and standardized the method and gave the rational for it. In 2010 David Dejour modified it to improve the correction of the different features of the trochlear dysplasia [4]. The procedure’s main aim is to decrease the trochlear prominence while creating a new groove with both a normal depth and orientation. 2 Radiologic Features and Classification Standard radiographic views, such as weight bearing true lateral view, axial view at 30° of knee flexion, and anteroposterior (AP) view, are mandatory to start a patellofemoral disorder evaluation [5, 6]. The lateral view has to be performed by superimposing the two posterior femoral condyles in a monopodal weight-bearing position with 20° of flexion. This projection shows from anterior to posterior the contour of the facets and the line representing the trochlear sulcus [5, 7]. The lateral condyle, and therefore the lateral facet, might be recognized, having a more visible condylotrochlear groove and a greater radiopacity. The line representing the trochlear sulcus is in continuity with the Blumensaat line, which is the line drawn along the roof of the intercondylar notch. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_34 491
492 Fig. 1 High grade trochlear dysplasia (anterior view of a right knee). There is no sulcus, and in the lateral aspect (right) a big bump can be observed Fig. 2 To analyse the trochlear dysplasia a true profile is needed with a perfect superimposition of the posterior femoral condyles. The three trochlear dysplasia signs are: the crossing sign, the supra-trochlear spur, the doublecontour which goes below the crossing sign E. Giovannetti de Sanctis and D. H. Dejour protuberance (bump or prominence) on the superolateral part of the trochlea with a functional effect, during the trochlear engagement, similar to the ski ramp pushing the patella on the lateral side and creating an antimaquet effect. The double contour sign represents the medial hypoplastic facet subchondral bone becoming posterior to the lateral condyle on the sagittal projection. Axial views obtained at 30° of knee flexion allow the measurement of the sulcus angle [8]. From the trochlear sulcus two lines are drawn going towards the most superior point of each facet. The mean normal value defined by Brasttorm was 145° (SD ± 6). Axial view provides a good assessment of the mid trochlea but might miss the flatness of the superior part of the trochlea. Therefore, the best way to screen the trochlear dysplasia on X-rays is on the sagittal view. However, frequently in a dysplastic trochlea no measurement can be made as there is no identifiable sulcus and we believe in the subjective impression of the trochlear shape. For those two reasons, the trochlear shape is best evaluated on axial cross-sectional images (CT scan or MRI). MRI has also the advantage of better assessing any softening and/or damage to the cartilage [10]. Based on these signs, and cross-checking the sagittal radiographs with the cross-sectional images the trochlear dysplasia might be classified in four types (Table 1) (Fig. 3) [11, 12]. 3 On the sagittal view the trochlear dysplasia is defined by three radiographic pillars: the crossing sign, the supratrochlear spur and the doublecontour sign (Fig. 2). The crossing sign is positive when the radiographic line of the trochlear sulcus crosses the anterior projection of the femoral condyles. It represents the exact position where the sulcus reaches the same antero-posterior height of the femoral condyles, corresponding to a macroscopic flat trochlea. The supratrochlear spur which is clearly identified during the surgical exposure, is a Function and Biomechanics The lateral facet is oriented obliquely in the coronal plane with an antero-lateral direction. The lateral facet is both larger and more protuberant anteriorly than the medial one, respectively in the coronal and sagittal plane. The corresponding lateral patellar joint surface follows this this shape. This bony constraint contributes preventing the patella from a lateral dislocation. The patella rests on the supratrochlear anterior femoral cortex in total extension, engaging the trochlea during early flexion.
Sulcus Deepening Trochleoplasty 493 Table 1 The Trochlear dysplasia Dejour’s classification.. CS: Crossing sign; SS: Supratrochlear spur; DC: Double contour Type Sagittal View Axial images A CS Shallower trochlea B CS and SS Flat or convex C CS and DC Convex lateral facet and hypoplastic medial facet D CS, SS, DC A prominent and convex lateral facet with a vertical connection to an hypoplastic medial facet almost absent (cliff pattern) Fig. 3 Trochlear dysplasia classification according to D. Dejour: Type A: Crossing sign (X-rays). Shallower trochlea (Slice images); Type B: Crossing sign and supratrochlear spur (X-rays). Flat or convex trochlea (Slice images); Type C: Crossing sign and double-contour sign (X-rays). Convex lateral facet and hypoplastic medial facet (Slice images); Type D: Crossing sign, supratrochlear spur, and double-contour sign (X-rays). Hypoplastic medial facet proximally short and almost absent with a vertical connection to a prominent and convex lateral facet defining the so called “cliff pattern” (Slice images)
494 E. Giovannetti de Sanctis and D. H. Dejour A posteriorly directed force produced, mainly by the quadriceps, pushes the patella against the trochlea. Both the articulating surfaces orientation and the tibial internal rotation during knee flexion, create a medially directed vector, directing the patellar tracking [13]. A trochlea without properly oriented facets (TD) prevents the patella from sliding properly up and down within the margins [14]. Trochlear shape guide the patellar tracking and therefore an incongruency between trochlear and patellar surfaces, has a high influence on patellar tilt, subluxation and lateral displacement [11]. The PF joint reaction force, which is linked to the onset and progression of orteoarthritis, depends also on the trochlear prominence. The bigger the trochlear prominence, the greater the compressive reaction force in flexion. Therefore, decreasing the protrusion would lead to an expected reduction of the PF reaction force. 4 Goals Sulcus deepening trochleoplasty has three functions while treating patients with trochlear dysplasia: it modifies the trochlear shape with a central groove and oblique medial and lateral facets; it decreases the patellofemoral joint reaction force by reducing the supratrochlear prominence (spur); and might reduce the TT–TG value by a proximal realignment. 5 Indications Sulcus deepening trochleoplasty has specific and selective indications: e.g.patients with types B and D trochlear dysplasia, in which the prominence of the trochlea (supratrochlear spur) is relevant (>5 mm); recurrent patellar dislocation and maltracking. In patients with patellofemoral osteoarthritis, open growth plates, and pain with no history of dislocations this procedure is contraindicated. Trochlear dysplasia type A is not considered a severe morphologic abnormality, as the groove is slightly modified: the sulcus is clearly visible although the groove has a shallower angle. No shape modifying procedures are necessary; recurrent dislocations or maltracking should be attributed to other anatomic risk factors: patella alta, tibial tubercle—trochlear groove (TT–TG) distance or patellar tilt. Although trochlear dysplasia type C has a shape substantially altered there is no prominence to be corrected, making the choice of the proper treatment controversial. Sulcus deepening trochleoplasty is not indicated for those patients, usually undergoing an alternative procedure like a mild medialization and/or distalization. The degree of instability and clinical symptoms should also be considered when proposing this procedure to a patient. Sulcus deepening trochleoplasty, as any other surgical procedure, is liable to failure and therefore, the indication should not be given lightly. Associated anatomic risk factors have to be evaluated preoperatively in order to plan an eventual correction: tibial tubercle distalization/ medialization and/or lateral release. Tibial tubercle medialization might be not necessary in cases of increased TT–TG, as sulcus deepening trochleoplasty lateralizes the groove, thus decreasing the this distance. The sulcus deepening trochleoplasty is part of the “menu à la carte”, meaning specific procedures for each of the main anatomic risk factors in patellar instability. The MPFL (Medial patello-femoral ligament) reconstruction is systematically added to the sulcus deepening trochleoplasty, in order to treat the consequence of the ligament rupture occurred during the first dislocation episode. 6 Surgical Technique The procedure is generally performed with the patient supine under both regional anesthesia and sedation. A thigh tourniquet is positioned. A straight midline incision is performed, with the knee flexed at 90°, from the superior pole of the patella to the tibiofemoral joint line. A transquadricipital approach is done.
Sulcus Deepening Trochleoplasty 495 Fig. 4 Surgical exposure. The periosteum is incised along the osteochondral edge and reflected away from the trochlear margin. The anterior femoral cortex should be visible to guide the bone resection The patella is not everted but retracted laterally and it is carefully inspected for cartilage damages. The trochlea is exposed (Fig. 4). An incision along the femoro-trochlear junction is performed and the peritrochlear synovium/ periosteum are reflected using a periosteal elevator. The anterior distal femoral cortex should be visible to evaluate the supratrochlear spur adapting the amount of deepening. With the trochlea fully exposed, the native trochlear groove is marked with a sterile pen. Two additional divergent lines, representing the lateral and medial facet limits, are drawn, from the notch going laterally and medially, through the condylotrochlear grooves (sulcus terminalis). Those two lines have to be out of the tibiofemoral articulation (Fig. 5). The planned trochlear groove is marked in a more lateral position according to the preoperative TT-TG value to be aligned with the anatomical femoral axis. Thereafter the under surface of the trochlea is assessed. A thin strip of femoral anterior cortical bone is removed all around the trochlea, with a thickness equal to the height of the prominence from the anterior femoral cortex, i.e., the bump formed. A sharp osteotome is used to remove the bone. Subsequently, cancellous bone must be removed from the under surface of the trochlea. Using an offset guide-equipped drill, different tunnels are made through the subtrochlear cancellous bone, from proximal to distal (top of the notch) and parallel to the anterior cortex. Fig. 5 After the surgical exposure, the new trochlea is drawn. From the intercondylar notch, the bottom of the sulcus and the facets are planned
496 E. Giovannetti de Sanctis and D. H. Dejour Fig. 6 In order to allow further modeling to the underlying bone bed, the osteochondral flaps may be cut in the sulcus and facets lines The offset guide tip is placed on the anterodistal part of the notch. The distance between the drill and guide tip never goes below 5 mm to ensure uniform thickness of the osteochondral flap and prevent cartilage damage. Thereafter, a high-speed burr is used to remove the cancellous bone bridges between the tunnels. The guide equipped with a cartilage palpator set at 5 mm is used to determine the thickness of the bone resection and avoid crossing the trochlea or producing cartilage injuries inflicted by heat. More cancellous bone could be then removed from the central metaphyseal part towards the notch, below the planned trochlear groove, to make the deepest part of the groove flush with the anterior cortex. Light pressure should be able to model the flap to the underlying cancellous bone bed in the distal femur. The groove, and the lateral facet external margin, might be cut to allow further modeling (Fig. 6). Pieces of bone graft, using the thin strip of femoral cortical bone removed previously, might be placed medially and laterally, between the flap and the bone bed, to elevate the medial and lateral facet and increase the angle of the new trochlea if necessary. A 145° Polyethylene Pusher is used to apply light pressure and mold the flap to the underlying cancellous bone bed (Fig. 7). The new trochlea is fixed by placing with one absorbable anchor with 2 absorbable sutures (Vicryl number 2) placed at the top of the notch. Fig. 7 Lateral and anterior views of the dysplastic trochlea after trochleoplasty
Sulcus Deepening Trochleoplasty Both ends of each suture are then fixed at the proximal lateral and proximal medial (trochlear facets) bone margins of the corresponding facet with a knotless anchor. Patellar tracking is tested and measures may be obtained. Periosteum and synovial tissue are sutured to the osteochondral edge. The associated procedures are then carried out. The lateral retinaculum is systematically released or lengthened due to its usual tightness. The other instability factors like patella alta or axial malalignment are corrected if needed according to the “menu à la carte” with medialization and/or distalization. The chronology of the procedure is trochleoplasty first, lateral release, tibial tubercle osteotomy and then MPFL reconstruction. 497 Phase 2 (46th to 90th day): closed kinetic chain (e.g. cycling) and weight- bearing proprioception exercises are started initially respectively with weak resistance and in bipodal stance. The anterior and posterior muscular chains are stretched. Phase 3 (4th to the 6th month): a gradually return to sport might be started. Running is allowed initially on a straight line. The patient is encouraged to proceed with the rehabilitation on his own. After 6 to 8 months sports might be resumed. An imaging follow-up is recommended a 6 weeks and 6 months respectively with radiographs (AP, sagittal and axial view at 30° of flexion) and CT scan (Figs. 8 and 9). 8 7 Post-Operative Care Sulcus deepening trochleoplasty by itself does not need weight-bearing restriction, range of motion (ROM) limitation or the use of a brace. Continuous passive motion (CPM) might improve cartilage healing. Furthermore, immobilization would decrease the trophism of Quadriceps femoris muscle and lead to a higher risk of postoperative knee stiffness. The rehabilitation protocol presented hereafter has to be used with patients undergoing only the sulcus deepening trochleoplasty. Associated procedures would need slight modifications like an extension brace for walking during 30 days if a tibial tubercle osteotomy is done. The rehabilitation protocol is divided in 3 phases. Phase 1 (1st to 45th day): passive and active ROM are started to facilitate osteochondral healing and further modelling of the newly formed trochlea by patellar tracking. Range of motion is gradually regained, avoiding forced and painful postures. Immediate weight-bearing is allowed. Quadriceps strengthening is allowed through static isometric contraction and stimulation. Results The sulcus deepening trochleoplasty results described by different authors are difficult to compare due to a non-uniformity in terms of associated procedures performed, inclusion criteria used and the presence/absence of previous surgery. The best post-operative results have been highlighted in patients with objective patellar instability, high-grade trochlear dysplasia (type B or D), and when all other anatomic risk factors are corrected simultaneously. This procedure has shown good postoperative clinical outcomes, a high rate of both subjective satisfaction and PF joint stability. Joint stiffness and pain are common complaints at follow up. Controversial is whether the sulcus deepening trochleoplasty influences the development of patello-femoral osteoarthritis. Trochlear cartilage damage, incongruence with the patella, and excessive or insufficient correction are potential complications. Schottle et al. [15] evaluated with a biopsy the trochlear cartilage lining of three patients after sulcus deepening trochleoplasty, outlining a low risk of damage. Instability recurrence is a rare complication and is frequently due to missed associated risk
498 E. Giovannetti de Sanctis and D. H. Dejour Fig. 8 Pre and postoperative lateral x-rays showing the resection of the supratrochlear bump and trochlear prominence correction Fig. 9 X-ray axial views before and after trochleoplasty. The trochlear sulcus is restored factors (patella alta, TT-TG, excessive patellar tilt). Zaffagnini et al. [16] reviewed the clinical outcomes of MPFL reconstruction with and without sulcus deepening trochleoplasty in patients affected by trochlear dysplasia. Altrough, no difference was found in the overall redislocation rate between those two groups, they stated that while treating severe trochlear dysplasia, the redislocation rate is lower when sulcus deepening trochleoplasty is added to MPFL reconstruction. Balcarek et al. [17] confirmed that in OPI patients with severe trochlear dysplasia, the sulcus deepening trochleoplasty has to be added to the MPFL reconstruction to lower the risk of post-operative redislocation/subluxation. Dejour et al. [18] evaluated 24 knees with a mean follow up of 66 months, undergoing a sulcus deepening trochleoplasty for failure of previous surgery with persistent patellar dislocation. Respectively 29.1% and 70.9% of patients had type B and D trochlear dysplasia. After the procedure, no recurrence of dislocation was recorded up to the last follow-up. Pain decreased significantly and the Apprehension sign was negative in respectively 72% and 75% of cases. Ntagiopoulos et al. [19] reviewed retrospectively the clinical outcomes of thirty-one sulcus deepening trochleoplasties. No cases of stiffness or instability recurrence or maltracking were recorded. The apprehension sign remained positive in 19.3% of cases. The mean preoperative and postoperative International Knee Documentation Committee (IKDC) score was respectively 51 (range, 25–80), and 82 (range, 40–100) (p < 0.001). The mean Kujala score improved
Sulcus Deepening Trochleoplasty from 59 (range, 28–81) to 87 (range, 49–100) (p < 0.001). PF stiffness has been shown as one of the main factors decreasing the postoperative clinical outcomes, leading sometimes to manipulation under anaesthesia or arthroscopic arthrolysis [20]. Zaffagnini et al. [16] have observed in their systematic review that the addition of the trochleoplasty to an MPFL reconstruction for the treatment of severe trochlear dysplasia might increase the risk of post-operative range of motion (ROM) limitation. Twenty-nine arthroscopic deepening trochleoplasties were followed up for more than twelve months by Blønd and Haugegaard [21]. No redislocations or arthrofibrosis were recorded. The median Kujala score (range) improved from 64 (12–90) preoperatively to 95 (47–100) postoperatively. The authors therefore stated that the use of this technique is safe and reproducible. Song et al. compared trochleoplasty with nontrochleoplasty surgical procedures as a treatment for patients with severe trochlear dysplasia, outlining inferior outcomes in terms of range of motion (ROM) in the first group [22]. In Verdonk et al. [23] although the results of the majority of patients scored fair/poor on an objective scoring system, seventy-seven % were satisfied with the procedure. Seventeen consecutive sulcus deepening trochleoplasties, with a one-year minimum follow up, were evaluated by Donell et al. [24] Patellar tracking normalized in eleven knees and had a slight J appearance in six. Seven patients showed a mild residual apprehension. In terms of subjective satisfaction, seven, six and two were respectively very satisfied, satisfied, and disappointed. Three patients returned to full sports and eight patients required further operations. Carstensen et al. [25] evaluated the clinical outcomes of 44 patients with Type B and D trochlear dysplasia, treated with sulcus deepening trochleoplasties plus MPFL reconstruction, with a minimum follow-up of 2-years. Although a 18% rate of postoperative arthrofibrosis and 27% rate of overall reoperation, patients reported 499 a high rate in: satisfaction (mean of 9.1/10), return to work (100%) and sport (84.8%). Lutz et al. [26] stated that the addition of bony procedures to MPFL reconstruction leaded to a low redislocation rate, improved physical and sexual activity and a quality of life comparable to values reported after isolated MPFT reconstruction. Longo et al. [27] in their systematic review outlined that the Dejour V-shaped sulcus deepening trochleoplasty leaded to the highest mean Kujala post-operative score (79.3) compared to the other trochlea modifying shape techniques. Debated is the efficacy of this surgical procedure in decreasing PF pain. Faruqui et al. [28] observed a greater risk of postoperative anterior knee pain after sulcus deepening trochleoplasty. Although four over six patients reported postoperative anterior knee pain, each one was satisfied with the postoperative clinical outcomes. Also Beaufils et al. [20] confirmed the residual mild anterior knee pain as a frequent complication after this procedure. Von Knoch et al. [29] evaluated forty-five consecutive sulcus deepening trochleoplasty, with a mean follow-up of 8.3 years; None of those had recurrence of dislocation, However, PF pain, referred pre-operatively in only 35 knees, worsened in 15 (33.4%), remained unchanged in four (8.8%) and improved in 22 (49%). Four knees not referring pain pre-operatively (8.8%) kept on being asymptomatic. Rouanet et al. [30] evaluated thirty-four sulcus deepening trochleoplasties with a follow up of 15 years. Sybjective patient satisfaction and postoperative occasional pain rate were respectively 65% and 53%. Controversial is the correlation between PF arthritis, patellar dislocations and sulcus deepening trochleoplasty. Theoretically, the severe altered morphology of the trochlea, influences the patellar kinematics leading to a greater risk of patellofemoral osteoarthritis [14]. Whether patients with OPI and undergoing sulcus deepening trochleoplasty are respectively more prone to and protected from developing osteoarthritis has not been determined clearly yet [31].
500 E. Giovannetti de Sanctis and D. H. Dejour Longo et al. [27] stated that sulcus deepening trochleoplasty is associated with improved clinical outcomes and stability and a relatively low rate of osteoarthritis and pain. In Von Knoch et al. [29] 30% of knees undergoing sulcus deepening trochleoplasty, evaluated at a mean follow up of 8.3 years, developed PF degenerative changes. None of the twenty-seven patients (thirty-one knees) evaluated by Ntagiopoulos et al. [19] showed radiographic evidence of PF cartilage severe degeneration at the latest followup. Song et al. [22] compared trochleoplasty with non-trochleoplasty procedures as a treatment for OPI patients with trochlear dysplasia type B to D. The trochleoplasty group had a decreased risk of redislocation and patellofemoral osteoarthritis (Iwano grade 2 or greater) progression. Rouanet et al. [30] evaluated thirty-four sulcus deepening trochleoplasties in terms of functional outcomes and rate of PF osteoarthritis. No recurrent dislocation was found at the latest follow-up. They highlighted that the outcomes were significantly greater for patients undergoing sulcus deepening trochleoplasty with a dysplasia characterized by a supratrochlear spur. Preoperatively the PF OA was diagnosed only in 10 patients (all with < Iwano 2). At latest follow-up the rate increased significantly. Osteoarthritis was though identified in 33 over 34 patients, 65% having more than Iwano grade 2. 9 Conclusion Only knees with high grade trochlear dysplasia (types B/D) in which the protuberance is over 5 mm, recurrent patellar dislocation and patellar maltracking might be treated with sulcus deepening trochleoplasty. It modifies the shape of the trochlea forming a new central sulcus and two oblique facets; it decreases the PF joint reaction force by reducing the trochlear prominence and decreases the distance between trochlear groove and tibial tuberosity. It is effective in restoring PF stability and in satisfying patients. Patients have to be aware of the risk of developing postoperative Joint stiffness and pain. Still Controversial is whether the sulcus deepening trochleoplasty influences the development of patello-femoral osteoarthritis. Acknowledgements The authors thank Paulo R.F. Saggin for his work on the previous edition of this chapter. References 1. Dejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994;2(1):19–26. 2. Masse Y. [Trochleoplasty. Restoration of the intercondylar groove in subluxations and dislocations of the patella]. Rev Chir Orthop Reparatrice Appar Mot. 1978;64(1):3–17. 3. Dejour H, Walch G, Neyret P, Adeleine P. Dysplasia of the femoral trochlea. Rev Chir Orthop Reparatrice Appar Mot. 1990;76(1):45–54. 4. Dejour D, Saggin P. The sulcus deepening trochleoplasty-the Lyon’s procedure. Int Orthop. 2010;34(2):311–6. 5. Maldague B, Malghem J. [Significance of the radiograph of the knee profile in the detection of patellar instability. Preliminary report]. Rev Chir Orthop Reparatrice Appar Mot. 1985;71 Suppl 2:5– 13. 6. Malghem J, Maldague B. Depth insufficiency of the proximal trochlear groove on lateral radiographs of the knee: relation to patellar dislocation. Radiology. 1989;170(2):507–10. 7. Malghem J, Maldague B. Patellofemoral joint: 30 degrees axial radiograph with lateral rotation of the leg. Radiology. 1989;170(2):566–7. 8. Merchant AC, Mercer RL, Jacobsen RH, Cool CR. Roentgenographic analysis of patellofemoral congruence. J Bone Joint Surg Am. 1974;56(7):1391–6. 9. Davies AP, Bayer J, Owen-Johnson S, Shepstone L, Darrah C, Glasgow MM, et al. The optimum knee flexion angle for skyline radiography is thirty degrees. Clin Orthop Relat Res. 2004;423:166–71. 10. Carrillon Y, Abidi H, Dejour D, Fantino O, Moyen B, Tran-Minh VA. Patellar instability: assessment on MR images by measuring the lateral trochlear inclination-initial experience. Radiology. 2000;216(2):582–5. 11. Tavernier T, Dejour D. [Knee imaging: what is the best modality]. J Radiol. 2001;82(3 Pt 2):387–405; 7–8. 12. Dejour D, Le Coultre B. Osteotomies in patellofemoral instabilities. Sports Med Arthrosc. 2007;15 (1):39–46.
Sulcus Deepening Trochleoplasty 13. Amis AA. Current concepts on anatomy and biomechanics of patellar stability. Sports Med Arthrosc. 2007;15(2):48–56. 14. Amis AA, Oguz C, Bull AM, Senavongse W, Dejour D. The effect of trochleoplasty on patellar stability and kinematics: a biomechanical study in vitro. J Bone Joint Surg Br. 2008;90(7):864–9. 15. Schottle PB, Schell H, Duda G, Weiler A. Cartilage viability after trochleoplasty. Knee Surg Sports Traumatol Arthrosc. 2007;15(2):161–7. 16. Zaffagnini S, Previtali D, Tamborini S, Pagliazzi G, Filardo G, Candrian C. Recurrent patellar dislocations: trochleoplasty improves the results of medial patellofemoral ligament surgery only in severe trochlear dysplasia. Knee Surg Sports Traumatol Arthrosc. 2019;27(11):3599–613. 17. Balcarek P, Rehn S, Howells NR, Eldridge JD, Kita K, Dejour D, et al. Results of medial patellofemoral ligament reconstruction compared with trochleoplasty plus individual extensor apparatus balancing in patellar instability caused by severe trochlear dysplasia: a systematic review and metaanalysis. Knee Surg Sports Traumatol Arthrosc. 2017;25(12):3869–77. 18. Dejour D, Byn P, Ntagiopoulos PG. The Lyon’s sulcus-deepening trochleoplasty in previous unsuccessful patellofemoral surgery. Int Orthop. 2013;37 (3):433–9. 19. Ntagiopoulos PG, Byn P, Dejour D. Midterm results of comprehensive surgical reconstruction including sulcus-deepening trochleoplasty in recurrent patellar dislocations with high-grade trochlear dysplasia. Am J Sports Med. 2013;41(5):998–1004. 20. Beaufils P, Thaunat M, Pujol N, Scheffler S, Rossi R, Carmont M. Trochleoplasty in major trochlear dysplasia: current concepts. Sports Med Arthrosc Rehabil Ther Technol. 2012;4:7. 21. Blond L, Haugegaard M. Combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament for patients with recurrent patella dislocation and trochlear dysplasia. Knee Surg Sports Traumatol Arthrosc. 2014;22 (10):2484–90. 501 22. Song GY, Hong L, Zhang H, Zhang J, Li X, Li Y, et al. Trochleoplasty versus nontrochleoplasty procedures in treating patellar instability caused by severe trochlear dysplasia. Arthroscopy. 2014;30 (4):523–32. 23. Verdonk R, Jansegers E, Stuyts B. Trochleoplasty in dysplastic knee trochlea. Knee Surg Sports Traumatol Arthrosc. 2005;13(7):529–33. 24. Donell ST, Joseph G, Hing CB, Marshall TJ. Modified Dejour trochleoplasty for severe dysplasia: operative technique and early clinical results. Knee. 2006;13 (4):266–73. 25. Carstensen SE, Feeley SM, Burrus MT, Deasey M, Rush J, Diduch DR. Sulcus Deepening trochleoplasty and medial patellofemoral ligament reconstruction for patellofemoral instability: a 2-year study. Arthroscopy. 2020;36(8):2237–45. 26. Lutz PM, Winkler PW, Rupp MC, Geyer S, Imhoff AB, Feucht MJ. Complex patellofemoral reconstruction leads to improved physical and sexual activity in female patients suffering from chronic patellofemoral instability. Knee Surg Sports Traumatol Arthrosc. 2021;29(9):3017–24. 27. Longo UG, Vincenzo C, Mannering N, Ciuffreda M, Salvatore G, Berton A, et al. Trochleoplasty techniques provide good clinical results in patients with trochlear dysplasia. Knee Surg Sports Traumatol Arthrosc. 2018;26(9):2640–58. 28. Faruqui S, Bollier M, Wolf B, Amendola N. Outcomes after trochleoplasty. Iowa Orthop J. 2012;32:196–206. 29. von Knoch F, Bohm T, Burgi ML, von Knoch M, Bereiter H. Trochleaplasty for recurrent patellar dislocation in association with trochlear dysplasia. A 4- to 14-year follow-up study. J Bone Joint Surg Br. 2006;88(10):1331–5. 30. Rouanet T, Gougeon F, Fayard JM, Remy F, Migaud H, Pasquier G. Sulcus deepening trochleoplasty for patellofemoral instability: a series of 34 cases after 15 years postoperative follow-up. Orthop Traumatol Surg Res. 2015;101(4):443–7. 31. Maenpaa H, Lehto MU. Patellofemoral osteoarthritis after patellar dislocation. Clin Orthop Relat Res. 1997;339:156–62.
Arthroscopic Deepening Trochleoplasty Lars Blønd 1 Introduction For a couple of decades, the trochleoplasty procedure has become a more established operation for symptomatic trochlear dysplasia (TD). In a cadaveric study TD was found in 17% of the knees and here among 5% with high degree of TD [1]. The fraction of those knees with TD that becomes symptomatic is still unknown. Symptoms related to TD are first of all patellofemoral instability (PFI), however some will experience patellofemoral pain (PFP) and some will develop isolated Patellofemoral osteoarthritis [2–8]. The exact definition and classification of TD is still evolving and yet there is no consensus on how to define. The Dejour classification was the first and is the most used, but due to problems with reliability, a new more reliable Oswestry-Bristol classification has been introduced. Both classifications are subjective, which limits the use for both clinical and scientific purposes. A classification based upon objective measures and biomechanical studies is needed. For objective measure the lateral trochlea inclination (LTI) has L. Blønd (&) Department of Orthopaedic Surgery, The Zealand University Hospital, Koege, Denmark e-mail: Lars.Blond@aleris-hamlet.dk Department of Orthopaedic Surgery, Aleris-Hamlet, Copenhagen, Denmark been found useful and has been suggested as a parameter to define TD [9–12]. Also measures like trochlea depth [13, 14], trochlea asymmetry [14], anterior posterior measurements [15] and trochlea bump [16] can advantageously describe the changes that separate TD from normal anatomy. The sulcus angle has commonly been used to quantify the degree of trochlea dysplasia. The sulcus angle varies from proximal to distal. The sulcus angle is measured on axial MRI or CT at the most proximal slice, depicting cartilage on both medial and lateral trochlea facet. A common limitation of the sulcus angle are those knees where the medial facet is undeveloped and first appears relative distal, since leads to lack of recognition of TD. A recent study found the sulcus angle less reliable [17]. Those problems with defining TD and the shortage of good quality comparable studies with longer follow-up between trochleoplasty and alternative surgeries, makes the indications of trochleoplasty surgery debatable. The primary causes of restraint for trochleoplasty have been risk of complications and lack of healing of the cartilage flap, but these concerns have proved unfounded [18]. So when a symptomatic TD is present, and surgery is needed, the aim must be to normalize anatomy. Surgery may not only be reserved for patients with recurrent patellar instability but can also include patients with patella subluxation after first time patella dislocation, while others reserve trochleoplasty for revisions of patellar instability. In respect to indication for surgery for chronic © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_35 503
504 patellofemoral pain, only three studies have reported on this and still restraint must be recommended [19–21]. Biomechanical studies have spotted that TD affects the kinematics of the patellofemoral joint and negatively influence the stabilizing forces for the patella [16, 22, 23]. Reviews and metaanalysis have reported low rate of re-dislocations, high satisfaction, a mean reduction of pain and a low rate of complications following trochleoplasty [24–27]. Several technical variations of deepening trochleoplasty procedures have been published and the Arthroscopic deepening trochleoplasty (ADT) that is going to be explained here, is a variant based upon the thin thin flap Bereiter technique [21, 28, 31]. The ADT is less invasive and considered to have the same known advantages from other techniques based on minimal invasive surgery. The ADT is in comparison to the open technique, more demanding but also more precise due to the enlargement of the arthroscope. The open trochleoplasty is associated with the risk of arthrofibrosis, infection, prolonged pain and scar formation [32] and those complication have yet not been observed by the ADT method. When ether this is due to the minimal invasive surgery itself or a less restrictive postoperative regime is unclear. Though never reported in the scientific literature it well known that there is a risk of cartilage flap fracture during the open trochleoplasty procedure, and this is significantly reduced with the ADT. A case series after ADT in combination with MFPL reconstruction demonstrated results comparable with the results obtained for open trochleoplasty procedures combined with MPFL reconstruction [33]. Open trochleoplasty surgery is considered complex and only for experiences patellofemoral surgeons, and similar applies for the ADT and additional arthroscopic skills is needed. Training on cadaver knees is recommend, despite cadaver knees typically contains a V shaped trochlea with fragile cartilage, which means that the release of the cartilage flake can be unachievable, but nonetheless it’s important to practice portals and cartilage fixation technique. The cartilage release is more ease when the trochlea is shallow or convex and the cartilage is more elastic as in clinical cases. The L. Blønd purposes of the ADT procedure is reshape the trochlea groove into a more normal configuration and indirectly to unload the compressive forces in the PF joint by deepening the trochlea. Indirectly this provides osseous stability by creating a lateral trochlea wall. Another issue, can in cases with a medialized groove, be to lateralize the trochlea as this can help the tracking forces. Ideally the trochlea is made approximately 4.5 mm deep and the trochlear should be lateralized to approximate a more normal figure of 50% trochlear symmetry [34]. By lateralizing the groove the TT-TG is reduced [35]. In cases with instability is the ADT technique combined with MPFL reconstruction and eventually lateral release or lateral lengthening. The MPFL reconstruction is needed since the trochlea do not provide stability to the patella until there is sufficient overlap between trochlea and patella, and that means for the first degrees of knee flexion a patella stabilizing is needed to help the patella to entrance the groove correctly. In cases with chronic anterior knee pain without instability is there no need to reconstruct MPFL. This chapter will focus only on the ADT technique. 2 Indication The main indication for ADT is symptomatic patellar instability or severe chronic anterior knee pain in patients with severe trochlear dysplasia evaluated by MRI axial scans. The author’s preferred parameters for evaluation of the degree of trochlear dysplasia is the lateral trochlea inclination angle and the threshold is 9 degrees, when using the 2 image technique by Joseph et al. [10, 12]. Other radiologic measurements which are included in the evaluation is trochlear asymmetry, trochlear depth and anterior posterior measurements in relation to the width of the knee [9, 14, 15]. Clinically the patellar instability patients must have a positive reverse dynamic patella apprehension test at a minimum of 30 degrees of flexion [36]. Contraindications are relative and can be severe PF osteoarthritis and open growth plates. Smaller grade 4 cartilage lesions are not
Arthroscopic Deepening Trochleoplasty necessary a contraindication and healing of the damaged cartilage flake occurs. Open growth plates are relative contraindication. If the growing potential is nearing its end, meaning that the patients are close to the height of the parents and if the girls have had menstruation for more than a year, the procedure can be done safely. 3 Technique A tourniquet is avoided due to production of free radicals that theoretically can impair healing and cause increased inflammation. To reduce intraoperatively bleeding, reduction of leaks from the portals in combination with gradually elevation of the arthroscopic pump pressure can secure visualization. One dose of intravenous antibiotics is given preoperatively. Antithrombotic prophylactic treatment is considered in patients above the age of 40 years or in cases with a history of thrombotic complications. 3.1 Preparation and Portal Placement Initially a standard knee arthroscopy is done through two small standard anterior portals and the knee is inspected for other intraarticular pathologies. The quality of the trochlear cartilage is evaluated to assure that the procedure is technically possible. A superior portal placed as proximal as possible to reach an optimal view of the trochlea and this is placed just medial to the quadriceps tendon. In case of a suprapatellar plica, this have to be resected such as the visualization is not inhibited. By insertion of a hypodermic needle the correct placement is identified, and a switching stick is introduced in the same direction into the most proximal part of the suprapatellar pouch followed by introduction of the arthroscope. Preferable scope is 45degrees, but a 30- or 70-degree scope can be used as well. With the scope introduced in the suprapatellar portal, the position for the lateral suprapatellar portal is localized by the needle technique. Correct placement of this portal is 505 vital. The correct location is parallel to the proximal extent of the flat part of the trochlear groove in both the frontal and transversal planes, to give the right working angle for the instruments. A too distal or too posterior placement can be detrimental since it will not be possible to get create the correct lateral wall angulation. A too proximal portal can make it difficult to reach the most distal part of the trochlea. A 8 mm PassPort Button Canula (ArthrexInc. Naples, FL) is useful as a working portal (Fig. 1). 3.2 Creation of the Cartilage Flap A 90-degree radiofrequency device is introduced through the lateral suprapatellar portal, the synovium/periosteum is released from the area proximal to the trochlear cartilage. The release is continued as long proximal so a clear area is ready for both using the shaver burrs and for later placement of the proximal anchors when the flap shall be reinserted. The cartilage flap is then released by the use of respectively a 3- or 4-mm round shaver burr without a shield, and a lambotte osteotome. Initially the shaver burr is moved from medial to lateral and vice versa. The cartilage is undermined, and the progression of the shaver continues more and more distally beneath the cartilage (Fig. 2). As a supplement to the shaver, a straight and curved lambotte osteotome (6 mm 27 cm) is needed. By adding the osteotome, the bone resection at the most lateral part of the trochlea is minimized, helping to achieve a normal lateral trochlear wall to provide the patella with osseous stability (Fig. 3). The cartilage flap separation from bone is continued distally until the shaver meets the curvature approximately 10 mm from the femoral notch. Before this point is reached distally, it is recommended to change the 4 mm shaver burr to a smaller 3 mm burr, thereby minimizing the bone resection in the area close to the hinge of the cartilage flap. The release should be continued in the medial and lateral directions, otherwise the hinge of the flap will not become sufficiently elastic such to be able to fit into the new trochlea.
506 L. Blønd Fig. 1 This demostrates outside and inside view of the superior suprapatellar portal with the arthroscope introduced and the lateral superopatellar portal with a PassPort canula mounted 3.3 Formation and Shaping of a Deeper Trochlear Groove The aim is to achieve a 4.5 mm trochlear depth and a more lateral sulcus orientation of the new groove. Therefore, the groove needs to be deepened and centralized using shaver burrs. A PowerRasp (Arthrex Inc., Naples FL) can be useful for smoothening the bony surface of the lateral wall of the trochlea. Part of the trochlear dysplasia is the medialized groove, so the amount of lateralization of the new groove should reflect the increased TT-TG measured preoperatively. Part of TD is the so-called crossing sign, meaning that the groove entrance is localized anteriorly to the femoral shaft. Therefor is amount of bone resection for the deepening of the trochlea estimated during surgery by looking at the most anterior part of the femur, since the resection proximally should allow for a smooth transition between groove and anterior cortex of the femur. The new groove is trimmed with the shaver burr and/or PowerRasp according to the preoperative plan and a good lateral wall is aimed (Fig. 4). The cartilage flap needs to have sufficient elasticity to integrate into the new groove, to get in contact with the underlying bone and to achieve the correct trochlea shape. The flap elasticity is tested, by pressing the flap into the new deepened trochlea using a blunt instrument (Fig. 5). In cases where
Arthroscopic Deepening Trochleoplasty 507 Fig. 2 This demonstrate the initial release of the cartilage flap using a shaver burr the cartilage flap is too stiff, excessive bone on the rear side of the flap should be gently and gradually removed until the needed elasticity is reached. 3.4 Fixation of the Cartilage Flap With the arthroscope remaining in the superior medial portal, the fixation of the cartilage flap is started by placing a biocomposite 3.5 mm PushLock anchor (Arthrex Inc., Naples FL) with the eyelet loaded with a resorbable tape and a suture, so the end of the tape and sutures are equal in length (one tape—Vicryl 3 mm BP-1, V152G, Ethicon and one 1–0 suture Vicryl CT-2 plus, V335 H) or since the tape is about to being pulled out of production, alternatively multiple 1–0 suture Vicryl CT-2 plus, V335 H can be used. The anchor is placed distal to the cartilage hinge, just proximal to the notch, through the medial joint line portal. In order to achieve a 90 degree insertion angle of the anchor, the knee has to be flexed close to 45 degrees. A bone socket
508 L. Blønd Fig. 3 This demonstrate outside and inside use of the osteotome to guide the direction of the osteotomy and to reduce the bone loss most laterally for the anchor is initially drilled central in the most distal part of the trochlea, just proximal to the notch and still distally from the cartilage flap. After having introduced the anchor into the socket, one of the tape endings are grasped and brought out through the canula and loaded into another similar anchor. On the lateral side, based upon the hardness of the bone, the socket can be prepared using either a taping device or a burr, placed in a spot superior to the cartilage flap and lateral to the center of the groove. The tape is gradually tensioned thereby pressing the cartilage flap into the new groove, and the anchor is inserted into its position. With the anchor positioned, the tape is locked, and the excess is cut. Next the arthroscope is introduced through the superior lateral canula. The superior medial portal is in a similar way used for insertion of the next anchor. This should also be placed superior to cartilage flap and medial to the center of the groove. The cartilage flap is now sufficiently stabilized into the new trochlea groove (Fig. 6). In about 50% of the cases a gap between the cartilage flap and the new trochlea and this requires an additional anchor now loaded with the vicryl (Fig. 7). Obviously, co-morbities are treated as indicated, such as medial patellofemoral ligament insufficiency with MPFL reconstruction, distalizations of the tibial tubercle in cases of patella alta, de-rotational osteotomies in cases of torsional abnormalites, varising osteotomies etc. From a biomechanical point it should be stressed that when a MPFL reconstruction is done in conjunction to an ADT, following issues have to be taken into consideration. The axis of rotation around the femoral epicondylar axis, as described by Coughlin et al. [37], is affected due to the bone resection caused by the ADT. The distance (radius) from the center of rotation (the foot print in the epicondyle) to the resection area in the new groove is shortened. Consequently, both the native MPFL and the MPFL graft are relatively slack in extension. If this is not
Arthroscopic Deepening Trochleoplasty 509 Fig. 4 This demonstrate how the PowerRasp can help creating a smooth lateral wall of the new trochlea accommodated this can have a detrimental impact on the outcome. The MPFL insertion point are more optimally placed in a little further distal anisometrical position and should be fixed with the knee in the specific degree of flexion (approx 70 degrees), where the patella is placed in the unaffected trochlea area, otherwise the graft will become too tight in flexion and consequently leads to flexion problems resulting in over tensioning of the graft and compression of the PF articular cartilage. 4 Video Latest video demonstrating ADT can be found here: https://youtu.be/94BEtkhGS3o. 4.1 Postoperative Regime Immediately after the surgery the patients are allowed to do full range of movements and full
510 L. Blønd Fig. 5 This demonstrate how the elasticity of cartilage flap can be tested using stump instrument weight bearing. This regime has been practiced for the past 8 years without related complications. Postoperative rehabilitation is detailed in Table 1. 5 Results The author has conducted the ADT procedure in more than 150 knees with a median age of 20 (range 12–51). The formalized registration has ended due to GPDR issues. In seven cases were the indication severe chronic patellofemoral pain and no MPFL reconstruction was done. The surgery has in all cases been one-day surgeries. The results from the first 29 cases of ADT in combination with MPFL reconstruction have been published [28], in which significant improvements in Kujala and KOOS scores were observed with 93% satisfied with the outcome and 55% returning to sports. In all cases the preoperative range of movements or more have been achieved. A later smaller case series with similar results have been published as an abstract [38]. 6 Complications Two complications (DVT) have occurred. Eight patients have had further surgery. Three patients who had high TT-TG distances above 20 mm developed symptomatic subluxations postoperatively and were subsequently successfully
Arthroscopic Deepening Trochleoplasty 511 Fig. 6 This demonstrates how the cartilage flap in pressed into the new trochlear groove by the tape fixation corrected by medialization of the tibial tubercle. Those cases were all operated in the start of the series and at that phase and due to lack of knowledge, the new trochlear groove was not lateralized during the trochleoplasty procedure. Three patients also from the start of the series experienced pronounced postoperative anterior knee pain in flexion. On examination, tightness of the lateral retinaculum was found, indicating lateral hyper-pressure syndrome, and they all responded positively to a subsequent lateral release. This have resulted in a more liberal use of a subsequent lateral release. Since there have been no further cases developing symptoms of hyperpressure. One patient who already have had five operations, developed severe anterior knee pain due to degeneration of cartilage in the lateral part of the trochlear. At further examination increased femoral anteversion was recognized. The patients had undergone external rotational distal femoral osteotomy and tibial internal osteotomy elsewhere. This procedure worsened the situation. Case number seven has redislocated (by report) due to overlooked excessive femoral anteversion. 7 Discussion For the past fourteen years period the author has performed the ADT in more than 150 knees, with no cases of arthrofibrosis or infections, however
512 L. Blønd Fig. 7 This demonstrates a cases with the use of the extra vicryl sutures in order to provide extra fixation compared to Fig. 6 complication as mentioned above have occurred. Since the original paper was published in 2010, the procedure has undergone minor changes in addition to above mentioned. The superior lateral canula have been omitted, since it wasn’t necessary and the PowerRasp 4.0 mm 13 cm AR8400PR (Arthrex Inc., Naples FL) was successfully introduced in 2016 and this has helped smoothening the lateral wall of the new trochlear groove. The fixation method for the cartilage flap, with the use of absorbable tapes in combination with suture anchors, was adopted for the open trochleoplasty several years ago. The ADT has until now only been combined with osteotomy in a single case, where the a distalisation of the tibial tubercle was done due to significantly reduced patellotrochlea overlap [39]. In the primary study, a median VAS pain score of 3 was observed 24 h postoperatively, and this equalized the level of pain scores from MPFL reconstructions alone. Based on these findings and later observations, we have experienced that the combined ADT and MPFL procedure unproblematic and can be carried out as one-day surgery. In a follow-up study of a consecutive series of 29 knees in patients troubled by patella instability and treated by combined ADT and MPFL reconstruction, significantly improved median knee scores for all measured parameters with no re-dislocations were found [28]. These results have later been confirmed in a second follow-up study including 18 more knees [38]. Based on the theory that the trochleoplasty doesn’t provide sufficient stability to the patella in the initial 20 degrees of flexion, concomitant MPFL reconstructions are more frequently a concomitant procedure with trochleoplasty as is evident in four recent series of trochleoplasty procedures [21, 40–43]. A significant relationship between trochlea cartilage lesions and trochlea dysplasia has been documented [5, 44, 45]. Neumann et al. observed, in a 50-month follow-up of 46 patients after trochleoplasty, that in a subgroup of 26 patients with radiographic degenerative changes or intraoperative findings of chondromalacia, that there were comparable subjective post-operative improvements in this group, compared to the patients without chondral changes [46]. Those findings have encouraged the author to include patients for ADT with more degenerative cartilage changes in the trochlea and the results have been positive.
Arthroscopic Deepening Trochleoplasty 513 Table 1 The physiotherapy guided rehabilitation program after arthroscopic deepening trochleoplasty Day Goal Exercise 0–1 Range of motion (ROM): CPM machine Ankel pumps Physical Therapy RICE: Rest, Compression, Ice 2–3 day: 30 min. Elevation 2–3 ROM, Focus Extension Heel slides, ankle pumps, seated heel slides PROM, retrograde massage, Pain control Strength Isometric quadriceps, VMO Maybe NMES (neuromuscular stimulation 30–40 Hz) Gait FWB (full weight bearing) with 2 crutches Gait training; heel-toe. AlterG Anti‐Gravity: 40–50% WB, 0.5–1 km/hr, 4–5 incline. 5–10 min RICE: Rest, Compression, Ice 2–3 day: 30 min. Elevation 4–7 Electrotherapy Vascularization 8 Hz and pain relief (Endorfin 5 Hz, or TENS) Laser Level IV laser for pain and swelling ROM: Focus Extension Heel slides, ankle pumps, seated heel slides PROM Strength Isometric quad sets, Assisted straight leg raises: FLX, ABD, EXT, Terminal knee extension (TKE), Bridge NMES (neuromuscular stimulation 30–40 Hz) Stretching Hamstring supine with strap Quad: prone with strap Calf: standing on step, push heel down Gait Weight bearing exercises Stationary bike High seat, slowly back and forth for ROM, do not force the knee around Manual therapy Prioprioception Gait traingn using two crutches AlterG Anti‐Gravity: 50% WB, 1–2 km/hr, 2–3 incline. 10–15 min Retrograde massage, Scar massage with vitamin-e, Patella mobes Superior-inferior. No Medial‐lateral with MPFL reconstruction for 4 wks Standing on 1 leg on even surface, if able to stand without knee extension dysfunction then close eyes Electrotherapy Vascularization 8 Hz and pain relief (Endorfin 5 Hz, or TENS) Laser Level IV laser for pain and swelling (continued)
514 L. Blønd Table 1 (continued) Day Goal Exercise Physical Therapy 1–4 wks ROM: Focus Extension Heel slides, ankle pumps, seated heel slides, prone FLX-EXT with strap If problems with getting full knee extension, try low load long duration stretch prone with rubber band 5–10 min daily PROM Strength Isometric quad sets, Assisted straight leg raises: FLX, ABD, EXT, Terminal knee extension (TKE), Bridge, mini squat, Heel glides on cloth supine NMES (neuromuscular stimulation 35–40 Hz) AlterG Anti-Gravity: 50% WB, 0 km/hr, 0 incline: bilateral heel lifts (progres to eccentric and unilateral), mini squat, single leg stance Stretching Hamstring supine with strap Quad: prone with strap Calf: standing on step, push heel down Manualstretching Gait Heel-Toe with 1–2 crutches Gait training using 1–2 crutches AlterG Anti-Gravity: 50% WB, 2–3 km/hr, 2 incline. 15–20 min Stationary bike High seat, slowly back and forth for ROM, try to cycle around back and forth with resistance: 10–15 min Manualtherapy Prioprioception Retrograde massage, Scar massage with vitamin-e, Patella mobes Superior-inferior No Medial-lateral with MPFL reconstuction for 4 wks Knee mobilisering: tibia A–P mobes, general mobes for FLX/EXT gr I–II Standing on 1 leg on even surface, if able to stand without knee extension dysfunction then close eyes Electrotherapy Vascularization 8 Hz and pain relief (Endorfin 5 Hz, or TENS) Laser Level IV laser for pain and swelling (continued)
Arthroscopic Deepening Trochleoplasty 515 Table 1 (continued) Day Goal Exercise Physical Therapy 4–6 wks ROM: Full Extension. Fleksion 90–120 Heel slides, seated heel slides, prone heel to buttocks with strap PROM Strength Isometric quad sets, straight leg raises (SLR): FLX, ABD, EXT, Terminal knee extension (TKE), Bridge, mini squat, Heel glides on cloth supine NMES (neuromuscular stimulation 50–70 Hz) AlterG Anti-Gravity: 50–80% WB, 0 km/hr, 0 incline: bilateral heel lifts (progres to eccentric and unilateral), mini squat, single leg stance Stretching Hamstring supine with strap Quad: prone with strap Calf: standing on step, push heel down Manual stretching Gait Gait training without crutches Gait training without crutches: heeltoe AlterG Anti-Gravity: 50%–80% WB, 2–4 km/hr, 2–3 incline. 15–20 min Stationary bike High seat, slowly back and forth for ROM, do not force the knee around Manual therapy Retrograde massage, Scar massage with vitamin-e, Patella mobes Superior-inferior No Medial-lateral with MPFL reconstuction for 4 wks Prioprioception Standing on 1 leg on even surface, if able to stand without knee extension dysfunction then close eyes Electrotherapy Vascularization 8Hz and pain relief (Endorfin 5Hz or TENS) Laser Single leg stance in trampoline, ball catch Level IV laser for pain and swelling (continued)
516 L. Blønd Table 1 (continued) Day Goal Exercise Physical Therapy 6–? Wks Progression as tolerated ROM: Full Extension. Fleksion 135–140 Heel slides, seated heel slides, prone heel to buttocks with strap PROM Strength Isometric quad sets, SLR: FLX, ABD, EXT (should be able to hold knee in full extension, otherwise cont. Ass), SLR with rubberband, Terminal knee extension (TKE), Bridge with leg lifts, wall squat, Heel glides on cloth supine Progression: standing slides on cloth, side step without and with rubberband, lunges, squats. Machines: Leg press, squat in smith rack, leg curls Free weights when full AROM and able to hold knee in full extension with SLR NMES (neuromuscular stimulation 50–70 Hz) AlterG Anti-Gravity: 50–80% WB, 0 km/hr, 0 incline: bilateral heel lifts (progress to eccentric and unilateral), mini squat, single legstance Stretching Hamstring supine with strap Quad: prone with strap Calf: standing on step, push heel down Manual stretching Gait Gait training without crutches Gait training without crutches: heeltoe AlterG Anti-Gravity: 50%–80% WB, 2–4 km/hr, 2–3 incline. 15–20 min Stationary bike Normal cycling on stationary bike, able to bike outside about 3 months after surgery if full AROM and Isometric strength normal compare to opposite leg Manual therapy Prioprioception 8 Retrograde massage, Scar massage with vitamin-e, Patella mobes Superior–inferior. Medial-lateral gr I–II Knee mobilisering: tibia A–P mobes, general mobes for FLX/EXT gr I–II Standing on 1 leg on even surface, if able to stand without knee extension dysfunction then close eyes Single leg stance in trampoline, ball catch. Mini jog on trampoline Electrotherapy Vascularization 8 Hz and pain relief (Endorfin 5 Hz, or TENS) Laser Level IV laser for pain and swelling Conclusion This is a description of the ADT, a technique that has been slightly optimized since the original paper. The technique has been found to be a reproducible and a safe technique with limited serious complications. Based upon personal communications other centers have implemented the technique achieving similar results. Clinically the AT has been found to give significant improvements in postoperative Kujala and
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Lengthening Trochleoplasty Roland M. Biedert 1 Introduction To understand the indications for a lengthening trochleoplasty it requires knowledge of the pathoanatomy of a too short proximal lateral trochlea as a specific form of trochlear dysplasia [1–4]. Our insight for the shape and kinematics of a too short lateral trochlea as well as the main indication to perform a lengthening trochleoplasty have evolved continuously during the last 20 years. The Albee procedure initiated our attention to the importance of the proximal lateral part of the trochlea [5]. Our key finding was that not only the height of the lateral condyle but, in particular, also the length of the lateral trochlea is most important for lateral patellar stability. Albee was the first to attribute an important role to the lateral condyle and trochlea in patellar stability [5]. He described the external condyle to be on the horizontal plane much below that of the internal condyle. He believed that the external condyle is not only flat, but also relatively further back than normal, mentioning also the importance of the rotation of the lower end of the femur. Since the soft tissue procedures have been R. M. Biedert (&) Orthopaedic Surgery and Sports Traumatology, Sportsclinic#1, Wankdorf Center, Papiermühlestrasse 73, CH-3014 Bern, Switzerland e-mail: r.biedert@bluewin.ch far less successful in securing the patella, Albee lifted the external femoral condyle with a wedge bone graft to block the recurrence of patellar dislocation. With this, the first reconstruction on the lateral trochlear facet to improve patellar stability was performed [5]. The procedure had the desired effect on stability, but the additional bony prominence caused problems by overtightening the lateral retinacular structures or by increased pressure across the lateral facet of the patellofemoral articulation with the potential to generate pain or osteoarthritis. Over time, this procedure fell out of favour. In addition, rising of the lateral edge of the trochlea did not correct an abnormal length of the lateral trochlea. Later, Brattström also emphasized the importance of the lateral facet of the trochlea as resisting lateral force against patellar instability [6]. He described a low lateral condyle and increased sulcus angle in patients with habitual patellar dislocation [6, 7]. Various biomechanical studies confirmed these descriptions [8–10]. The shape of the femoral trochlea and its relationship to the patella dictate the patellofemoral kinematics [2, 11]. The normal articular surface of the trochlea consists of the lateral and medial facets of the femoral sulcus and is defined by different criteria in the proximal–distal, medio-lateral, and antero-posterior direction [12]. The normal trochlea is concave and deepens from proximal to distal. It is longest laterally and shortest on the medial side in the proximal–distal direction (Fig. 1) [2, 12–14]. The deepened © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_36 521
522 Fig. 1 Normal articular morphology and supero-lateral length of the trochlea (anterior view, left knee) trochlear groove separates the lateral facet from the medial part. In the antero-posterior measurements, the most anterior aspect of the lateral condyle is normally higher than the medial condyle and the deepest point is represented by the center of the trochlear groove [15]. The large lateral facet in extension is the feature that must “capture” the patella when the knee starts to flex, to ensure that it is guided into the trochlear groove, and to achieve patellofemoral stability [8, 9]. Normally, the contact between the articular surface of the trochlea and the articular cartilage behind the patella is about one third of the length of the patellar cartilage in extension [1, 2, 13]. In this normal situation, quadriceps muscle contraction pulls the patella proximally, but without lateral subluxation. The patella is still guided by the most proximal articular lateral trochlea. Trochlear dysplasia is defined as variable abnormality of shape and depth of the trochlear groove and alters the patellofemoral congruency [14, 16]. It represents an important pathologic articular morphology and a strong risk factor for permanent patellar instability [3, 14, 17, 18]. R. M. Biedert Different forms of trochlear dysplasia are described, such as decreased depth of the groove, decreased inclination of the lateral facet, flat trochlea, trochlear bump (anterior translation of the trochlear floor), and hypoplasia of the medial trochlea [5, 14, 16, 18–20]. Most forms of trochlear variations are located at its proximal extent and cause decreased bony stability in the trochlear groove. As a result, the patella is poorly guided osseously at the entrance into the trochlea in early knee flexion and lateral instability may occur. Various classifications for evaluating trochlear dysplasia are described using radiographs or computed tomography images, the best known with the four-grade classification by Dejour [14]. However, these classifications describe the forms of dysplasia only in the axial and sagittal planes, the coronal view is not considered [1–3, 14]. As the shape of the articular trochlea can also be dysplastic in the coronal plane, we paid increased attention to the too short proximal-lateral extension of the trochlea causing dynamic proximallateral patellar instability during the last two decades [1–4] (Fig. 2). Decades later, the concept of deepening the dysplastic trochlea was published and first carried out by Masse in 1978 [21]. This technique has been continuously modified and standardized by H. Dejour and Bereiter to eliminate possible complications [14, 19]. Today, deepening trochleoplasty is a widely used complex surgical treatment to improve patellar stability with precise indications, but also with late effects and complications [20, 22]. Deepening of the trochlea mainly improves the guidance of the patella from the point of entry into the new sulcus distally, but towards proximally it has no influence. Neither shape nor length of the proximal lateral articular trochlea are changed with this procedure. Our findings and observations of a dynamic proximal-lateral patellar instability could not be explained by the concept with the four types of trochlear dysplasia. The inclusion of the coronal plane was missing. Therefore, the first goal was to define a reliable method to assess the proximal lateral cartilagineous extension of the lateral
Lengthening Trochleoplasty 523 facet. This discrepancy between a well-centered patella under relaxed conditions and the dynamic supero-lateral instability caused by quadriceps muscle contraction confirms the proximal lateral patellar instability. This type of patellar instability may also be depicted by manual examination in complete extension of the knee. Manual pressure from medial to lateral would cause subluxation, discomfort and often pain to the patient. With increasing knee flexion, the patella shifts medially entering into the more distal and normal part of the trochlear groove and becomes therefore stable. Stability and gliding tests to medial are normal. It must be considered, that other pathologic factors, such as patella alta, hyperlaxity, rotational abnormalities, excessively tight lateral retinaculum, and increased TT-TG distance may be present at the same time and influence the physical examination. Fig. 2 Too short lateral articular trochlea (proximal end marked by arrow) in relation to the medial facet and the normal trochlear sulcus (lateral view, left knee) trochlea. With the application of the new lateral condyle index (LCI) using sagittal MR images it became possible to measure the proximal length of the lateral trochlea and to document this type of trochlea dysplasia [2]. With this, the importance of the shape and length of the proximal lateral trochlea was confirmed [1, 2]. 2 Physical Examination The most important and specific finding during physical examination is the dynamic superolateral patellar instability [1, 4, 13]. Under relaxed conditions, the patella is well centered in the trochlear groove (Fig. 3A). Muscular contraction of the extensor mechanism leads to proximalization and lateralisation of the patella resulting in dynamic supero-lateral subluxation (Fig. 3B). The lateral subluxation of the patella is caused by the absence of the osteochondral opposing restraint of the short lateral trochlear 3 Imaging 3.1 Radiographs Patients with a too short lateral facet of the trochlea have mostly normal radiographs. Specific radiographic features of trochlear dysplasia in the true lateral view, such as the crossing sign, supratrochlear spur, double contour, or lateral trochlear sign are missing or only present in combination with other trochlear abnormalities. In addition, the different radiographic indices to assess patellar height are normal. 3.2 MR Measurements MR images represent the best modality to assess the proximal part of the trochlea [1, 2, 13, 23, 24]. According to this, the LCI is the preferred diagnostic MR measurement tool with good reliability in patients with suspected too short lateral facet [2]. MR measurements are performed with the knees placed in a standard knee
524 (A) R. M. Biedert (B) Fig. 3 A Well-centred patella under relaxed conditions. B Dynamic supero-lateral patellar subluxation (arrow) caused by muscle contraction coil in extension, the foot in 15° external rotation, and the quadriceps muscle consciously relaxed [1, 2, 4]. All measurements are performed on sagittal images. Firstly, on sagittal images showing the anterior cruciate ligament, the longitudinal axis (Ca) of the femoral shaft is defined by drawing a proximal and a distal circle (C1 and C2, respectively) (Fig. 4A). Secondly, the most lateral sagittal image on which the articular cartilage of the lateral condyle still can be seen is selected. The measurements include different parameters (Fig. 4B) [1, 2, 4]. The length of the anterior articular cartilage of the lateral trochlea (a) is calculated using as a reference to the length of the posterior articular cartilage of the lateral condyle (p). For each individual subject p is always considered to be 100%. The variable length of a is calculated in percentages with regard to p. The LCI compares the length a with the length p and is expressed in percentages [1, 2, 4]. The mean value of the LCI in a normal population without any patellofemoral complaints is 93% [1, 2, 4]. Therefore, an anterior length of the lateral articular facet of the trochlea with index values of 93% or more, compared with the length of the posterior articular cartilage, is considered normal. LCI values of less than 93% are considered pathologic, and values of 86% or less confirm the presence of a too short lateral facet (Fig. 5). LCI values between 86 and 93% need additional assessment, such as patellotrochlear index or radiographic patellar height measurements, to document or exclude patella alta [13]. Combinations of a short proximal-lateral trochlea and patella alta are possible (Fig. 6A and B). 4 Differential Diagnosis The dynamic supero-lateral patellar instability must be differentiated from other diagnoses. 4.1 Patella Alta Specifically, differentiation from patella alta may be difficult [25, 26]. The most important differences in patients with a too short lateral trochlea are: normal patellar height, no patellar
Lengthening Trochleoplasty 525 (A) C1 Proximal circle in the femoral shaft. C2 Distal circle in the femoral shaft. Ca Central axis Fig. 4 A. MR measurements [2, 3, 16] (Reused with permission from Springer. From: The lateral condyle index: a new index for assessing the length of the lateral articular trochlea as predisposing factor for patellar instability. Int Orthop. 2011; 35(9):1327–31). B MR measurements [2, 3, 16]. (Reused with permission from Springer. From: Lengthening osteotomy with or without elevation of the lateral facet. In: Dejour D, Zaffagnini S, Arendt EA (Eds) Patellofemoral pain, instability, and arthritis. Springer, 2020) subluxation under relaxed conditions, and immediately improved patellar stability at the beginning of knee flexion. However, it must be considered that both pathologies can occur in combination. 4.3 Lateral Pull Sign The lateral pull sign occurs due to soft tissue abnormalities (atrophy medially, hypertrophy laterally) by missed osteochondral opposing force on the lateral trochlear facet [29]. The LCI is normal. 4.2 J-Sign 4.4 Hyperlaxity The J-sign describes an excessive lateral translation of the patella in terminal knee extension. The patella disengages from the intertrochlear groove caused by excessively tight lateral retinaculum [27, 28]. As most important difference, this lateral translation occurs when the knee is extended from 90° of flexion to full extension. General hyperlaxity may also be a cause of lateral patellar instability. Applied load at full extension may show increased lateral patellar mobility. With hyperlaxity, the Beighton score is =<4 out of 9. Passive hyperextension of the knee of 10° or more is present [27, 30].
526 R. M. Biedert (B) d Baseline distal condyle (perpendicular to Ca) 1 Superior most aspect of the anterior cartilage of the lateral condyle 2 Superior most aspect of the posterior cartilage of the lateral condyle a Length of the anterior articular cartilage of the lateral condyle (red line) p Length of the posterior articular cartilage of the lateral condyle (blue line) Fig. 4 (continued) 4.5 Apprehension Test 5 The patellar apprehension test is performed in 20° to 30° of knee flexion under relaxed conditions [3, 4, 27]. A positive test is when decreased medial stability allows increased lateral glide. In contrast, the test for patients with a too short lateral trochlea are performed in extension and the supero-lateral patellar instability is caused by muscle contraction. Surgery 5.1 Preoperative Planning Surgery aims to correct the underlying pathologic morphology. Considering this, lengthening trochleoplasty is indicated when a too short lateral trochlea is documented (clinically and with MRI) and when the patients remain symptomatic
Lengthening Trochleoplasty 527 Dotted red line: length of the anterior articular cartilage of the lateral condyle Dotted blue line: length of the posterior articular cartilage of the lateral condyle Fig. 5 MR measurement with too short anterior articular cartilage of the lateral facet of the trochlea. The LCI is 77% after conservative treatment. A clear indication for lengthening trochleoplasty is given when the LCI is 86% or less. Lenghtening trochleoplasty is designed to create a longer proximal extension of the lateral trochlear facet to improve the contact within the patellofemoral joint, both relaxed and under muscle contraction. A longer lateral trochlear facet is the feature that must “catch” the patella in extension before the knee starts to flex, to ensure that it is guided and shifted medially into the more distal trochlear groove. Normally, the overlapping between the articular surface of the trochlea and the articular cartilage of the patella is about one third of the length of the patellar cartilage (measured using the patellotrochlear index) [13]. This value is helpful both in planning (using MRI) and during surgery to determine how much lengthening to proximal should be performed. 5.2 Lengthening Using a short parapatellar lateral incision of about 5 cm length, the superficial retinaculum is localized [1, 3, 4]. It is longitudinally incised 1 cm from the border of the patella and carefully separated from the oblique part of the retinaculum in the posterior direction to allow lengthening of the lateral retinaculum at the end of surgery if needed. After incision of the synovial membrane, the patellofemoral joint is open. The proximal shape and extension of the lateral facet of the trochlea and the length of the articular cartilage are assessed with regards to the length of the sulcus and the medial facet of the trochlea. The presence of a too short lateral articular facet is reconfirmed (Fig. 7A). In this situation, the patellotrochlear overlap is decreased (less than one third). The existing overlap allows the
528 Fig. 6 MR measurements with too short anterior articular cartilage of the lateral facet of the trochlea A and patella alta B in the same patient R. M. Biedert (A) LCI of 76% (B) Patellotrochlear index: 15%, too long patellar tendon (>56mm), Caton-Deschamps index: 1.3 calculation of lengthening of the lateral facet. The overlap should be about one third at the end, measured in extension (0° of flexion) [1, 2, 4, 13]. The incomplete lateral osteotomy is performed at least 5 mm from the cartilage of the trochlea to avoid necrosis or breaking of the lateral facet. The osteotomy starts at the end of the cartilage and is continued approximately 1 to 1.5 cm to distal into the femoral condyle and to proximal into the femoral shaft, always according to the calculated lengthening and planned patellofemoral overlapping (Fig. 7B). The osteotomy is opened carefully with the use of a chisel. Small fractures of the distal cartilage may occur and have no consequences; however sharp edges must be smoothed. Elevation above the maximum height of the lateral trochlea should be avoided to prevent hypercompression. Cancellous bone (obtained through a small cortical opening from the posterior aspect of lateral femoral condyle) is inserted into the osteotomy site and impacted (Fig. 7C). Additional fixation is possible using resorbable sutures. To finish, the synovial membrane is adapted and the lateral retinaculum reconstructed in about 60° of knee flexion to avoid overtensioning.
Lengthening Trochleoplasty 529 (A) Too short lateral articular facet of the trochlea (arrow) . (B) Completed lengthening osteotomy with inserted cancellous bone (C) Amount of lengthening (arrow: end of the original trochlea; dotted arrow: new end). Increased patellofemoral overlap Fig. 7 Lengthening trochleoplasty. (Reused with permission from Springer. From: Osteotomien. Orthopäde. 2008; 37:872–883)
530 R. M. Biedert (A) Preoperative MR measurement with too short anterior articular cartilage of the lateral facet of the trochlea (red arrow). The LCI is 76%. Decreased patellofemoral overlap (B) Postoperative MR measurement with lengthened anterior lateral facet of the trochlea (green arrow). The LCI is 98%. Increased patellofemoral overlap Fig. 8 Assessment of lengthening trochleoplasty 5.3 Postoperative Care Physical therapy starts immediately after surgery and is continued until normal knee function is regained. Partial weight bearing (20 kg) is recommended for 3 to 4 weeks to avoid hypercompression of the osteotomy. Range of motion is limited (0°–90°) during the 1st week to decrease swelling and pain. Continuous passive motion starts immediately to improve the patellofemoral gliding mechanism. Bicycling and swimming are allowed after 2 to 3 weeks and after complete wound healing. Sports activities without any restriction are permitted after 3 months. The overall recovery time can be expected to be about 4 months (Fig. 8A and B).
Lengthening Trochleoplasty 531 5.4 Complications The risk for complications is low and include deep vene thrombosis, infection, scar formations, and knee stiffness. The most important complications specific to the described surgery are small fractures and iatrogenic chondral injuries. Necrosis of the partially detached lateral femoral condyle or breaking was never noted. • • • 6 Results Clinical results are generally good and patella stability is improved. Due to the relatively small number of cases, a prospective outcome study with a control group was not possible so far. 7 Conclusions The too short lateral articular trochlea in its proximal extend is another relevant factor for lateral patellar instability and represents a rare form of trochlear dysplasia. Lengthening trochleoplasty is indicated in patients with dynamic supero-lateral patellar instability due to a too short lateral articular facet not responding to conservative treatment. The LCI is the most reliable and reproducible method for assessing the length of the lateral trochlea and to depict exactly the patients suffering from this pathology. Index values of less than 86% confirm the presence of a too short lateral facet. Lengthening trochleoplasty improves the supero-lateral contact between the trochlear facet and the distal patella. This maintains patellar stability against lateral subluxation under muscle contraction. 8 Take Home Messages • The too short lateral articular trochlea is another relevant factor for lateral patellar • instability and represents a rare form of trochlear dysplasia in the coronal plane. The discrepancy between a well-centered patella under relaxed conditions and the dynamic supero-lateral instability caused by quadriceps muscle contraction confirms the proximal lateral patellar instability. The lateral condyle index is a reliable measurement method on sagittal MRI to assess the length of the lateral trochlea Index values <86% confirm a too short lateral trochlear facet. Lengthening trochleoplasty represents the tailored surgical treatment to correct this specific type of dysplastic trochlea. References 1. Biedert RM. Trochlear lengthening osteotomy with or without elevation of the lateral trochlear facet. In: Zaffagnini S, Dejour D, Arendt EA, editors. Patellofemoral pain, instability, and arthritis. Berlin Heidelberg: Springer-Verlag; 2010. p. 209–15. 2. Biedert RM, Netzer P, Gal I, Sigg A, Tscholl Ph. The lateral condyle index–a new index for assessing the length of the lateral articular trochlea as predisposing factor for patellar instability. Int Orthop. 2006; 35:1327–31. 3. Biedert RM. Osteotomies. Orthopade. 2008;37 (9):872–83. 4. Biedert RM. Lengthening osteotomy with or without elevation of the lateral trochlear facet. In: Dejour D, Zaffagnini S, Arendt EA, editors. Patellofemoral pain, instability, and arthritis. Berlin Heidelberg: Springer-Verlag; 2020. p. 335–41. 5. Albee FH. The bone graft wedge in the treatment of habitual dislocation of the patella. Med Rec. 1915;88:257–63. 6. Brattstroem H. Shape of the intercondylar groove normally and in recurrent dislocation of the patella. A clinical and x-ray-anatomical investigation. Acta Orthop Scand. 1964; Suppl 68:1–148. 7. Zaffagnini S, Pizza N, Del Fabbro G, et al. Anatomic instability factors: principals and secondary for patellar instability. In: Dejour D, Zaffagnini S, Arendt EA, editors, et al., Patellofemoral pain, instability, and arthritis. Berlin Heidelberg: Springer-Verlag; 2020. p. 167–81. 8. Amis AA. Patellofemoral joint biomechanics. In: Biedert RM, editor. Patellofemoral disorders. Chichester: John Wiley & Sons, Ltd.; 2004. p. 37–53.
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Tibial Tubercle Osteotomy in Patients with Patella Supera or Infera Joan Carles Monllau and Enrique Sanchez-Muñoz 1 Historical Introduction The patella is a sesamoid bone located in the anterior part of the knee and being part of its extensor mechanism. It grows the leverage that the quadriceps tendon exerts on the tibia by increasing the angle at which it acts. In conformity with its sagittal location, the patella can be classified as either alta (supera) or baja (infera). The alta is defined as an abnormally high-riding patella in relation to the femur and the baja as an abnormally low-lying patella. Blumensaat [1] first described a practical radiographic technique for measuring patellar height. Since then, several other radiographic measurements have been proposed. The Caton-Deschamps index (CDI), a ratio between the length of the patellar articular surface and its distance from the tibia, has been J. C. Monllau (&) Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain e-mail: jmonllau@psmar.cat Catalan Intitute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain Universitat Autònoma de Barcelona (UAB), Barcelona, Spain E. Sanchez-Muñoz Knee Unit, Department of Trauma and Orthopaedic Surgery, Toledo University Hospital, Toledo, Spain found one of the most reproducible. It has a cutoff value of 1.2 [2]. Patella alta is significantly associated with patellar dislocation. To address the problem, tibial tubercle osteotomy (TTO) with distalization is an effective technique that decreases patellar height, thereby favoring the earlier engagement of the bone in the trochlea during knee flexion movement. In that way, it reduces the risk of dislocations [3]. However, the indication for this procedure remains controversial among orthopaedic surgeons as it can increase patellofemoral contact pressure, which leads to anterior knee pain and chondral degeneration [3, 4] along with loss of fixation, impairment of bone healing, and fractures. Patella baja is the opposite of patella alta. It is often associated with restricted range-of-motion, crepitations, and retropatellar pain. Those conditions are probably due to its constant engagement in the trochlea. Patella baja sits too low down. In that position, it causes significantly increased patellofemoral contact pressures [5]. That increased wear and tear to the articular cartilage, and eventually patellofemoral osteoarthritis. Patella baja can be a congenital condition with a too short patellar tendon (PT). However, it is often caused by tendon scarring after trauma (Fig. 1) or surgical procedures like patellar tendon harvesting for an ACL reconstruction or a total knee replacement. Much less frequently, it can be the result of a tibial tubercle transfer before the closure of the physis. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_37 533
534 J. C. Monllau and E. Sanchez-Muñoz Fig. 1 AP and lateral-view radiograph of left knee showing a significant posttraumatic patella baja Treatment strategies for sagittal patella variants are still poorly explored. Therefore, further study in that area is warranted. The aim of this chapter is to present some techniques to address these problems based on the author’s experience. 2 Indications and Contraindications 2.1 Patella Alta The indications for TTO with distalization have not been fully defined. Moreover, they depend on multiple factors. In general, the indication of surgery is based on measurements of patellar height in skeletally mature patients. Several measurements have been introduced over time. In the author’s experience, the Caton-Deschamps index is the most useful among them. Patella alta is defined as a CDI of more than 1.2. However, surgical treatment is not regularly recommended until the ratio is more than 1.4 [6]. In case of patellar instability, MPFL reconstruction should also be considered as a crucial part of the procedure since this ligament is a primary restraint to lateral patellar dislocation. Yet, patellar instability is the result of several anatomical factors that include trochlear dysplasia and lateralized tibial tuberosity (TT) that should also be corrected in some circumstances. While an increased (more than 20 mm) tibial tuberosity-trochlear groove (TT-TG) distance [9] correction can be easily added to the index procedure by medializing its bony attachment, the decision to perform a trochleoplasty can be harder as the procedure is much more delicate and there is no clear cut-off value. 2.2 Patella Baja Patella baja is defined by a CDI of 0.6 or less or and Insall-Salvati index of less than 0.8 or a difference in the length greater than 15% in comparison to the contralateral side [7]. Lengthening of the patellar tendon is indicated in patients with symptomatic patella baja not responsive to conservative treatment for more than 3 months [7, 11]. The surgical options for patella baja include the excision of the lower
Tibial Tubercle Osteotomy in Patients … third of the patella, lengthening of the patellar tendon with a PT plasty, reconstruction of the patellar tendon using tendon allografts and proximalization TTO, or a combination of the all those procedures [7, 10, 11]. When associated with other conditions like arthrofibrosis and soft-tissue adhesions between the PT and proximal tibia, those pathologies should also be addressed to arrive at good outcomes [10, 11]. If patella baja is associated with a total knee replacement (TKR), a differential diagnosis with pseudo patella baja is advised as the latter condition needs a different approach from patella baja [12]. 3 Surgical Technique, Tips and Tricks 3.1 Patella Alta TTO with distalization is performed under spinal anaesthesia. A tourniquet is placed high on the thigh (although its use is optional) and the patient is positioned supine with the surgical knee at 90º flexion, with the help of a foot stopper. An incision of approximately 6 to 8 cm is made just distal to the knee, directly over the tibial tuberosity. After identifying the patellar tendon attachment and marking the osteotomy cut with 2 Kirschner wires, two 4.5 mm holes are drilled on the anterior cortex of the tibial tuberosity for later lag-screw compression fixation of the osteotomized bone. Afterwards, the osteotomy (some 6 cm in length and 8 mm deep) is performed with the help of an oscillating saw and osteotomes. The cut is done from medial to lateral and then the bone block is shifted downwards as much as necessary, according to a prior calculation, either reducing the bone block of the tibial tuberosity or removing some more cortical bone in the distal part of the osteotomy. The detached tibial tuberosity is then fixed back in its new position using two 4.5 mm compression lagscrews (Fig. 2). Additionally, to reduce the PT length, two anchors are positioned in the upper part of the tibial osteotomy site and the distal patellar tendon is sewn and fixed to the bone. 535 This tenodesis shortens the whole length of the PT, otherwise the CD index is normalized but the Insall-Salvati index remains the same (as the tendon maintains its length unchanged). Post-operatively, partial weightbearing is allowed with two crutches, wearing a brace for the first couple of weeks. Then, weightbearing status is gradually increased. The knee is checked with X-rays, and when the healing of the bone is seen to be well under way (normally by about 6 weeks) in them, then the brace and subsequently the crutches are discarded. 3.2 Patella Baja The aim of the surgical procedure is to proximalize the patella. Several techniques have been proposed to that end. They include a transposition of the tibial tubercle and some variants of patellar tendon lengthening. However, there is currently no gold standard for treating patella baja [7–12]. The transfer of the tibial tubercle is a popular method to restore patellar height and has the advantage of permitting early mobilization, which may help in preventing the recurrence of the condition [8]. However, it does not consider the underlying cause. Additionally, changing the extensor mechanism attachment point nearer to the joint line might cause potential dysfunction of the quadriceps muscle as a result of detachment of the PT [7]. Lastly, although the patellar position can be normal at the end of the surgical procedure, the PT length will remain the same (Fig. 3). Our preferred technique consists of a partial TTO proximalization with a modified Z plasty of the patellar tendon [7]. The anaesthesia, patient positioning and surgical approach are the same as previously described for patella alta. A midline incision from the distal third of the patella to the TT that goes along the midline of the patellar tendon is made. In a Z-shape, two flaps are developed, the medial one including an osteotomized bone block made from the medial portion of the TT, that is distally detached, and the lateral one including a periosteal flap proximally
536 Fig. 2 A Surgical view, performing the TT osteotomy with an oscillating saw. B After removing some cortical bone in the distal part of the osteotomy the TT is reduced and fixed back in its new position using two lagscrews. C Image intensifier sagittal view showing the final result J. C. Monllau and E. Sanchez-Muñoz A B detached from the patella. The medial flap is moved proximally while the lateral one is moved distally, both at the same distance (Fig. 4). After checking the X-rays to make sure that the adequate patellar position is reached. With the knee at 90º of flexion, the lateral flap is proximally fixed at the patella with suture anchors while the bone block of the medial flap is fixed at the tibia with a 3.5 mm cortical screw. Finally, the 2 reins of the patellar tendon are sutured with #2–0 interrupted suture. In cases of high-risk of recurrence or bad tissue quality, augmentation with an Aquiles allograft with a bone block is recommended (Fig. 5).
Tibial Tubercle Osteotomy in Patients … C 537 4 Results Patellar instability is the most usual indication for TTO, usually in association with other procedures [9, 13]. Good outcomes have been reported after a distalization TTO with associated medialization, if needed, to correct CDI, decrease pain and improve functionality [9, 13]. Addressing concomitant pathologies is mandatory to obtain good outcomes, with and increased risk of persistent pain associated to grade 3 and 4 ICRS cartilage lesions [13]. Regarding the proximalization TTO, current evidence is scarce [9]. It is most usually presented as a surgical complication with associated arthrofibrosis and limited range-of-motion, results of this procedure are not as predictable as with distalization TTO. With proper preoperative planning, adequate correction of the CDI along with an improvement in terms of pain and function is to be expected [7, 9, 11, 14]. Although there is an improvement relative to pain and function, outcome measures tend to remain diminished when compared to the general population baseline [11]. Fig. 2 (continued) Postoperatively, immediate passive motion is of paramount importance to avoid recurrence of arthrofibrosis and improve range of motion (ROM). Together with ROM exercises, muscular strengthening exercises are begun on the first day post-op. For the first 2 weeks ROM is limited to 0–90°, with a brace looked in full extension that should only be removed for physiotherapy exercises. Full weight bearing is allowed with a brace looked in full extension for the first 4 weeks, posteriorly discontinued if there is good muscular control. Pivoting and strenuous activities are allowed not before 3 months, with sports limited to light activities for the first 6 months. 5 Scientific Evidence The current bibliography on tibial tubercle osteotomies is of low-quality, being mainly level III and IV evidence studies that do not allow solid meta-analysis [9]. In fact, most of the studies are cases series with small sample sizes [6, 11–14]. Thus, there is a need of better-quality studies with larger sample sizes and better reports on data and outcomes to make it possible to draw any sound conclusion. 6 Complications Painful hardware is the more common complication [9, 11, 13], and may need reoperation for hardware removal [9, 11], but do not associates
538 A J. C. Monllau and E. Sanchez-Muñoz B Fig. 3 A Operative image of a left knee. The patient placed in supine position with 90° flexed knee. B Image intensifier sagittal view. A long sleeve of the tibial tuberosity has been detached and proximalized to the level of the joint line worse functional outcomes [9]. Recurrent patellar dislocation, TT fractures, proximal tibial fractures, infection and TTO non-union [14] are potential complications with overall lowincidence rate [9, 13], and some series reporting no cases of them [11]. Concerns with this technique also focus around patellofemoral contact pressure [7, 13] in relation to patella cartilage damage. Many papers have described persistent pain [9, 11], in general correlated with patellar cartilage defect severity [13]. This compares to our experience. Another common objection to TTO is the concern with failed osteotomy healing [14]. In our series (unpublished data), we had only seen one case of non-union. A long (>6 cm) and thick (>8 mm) bone fragment [13] had a good bony surface area for healing and is stable. When performing a distalization tubercle osteotomy, I do like to place a bone autograft between the proximal tibia bumper and the fragment to more closely calculate the exact amount of distalization. 7 Take Home Message The tibial tubercle osteotomy with distalization is an effective technique for patellar height correction and eventually to prevent recurrent patellar dislocations. The tibial tubercle osteotomy with proximalization with or without a patellar tendon plasty effectively corrects patella baja and brings improvement in terms of pain, range-of-motion and knee function. Patellar height disorders are usually associated with other underlying conditions and, especially in patella baja, previous surgeries. If these problems are not adequately addressed, the tibial tuberosity osteotomy alone will not bring about good outcomes.
Tibial Tubercle Osteotomy in Patients … A 539 B C Fig. 4 A Lateral imaging of posttraumatic patella baja, showing Caton-Deschamps measurement. B Frontal view of the same knee, after detached from the TT, the medial half of the PT is moved proximally and the lateral one, subperiostically dissected from the patella, is moved distally the same distance. C Final result. A PF prothesis was added in this case due to the degree of OA in the articulating PF surfaces
540 J. C. Monllau and E. Sanchez-Muñoz Fig. 5 Surgical view showing augmentation of the repair using an Aquiles allograft with a bone block References 1. Blumensaat C. Die Lageabweichungen und Verrenkungen der Kniescheibe. Ergebn Chir Orthop. 1938;31:149–223. 2. Enea D, Cane PP, Fravisini M, Gigante A, Dei GL. Distalization and medialization of tibial tuberosity for the treatment of potential patellar instability with patella alta. Joints. 2018;6(2):80–4. 3. Magnussen RA, De Simone V, Lustig S, Neyret P, Flanigan DC. Treatment of patella alta in patients with episodic patellar dislocation: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2014;22(10):2545–50. 4. Payne J, Rimmke N, Schmitt LC, Flanigan DC, Magnussen RA. The incidence of complications of tibial tubercle osteotomy: a systematic review. Arthroscopy. 2015;31(9):1819–25. 5. Yang JS, Fulkerson JP, Obopilwe E, et al. Patellofemoral contact pressures after patellar distalization: a biomechanical study. Arthroscopy. 2017;33 (11):2038–44. 6. Caton J, Deschamps G, Chambat P, Lerat JL, Dejour H. [Patella infera. Apropos of 128 cases]. Rev Chir Orthop Reparatrice Appar Mot. 1982;68 (5):317–25. 7. Perelli S, Ibañez M, Morales-Marin C, et al. Patellar tendon lengthening: rescue procedure for patella baja. Arthrosc Tech. 2020;9(1):e1–8. 8. Drexler M, Dwyer T, Marmor M, Sternheim A, Cameron HU, Cameron JC. The treatment of acquired patella baja with proximalize the tibial tuberosity. Knee Surg Sports Traumatol Arthrosc. 2013;21(11):2578–83. 9. Saltzman BM, Rao A, Erickson BJ, et al. A systematic review of 21 tibial tubercle osteotomy studies and more than 1000 Knees: indications, clinical outcomes, complications, and reoperations. Am J Orthop (Belle Mead NJ). 2017;46(6):E396-407. 10. Wierer G, Hoser C, Elmar H, Elisabeth A, Christian F. Treatment of patella baja by a modified Zplasty. Knee Surgery Sport Traumatol Arthrosc. 2016;24:2943–7. 11. Schmidt S, Mengis N, Rippke JN, et al. Treatment of acquired patella baja by proximalization tibial tubercle osteotomy significantly improved knee joint function but overall patient reported outcome measures remain diminished after two to four years of follow up. Arch Orthop Trauma Surg. 2021. 12. Vandeputte FJ, Vandenneucker H. Proximalisation of the tibial tubercle gives a good outcome in patients undergoing revision total knee arthroplasty who have pseudo patella baja. Bone Jt J. 2017;99-B:912–6.
Tibial Tubercle Osteotomy in Patients … 13. Leite CBG, Santos TP, Giglio PN, Pecora JR, Camanho GL, Gobbi RG. Tibial tubercle osteotomy with distalization is a safe and effective procedure for patients with patella alta and patellar instability. Orthop J Sport Med. 2021;9(1):2325967120975101. 541 14. Vives-Barquiel MA, Torrents A, Lozano L, et al. Proximalize osteotomy of tibial tuberosity (POTT) as a treatment for stiffness secondary to patella baja in total knee arthroplasty (TKA). Arch Orthop Trauma Surg. 2015;135:1445–51.
Tibial Tubercle Anteromedialization Osteotomy (Fulkerson Osteotomy) Andrew Gudeman and Jack Farr 1 Introduction The tibial tubercle (interchangeable with tuberosity) is the most distal attachment of the extensor mechanism. As a result, it and can serve as a tool in altering patellofemoral (PF) mechanics. Known collectively as tibial tubercle osteotomies (TTO) or distal realignment procedures, osteotomies of the tibial tubercle are a useful method to treat a variety of PF conditions by allowing coronal, axial, and sagittal plane adjustments of the patellofemoral articulation, which redistribute patellar contact pressures (force and contact area) and potentially improve tracking. Numerous tibial tubercle osteotomies have been described in the literature to treat PF pain, chondrosis, and/or instability. The procedure was initially described by Goldthwaite in 1896 [1]. Roux, and later Elmslie Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/978-3-031-09767-6_38. A. Gudeman Indiana University School of Medicine, Indianapolis, IN, USA J. Farr (&) Knee Preservation and Cartilage Restoration Center, OrthoIndy, Indianapolis, IN, USA e-mail: jfarr@orthoindy.com and Trillat, popularized their technique for the treatment of PF instability [2]. Anteriorization of the tibial tubercle was described by Maquet [3] to treat PF pain associated with arthritis. Each of these historical procedures takes advantage of important alterations in patellar kinematics. To avoid complications associated with the Maquet procedure, Fulkerson [4] designed a tubercle osteotomy known as the anteromedalization (AMZ) technique to address PF pain in conjunction with patellar maltracking. The oblique nature of the Fulkerson osteotomy allows for simultaneous anteriorization and medialization of the tibial tubercle. By varying the angle of the osteotomy, the tubercle can be biased to a more anterior or more medial position. Anteriorization of the tubercle elevates the distal extensor mechanism attachment and serves to shift patellar contact forces proximally as well as decrease the applied force, while medialization results in a decrease of the lateral force vector in patellar instability. It is necessary to be mindful that the Fulkerson osteotomy, while decreasing distal lateral loads, concomitantly shifts contact forces to the medial side of the patellofemoral compartment. These load modifications were initially demonstrated in the lab with Fuji pressure sensitive contact film [5] and with finite element analysis by Cohen and Ateshian [6]. To address this, Rue et al. introduced force/contact assessment with TekScan sensors and showed that straight anteriorization of the tubercle significantly decreased © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_38 543
544 A. Gudeman and J. Farr contact pressures in the trochlea (without an increase in medial contact pressures) [7, 8]. Incidentally, the described technique was similar to the Maquet technique but without bone grafting [9]. 2 Indications When discussing the indications for AMZ it is important to note that as with most patellofemoral surgeries, it should only be performed after the patient has failed exhaustive nonoperative measures that include a comprehensive “core to the floor” program of rehabilitation as well as bracing and orthotics. The indications for this procedure have evolved and continue to be refined. This has been primarily driven by the evolution and outcomes of patellofemoral resurfacing procedures, as well as improved objective measures of patellar alignment, contact area and forces. These alterations redistribute the contact forces within the patellofemoral compartment and a keen understanding of these changes is paramount in optimizing forces on areas of chondral damage and restoration [10]. Indications for AMZ are primarily based upon the mechanical and chondral pathologies specific to each individual knee. Malalignment is a term that has different meanings to different experts, but for the purposes of this chapter it simply means alignment that is different from the average asymptomatic individual. A comprehensive review by Post et al. [11] demonstrated that the “Q” angle was inadequate (within the studies reviewed) to use as a measure of malalignment of the tibial tuberosity. Although, a recent improvement in Q angle measurement with a long goniometer has the potential to improve the intra- and inter-observer reliability [12]. The tibial tuberosity to trochlear groove (TTTG) distance, popularized by Dejour et al. [13] as an objective measure of tuberosity position, has helped quantify abnormal tuberosity position and enhanced appropriate candidate identification for all tuberosity osteotomies, including the AMZ. This is important as patellar contact pressures are very sensitive to distal realignment [14]. The role of the TT-TG in surgical planning continues to evolve. It is important to keep in mind the limitations of this measurement: Knee flexion/tibial on femur rotation and trochlear dysplasia may alter the measurement and thus make the measurement less “precise” [15]. Thus, some surgeons have suggested adding the tibial tubercleposterior cruciate ligament (TT-PCL) distance as a reliable alternative [16, 17], as well as measuring the tubercle position as an angle within the coronal plane. The TT-TG in asymptomatic patients has been reported from 11–13 mm and those with instability symptoms have average measurements of over 15 mm [17, 18]. A panel of patellofemoral experts agreed that TT-TG distances of over 20 mm were definitely abnormal and would be potential (key word as other factors must also be considered) candidates for moving the tibial tubercle [19]. Results of medial patellofemoral ligament reconstruction have also been shown to improve with TTO for patients with TT-TG distances of 17–20 [20]. The upper limit of asymptomatic patient’s TT-PCL distance has been reported at 24 mm [10]. Several studies have compared the efficacy of a TT-TG of 20 mm versus a TT-PCL of 24 mm with mixed results [21–23]. An understanding of both measurements and the limitations with abnormal PF anatomy is important for the surgeon before consideration of a distal realignment surgery. Patients with isolated chondrosis of the distal or lateral patella, who have excessive lateral patellar tilt and/or subluxation associated with an increased TT-TG distance and minimal trochlear chondrosis are optimal AMZ candidates based on a retrospective review of AMZ outcomes by Pidoriano [24]. It has been argued that rotational tuberosity abnormalities associated with subjective instability and pain may be sufficiently treated with straight medialization or derotation of the tibial tubercle, although Pritsch et al. [25] found 80% of 66 patients undergoing tubercle transfer for patellar instability and pain associated with maltracking required anteriorization based on intraoperative examination. Secondly, patients who are undergoing PF cartilage restorative procedures have been shown to
Tibial Tubercle Anteromedialization Osteotomy … 545 Table 1 Summary of indications for anteromedialization Summary of AMZ indications • Lateral or distal patella chondrosis with an increased TT-TG distance, excessive lateral tilt/subluxation and the absence of trochlea chondrosis • As an adjunct procedure to patellofemoral cartilage restoration in an effort to improve the contact area and decrease PF forces to optimize the biomechanical environment of the new cartilage implant • Possibly, in conjunction with MPFL repair or reconstruction in patients with markedly increased TT-TG distance benefit from a combined AMZ procedure [26, 27] where optimization of the biomechanical environment and decreased stress across the restored cartilage is required. Additionally, in patients undergoing MPFL repair or reconstruction for recurrent lateral patella instability, AMZ may be indicated only in the setting of a significantly increased TT-TG distance. However, it should be noted that while this theoretically decreases the lateral vector forces on the healing MPFL tissues, there is no randomized study of AMZ plus MPFL surgery versus MPFL surgery alone published as of this writing. In addition, combining AMZ with PF cartilage restorative procedures such as autologous chondrocyte implantation and osteoarticular grafting procedures within the PF compartment have demonstrated superior results to either procedure performed independently [26, 27]. A summary of AMZ indications is presented in Table 1. 3 Contraindications Several contraindications to AMZ exist and potential candidates must be assessed carefully prior to surgery. Anteromedialization is contraindicated in patients with a normal TT-TG distance and in patients who have symptoms not explained by an increased TT-TG distance. The condition of the medial PF articulation should be carefully assessed as medialization will significantly increase contact pressures between the medial patellar facet and trochlea [7]. In addition, AMZ is contraindicated for proximal patella, panpatella and bipolar chondrosis based upon the outcomes from Pidoriano et al. [24]. Advanced chondrosis of the central trochlea has been associated with sub-optimal results and is considered a contraindication to AMZ as an isolated procedure [7, 28]. Standard contraindications to any osteotomy must also be considered, which includes smoking, infection, inflammatory arthropathy, marked osteoporosis inhibiting adequate fixation, complex regional pain syndrome, arthrofibrosis, inability to minimally weight-bear and non-compliant patients. A summary of AMZ contraindications is presented in Table 2. A final caution has been championed by Teitge: if the malalignmet is from excessive femoral or tibial rotation, a correction of the source of malalignment should be entertained [29]. Table 2 Summary of contraindications to anteromedialization Summary of contraindications to isolated AMZ • Normal TT-TG distance • Medial patellofemoral chondrosis (only if not combined with cartilage restoration procedure) • As an isolated procedure, when not combined with cartilage restoration, to treat proximal pole, pan patella, trochlear or bipolar chondrosis • General contraindications to osteotomy (i.e. smoking, osteoporosis, inflammatory arthropathy)
546 4 A. Gudeman and J. Farr Surgical Technique Techniques for AMZ have classically been described as an isolated procedure; however, AMZ typically includes lateral retinacular release or lengthening to untether the patella allowing the patellar medialization component and is not uncommonly performed in conjunction with procedures such as MPFL repair/reconstruction or cartilage restorative procedures. These procedures must be taken into consideration when planning the surgical approach. 4.1 Pre-operative Assessment and Planning The desired amount of anteriorization and medialization (based on the objective measurement of the TT-TG distance) may be calculated pre-operatively and used as a reference during surgery. Trigonometric ratios can be used to determine the desired angle for the osteotomy. Anteriorization of between 10 and 15 mm is most commonly recommended as it decreases PF stress loads by approximately 20% [6] and results in minimal sagittal rotation of the patella. In regard to the medialization component, the goal of the osteotomy is to normalize the TT-TG distance, which based on the literature, is within a range of 10–15 mm. By varying the slope and the extent of anteriorization, a variety of medialization distances can be achieved. The required angle can be calculated by the inverse tangent of the desired anterior movement divided by the desired medial movement (Table 3). For example, a 60° osteotomy with 15 mm of elevation will produce 8.7 mm of medialization, which will normalize most tuberosity positions as it is rare for TT-TG distances of over 25 mm. When more medialization is required, the slope may be decreased; a slope of 45° would move the tubercle 15 mm medially with 15 mm of elevation. Surgeons may tend to underestimate the anteriorization and osteotomy angle during Fulkerson osteotomy, which must be taken in to account [30]. 4.2 Set up and Positioning of the Patient The patient is positioned in the supine position with a side post and a gel-pad under the ipsilateral hemipelvis. This facilitates an initial arthroscopic evaluation of the knee and limits external rotation of the limb during the osteotomy. All extremities are well padded, a tourniquet is applied, and prophylactic antibiotics are administered. General, spinal, epidural or regional block anaesthesia can be used depending upon patient and surgeon preference. A thorough examination under anaesthesia includes assessment of range of motion, patella tracking and patella displacement. The patient is then prepped and draped in standard fashion. 4.3 Arthroscopic Evaluation Initially, arthroscopic evaluation and documentation of patellofemoral chondrosis is performed. The areas of chondrosis are regionally mapped using the ICRS region knee mapping system noting that significant patellar chondrosis may lead to termination of the procedure unless concomitant cartilage restoration has been planned. Certainly, other contraindications may be discovered at arthroscopy and would also halt proceeding with AMZ. At this stage, based on Table 3 Reference guide for osteotomy slope Osteotomy slope Elevation (mm) Medialization (mm) 60° 15 8.7 50° 15 12.5 45° 15 15
Tibial Tubercle Anteromedialization Osteotomy … 547 clinical tilt or CT/MRI documented patellar tilt, an arthroscopic lateral release may be performed if indicated. When combined with PF cartilage restoration the lateral release or lateral lengthening is performed in an open manner to allow direct access for performing the cartilage restoration procedure. Lateral release should allow neutralization of patella tilt and unrestricted central positioning of the patella relative to the trochlea, however, care must be taken to ensure medial patella subluxation does not occur. It should be noted that lateral lengthening can maintain control not offered by lateral release [31]. 4.4 Incision and Exposure The longitudinal incision runs approximately 8 to 10 cm distally beginning at the patellar tendon insertion to the tibial tubercle. The incision may be extended proximally to allow adequate exposure if concomitant cartilage restoration is being performed. The patella tendon is identified and released from capsule medially and laterally to allow protection with a retractor and later tubercle elevation. The lateral incision is extended distally along the lateral margin of the tibial tuberosity and tibial crest allowing subperiosteal elevation of the anterior compartment musculature and thereby exposing the lateral wall of the tibia. A retractor is positioned at the posterior aspect of the lateral tibia in order to protect the posterior neurovascular structures (deep peroneal nerve and anterior tibial artery) (Fig. 1). 4.5 Performing the Osteotomy For the highly experienced surgeon the osteotomy may be performed free hand. Fulkerson originally used an external fixator pin clamp to direct multiple pins in the osteotomy plane and then complete it with osteotomes [4]. Today, there are two commercially available AMZ osteotomy systems available (Tracker, DePuy Synthes Mitek Sports Medicine, Raynham, MA and the T3 System, Arthrex, Inc., Naples, FL). The Tracker system was available first and Fig. 1 Anterior compartment musculature is elevated from the lateral wall of the tibial with retractor protecting neurovascular structures posteriorly detailed illustrated surgical techniques using the jig system have been published by both Fulkerson and Farr. The T3 system will be used in this section to illustrate the operative technique; however, the approach for each system and steps following fixation of the cutting guide are similar. For the T3 system, an initial reference pin is orientated perpendicular to the posterior cortex of the proximal tibia (Fig. 2). The reference pin is inserted through the pin guide into the tibial tuberosity, just distal to the patellar tendon attachment to the tibial tuberosity (Fig. 3). Using preoperative calculations for anteriorization and medialization, the desired slope angle guide is assembled with the cutting block and cutting block post. The cutting guide is then placed over the reference pin and the cutting block is positioned immediately medial to the tibial crest beginning directly in line with the medial border of the patella tendon, as it attaches to the tibial tuberosity (Fig. 4) and angled laterally to allow a lateral exit of the osteotomy distally. For emphasis, the desired osteotomy forms a triangle shape that tapers distally allowing an exit through the anterior cortex to the lateral wall of the tibia. The desired pedicle length for the osteotomy is approximately 7–10 cm. When correct positioning has been achieved and the entry and exit sites have been confirmed, two
548 A. Gudeman and J. Farr Fig. 2 The reference pin guide is orientated so it is perpendicular to the posterior cortex of the tibia Fig. 3 Reference pin is inserted through the guide just distal to Gerdy’s tubercle break-away pins secure the cutting block in position (Fig. 5). With the retractor still protecting neurovascular structures posteriorly, the cut is made with an oscillating saw, which is simultaneously cooled with saline (Fig. 6). The cutting block is removed, and the oscillating saw is directed towards the distal exit of the osteotomy to finish the distal cut. A small osteotome is used to complete the proximal osteotomy, approaching the tibial tuberosity medially and laterally at the level of the patella tendon insertion (Fig. 7). The tuberosity is now free. A recent study showed that complete detachment of the tubercle compared to leaving a hinge results in higher rates of arthrofibrosis and must be used judiciously when needed for exposure [32]. (Note that the senior author detached the tubercle pedicle in all cases and complications were within the ranges reported in the literature).
Tibial Tubercle Anteromedialization Osteotomy … 549 Fig. 4 The cutting guide is placed over the reference pin and the cutting block is positioned medial to the patella tendon 4.6 Positioning and Fixation Fig. 5 Break-away pins secure the cutting block after positioning is confirmed A ruler is used to measure the required amount of anteriorization and medialization based on preoperative calculations and the pedicle position is adjusted along the osteotomy slope. If required, the pedicles can be moved proximally or distally to address any underlying patella alta or infra. A Kirschner wire is used to temporarily secure the pedicle when correct positioning has been achieved. The tuberosity fragment is then drilled using interfragmentary lag technique and secured using two countersunk 4.5 mm cortical screws (Fig. 8). The screws are positioned perpendicular to the osteotomy (angled from the anterolateral aspect of the pedicle to posteromedial tibia) so they are directed away from posterior neurovascular
550 A. Gudeman and J. Farr Fig. 6 Oscillating saw cooled with saline creates the initial sloped osteotomy, exiting on the protective retractor Fig. 7 Proximal cuts are completed with small osteotome structures. Cosgarea prefers 3.5 mm headless screws as he reports less hardware (screw) pain in the delayed post-operative setting [33]. The surgical site is closed in a standard fashion. 5 Pearls and Pitfalls 5.1 Pearls • Preoperative rehabilitation and expectation counselling is extremely important to prepare the patient for surgery and recovery. • The TT-TG measurement is an objective alternative to the Q-angle, quantifying the concept of tibial tuberosity malalignment. It is a single data point and should not be the sole indication for TTO. • The mean TT-TG distance is 11–13 mm in asymptomatic patients and is considered excessive when above 20 mm. • The TT-PCL measurement can be a useful adjunct in patients with trochlear dysplasia. • The goal is to ‘normalize’ the tibial tubercle position, that is, keeping within a range of 10–15 mm.
Tibial Tubercle Anteromedialization Osteotomy … Fig. 8 The distance of medialization and anteriorization is measured directly and the pedicle is secured with 2–4.5 mm screws 551 A B • The required amount of anteriorization and medialization needed for normalization should be considered independently. The required angle for osteotomy angle is determined based upon these values. • The osteotomy angle is equal to tan−1 of the desired anterior movement (y) divided by the desired medial movement (x), e.g., Angle = tan−1 (y/x). For simplicity, see Table 3. • Assessment for patella alta using the CatonDeschamps ratio (normal range 0.8 to 1.2) is required to determine if distalization is recommended (typically over 1.4) [10]. • Strengthening of proximal core muscles must be a focus of rehabilitation in conjunction with local musculature. • Anteromedialization can be performed in conjunction with other procedures including lateral release/lateral lengthening, MPFL repair or reconstruction or cartilage restoration procedures. 5.2 Pitfalls • Over medialization of the tibial tubercle can be detrimental secondary to increased medial patellofemoral and tibiofemoral stress • Patients should be aware that pain over the screw site is common, and they may need removal at a future date. • Weight bearing too early can lead to a fracture of the proximal tibia if the patient is returned to full weight bearing prior to radiographic healing [34]. • The MPFL is recognized as the key restraint to lateral patella dislocation. Isolated tibial tuberosity AMZ is not a substitute for MPFL repair or reconstruction.
552 A. Gudeman and J. Farr • Excessive anteriorization of the tuberosity can lead to skin healing problems and can cause clinically significant sagittal plane rotation of the patella altering contact areas. • Isolated AMZ performed in the presence of chondrosis will yield poor results when the wear patterns are in the: proximal patella, panpatella or trochlea. However, AMZ in conjunction with cartilage restoration procedures in these regions can achieve good results. 6 Complications Potential complications include those generally associated with osteotomies of the lower limb. General complications include malunion, nonunion, fracture at the osteotomy site [34], venousthromboembolism, compartment syndrome, infection and loss of fixation. The major complication rate of TTO has been reported to be approximately 3% [35]. Complications specific to AMZ include persistent pain, arthrofibrosis and stiffness, progressive chondral deterioration, symptomatic hardware, complex regional pain syndrome and intraoperative injury to the neurovascular structures including the popliteal artery and its trifurcation [36] and the deep peroneal nerve. Registry data have shown no increased risk for adverse events between isolated MPFLR and concomitant MPFLR and TTO [37]. 7 Post-Operative Management To improve postoperative recovery and prepare for surgery, the patient should undergo a preoperative proximal core and kinetic chain strengthening program (lower back, pelvis, hip thigh, and leg). Postoperatively the patient is treated with standard compression dressings, protective bracing, cryotherapy and is monitored for immediate complications. For the first 6 weeks the patient is limited to touch weight bearing with crutches and begins transitioning to full weight bearing after radiographs are noted to be acceptable at 6 weeks. The knee is protected with a hinged knee brace in extension which is unlocked at 2 weeks and discontinued when there is adequate lower extremity control (usually by 8 weeks). Early core proximal strengthening, quadriceps strengthening, and knee range of motion exercises are essential and a close relationship with an experienced physical therapist is key to optimal results. The safe range of motion may need to be modified throughout the rehabilitation process to accommodate for concomitant cartilage restorative procedures. Return to play outcomes after TTO have been poorly reported, with variable return criteria including quadriceps strength, range of motion, radiographic healing, and physical therapy protocols [38]. 8 Key Message and Take-Home Points Key Message: AMZ has been shown to improve outcomes for patients with patellar instability and patellofemoral cartilage restoration when appropriately indicated with other concomitant procedures (Table 4). Take Home Points: • The expert consensus is that AMZ should be considered in patients with TT-TG greater than 20 mm and TT-PCL of 24 but has also been shown to be beneficial in patients with smaller distances. • Careful scrutiny of other concomitant pathology including femoral anteversion and trochlear dysplasia must also be analyzed preoperatively and addressed. • Pre-operative planning to determine desired amount of anteriorization and medialization, with the corresponding osteotomy angle, are crucial for success. • AMZ is contra-indicated in medial and panpatellar chondral defects due to increased contact pressures. • A straight anteriorization may be beneficial to offload those chondral injuries that are not amenable to AMZ.
Tibial Tubercle Anteromedialization Osteotomy … 553 Table 4 Anteromedialization outcomes Author Patient number Mean follow-up (range) Reported outcomes Fulkerson [4] 8 n/a Substantial relief of pain and disability for all patients Cameron [39] 53 >12 mo 66% Excellent, 16% Good, 11% Fair, 7% Poor Fulkerson [40] 30 35 mo (26–50) 35% Excellent, 54% Good or Very Good, 4% Fair, 7% Poor Sakai [41] 21 5 yrs (2–13) Pain relief in ascending and descending stairs for 20/21 Pidoriano [24] 37 47 mo (12–96) 87% Good to Excellent results with lateral or distal lesions, 55% Good to Excellent results with medial lesions, 20% Good to Excellent results with proximal or diffuse lesions Bellemans [42] 29 32 mo (25–44) Significant improvements in mean Lysholm (62 pre, 92 post, p < 0.001) and Kujala scores (43 pre, 89 post, p < 0.001) Buuck [28] 42 8.2 yrs (4–12) 86% Good to Excellent subjectively, 86% Good to Excellent on clinical examination Franciozi [20] 42 (18 in AMZ group) 40.86 months (24–60 months) With TT-TG between 17–20 mm, TTO + MPFLR had better PROs compared with MPFLR in isolation Zarkadis [27] 72 with PF ACI (91% with AMZ) 4.3 years (2.0–9.9) 78% returned to moderate to very heavy occupational demand • Use of the pearls and pitfalls outlined in this chapter can help minimize complications and maximize success. References 1. Goldthwait JE. Dislocation of the patella. JBJS. 1896;1(1):237–8. 2. Trillat A. Diagnostic et traitement des subluxations recidevantes de la rotule. Rev Chir Orthop. 1964;50:813–24. 3. Maquet P. Biomechanics of the patello-femoral joint. Acta Orthop Belg. 1978;44(1):41–54. 4. Fulkerson JP. Anteromedialization of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res. 1983;177(177):176–81. 5. Ramappa AJ, Apreleva M, Harrold FR, Fitzgibbons PG, Wilson DR, Gill TJ. The effects of medialization and anteromedialization of the tibial tubercle on patellofemoral mechanics and kinematics. Am J Sports Med. 2006;34(5):749–56. 6. Cohen ZA, Henry JH, McCarthy DM, Mow VC, Ateshian GA. Computer simulations of patellofemoral joint surgery. Patient-specific models for tuberosity transfer. Am J Sports Med. 2003;31 (1):87–98. 7. Rue JP, Colton A, Zare SM, Shewman E, Farr J, Bach BR, et al. Trochlear contact pressures after straight anteriorization of the tibial tuberosity. Am J Sports Med. 2008;36(10):1953–9. 8. Lansdown DA, Christian D, Madden B, Redondo M, Farr J, Cole BJ, et al. The sagittal tibial tubercletrochlear groove distance as a measurement of sagittal imbalance in patients with symptomatic patellofemoral chondral lesions. Cartilage. 2021;13 (1_suppl):449S–455S. 9. Patel RM, Wright-Chisem J, Williams RJ. Anteriorizing tibial tubercle osteotomy for patellofemoral cartilage lesions. Arthrosc Tech. 2021;10(9): e2181–7. 10. Sherman SL, Humpherys J, Farr J. Optimizing patellofemoral cartilage restoration and instability with tibial tubercle osteotomy. Arthroscopy. 2019;35 (8):2255–6. 11. Post WR, Teitge R, Amis A. Patellofemoral malalignment: looking beyond the viewbox. Clin Sports Med. 2002;21(3):521–46. 12. Merchant AC, Fraiser R, Dragoo J, Fredericson M. A reliable Q angle measurement using a standardized protocol. Knee. 2020;27(3):934–9. 13. Dejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994;2(1):19–26. 14. Kuroda R, Kambic H, Valdevit A, Andrish J. Distribution of patellofemoral joint pressures after femoral trochlear osteotomy. Knee Surg Sports Traumatol Arthrosc. 2002;10(1):33–7. 15. Elias JJ, Soehnlen NT, Guseila LM, Cosgarea AJ. Dynamic tracking influenced by anatomy in patellar instability. Knee. 2016;23(3):450–5. 16. Seitlinger G, Scheurecker G, Högler R, Labey L, Innocenti B, Hofmann S. Tibial tubercle-posterior cruciate ligament distance: a new measurement to define the position of the tibial tubercle in patients
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Rotational Osteotomy. Principles, Surgical Technique, Outcomes and Complications Vicente Sanchis-Alfonso, Alejandro Roselló-Añón, Cristina Ramírez-Fuentes, and Robert A. Teitge 1 Introduction There is growing evidence that increased external tibial torsion and femoral anteversion (FAV) play a major role in the genesis of anterior knee pain (AKP) and patellar instability (PI) [1–26]. Torsional abnormalities can provoke an increment in patellofemoral contact pressure that may result in patellar cartilage damage, patellofemoral osteoarthritis and patellar subluxation or dislocation [7, 11, 21, 27, 28]. Therefore, torsional abnormality is a relevant clinical issue given that it might contribute to the development of knee osteoarthritis. Diederichs and colleagues have recently analyzed rotational limb alignment in patients with non-traumatic PI and in controls using magnetic resonance imaging (MRI) [29]. They found that PI patients have greater internal femoral rotation, greater knee rotation and more of a tendency to genu valgum when compared with healthy controls. However, those authors did not find significant differences in tibial tor- V. Sanchis-Alfonso (&) A. Roselló-Añón Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com C. Ramírez-Fuentes Medical Imaging Department, Hospital Universitario y Politecnico La Fe, Valencia, Spain R. A. Teitge Wayne State University, Detroit, MI, USA sion in PI patients in comparison with the control group. They concluded that rotational malalignment may be a primary risk factor in PI that has so far been underestimated. The authors also concluded that a concomitant rotational femoral osteotomy should be considered along with medial patellofemoral ligament reconstruction (MPFLr) if increased FAV is present. Moreover, it has been demonstrated that rotational osteotomy is a beneficial treatment for those patients as good clinical results have been reported [1–6, 8– 10, 12–20, 22–26]. The objective of this chapter is to present, in detail, how we perform a rotational osteotomy on both the tibia and femur along with an analysis of the outcomes and complications. 2 Principles of Rotational Osteotomy Surgery – Torsion of a long bone is the physiological rotation of the bone on its longitudinal axis. It is defined as the degree of twist between two axes, one proximal and one distal (Fig. 1). The range of normal values is broad for both femoral and tibial torsion [30, 31]. Moreover, there are differences between different ethnic groups [32]. Our normal reference values are a FAV of 13º for both sexes and 21º of external tibial torsion in males and 27º in females [33, 34]. Our preferred method to measure femoral torsion is the one described © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_39 555
556 V. Sanchis-Alfonso et al. only correct the transverse deformity in these cases, not the coronal one (Fig. 2). – An asymptomatic torsional abnormality should never be corrected. Correction for cosmetic reasons is contraindicated. We must only correct symptomatic cases. However, the problem is that we do not have scientific evidence to tell us from which torsional angles we should make a surgical correction of the torsional abnormality in cases where there are symptoms. Furthermore, the etiology of pain is multifactorial. Moreover, we do not know to what degree the torsional alteration contributes to the magnitude of pain. This might be why rotational osteotomy is not a common operation. – The selection of the level of the osteotomy is the surgeon’s choice. There is no scientific evidence to support decisions regarding the level of osteotomy. Rotational osteotomy may be performed, in theory, anywhere between the reference lines used to measure torsional abnormality. Osteotomies at different levels would have the same effect on overall version. However, we must note that healing in the metaphyseal area is excellent and fast, whereas healing in the diaphyseal region Fig. 1 Planes defining femoral anteversion by Murphy and colleagues in 1987 [35]. Regarding tibial torsion, our preferred method is the one described by Yoshioka and colleagues in 1989 [34]. – An erroneous start makes for an erroneous finish. Therefore, we must avoid an erroneous diagnosis, because it will lead us to an error in treatment, and we will cause iatrogenesis. In many cases, pathological external tibial torsion is associated with knee varus (Fig. 2). However, this varus is not real in most cases. It reflects the tibial torsion. That is why we speak about “pseudo-varus.” Obviously, we can see varus correction after isolated internal tibial rotational osteotomy. In the same way, we can observe a “pseudo-valgus” in patients with pathological FAV. Evidently, we must Fig. 2 Left pseudo-varus in a A patient with external tibial torsion (A). Observe varus correction after isolated internal tibial rotational osteotomy (B). In the same way, we can observe a “pseudo-valgus” in patients with pathological FAV. A true AP standing radiograph shows a normal mechanical axis (C). (Figure C—Courtesy of Robert A. Teitge, MD) B C
Rotational Osteotomy. Principles, Surgical Technique … requires more time. The difference between the two would be a point in favor of performing the osteotomy in the metaphyseal region. Then again, the osteotomy should theoretically be located in the osseous segment that mainly contributes to the deformity. If done in that way, it would prevent the creation of a new deformity on the coronal or sagittal plane in spite of the fact that good correction of the total torsional angle can be obtained [36]. – Regarding FAV, both the femoral neck and the diaphysis have an overall influence on femoral torsion [36–38]. Archibald and colleagues [36] evaluated 1210 paired adult femora from a well-preserved osteological collection. They have shown that both the femoral neck and femoral shaft substantially contribute to femoral version. Seitlinger and colleagues [37] have demonstrated that the neck, mid and distal femur contribute to the total femoral torsion. Sanchis-Alfonso and colleagues [38] have shown that pathological FAV in the AKP patient depends on both the neck and the shaft. In those patients, the increased anteversion of the femur is a result of increased proximal anteversion of the neck and reduced torsion of the diaphysis in the opposite direction [38]. The version angle of the neck and the diaphysis cannot separately explain the total FAV because it is a global torsional deformity that involves the entire femur. A strong negative correlation between neck torsion and shaft counter direction torsion has been found [38]. It suggests that the shaft version acts as a compensatory mechanism for the increased version of the neck, and this compensatory mechanism fails in pathological cases. They have shown that the difference in total FAV between healthy and pathological subjects is due in 40% to the higher version of the neck in the pathological group, and in 60% to the decreased diaphyseal rotation in the opposite direction [38]. Moreover, they observed that shaft version values better explain the phenomenon of pathological FAV since the values of shaft version are less dispersed and 557 better fit the linear model than those of the neck. However, the fact that the diaphysis only explains 12% of the variability of the total FAV angle in the linear regression analysis performed in the pathological group indicates that its influence on the total FAV is not important enough to unequivocally recommend that the osteotomy be performed distal to the lesser trochanter [38]. Therefore, we must look for other arguments to opt for an intertrochanteric or a diaphyseal osteotomy to treat pathological FAV in AKP patients. Our preferred options for the rotational osteotomy of the femur are at the (1) intertrochanteric level and the (2) supracondylar level. In cases of an isolated transverse plane correction, the proximal intertrochanteric osteotomy is our choice because it prevents damage to and scarring in the distal quadriceps avoiding the risk of knee stiffness. Rotational osteotomy is the most effective treatment for the AKP patient with pathological FAV. It is well-known that the quadriceps, is responsible for the force exerted on the patella. The osteotomy changes the direction of the quadriceps and therefore the force acting on the patella. This could be another argument for an intertrochanteric femoral osteotomy. However, if there is a malalignment on the coronal plane that must be addressed, our choice is a supracondylar femoral osteotomy. On the other hand, Kim and colleagues [39] showed that femoral torsion could occur either in the supratrochanteric region, the infratrochanteric region, or in both sites. However, Waisbrod and colleagues [40] have proposed that femoral torsion is a subtrochanteric deformity. – As with the femoral osteotomy, the tibial rotational osteotomy has also been performed at every level. In terms of the rotational osteotomy of the tibia, our preference is the infratuberosity osteotomy. On the other hand, other orthopedic surgeons suggest a supratuberosity osteotomy. Yet again, there are others who are inclined toward a mid-shaft or distal (supramalleolar) osteotomy. We must note that an osteotomy below the tuberosity
558 has poorer consolidation than one done above the tuberosity even though it allows for good fixation. We will do our best to explain our option. Osteotomies above the tuberosity lead to medial or lateral tuberosity displacement. That is why it may be necessary to add a tibial tubercle osteotomy if a supratuberosity osteotomy is performed. However, the infratuberosity osteotomy does not provoke tuberosity translation. For example, in the patient in Fig. 3 with a TT-TG distance of 14 mm, a 35º supra-tuberosity osteotomy will produce a tuberosity medialization of 11.4 mm that will provoke a postop TT-TG distance of 2.54 mm. That TT-TG distance is obviously pathological given that normal TT-TG distance is from 10 to 15 mm. If we place the osteotomy above the tubercle, we will move it medially. Doing so will create joint imbalance. Kuroda and colleagues [41] have demonstrated that a medial tuberosity transfer from the normal position provokes an increase in medial tibiofemoral compartment pressure and medial patellofemoral pressure that theoretically leads to medial compartment osteoarthritis, degenerative tears of the medial meniscus, and medial patellofemoral osteoarthritis. Another argument for the infratuberosity osteotomy is that the goal of osteotomy is to realign the knee joint axis with the ankle joint axis on the transverse plane, leaving the TT untouched. We must note that we should only medialize an V. Sanchis-Alfonso et al. – – – – Fig. 3 Calculation of tuberosity medialization after a rotational tibial osteotomy actual lateral placement of the TT on the proximal tibia. Recently, Winkler and colleagues [42] have shown that increased external tibial torsion is an infratuberositary deformity and is not correlated with a lateralized position of the tibial tuberosity. There is no scientific evidence as to the amount of torsion we should correct in a patient with a symptomatic torsional abnormality. In our experience, undercorrecting is better than overcorrecting. The objective is a correction that is slightly less than what a torsion measurement might indicate. For example, the aim should be an external femoral rotation of 30° but not more (49 − 30 = 19) if a patient has a femoral anteversion of 49°. For an external tibial torsion of 60°, we would propose an internal rotational osteotomy of 30° (60 − 30 = 30). But again, we do not know what minimum correction is necessary for the surgery to be successful. This might be another reason why rotational osteotomy is not a common operation. The surgeon may select any internal (or external) fixation device which allows for maintaining the correction. Therefore, the selection of the fixation device is also a surgeon´s choice. The objectives of rotational osteotomy are: (1) the correction of the deformity, (2) rapid bone consolidation, (3) minimal soft-tissue injury, (3) no restrictions in terms of range-ofmotion, and (4) immediate muscular activation. Changing the limb alignment by means of osteotomy is the single most powerful and underutilized treatment available for treating AKP and PI patients with a pathological torsional abnormality. The quadriceps is responsible for the force acting on the patella. The osteotomy changes the quadriceps direction and therefore the force acting on the patella. If one operates on the traumatized tissue (bone, ligament or cartilage) without changing the force which produced the trauma, one should expect an unsuccessful outcome.
Rotational Osteotomy. Principles, Surgical Technique … 3 Rotational Osteotomy. Surgical Techniques Step-by-Step. Pearls and Tips 3.1 Rotational Osteotomy of the Tibia 3.1.1 Positioning The patient is placed in the supine position on a radiolucent table. The entire limb is draped from the foot to the iliac crest. In that way, we can look at the entire limb after correction. A tourniquet is not used. The image intensifier is placed on the opposite side to the operated limb. The knee is slightly flexed on a towel roll. 3.1.2 Surgical Approach It proceeds with an anterolateral curved approach. The fascia of the tibialis anterior is sectioned longitudinally 1 cm lateral to the tibial attachment for it to be reattached later. The proximal tibialis anterior muscle is detached to expose the proximal lateral tibia. If a fibular osteotomy and release of the peroneal nerve is necessary, the surgical incision is extended proximally in a similar way to the incision used in the reconstruction of the posterolateral corner ligaments. Soft tissues are removed from the tibia with a curved raspatory. The plate is positioned A B Fig. 4 K-wire that help us to position the plate once the osteotomy has been performed (1); K-wires marking the osteotomy level (2) (A). K-wires at the desired correction 559 under the image intensifier on top of the lateral tibia to evaluate the correct position. We insert a K-wire if the position of the plate is correct. This K-wire will aid in positioning the plate once the osteotomy has been performed (Fig. 4A). 3.1.3 Fibular Osteotomy and Peroneal Nerve Release Like other authors, we perform a fibular osteotomy and peroneal nerve release when the rotational osteotomy of the tibia is going to be greater than 20º [43]. We never perform a release of the proximal tibiofibular joint. The fibular osteotomy is recommended before making the tibial rotation for two reasons. The first reason is that the fibula limits internal rotation of the tibia. The second is that the fibula pulls on the proximal and distal tibio-fibular capsule, which could be painful. A long proximal oblique cut of the fibula is recommended because it provides a larger surface contact area between both segments of the bone, making healing easier. Note that the peroneal nerve is at risk during a fibular neck osteotomy. Therefore, the nerve must be protected by using two hallux retractors around the neck of the fibula while doing the osteotomy with a small saw. Moreover, peroneal nerve palsy, might be secondary to overextension of the nerve due to internal tibial rotation (Fig. 5). C angle (3), using a triangle of 25° (B). The distal segment of the tibia is de-rotated internally until both K-wires are parallel (C)
560 V. Sanchis-Alfonso et al. A B Fig. 5 Peroneal nerve (arrows) before internal rotation of the distal segment of the tibia (A). Overextension of the nerve due to internal rotation of the distal segment of the tibia (B) 3.1.4 Tibial Osteotomy The osteotomy plane must be perpendicular to the mechanical axis of the lower limb. A long rod (DePuy Synthes) is used to define the mechanical axis intraoperatively. To make the cut perpendicular to the mechanical axis on both the anteroposterior and sagittal planes, two K-wires that will serve as a guide are used (Fig. 4A). These K-wires are positioned under the image intensifier viewer. Prior to the tibial osteotomy, two threaded K-wires inserted bicortically are put in place. One is placed perpendicular to the proximal tibia and proximal to the plane of osteotomy and the other one distal to the plane of osteotomy at the desired correction angle (Fig. 4A, B) using triangular measuring templates (Fig. 4B). Moreover, an iPhone app called “angle meter” might be used to estimate the angle of correction instead of triangular templates (Fig. 6). Saw 3D printed surgical guides are not routinely used.They might improve surgical accuracy. After that, we perform the osteotomy below the tibial tuberosity. The cut of the osteotomy, from lateral to medial, is performed using 0.6 mm thick saw blades under image intensification. If the saw blades employed in prosthetic surgery are used, which are thicker (1.2 mm), the control we have over the saw is decreased. Therefore, the cut is less precise. Moreover, there is more trauma to the bone and more heat is generated with a thicker saw blade. This might affect bone healing. A Hohmann retractor placed Fig. 6 An iPhone app called “angle meter” might be used to estimate the angle of correction behind the tibia is used to protect the neurovascular bundle. It is necessary a complete circumferential soft tissue release to obtain an unrestricted correction. After that, the distal segment of the tibia is de-rotated internally until both K-wires are parallel (Fig. 4C), and the correction is checked. The osteotomy can be stabilized temporarily, prior to the fixation of the plate, using reduction forceps or K-wires. The varus in patients with external tibial rotation may be real or it may reflect tibial torsion (pseudo-varus). In most cases, we can see a varus correction after an isolated internal tibial rotation osteotomy. Therefore, it is very important to check whether there is neutral coronal plane alignment after rotation before fixation by using the image intensifier. We use the alignment rod
Rotational Osteotomy. Principles, Surgical Technique … from the center of the femoral head to the center of the talus to make sure the mechanical axis falls near the medial tibial spine. A normal mechanical axis is near the medial tibial spine, not in the middle of the knee joint. The patella must always be pointing straight forward. In addition, it should also be in the middle of the distal femur on the anteroposterior image. 3.1.5 Fixation of the Osteotomy We use a lateral tomofix plate (DePuy Synthes) with 3 proximal and 3 distal screws. The plate is positioned using the K-wire inserted at the beginning of the procedure (Fig. 4A). This plate does not fit well, because it is designed for the valgus tibial osteotomy. Therefore, we usually bend it so as not to pull the distal fragment into valgus or leave the plate too far off the lateral tibial cortex tenting the anterior compartment. In cases of real varus, tension in the plate to compress the osteotomy pulls the tibia into valgus. Therefore, no bone cut is necessary to do a corrective valgus osteotomy. Correction Loss After Fixation—“Incongruity” is the Problem If the tibia had a circular section, the plate would rest completely on the lateral aspect of both bone segments when making a transverse osteotomy and rotating the distal segment. However, the cross section of the tibia is triangular. Therefore, the anterolateral aspect of the proximal segment of the tibia will be on a different plane than the anterolateral aspect of the distal segment when rotating the distal segment about the proximal one after a transverse osteotomy. When positioning the plate, it only rests fully on the proximal segment. When we fix the distal part of the plate using bicortical screws, there will be a loss of correction. “Incongruity” is to blame for correction loss after fixation. A cortical screw permits compression of the focus of the osteotomy as it is screwed into an oval plate hole eccentrically (absolute stability). But the cortical screw, in addition to compressing the focus of osteotomy, also compresses the bone on the plate. That is, it 561 A B Fig. 7 Plate resting on the lateral aspect of the tibia after rotational tibial osteotomy (A). Rotational tibial osteotomy smoothing the cortex of the proximal segment (B) attracts the bone to the plate. Therefore, we will bring the bone that was separated towards the plate as we tighten the screw, losing correction. How to Avoid the Correction Loss There are three ways to avoid the loss of correction. This is done by using plate-threaded screws in the part of the plate distal to the osteotomy site. In this way, there is no compression of the focus of the osteotomy and all the tension is supported by the plate (relative stability). Similarly, we do not attract the bone to the plate as we squeeze it. Another way to avoid the loss of correction would be by smoothing the cortex of the proximal segment (Fig. 7). A third way, using bicortical screws, would be to fill the space between the bone and the plate with a supplement and not remove it. If it is also biodegradable, it can serve its purpose of facilitating the construction of an assembly with absolute stability and compression of the osteotomy focus until the osteotomy consolidates and can then be resorbed. Custom supplements could be designed with PLA (polylactic acid) and 3-D printed. 3.1.6 Closure We always use a drain over 24 hours to reduce the risk of hematoma and compartment syndrome. The fascia of the tibialis anterior muscle
562 is reattached, covering the plate if it is possible. If the anterior compartment is very tight, we leave the fascia open. It is not a problem. 3.1.7 Postoperative Management We encourage active ankle and knee motion immediately after surgery. We use CPM in the hospital and at home if it is possible. The patient uses crutches to prevent bearing weight with the operated leg. Loading is permitted after 6 weeks. 3.2 Rotational Osteotomy of the Proximal Fermur 3.2.1 Positioning The patient is placed in the supine position on a fracture table holding both legs under controlled traction (Fig. 8). Abduct the unaffected lower limb as much as possible to permit fluoroscopic examination using an image intensifier (Fig. 8). V. Sanchis-Alfonso et al. 3.2.2 Lateral Approach to the Proximal Femur A lateral longitudinal incision is made over the hip. We locate the lesser trochanter with image intensifier. The incision is made at the level of the lesser trochanter, centered on the shaft and is then prolonged proximally and distally. The fascia lata is incised with a scalpel and split with scissors. The vastus lateralis is separated by blunt dissection from the fascia lata and then elevated anteriorly. The perforating vessels must be ligated. Finally, the proximal femoral shaft is exposed. To expose the femur without sectioning the muscle fibers of the vastus lateralis, the hiatus must be located distal to the insertion of the vastus lateralis on the lateral aspect of the greater trochanter. This is done by means of blunt dissection with the finger. The inferior border of the vastus lateralis is palpated until a space is found. That makes for the passage of the finger towards the anterior aspect of the femur. In this hiatus, a Hoffman retractor will be placed to fold the vastus lateralis anteriorly and expose the diaphysis (Fig. 9). To improve access, part of the insertion of the vastus lateralis on the lateral greater trochanteric aspect can be sectioned with electrocautery when tensioned with a Hoffman retractor. 3.2.3 Femoral Osteotomy The plate is positioned under the image intensifier on the lateral proximal femur to evaluate the correct position. If the position of the plate is correct, we insert 2 K-wires. These K-wires aid Fig. 8 Patient positioning for performing a rotational osteotomy of the proximal femur Fig. 9 Hiatus located distal to the insertion of the vastus lateralis on the lateral aspect of the greater trochanter
Rotational Osteotomy. Principles, Surgical Technique … 563 Fig. 10 If the position of the plate is correct, we insert 2 K-wires (1) (2). These K-wires will help us to position the plate once the osteotomy has been performed. K-wire marking the osteotomy site (5). K-wires for performing the rotational correction (3) (4) in positioning the plate once the osteotomy has been performed (Figs. 10 and 11). After marking the osteotomy level with a Kwire (Figs. 10 and 11), two threaded K-wires are inserted at an angle equal to the desired rotational correction. One is put in place proximal and the other distal to the osteotomy site (Figs. 11 and 12) using triangular measuring templates (Fig. 12). The cut of the osteotomy is performed using 0.6 mm thick saw blades under image intensification from lateral to medial while protecting soft tissues with two Hohmann retractors. The C-arm is used to confirm that the cut is perpendicular to the shaft of the femur. After the osteotomy is complete, external rotation of the distal fragment is performed until both K-wires are parallel, which indicates that the planned correction has been achieved (Fig. 12). We can use reduction forceps for temporary stabilization of the osteotomy prior to the insertion of the plate (Fig. 12). Another way to stabilize the osteotomy is with K-wires. Danger The magnitude of the rotational osteotomy does not show a 1:1 relationship with an effect on the correction of the deformity in all the cases. Not only does 3D technology permit measuring the femoral torsion (see chapter “Femoral and Tibial Rotational Abnormalities are the Most Ignored Factors in the Diagnosis and Treatment of Anterior Knee Pain Patients. A Critical Analysis Review”), but also to quantify the effect of the osteotomy on the femoral torsion after the planned osteotomy. In other words, it allows us to
564 V. Sanchis-Alfonso et al. Fig. 11 Two K-wires (1) (2) will help us to position the plate once the osteotomy has been performed. K-wire marking the osteotomy site (5). K-wires for performing the rotational correction (3) (4) A B D Fig. 12 Two threaded K-wires (3, 4) are inserted at an angle equal to the desired rotational correction (A). One is put in place proximal and the other distal to the osteotomy site using triangular measuring templates (B, C). K-wire marking the osteotomy site (5) (A). K-wires for C E performing rotational correction (3) (4) (A, B, C, D). Triangular measuring template (B, C). Stabilization using reduction forceps (D). K-wires (3) (4) are parallel after the planned correction has been achieved (D, E)
Rotational Osteotomy. Principles, Surgical Technique … estimate the final effect of the derotational femoral osteotomy (see Video Case # 1). 3.2.4 Fixation of the Osteotomy, Closure and Postoperative Management We use a proximal femoral locking compression plate (LCP) 4.5/5.0 (DePuy Synthes). The plate is positioned using the K-wires inserted at the beginning of the procedure (Figs. 10 and 11). We always use a drain to reduce risk of hematoma. Active hip, knee, and ankle motion immediately after surgery is encouraged. The patient uses crutches to prevent bearing weight with the operated leg. Loading is permitted after 6 weeks. 3.3 Rotational Supracondylar Femoral Osteotomy 3.3.1 Positioning The patient is placed in supine position on a radiolucent table. The entire limb is draped from the foot to the iliac crest. Therefore, we can look at the entire limb after correction. A tourniquet is not used. The C-arm is placed on the contralateral side of the operated limb to assess the whole lower limb in order to evaluate the alignment on the frontal plane. It must be acknowledged that in many cases there is a valgus associated with transverse plane malalignment and therefore is mandatory preop and postop evaluation in the coronal plane. 3.3.2 Surgical Approach The distal approach to the femur can be medial or lateral. We do the lateral because this type of surgery is done on patients with instability and associated femoral anteversion. If an MPFLr is associated with the osteotomy, the lateral approach is better than the medial, because there may be problems in achieving ideal femoral anchoring of the MPFL if a plate is placed on the medial aspect of the femur. 565 A standard lateral longitudinal incision is performed, the iliotibial band is incised following the fiber orientation and the vastus lateralis is separated by blunt dissection from the fascia lata and then elevated anteriorly. The septum intermusculare is detached from the femur at the level of the osteotomy with a curved raspatory. 3.3.3 Femoral Osteotomy After defining the osteotomy level on the femur with a K-wire perpendicular to the mechanical axis of the lower extremity, we insert two threaded K-wires at an angle equal to the desired rotational correction. One is put in place proximal and one distal to the osteotomy site using triangular measuring templates. If the osteotomy is not perpendicular to the mechanical axis of the femur, it is possible to modify the mechanical axis on the coronal plane. The osteotomy is performed using an oscillating saw (0.6 mm thick) while protecting posterior neurovascular structures with two Hohmann retractors. After the osteotomy is complete, external rotation of the distal fragment is performed until both Kwires are parallel, which indicates that the planned correction has been achieved. It is very important to check whether there is neutral coronal plane alignment after rotation before fixation by using the image intensifier (Fig. 13). We use the alignment rod from the center of the femoral head to the center of the talus to make sure the mechanical axis falls near the medial tibial spine. A normal mechanical axis is near the medial tibial spine, not in the middle of the knee joint. The patella must always be pointing straight forward. In addition, it should also be in the middle of the distal femur on the anteroposterior image. Technical Considerations when an MPFLr is Associated The osteotomy must be carefully planned so that the distal end of the plate is located proximally to the MPFL femoral attachment point if a plate is placed on the medial aspect of the femur. In
566 V. Sanchis-Alfonso et al. Fig. 13 Evaluation of coronal plane alignment after rotation addition, the direction of the femoral tunnel must be evaluated by means of fluoroscopy to avoid collision with the screws of the plate. 3.3.4 Fixation of the Osteotomy, Closure and Postoperative Management We use a distal femoral lateral TomoFix plate (DePuySynthes). However, other plates can as well be used. We always use a drain to reduce risk of hematoma. We also encourage active ankle and knee motion immediately. We use CPM in the hospital and at home if it is possible. The patient uses crutches to prevent weightbearing on the operated leg. Loading is permitted after 6 weeks. 4 Case Examples CASE # 1 - SYMPTOMATIC EXCESSIVE FEMORAL ANTEVERSION AND IN-TOEING GAIT. ROTATIONAL OSTEOTOMY OF THE PROXIMALFERMUR (INTERTROCHANTERIC OSTEOTOMY) 18 y/o female gymnast with severe right hip pain and severe right AKP for 3 years, both recalcitrant to conservative treatment (NSAIDS and Physical Therapy). AKP appeared several months after hip pain. The contralateral side was completely asymptomatic. There was a significant worsening in the last year.
Rotational Osteotomy. Principles, Surgical Technique … BMI: 18.78 (1.68–53 kg). Knee VAS 7. Hip VAS 8. Kujala score 86/100. IKDC 78.2/100. NAHS 77.5/100. Marx Activity Rating Scale 15/16–Rhythmic gymnastics. HAD: Anxiety 2/21–Depression 1/21–(Cutting point 11; no anxiety, no depression). Tampa Scale for Kinesiophobia 34/68 (Cutting point 40; no kinesiophobia). Pain Catastrophizing Scale (PCS) 36/52 (Cutting point 24; catastrophizing). EuroQol-5D 0.429/1. Conventional imaging studies normal or at least without evident pathology. CT: TT-TG distance: right 17 mm, left 18 mm; Patellar tilt: right 20º, left 12º. The presence of severe pain (VAS 7), absence of objective structural anomalies in the knee, absence of disability most of the time (Kujala 86, IKDC 78.2) and the presence of psychological problems (catastrophizing) is an explosive mixture that leads other people to believe the person is mad. This patient had made 17 visits to the emergency unit of the hospital in the year prior to surgery due to severe pain. There were many normal imaging studies. The doctors said that she was a “somatizer”. However, nobody had ever told her to undress to see her lower limbs while she was standing straight up. In Fig. 14A, B, C, you can see her legs. In the right one, one can clearly see a squinting patella, a tibia varus, a genu recurvatum and pronated foot. In this case, there is an evident asymmetry. It seems clear that there is abnormal torsion. From a clinical standpoint, there clearly is right femoral anteversion given that internal rotation of the right hip exceeds external rotation by more than 30º in prone position (Fig. 15). Moreover, there was a gait pattern with an internal foot progression angle (i.e., an in-toeing gait). A Torsional CT scan revealed femoral anteversion based on Murphy´s method, right 39º and left 15º. It is our belief that 39º of femoral anteversion might be enough to cause some posterior impingement between the neck and acetabulum when the patient attempts to externally rotate the limb (Fig. 16). Therefore, the hip muscles will not work in a balanced fashion. This could justify the hip pain in this patient. In fact, she had hip 567 pain with external hip rotation. On the other hand, she had no pain with internal hip rotation. A 20º external femoral rotation intertrochanteric osteotomy was performed (Fig. 17). In Figs. 14D, E, F and 18 you can observe clinical correction of torsional malalignment after rotational femoral osteotomy. In Fig. 19 you can see what she is able to do painlessly at the 3month follow-up. At the 6-month follow-up, the knee VAS was 0 and the hip VAS was 0. Furthermore, there was no catastrophizing, no disability and the patient was leading a normal life. At the 4-year follow-up, she was completely asymptomatic, and the physical examination was completely normal. CASE # 2 -SYMPTOMATIC EXCESSIVE EXTERNAL TIBIAL TORSION AND OUT-TOEING GAIT – INFRATUBEROSITY ROTATIONAL OSTEOTOMY OF THE TIBIA 18 y/o female gymnast with severe left AKP for 2 years recalcitrant to conservative treatment (NSAIDS and Physical Therapy). “My body is out of whack!”, were her first words upon visiting my office. BMI: 18.29. VAS 8. Kujala score 63/100. IKDC 44.8/100. Marx Activity Rating Scale 1/16 –Before the onset of pain rhythmic gymnastics. HAD: Anxiety 1/21 – Depression 2/21 – (Cutting point 11; no anxiety, no depression). Tampa Scale for Kinesiophobia 40/68 (Cutting point 40; low level of kinesiophobia). Pain Catastrophizing Scale (PCS) 13/52 (Cutting point 24; no catastrophizing). During physical examination, we saw a bilateral squinting patella and tibia varus when the patient was standing with their feet forward (Fig. 20). We were also able to discern a correction of both squinting patella and tibia varus with the legs in external rotation (Fig. 20). In most cases, the varus is not real but reflects the tibial torsion (pseudo-varus) (Fig. 20). During gait, we observed that the left foot was externally rotated during the swing phase. Therefore, an internal rotational tibial osteotomy should result in a neutral foot progression angle during the stance phase, and that is good. If the foot is
568 V. Sanchis-Alfonso et al. A B C D E F Fig. 14 Preop physical examination (A, B, C). On the right side, squinting patella, a tibia varus, a genu recurvatum and pronated foot can be seen. Postop physical examination (D, E, F). Clinical correction of torsional malalignment after intertrochanteric rotational femoral osteotomy
Rotational Osteotomy. Principles, Surgical Technique … 569 Our option was an internal tibial rotational osteotomy of 35º just distal to the tibial tuberosity. Therefore, we have gone from 64º to 29º. Before the tibial osteotomy, a proximal fibular osteotomy to obtain an easier tibial correction was performed. Moreover, a release of the peroneal nerve was done to avoid a peroneal nerve palsy. However, the 35º of internal rotation planned in the preop could not be reached. The reason for not arriving at that degree was that the peroneal nerve was too tense and flat at 30º and the perineural vessels disappeared. To avoid nerve damage, we did not go for the ideal correction. Five years after surgery the patient was pain-free (VAS 0, Kujala 91, IKDC 95.4, anxiety 1, depression 1, kinesiophobia 24, and catastrophization 4). 5 Fig. 15 Right femoral anteversion. Internal rotation of the right hip exceeds external rotation by more than 30º neutral during the swing phase, then internal rotational osteotomy can result in an in-toeing gait during the stance phase, and that is not good. An AP weight-bearing x-ray with the patient standing with their feet forward demonstrated a not well-centered patella and tibia varus. However, in the same radiological projection with feet in external rotation, a well-centered patella and correction of the tibia varus was seen (Fig. 21). CT: TT-TG distance: right 13 mm - left 14 mm, External tibial torsion: right 63º–left 64º, Femoral anteversion: right 31º–left 30º. A B Clinical Outcomes. Scientific Evidence From 1990 to June of 2021, only 22 published papers in English could be found in which the association between patellofemoral disorders (anterior knee pain and patellar instability) in adolescents and adult young patients and torsional abnormalities of the femur and/or tibia are analyzed from a clinical point of view [44]. It has been demonstrated that rotational osteotomy is a beneficial treatment for those patients as good clinical results have been reported [1–6, 8–10, 12–20, 22–26] Of the 22 papers, 19 (86%) were case series (level of evidence IV), 2 (9%) were cohort studies (level of evidence III) and only 1 C Fig. 16 Posterior impingement between the neck and acetabulum when the patient attempts to externally rotate the limb. Normal anteversion (A). Excessive anteversion (B). Excessive anteversion with “in-toeing” (C)
570 A V. Sanchis-Alfonso et al. B Fig. 17 Preoperative position of the patella with respect to the femur with the knee in extension (A). Position of the patella with respect to the femur with the knee in C extension after the rotational femoral osteotomy. Correct patellofemoral congruence can be observed (B). X-rays after an intertrochanteric rotational femoral osteotomy (C) Fig. 18 Clinical correction of torsional malalignment after an intertrochanteric rotational femoral osteotomy (5%) was a prospective cohort study (level of evidence II). An important limitation and source of bias in these papers is that, in many cases, rotational osteotomy has been combined with other surgical procedures like varization of the femur, tibial tuberosity transfer, MPFLr, lateral retinaculum release, etc. Therefore, we cannot know which surgical procedure has been decisively responsible for the improvement in terms of pain or instability with certainty. Furthermore, 77% of those papers have been published since 2004, the majority being carried out by European authors. No surprise that what we are looking at is a surgery that started to take off a relatively few years ago, especially in Europe. James, in 1979, presented a comprehensive review of AKP in which he described the condition of “miserable malalignment” for the first time in the medical literature [45]. In other words, that is increased femoral anteversion and increased external tibial torsion [45]. In 1995, James reported on 7 patients with “miserable malalignment” who had been treated with an internal rotational tibial osteotomy over an 18year period [2]. Torsional femoral deformity was considered mild in all those cases, and they had not been corrected. Subjectively, 85% of the patients had satisfactory results. Functionally, the results were good in 4 patients and excellent in 3 [2]. However, the most relevant finding of that study was that the results do not degrade with time (average follow-up, 10 years/range, 4–16). Several years earlier, in 1990, Cooke and colleagues [1] described the internal rotational
Rotational Osteotomy. Principles, Surgical Technique … 571 Fig. 19 3-month follow-up after intertrochanteric rotational femoral osteotomy proximal tibial osteotomy in 7 patients presenting with AKP. They drew attention to the inwardly pointing knee as an unrecognized cause of AKP. The outcomes evaluation after 3 years of follow-up were excellent. In 1996, Cameron and Saha [3] drew attention to an underrecognized cause of recurrent patellar dislocation, which is the pathological external tibial torsion. They analyzed 17 cases of this type of patients who had undergone a rotational tibial osteotomy proximal to the tibial tubercle with a mean follow-up of 25 months. Some 76% of their patients had a satisfactory clinical result. Delgado and colleagues [4] presented 3 cases of double level osteotomy (femoral and tibial) with a marked decreased in knee pain. Server and colleagues [5] evaluated 35 medial rotational proximal tibial osteotomies performed in 25 patients with chronic disability due to AKP and PI recalcitrant to conservative treatment in 1996. The average follow up was of 4.3 years (range 1–8 years). The results were good or excellent in 88.5%, fair in 5.7% and poor in 5.7%. Twentythree patients were satisfied and 2 were not. It took 8 years for another publication that analyzed the relationship between patellofemoral disorders and torsional abnormalities to appear in the medical literature. In 2004, Bruce and Stevens [6] retrospectively reviewed 14 consecutive AKP patients (27 limbs with both excessive femoral anteversion and excessive external tibial torsion), with a mean follow-up of 5.2 (2–12)
572 A V. Sanchis-Alfonso et al. B Fig. 20 Bilateral squinting patella and tibia varus (A). Correction of squinting patella and tibia varus with the legs in external rotation (B). A varus correction after an isolated internal tibial rotational osteotomy can be observed on the left limb (C). (Republished with A C permission of AME Publishing Company. From Sanchis-Alfonso V, et al. Evaluation of anterior knee pain patient: clinical and radiological assessment including psychological factors. Ann Joint, 3:26, 2018) B Fig. 21 X-rays with feet forward (A) and with feet in external rotation (B)
Rotational Osteotomy. Principles, Surgical Technique … years. They had been treated by means of rotational femoral and tibial osteotomy with satisfactory clinical outcomes. The authors highlighted that when evaluating AKP patients, assessing the rotational profiles of the femur and tibia is essential. When evaluang paents with patellofemoral disorders, assessment of the rotaonal profiles of the femur and bia is prerequisite In 2009, Paulos and colleagues [8] compared two surgical techniques in a cohort of patients with patellar instability and limb malalignment. In one group, they performed a proximal realignment associated with a rotational tibial osteotomy and in the other one was an ElmslieTrillat-Fulkerson proximal–distal realignment. They concluded that rotational abnormality correction produced significantly better results than conventional proximal–distal realignment. In 2014, Drexler and colleagues [12] evaluated 15 knees (12 patients) in which a rotational tibial osteotomy proximal to the tibial tuberosity associated with a tibial tubercle transfer was performed in the face of a diagnosis of recurrent patella subluxation secondary to excessive external tibial torsion. The authors showed a satisfactory clinical outcome at a median followup of 84 months (range 15–156). The high number of patients with previous failed surgeries in this series provides some evidence that tibial tubercle medialization associated with soft tissue plication is not sufficient to correct PI in patients with excessive external tibial torsion. Stevens and colleagues [14], in 2014, analyzed 16 consecutives patients (23 knees) with a failed knee surgery (tibial tubercle osteotomy in 12 knees and arthroscopic debridement in 9) before which a femoral or tibial torsional abnormality was recognized and subsequently treated by means of rotational osteotomy. They demonstrated clinical improvement after osteotomies of the femur and/or tibia in those patients. The authors stated that many orthopedic surgeons only focus on the knee when they see an AKP patient. Torsional abnormalities often go 573 unrecognized. Those authors observed that addressing rotational abnormalities in the index surgery provides better clinical results than osteotomies performed after previous knee surgeries for treating AKP and/or PI. Tibial tubercle medializaon is not sufficient to correct AKP and/or patellar instability in paents with torsional abnormalies Just as the papers published on osteotomies carried out up to 2014 focused on the tibial osteotomy in most of the cases, most publications since 2014 are above all on the femoral osteotomy indicated to treat patellar instability. In 2015, Nelitz and colleagues [15] evaluated 12 consecutive PI patients (12 knees) with pathological femoral anteversion that had undergone an anatomical MPFLr associated with rotational femoral osteotomy. The average follow-up after surgery was 16.4 months (range, 12–28 months). There were no redislocations of the patella, and there were significant improvements in the Kujala score, IKDC score and VAS. However, there were no statistically significant changes in the activity level according to the Tegner activity score. That finding was explained by the fact that patients are aware that the risk of a new dislocation is greater if they practice contact sports. For that reason, they voluntarily reduced their sports practice. Dickschas and colleagues evaluated 35 rotational femoral osteotomies in 25 patients with AKP and/or PI in 2015 [16]. The average follow-up was of 41 months (range 6– 113). No re-dislocation occurred during the follow-up. Using the VAS, pain was significantly reduced (from 5.6 to 2.4). Moreover, the functional scores (Lysholm and Japanese Knee Society score) improved significantly (Lysholm from 66 to 84 and Japanese from 73 to 87). However, the Tegner activity score did not show significant changes in the postop. In 2017, Dickschas and colleagues [17] published a series of 49 supratuberositary tibial internal rotational osteotomies performed on patients with a tibial maltorsion with AKP or PI. The VAS went down 3.4 points (SD 2.89), from
574 5.7 (SD 2.78; range 0–10) to 2.3 (SD 1.83; range 0–7). The Lysholm score increased 26 points (SD 16.32), from 66 (SD 14.94; range 32–94) to 92 (SD 9.29; range 70–100). Regarding patellar instability, no redislocation occurred in the follow-up period. The improved clinical scores and VAS and no redislocations demonstrated the value of this surgical procedure. Naqvi and colleagues [18] evaluated outcomes after proximal femoral rotational osteotomy in patients with symptomatic excessive femoral anteversion and intoeing gait in 2017. They evaluated 21 patients (35 operated limbs). In 13 out of 21 patients, the reason for the visit was knee pain. The mean follow-up after surgery was 16 months (6– 36 months). Ten out of 13 patients complained of knee pain that was resolved. There was no improvement for 3 after the surgery. The authors highlight that excessive femoral anteversion is associated with increased external tibial torsion in some cases. In these cases, an isolated correction of femoral anteversion can have a detrimental effect on external tibial torsion and patellofemoral tracking may worsen. In these selected cases a double level osteotomy would be indicated. Stambough and colleagues [20], in 2018, showed that a rotational femoral osteotomy over an intramedullary nail performed in adolescents with AKP and excessive femoral anteversion is a reliable surgical option. They found that it results not only in deformity correction but also in a significant improvement relative to both pain and function. A relevant finding in their study is that those adolescents with lower preop function scores do significantly better in the postoperative IKDC than those who had preoperative scores of more than 70 points. Frings and colleagues [22], in 2019, analyzed 31 distal rotational femoral osteotomies performed on 25 patients with PI and maltracking secondary to a femoral torsional abnormality. The average follow-up was 27 months (range 12–64). They also did 19 MPFL reconstructions, 14 tibial tuberosity transfers, varization in 4 cases and a valgus correction in 1 case. The VAS improved from 6.2 to 1.5, the Kujala score from 45.0 to 81.5, the Lysholm score from 40.3 to V. Sanchis-Alfonso et al. 83.9, and the Tegner score went from 2.1 to 3.9. No re-dislocations were observed. Preoperative cartilage damage significantly influenced the clinical outcome. They concluded that patellofemoral maltracking and PI in patients with pathological femoral maltorsion can successfully be treated by means of combined distal rotational femoral osteotomies and it shows excellent clinical results. Imhoff and colleagues [23] evaluated 42 patients (44 knees) with PI that underwent distal femoral rotational osteotomy with a mean follow-up period of 44 months (range 12–88) in 2019. In 28 cases, a rotational osteotomy was associated with an MPFLr, with valgus correction in 22 cases, patellofemoral arthroplasty in 8, a trochleoplasty in 6 and a tibial tubercle transfer in 6. During the follow-up period, no patellar re-dislocations were observed. The authors concluded that combined rotational osteotomy is a suitable treatment for PI due to femoral torsional abnormality as it leads to a significant reduction in pain and a significant improvement in knee function. To avoid overtreatment, the authors recommend doing the rotational osteotomy first and follow it with a physical examination to evaluate patellar tracking. Based on the results of these evaluations, an MPFLr or a tibial tubercle transfer can proceed. In 2020, Tian and colleagues [25] evaluated 17 femoral rotational osteotomies performed on 16 patients with recurrent patellar dislocation. In 8 cases, the rotational osteotomy was an isolated procedure. In 5 cases, it was associated with medial retinaculum reefing. It was associated with an MPFLr in 4 cases. The authors have shown that the supracondylar femoral rotational osteotomy may be an effective treatment for recurrent patellar dislocation induced by increased femoral internal torsion as good clinical results and improvement in patellofemoral congruence were obtained. In a 2021 cohort study (level 3 of evidence), Zhang and colleagues [26] evaluated the results of the isolated MPFLr and those of the MPFLr associated with the distal derotational femoral osteotomy in patients with recurrent patellar dislocation with increased femoral anteversion.
Rotational Osteotomy. Principles, Surgical Technique … 575 They conclude that the results are more favorable when MPFLr is associated with a femoral osteotomy, especially when the patients had a preop high-grade J-sign. Abnormal femoral torsion may be a primary risk factor in PI that has so far been underesmated. If increased femoral anteversion is present, a concomitant rotaonal femoral osteotomy should be considered along with MPFLr, especially when the paents have a high-grade preop J-sign Finally, Leonardi and colleagues [13] presented 3 patients in 2013 that had undergone a double level (femoral and tibial) bilateral osteotomy (12 osteotomies) with a mean follow-up of 16 years. At final follow-up, no patient reported knee or hip pain. According to those authors, internally rotating the tibia alone is not sufficient in cases of significant deformity because these patients rarely have sufficient passive external rotation of the femur to accommodate the operatively internally rotated tibia. Ipsilateral outward femoral and inward tibial osteotomies performed in the same surgical setting is the current recommendation of Leonardi and colleagues [13]. One-level osteotomy is not sufficient in cases of significant “miserable malalignment” 6 Complications. Scientific Evidence (See Tables 1, 2, 3 and 4) Rotational osteotomy is not a common surgical technique in our armamentarium to treat AKP and/or PI patients. A more widespread surgical technique for treating AKP and PI is the tibial tubercle osteotomy, which has clearly overshadowed the rotational osteotomy. Detractors of the rotational osteotomy argue that it is an aggressive surgery that is prone to bring on serious surgical complications. However, the frequency and types of complications seen in rotational osteotomy surgeries are similar to those of the tibial tubercle osteotomy. Payne and colleagues [46], in a systematic review, found an overall risk of major complications of 3% after tibial tubercle osteotomy. Sanchis-Alfonso and colleagues [44] did a systematic review with meta-analysis to evaluate Table 1 Demographics Demographics—(22 papers) Author Type of study Mean age Sex Number of patients Number of osteotomies Cooke T.D.V et al., 1990 Case series (IV) 18 (one patient 46 yrs) 9 Females/3 Males 12 9 Meister K. and James S. L., 1995 Case series (IV) 20.8 (15–30) 7 Females 7 8 Cameron J.C. and Saha S., 1996 Case series (IV) 27.6 (14–42) 16 Females 16 17 Delgado E.D. et al., 1996 Case series (IV) 14.18 (10–18) 6 Males/3 Females 9 20 Server F. et al., 1996 Case series (IV) 20 (15–45) 22 Females/3 Males 25 35 Bruce W.D. and Stevens P.M., 2004 Case series (IV) 14.9 (11.75–18) 13 Females/1 Male 14 54 Paulos L. et al., 2009 Cohort Study (III) 20 (15–30) 9 Females/3 Males 12 12 Fouilleron N. et al., 2010 Case series (IV) 26.5 (18–44) 24 Females/5 Males 29 3 (continued)
576 V. Sanchis-Alfonso et al. Table 1 (continued) Demographics—(22 papers) Author Type of study Mean age Sex Number of patients Number of osteotomies Leonardi F. et al., 2014 Case series (IV) 20.6 (17–24) 3 Females 3 6 Stevens P.M. et al., 2014 Case series (IV) 17 (9–30) 13 Females/3 Males 16 12 Drexler M. et al., 2014 Case series (IV) 34.6 (19–57) 11 Females/1 Male 12 15 Dickschas J. et al., 2015 Case series (IV) 30.5 (15–47) 19 Females/6 Males 25 33 Nelitz M. 2015 Case series (IV) 18.2 (15–26) 12 Females 12 12 Dickschas J. et al., 2016 Case series (IV) 27 (13–48) 29 Females/13 Males 42 49 Naqvi G. et al., 2017 Case series (IV) 13.3 (8–18) 15 Females/6 Males 21 35 Frings J. et al., 2017 Case series (IV) 24 (15–46) – 25 31 Stambough J.B. et al., 2018 Cohort study (II) 12.7 16 Females/6 Males 22 32 Iiobst C.A. and Ansari A., 2018 Case series (IV) 12 4 Males/4 Females 8 16 Imhoff F.B. et al., 2019 Case series (IV) 28 – 42 44 Manilov R. et al., 2020 Case series (IV) 30.5 (18–61) 50 Females/10 Males 60 60 Tian G. et al., 2020 Case series (IV) 20.8 (15–41) 11 Females/5 Males 16 17 Zhang Z. et al., 2021 Cohort study (III) 21.3 59 Females/7 Males 66 70 major complications in rotational osteotomy surgery. They found an overall risk of major complications after rotational osteotomy of 3.3% [44]. The authors concluded that rotational femoral and/or tibial osteotomy is a safe surgical procedure in the treatment of patellofemoral disorders in adolescents and active young people. Among all the complications, the most devastating is non-union at the osteotomy site. Sanchis-Alfonso and colleagues [44] found that 1.08% had non-union at the osteotomy site. In all those cases, a new surgical intervention was required. Surgery involved additional plate osteosynthesis, an autologous bone graft and drilling of the non-union. The risk of non-union was greater in femoral osteotomies (1.73%) than in tibial osteotomies (0.75%), which is not surprising because the tibial osteotomies were performed proximally to the tibial tuberosity in most of the cases. In the proximal region of the tibia, there is a lot of trabecular bone. Therefore, union of the osteotomy is easier at this location. Moreover, patient factors including obesity and smoking may also affect the risk of non-union [44]. Such factors should be modified before osteotomy. It is advisable for the patient to lose weight and quit smoking before osteotomy. Careful attention to surgical technique might minimize the risk of non-union. In some cases, the fibula provides a considerable degree of resistance to the rotation of the tibia. In those cases, a fibular osteotomy must be carried out. As soon as the fibula is cut, tibial rotation becomes very easy. Fouilleron and colleagues [9], systematically cut the fibula to obtain easy tibial correction. Proximal fibular osteotomy also
Type of osteotomy Derotation valgus tibial osteotomy Proximal tibial osteotomy Proximal tibial osteotomy Distal femoral (DF) (4) /Proximal Tibial (PT) (6) / Distal Tibia (DT) (4), DF + PT (2), DF + DT (1) Proximal tibial osteotomy Double-level: DF(13), Dyaphiseal femoral (8), Intertrochanteric (6), Tibia supramaleolar (20) Dyaphiseal tibia (7) Derotational high tibial osteotomy Proximal tibial derotation osteotomy Double-level (3): Proximal femoral (2), DF (4), PT (6) Isolated F midshaft (1)/Isolated T (midshaft vs. supramaleolar) (14)/Double level (8) Derotational high tibial osteotomy Isolated distal femoral osteotomy (27), Double-level (3) Author Cooke T.D.V et al., 1990 Meister K. and James S. L., 1995 Cameron J.C. and Saha S., 1996 Delgado E.D. et al., 1996 Server F. et al., 1996 Bruce W.D. and Stevens P. M., 2004 Paulos L., et al., 2009 Fouilleron N. et al., 2010 Leonardi F. et al., 2014 Stevens P.M. et al., 2014 Drexler M. et al., 2014 Dickschas J. et al., 2015 AKP (17), Patellar instability (15) Patellar instability AKP and Patellar instability AKP AKP (31), Patellar instability (5) Patellar instability AKP AKP (23 patients). Patellar instability (2 patients) AKP 17 patients patellar instabilty and 5 patients AKP Anterior knee pain Anterior Knee Pain (AKP) Indications Surgical details and individual study complications (22 papers) Table 2 Surgical details and individual study complications Valgisation (8), Varisation (6), Extension (2) TTO LRR (8 cases) NO TTO Proximal realignment LRR (13 limbs) NO NO NO TTO of medialization (2) Lateral Retinaculum Release (LRR) Concomitant procedures 3.4 7 4.9 16.3 4.6 4.2 5.2 ? 2.7 2.1 10.1 ? Follow up Non-union (2) (continued) Non-union (heavy smoker) (1), collapse at the site of osteotomy with varus malalignment (1) Femoral non-union (1), Peroneal nerve irritation (1) NO Stiffness (1), DVT (1), Transitory peroneal nerve palsy (1) Plate removal (1), Knee stiffness (1) Painful fibular non-union (1) (22 fibular osteotomies) Phlebitis (1) Fracture (1) NO Staples remove due to pain (2) Staples remove due to pain (3) NO Complications Rotational Osteotomy. Principles, Surgical Technique … 577
Type of osteotomy Distal femoral osteotomy Tibial osteotomy Proximal femoral derotation osteotomy Distal femoral osteotomy Midshaft derrotational femoral osteotomy Femoral ostetomy Femoral osteotomy High tibial derotational osteotomy Femoral osteotomy Derotational distal femoral osteotomy Author Nelitz M. et al., 2015 Dickschas J. et al., 2016 Naqvi G. et al., 2017 Frings J. et al., 2017 Stambough J. B. et al., 2018 Iobst Ch. A and Ansari A. 2018 Imhoff F.B. et al., 2019 Manilov R. et al. 2020 Tian G. et al., 2020 Zhang Z. et al., 2021 Patellar instability Patellar instability AKP Patellar instability AKP AKP Patellar instability Int toeing (19), AKP (13), Hip pain (8) AKP (42), Patellar Instability (19) Patellar Instability Indications Surgical details and individual study complications (22 papers) Table 2 (continued) MPFLr (66), TTO (30) MPFLr (4), Medial Retinaculum Constriction(5) NO Valgus correction (22), (MPFLr (28), PFA (8), Trochleoplasty (6), TTO (6) NO NO MPFLr (19), TTO (14), Varus correction (4), Valgus correction (1) NO LRR in all the cases, Valgisation (21), Fibular osteotomy (7) MPFL r Concomitant procedures 3.7 2.2 5.5 3.7 0.8 1 2.3 1.3 3.5 1.4 Follow up NO Stiffness (2) Hardware removal (11), Knee Stiffness (2), Tibial Fracturte (1), Transitory Peroneal Nerve Palsy (1), Permanent Peroneal Nerve Palsy (1) NO NO Non-union (1), Hardware removal (6) Superficial wound infection (1) Non-union (1) Non-union (1), Compartment syndrome (1), Transitory peroneal nerve palsy (1), Symptomatic fibular pseudoarthrosis (1) NO Complications 578 V. Sanchis-Alfonso et al.
Rotational Osteotomy. Principles, Surgical Technique … 579 Table 3 Risk of major complications Overall risk of major complications (22 papers) Complications Tibial osteotomy (n = 265) Femoral osteotomy (n = 289) Double-level osteotomies (At the same time) (n = 94) Total (n = 648) Osteotomy nonunion 2 (0.75%) 5 (1.73%) – 7 (1.08%) Transitory peroneal nerve palsy 4 (1.50%) – – 4 (0.61%) Permanent peroneal nerve palsy 1 (0.37%) – – 1 (0.15%) Neurologic damage – – – – Vascular damage – – – – DVT 1 (0.37%) – – 1 (0.15%) Compartment Syndrome 1 (0.37%) – – 1 (0.15%) Fractures 2 (0.75%) – – 2 (0.30%) Stiffness 4 (1.50%) – – 4 (0.61%) Symptomatic fibular pseudoarthrosis 2 (0.75%) – – 2 (0.30%) Total 17 (6.41%) 5 (1.73%) 0 22 (3.39%) Table 4 Risk of minor complications Overall risk of minor complications (22 papers) Complications Tibial Osteotomy (n = 265) Femoral Osteotomy (n = 289) Combined Tibial and Femoral Osteotomies (At the same time) (n = 94) Total (n = 648) Hardware removal 17 (6.41%) 6 (2.47%) – 23 (3.54%) Phlebitis 1 (0.37%) – – 1 (0.15%) Superficial wound infection – 1 (0.36%) – 1 (0.15%) Total 18 (%) 7 (2.42%) 0 25 (3.85%) presents a risk of non-union and can therefore be a source of pain and require surgery. Two patients (0.75%) in our systematic review had symptomatic fibular pseudoarthrosis [44]. Sanchis-Alfonso and colleagues [44] found peroneal nerve palsy in 1.87% of rotational tibial osteotomies. It can be secondary to overextension of the nerve or entrapment due to internal tibial rotation, or it could be secondary to a fibular neck osteotomy. A large tibial correction will put tension on the peroneal nerve. In those cases of internal tibial torsion of more than 20°, release of the peroneal nerve is essential to preventing peroneal nerve palsy. The fibular neck osteotomy must be performed meticulously because of the anatomical situation of the peroneal nerve. The risk of an intraoperative tibial fracture is 0.3%. One way to prevent it is to make a precise cut with the saw and dispense with the
580 V. Sanchis-Alfonso et al. osteotome. A drain should be used to reduce the risk of hematoma and compartment syndrome (0.15%). If the anterior compartment of the leg is very tight, we should leave the fascia open. In our systematic review, only 1 postoperative case of DVT was found (0.15%). Not using a tourniquet may be a factor that is related to the low incidence of DVT in that group of patients. Immediate active ankle and knee motion and the use of CPM in the hospital are advocated to prevent DVT and avoid knee stiffness. The most important finding of our systematic review is that the location of the osteotomy (tibial vs. femoral vs. double level) has an influence on the risk of complications [44]. The risk of complications is greater in the tibial osteotomy (6.41%) than when the osteotomy is performed on the femur (1.73%) [44]. Surprisingly, the risk of complications is nil in double level osteotomies [44]. 7 The Patient Experience Before and After Rotational Femoral and/or Tibial Osteotomy. A Qualitative Analysis When evaluating an AKP patient with torsional abnormalities before and after rotational osteotomy surgery, we usually use analog scales in order to quantify the pain, functional scores to evaluate disability, as well as biomechanical tools and imaging techniques. However, it is not usual to analyze the patient from the point of view of her individual experience. We have done a similar analysis to that carried out by Smith and colleagues [47] in their study “The experience of living with patellofemoral pain”. We have evaluated the personal experience of living with AKP secondary to tibial and/or femoral maltorsion before and after an isolated or combined femoral and/or tibial rotational osteotomy. The participants have offered us the personal impact that their pathology has had on them in detail. It included the impact of the pain, the loss of physical and functional capacity, the loss of own identity, the confusion related to pain and the difficulty making sense of their pain and fear of the future. What has proved most impressively with following these patients is the frequent number of observations made by patients which do not appear in any usual outcome measures. This suggests that specific and validated outcome measures must be developed for different clinical conditions and diagnoses. Interestingly, Lutz and colleagues [48] analyzed the limitations in sexual activity in female patients with chronic patellar instability and sexual function after complex patellofemoral reconstructions including rotational osteotomy. The authors reported preop restrictions of sexual activities due to patellar instability preoperatively. Sexual activity was improved in 60% of females with preoperative restrictions. However, there are no studies that analyze the limitations in sexual activity in female patients with AKP secondary to torsional abnormalities. 7.1 Patient Observations Before Surgery Include the Following 7.1.1 Uncertainty, Confusion and Sense Making When the patient comes to the consultation he tries to explain to us what she thinks is causing her pain. They are distraught because they have gone to several doctors previously and the doctors have not understood them. The following are typical expressions that the patient usually uses: My body is out of whack. My body is twisted. I noticed a lot of pressure in my knee. It was as if someone were squeezing my knee very hard. When I bend my knee, it is as if it was going to break, feeling pins and needles, or like being hit on your finger with a sledgehammer. It is a very sharp pain. During a family trip, I stayed in the hotel room most of the time due to the pain. However, I felt OK after coming back. I did not understand why I was so bad-off and I had excruciating pain and suddenly the pain stopped, and I was able to carry on with my normal activity. Similarly, on another occasion, I went to a concert with my friends and
Rotational Osteotomy. Principles, Surgical Technique … spent the whole time sitting because of the knee pain, too. People around me thought I was doing it on purpose. 7.1.2 Impact on Self and Loss of Selfidentity Pain is omnipresent in the daily life of these patients and results in a loss of physical capacity and even in a loss of self-identity. Every single day is complicated for me, from the moment I wake up until I go to bed. Some days when I get out of bed and put my feet on the floor, I can already feel the pain in my knee. Other days, I have no pain when I get out of bed but as soon as I start to walk or do anything the pain appears again. My knee severely limited my everyday activities, like cleaning the house, making the bed, going for a walk, etc. Climbing the stairs was like climbing a mountain. My knee hurt a lot and my leg was stuck. The pain was horrible. 581 why I´m wearing scruffy jeans with holes on the knees. I like wearing high heels a lot, but the pain was so strong that I was only able to wear them once or twice a year. 7.1.4 Expectation of the Future I would love to be a mum, but I dread to imagine what my legs would have to go through due to the extra kilos. What will my life look like in 20 years’ time? I would prefer not to live than live like that. I have no idea why my boyfriend puts up with me. I have so many limitations. 7.2 Patient Observations After Surgery Include the Following I had to go down the stairs step-by-step, holding on to the banister and, even so, at times I would fall. When I would go to a party, my friends would leave me behind, leaving me alone. When I woke up after surgery, my thoughts were automatically about my operated leg and I felt like the bones were in their right place, that the tibia was in its right place, that the femur was in its correct place, everything was in its proper place. Deciding on the clothes to wear is a nightmare. There are no shoes that make me feel dressed up and comfortable at the same time. The operation was magical for me. The pain disappeared all of a sudden. Driving to work is just terrible. Pressing the clutch is very painful. Before I had my surgery, I was very irritable, I would get angry with my parents and friends for no reason at all. I wasn’t myself anymore. Teachers, especially in physical education as well as doctors and physiotherapists told me I was crazy, that I was nuts, that I was an idiot and that I complained just for fun. 7.1.3 Coping Strategies and Activity Beliefs I try to sit idly most of the time. I was usually in the emergency room every few weeks due to pain so that they would give me something for my pain. The pain was very intense and would wake me up at night. I could hardly sleep. I even had to take painkillers and sleeping pills. The pain was excruciating. Putting my tight jeans on is extremely painful. The touch of the fabric hurts my skin. This is the reason My knee no longer hurts me, not at all. it’s really incredible. I have never again had pain. The pain has completely gone away, and I can sleep again. I couldn’t be happier. After two years of severe pain, I no longer have pain with anything I might do. Before, I was in continual pain. I did not feel happy at not being able to find a good position where I truly felt comfortable. Now I can sit in a chair and not feel pain. And when I go to bed, I don’t have any problem. I have recovered the autonomy I didn’t have before. I can go to the movies, go down stairs, take a normal walk without having to use crutches or a wheel chair or have someone help me. Now I can go up and down stairs, bend my knees, and do everything a girl of my age should do. I go to bed, and I am calm, without having to move around constantly to find a comfortable position so as not to have pain in my knee. And I don’t have nightmares any more about my knee.
582 V. Sanchis-Alfonso et al. It’s like having a new leg. Now I feel that my leg is finally no longer a dead weight, that I can be pain-free, something I thought was impossible before, and I can sleep all through the night at one stretch. I had never thought about a future with children. But now I am pregnant and thrilled. My knee hasn’t given me any trouble during my pregnancy. This surgery changed my life completely. My life and my personality as well as my relationship with my family have changed completely. Before I was mad at the world, was always in a bad mood, quite depressed, more aggressive, any excuse to be angry. I am myself again, both physically and mentally. My personality is back again. My knee feels perfect. I’m able to do things I couldn’t do like go hiking, go clubbing and not feel like sitting down, work standing on my feet many hours, kneel, crouch, cross my legs, do sports–in short, lead a normal life. I’d have this operation a hundred times more, without any doubt whatsoever. I have recovered my life. 8 Take Home Message The techniques described in this chapter, when well-indicated and well performed technically, provide very good results in AKP or PI patients with pathological torsional abnormalities. References 1. Cooke TD, Price N, Fisher B, et al. The inwardly pointing knee. An unrecognized problem of external rotational malalignment. Clin Orthop Relat Res. 1990;(260):56–60. 2. Meister K, James SL. Proximal tibial derotation osteotomy for anterior knee pain in the miserably malaligned extremity. Am J Orthop (Belle Mead NJ). 1995;24(2):149–55. 3. Cameron JC, Saha S. External tibial torsion: an underrecognized cause of recurrent patellar dislocation. Clin Orthop Relat Res. 1996;328:177–84. 4. Delgado ED, Schoenecker PL, Rich MM, et al. Treatment of severe torsional malalignment syndrome. J Pediatr Orthop. 1996;16(4):484–8. 5. Server F, Miralles RC, Garcia E, et al. Medial rotational tibial osteotomy for patellar instability secondary to lateral tibial torsion. Int Orthop. 1996;20 (3):153–8. 6. Bruce WD, Stevens PM. Surgical correction of miserable malalignment syndrome. J Pediatr Orthop. 2004;24(4):392–6. 7. Teitge RA. Patellofemoral syndrome a paradigm for current surgical strategies. Orthop Clin N Am. 2008; 287–311. 8. Paulos L, Swanson SC, Stoddard GJ, et al. Surgical correction of limb malalignment for instability of the patella: a comparison of 2 techniques. Am J Sports Med. 2009;37(7):1288–300. 9. Fouilleron N, Marchetti E, Autissier G, et al. Proximal tibial derotation osteotomy for torsional tibial deformities generating patello-femoral disorders. Orthop Traumatol Surg Res. 2010;96(7):785–92. 10. Dickschas J, Harrer J, Pfefferkorn R, et al. Operative treatment of patellofemoral maltracking with torsional osteotomy. Arch Orthop Trauma Surg. 2012;132(3):289–98. 11. Teitge RA. Does lower limb torsion matter? Tech Knee Surg. 2012;11:137–46. 12. Drexler M, Dwyer T, Dolkart O, et al. Tibial rotational osteotomy and distal tuberosity transfer for patella subluxation secondary to excessive external tibial torsion: surgical technique and clinical outcome. Knee Surg Sports Traumatol Arthrosc. 2014;22(11):2682–9. 13. Leonardi F, Rivera F, Zorzan A, et al. Bilateral double osteotomy in severe torsional malalignment syndrome: 16 years follow-up. J Orthop Traumatol. 2014;15(2):131–6. 14. Stevens PM, Gililland JM, Anderson LA, et al. Success of torsional correction surgery after failed surgeries for patellofemoral pain and instability. Strateg Trauma Limb Reconstr. 2014;9(1):5–12. 15. Nelitz M, Dreyhaupt J, Robert S, et al. Combined supracondylar femoral derotation osteotomy and patellofemoral ligament reconstruction for recurrent patellar dislocation and severe femoral anteversion syndrome: surgical technique and clinical outcome. Int Orthop. 2015;39(12):2355–62. 16. Dickschas J, Harrer J, Reuter B, et al. Torsional osteotomies of the femur. J Orthop Res. 2015;33 (3):318–24. 17. Dickschas J, Tassika A, Lutter C, et al. Torsional osteotomies of the tibia in patellofemoral dysbalance. Orthop Trauma Surg. 2017;137(2):179–85. 18. Naqvi G, Stohr K, Rehm A. Proximal femoral derotation osteotomy for idiopathic excessive femoral anteversion and intoeing gait. SICOT J. 2017;3:49. 19. Iobst CA, Ansari A. Femoral derotational osteotomy using a modified intramedullary nail technique. Tech Orthop. 2018;33(4):267–70. 20. Stambough JB, Davis L, Szymanski DA, et al. Knee pain and activity outcomes after femoral derotation
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Bipolar Fresh Osteochondral Allograft Transplantation of the Patellofemoral Joint Vicente Sanchis-Alfonso and Joan Carles Monllau 1 Introduction The treatment of large osteochondral lesions in young patients is a great challenge for the orthopedic surgeon. In this type of patient, there is a reluctance to use prostheses for fear of wear and loosening. An enticing therapeutic alternative would be fresh osteochondral allograft transplantation. The objective of that technique is to provide viable articular hyaline cartilage without the size limitations imposed with the use of autografts. It is unlike what occurs with other techniques like autologous chondrocyte transplantation, which requires two surgeries, osteochondral allograft transplantation is performed in a single surgical procedure. The ultimate goal is to relieve pain, improve function, and delay the V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com J. C. Monllau Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain Universitat Autònoma de Barcelona (UAB), Barcelona, Spain time for prosthetic surgery. Here, we present our surgical technique for the treatment of massive osteochondral lesions of the patellofemoral joint in the young patient. The final objective is to treat the osteochondral lesion along with anatomic and biomechanical abnormalities. 2 Indications and Contraindications The ideal patient to perform a fresh osteochondral allograft would be a young person (<50 years) with a grade III or IV osteochondral or chondral lesion of more than 2 cm2, contained or uncontained (Fig. 1). Moreover, there must be a correct alignment of the lower extremity on the three planes of space, and a correct patellofemoral tracking (negative J-sign). Only patients with severe chronic pain recalcitrant to conservative treatment and significant disability for activities of daily living as a result of the injury are candidates for this surgical technique. Wang and colleagues [1] have introduced the concept of “significant clinical benefit” as a guideline in the clinical decision when indicating an osteochondral graft. Those authors show that the “significant clinical benefit,” a concept that has nothing to do with “statistical significance,” is 30 ± 6.9 for the IKDC. This means that if the IKDC goes from 70 to 80 after an osteochondral allograft, the patient will not perceive any objective benefit from surgery even if the difference between 70 and 80 was © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_40 585
586 V. Sanchis-Alfonso and J. C. Monllau Fig. 1 The ideal indication for a total resurfacing osteochondral transplantation is the presence of a large cartilage injury or multifocal lesions and a dysplastic trochlea statistically significant. For the patient to notice an improvement in this case, it would have to go from 70 to 100. Therefore, we must analyze the patient’s expectations regarding the results of the surgery and see if it is really feasible to achieve that “significant clinical benefit”. Therefore, it would be reasonable to operate on those patients with an IKDC of <50 points. The main exclusion criteria are advanced osteoarthritis of other knee compartments, locally aggressive rheumatic disease, infections, tumors, diabetes, and vasculitis. Relative contraindications are being older than 50 years and having a body mass index greater than 30 [2]. Smoking must be stopped 30 days prior to surgery and for at least 6 months after the operation [2]. 3 The Keys for a Successful Osteochondral Allograft Transplantation of the Patellofemoral Joint We must make sure that chondropathy is responsible for the pain that the patient has. This is especially true in the patellofemoral joint, where it is relatively common to find severe chondropathies as an incidental finding. The graft must be “fresh,” not cryopreserved. In addition, what we transplant is an osteochondral “shell”, whenever possible. Osteochondral grafts should not be too thick. The more bone the graft has, there is a greater risk not only of an immune response but also of graft necrosis. We must use of the least amount of subchondral bone possible, the minimum necessary for cartilage fixation. The bone component of the osteochondral allograft acts as a support for the hyaline cartilage and as a connecting link with the host bone. In the future, the bone component of the allograft will be replaced by bone from the host through a phenomenon of “creeping substitution”. Patellofemoral chondropathy can be secondary to trauma, patellar instability, or lower limb malalignment. Therefore, for the resurfacing surgery to be successful, we must first correct the instability and/or malalignment to eliminate the shearing forces on the cartilage and the overload of the repair. If we do not do this, the graft cartilage will deteriorate in the same way that the original cartilage did, and the surgery will fail in the medium or long term. 4 Surgical Thecnique First of all, the distal femoral and patellar grafts are inspected to ensure the absence of macroscopic damage and adequate morphology (that is, non-dysplastic trochlea) (Fig. 2). The first step when considering doing a massive osteochondral
Bipolar Fresh Osteochondral Allograft Transplantation … 587 Fig. 2 Distal femur and patella of a donor with adequate cartilage for transplantation and adequate trochlear morphology (non-dysplastic trochlea) allograft of the patellofemoral joint is to choose a patella and trochlea with a size similar to that of the recipient. In addition, the side must match. If the recipient’s knee is the right, the donor’s side must also be the right. The patient is placed in the supine position with a support for the foot and a lateral support for the thigh to maintain the knee at 45° of flexion. The contralateral limb is placed in full extension. The surgical intervention should be performed by two surgical teams that will work simultaneously, two surgeons to work in the surgical field (arthrotomy, preparation of the recipient area and subsequent implantation of the graft) and another to prepare the graft. A longitudinal midline incision is used. Once the joint is exposed through a conventional medial parapatellar approach, the patella is everted. The thickness of the patella is measured. The surgical technique to prepare the patella is identical to the one used in prosthetic surgery when we are going to put in the patellar component. The articular surface of the patella is resected using a standard cutting patellar guide like that used in total knee arthroplasty (Fig. 3). An oscillating saw is used, leaving a patella remnant of about 13 mm (Fig. 3). We routinely perform a peripatellar denervation with the electrocautery with the theoretical idea of reducing the postoperative incidence of anterior knee pain. Resection of the recipient trochlea is performed similarly to the anterior resection of the distal femur in a patellofemoral arthroplasty (Fig. 4). Meanwhile, the other surgical team prepares the allograft, also using the knee prosthesis Fig. 3 Resection of the articular surface of the patella using a standard cutting patellar guide
588 V. Sanchis-Alfonso and J. C. Monllau Fig. 4 Resection of the recipient’s trochlea using the Zimmer patellofemoral prosthesis guide Fig. 5 Resection of the donor patella using a standard cutting patellar guide instruments (Figs. 5 and 6). The proximal and lateral part of the patella is marked with a sterile skin marker to help place the graft in the recipient area in the appropriate position (normoposition) (Fig. 7). Resection of the donor trochlea is performed similarly to the anterior resection of the distal femur in a patellofemoral prosthesis (Fig. 6). We must reduce the thickness of the bone component of the graft as much as possible (6–8 mm) to minimize the risk of immune reaction [3]. Before placing the patellar and trochlear grafts, the bone component of the graft is cleaned with a brush and washed for at least 15 min with a pulsatile irrigation system with high-pressure sterile saline solution to remove blood from the graft and thus reduce a possible immunogenicity (Fig. 8). During this cleaning process, care must be taken not to injure the cartilage. Then, the trochlear allograft is implanted, and it is fixed with two medial and two lateral screws associated or not with resorbable pins (Figs. 9 and 10). After that, the patellar allograft is implanted over the reception area and provisionally fixed with two Kirschner wires introduced through the anterior cortex of the patella (Fig. 11). The definitive fixation of the graft is performed with resorbable pins. Once the patellar graft is fixed, the K-wires are removed. Initially,
Bipolar Fresh Osteochondral Allograft Transplantation … 589 Fig. 6 Resection of the donor trochlea using the Zimmer patellofemoral prosthesis guide we used four compression screws from the dorsal aspect of the patella. They provided perfect fixation but caused artifact problems on the control CT or MRI. The total thickness of the patella after implantation of the patellar allograft should be similar to that of the original patella. Once the grafts have been fixed, it is verified that the patellofemoral tracking is correct, and it is closed plane by plane. Continuous passive mobilization begins immediately. Assisted loading with two crutches is authorized the following day depending on pain, with a knee brace locked in extension and maintained for 4 weeks for ambulation. Otherwise, the rehabilitation of these patients does not differ at all from that conducted with patients with a primary knee prosthesis. 5 What Can We Expect from a Fresh Osteochondral Allograft? Literature Review. Scientific Evidence Articular cartilage injuries in the patellofemoral joint are quite a challenge for the orthopedic surgeon. Due to the anatomy of the patellofemoral joint and its biomechanical complexity, transplantation in this location is more demanding than in the tibiofemoral joint. This may explain the high rates of allograft revisions, up to 60%, and the high percentage of failures (28.6%) [4]. Gracitelli and colleagues [4] observed a graft survival rate of 78% at 10 years and 56% at
590 V. Sanchis-Alfonso and J. C. Monllau Fig. 8 Before placing the graft, the bone component is cleaned with a brush and washed with a pulsatile irrigation system with high-pressure saline to remove blood from the graft Fig. 7 Marking of the graft to place it in the proper position. We mark the lateral edge of the patella with two points and the proximal pole with one point 15 years follow-up. The authors conclude that the patellar allograft is an effective treatment for symptomatic chondropathies of the patella. However, the results are much better in isolated trochlear injuries. Cameron and colleagues [5] published the results of a series with a minimum evaluation at 2 years and a maximum evaluation at 20 years (mean 7 years) with excellent clinical results in terms of pain and function and high patient satisfaction (90%). Those authors described a graft survival rate of 100% at 5 years and 91.7% at 10 years. Studies on bipolar patellofemoral osteochondral transplantation of the patella and trochlea are few. The risk of failure is great but allografts that survived showed significant Fig. 9 Provisional fixation of the graft with Kirschner wires and definitive fixation with Acutrak screws
Bipolar Fresh Osteochondral Allograft Transplantation … 591 Fig. 10 Definitive appearance of the already implanted trochlea graft Fig. 11 Provisional fixation of the graft with Kirschner wires. Definitive graft fixation with resorbable pins improvements in function, pain relief, and rangeof-motion [6–10]. Torga Spak and Teitge [10] presented 12 bipolar patellofemoral joint allografts for patellofemoral osteoarthritis. At the last follow-up (mean, 10 years; range, 2.5– 17.5 years), 8 grafts were still functioning. 6 Conclusion Fresh osteochondral allograft is a salvage surgery intended for young patients with disabling osteochondral or chondral lesions. The final
592 objective is to delay the moment of the prosthesis. If the patient is clear on the fact that it is a “salvage surgery”, we avoid the frequent failures related to not fulfilling the expectations of the patient. References 1. Wang D, Chang B, Coxe FR, et al. Clinically meaningful improvement after treatment of cartilage defects of the knee with osteochondral grafts. Am J Sports Med. 2019;47(1):71–81. 2. Gelber PE, Ramírez E, Grau A, et al. Fresh osteochondral resurfacing of the patellofemoral joint. Arthrosc Tech. 2019;13(8):e1395–401. 3. Sherman SL, Garrity J, Bauer K, et al. Fresh osteochondral allograft transplantation for the knee: current concepts. J Am Acad Orthop Surg. 2014;22 (2):121–33. V. Sanchis-Alfonso and J. C. Monllau 4. Gracitelli GC, Meric G, Pulido PA, et al. Fresh osteochondral allograft transplantation for isolated patellar cartilage injury. Am J Sports Med. 2015;43 (4):879–84. 5. Cameron JI, Pulido PA, McCauley JC, et al. Osteochondral allograft transplantation of the femoral trochlea. Am J Sports Med. 2016;44(3):633–8. 6. Jamali AA, Emmerson BC, Chung C, et al. Fresh osteochondral allografts: results in the patellofemoral joint. Clin Orthop Relat Res. 2005;437:176–85. 7. Giannini S, Buda R, Ruffilli A. Failures in bipolar fresh osteochondral allograft for the treatment of endstage knee osteoarthritis. Knee Surg Sports Traumatol Arthrosc. 2015;23:2081–9. 8. Meric G, Gracitelli GC, Gortz S, et al. Fresh osteochondral allograft transplantation for bipolar reciprocal osteochondral lesions of the knee. Am J Sports Med. 2015;43:709–14. 9. Mirzayan R, Charles MD, Batech M, et al. Bipolar osteochondral allograft transplantation of the patella and trochlea. Cartilage. 2018:1947603518796124. 10. Torga Spak R, Teitge RA. Fresh osteochondral allografts for patellofemoral arthritis: long-term followup. Clin Orthop Relat Res. 2006;444:193–200.
Patellofemoral Arthroplasty. Pearls and Pitfalls Pedro Hinarejos 1 Introduction Isolated patello-femoral osteoarthritis (PF-OA) without involvement of the femoro-tibial joint (Fig. 1) is a common condition, which affects 9% of the population in their forties and its incidence increases significantly as age increases [1], affecting 11% of men and up to 24% of women over 55 years. Isolated PF-OA is much more common in women, with an estimated 75% of cases [2]. This is believed to be secondary to the higher prevalence of trochlear dysplasia and patellar instability in women. Knee osteoarthritis has biological factors, such as the presence of inflammatory pathology or infection, and mechanical factors. In the case of PF-OA mechanical factors, mainly trochlear dysplasia and extensor mechanism malalignment, are of the greatest importance [3] although some mechanical factors like obesity or genu valgum are also frequently associated with global osteoarthritis of the knee. P. Hinarejos (&) Consorci Parc de Salut Mar. Barcelona Universitat Pompeu Fabra, Barcelona, Spain e-mail: PHinarejos@parcdesalutmar.cat 2 History of Patellofemoral Arthroplasty (PFA) The first precedent of patello-femoral arthroplasty (PFA) was described by McKeever in 1955, and it consisted in the isolated replacement of the patella by means of a metallic component of vitalium, without a trochlear component, on the basis where the patella is usually more degenerated than the femoral side. The results with these isolated patellar prostheses were poor, with progressive degeneration of the femoral trochlea. PFAs have evolved and for the last 50 years they have been made up of 2 components: a femoral trochlea, which is metallic, and a patellar component made of polyethylene. The first generation of PFAs were first used in 1974. The most widely used were Lubinus® (Waldemar Link, Germany) and RichardsBlazina® (Smith-Nephew Richards, USA), and they had a relatively small trochlear component, which was narrow and deep, with significant constriction of the patella in the trochlear groove as knee flexion increased. This first generation of PFAs have been associated with a high rate of patellar clunks, and patellar instability [4]. The second generation of PFAs were introduced in the 1990s, and they evolved to a wider and shallower design of the trochlear component, with a longer proximal extension and a sagittal radius of curvature that better reproduces the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_41 593
594 P. Hinarejos Fig. 1 Isolated patellofemoral osteoarthritis, with complete chondral lesions in the femoral trochlea and patella, but healthy cartilage in the femoro-tibial compartments original anatomy. This evolution in design reproduces the biomechanics of the patellofemoral joint in a better way [5]. In fact, the design of the trochlea is more decisive in PFAs than in TKAs, since more than 70% of patients diagnosed with isolated PF-OA present trochlear dysplasia [6] and poor alignment of the extensor mechanism [7]. Ackroyd has reported a very significant reduction in the rate of patellar instability using the Avon® PFA (Stryker) compared to the Lubinus. Mid-term implant survival of these second generation PFAs was significantly improved [8]. In the last decades, a third generation of PFAs have appeared, which are anatomical (right or left implants). They have a lateral facet of the trochlea that is higher than the medial one to resist the lateral translational forces of the extensor mechanism. Third-generation PFAs, e.g. the Journey® (Smith & Nephew) or the Gender® (Zimmer) incorporate a valgus alignment of about 7–10° (Fig. 2). The length of the trochlea is different from one model to another, in such a way that some extend more proximally, favoring the contact of the patella with the trochlea even in full extension, and others also extend distally, increasing the contact of the patella with the trochlear component also in deep flexion. 3 Types of PFA Implants Based on their design, PFAs can be classified into two types: “inlay” (or resurfacing) and “onlay” (or anterior trochlear cut). 1. “Inlay” or resurfacing PFAs The design of these prostheses seeks to replace only the articular cartilage, being very conservative in the sacrifice of bone and therefore, they depend on the anatomy of the patient’s trochlea, not allowing changing the original anatomy [7]. Some inlay prostheses are symmetrical (Richards III® or Lubinus®) and tend to have a fairly closed trochlar angle, while others are asymmetrical (DePuy’s LCS® or FH’s Spherocentrica®), and these inlay PFAs have a very thin implant in the trochlea (Fig. 3). 2. “Onlay” or anterior cut PFAs In this type of PFAs, the preparation of the trochlear component begins with an anterior cut in the trochlea area, very similar to the anterior cut of the femoral component of the TKAs (Fig. 4). Onlay PFAs can also be symmetrical (like Stryker’s Avon®) or asymmetrical (like Biomet’s Vanguard®, Smith & Nephew’s Journey®, or Zimmer’s Gender®).
Patellofemoral Arthroplasty. Pearls and Pitfalls 595 Fig. 2 Third generation onlay patello-femoral arthroplasty (Gender, from Zimmer) with anatomical design, with valgus in the trochlear groove component is usually cemented, with an additional fixation around small lugs or small keels. The thickness of the trochlear component ranges between 4 and 9 mm, although in onlay PFAs it is greater than in inlay PFAs. The patellar component consists of a polyethylene button, which can be symmetrical (domeshaped, or with 2 facets) (Fig. 2) or asymmetrical. The patellar component is cemented and the dome-shaped components have the advantage of being more permissive with a residual tilt of the patella allowing its self-centering. In case of revision to a TKA the same patellar component can be maintained due to its compatibility with the femoral component of the TKA [9]. Fig. 3 Inlay patello-femoral arthroplasty (lateral view): The metallic trochlear component is thin, to replace only the cartilage, preserving as much bone as possible All onlay PFA models have a cobaltchromium trochlear component (although they may also have a titanium oxide coating such as Smith & Nephew’s Journey®) and the trochlear 4 Indications (Table 1) The success of PFAs is highly dependent on the correct indication of surgery. The indication for a PFA is severe PF-OA with indemnity of the
596 P. Hinarejos Fig. 4 Anterior cut of the onlay patello-femoral arthroplasty, similar to that of TKA. Correct rotation of the trochlear component is important for the stability of the extensor mechanism Table 1 Patello-femoral arthroplasty indications – Primary isolated patello-femoral osteoarthritis – Osteoarthritis due to trochlear dysplasia – Postraumatic osteoarthritis: Patella fractures Fig. 5 Patello-femoral osteoarthritis secondary to trochlear dysplasia femoro-tibial compartments. This isolated PFOA can be idiopathic, secondary to trochlear dysplasia (Fig. 5) or post-traumatic, especially after patella fractures. The ideal requirements for a PFA are the presence of severe signs and symptoms, without improvement after a conservative treatment, the absence of involvement of the femoro-tibial
Patellofemoral Arthroplasty. Pearls and Pitfalls 597 Table 2 Patello-femoral arthroplasty contraindications Absolute contraindications – Femoro-tibial significant osteoarthritis – Active infection – Inflammatory arthritis – Flexion contracture >10° – Significant malalignment (varus or valgus >5°) Relative contraindications – Patela baja – Chondrocalcinosis – Obesity – Previous meniscectomy – Elderly patients (>70 years) compartments and the absence of a significant femoro-tibial malalignment that suggests a quick deterioration of the femoral or tibial cartilage after PFA. PFA may be indicated as salvage surgery after other surgeries as realignment of the extensor mechanism. It is frequently indicated in patients with patellar instability who were previously treated with realignment, if this surgery has improved the recurrent dislocation of the patella, but the pain is significant because of the arthritic changes that such instability have caused. To confirm the correct criteria for the indication of PFA, we need a complete radiological examination protocol, as it is later explained. 5 Fig. 6 Lateral view in maximum flexion in a patellofemoral arthroplasty with a low patella, where the patella contacts distally, outside the trochlear component Contraindications (Table 2) Contraindications to PFA are the presence of a significant femoro-tibial osteoarthritis, higher than Ahlback grade I, the presence of a moderate or severe limb malalignment (varus or valgus >5°), the presence of an inflammatory arthritis, or knee instability [10]. Other authors argue that chondrocalcinosis is also considered a contraindication [2]. The presence of a low riding patella preoperatively is also considered a contraindication, at least relative, since it would cause the patella not to articulate against the trochlear component, but more distally, in deep flexion (Fig. 6). Obesity, with a body mass index greater than 30 kg/m2, is considered a relative contraindication, since obese patients have a higher risk of disease progression to the femoro-tibial compartments. Furthermore, the flexion of 60° and 130° increases the reaction forces in the patello-femoral joint 3.3 and 7.8 times with respect to the body weight and could be excessive and facilitate loosening in very obese patients. Obesity has also been observed to be a risk factor for readmission and early reoperation after PFA [11]. Nevertheless, a recent study has found similar outcomes of PFAs in obese or nonobese patients in the mid-term and, according to these authors, obesity should not be considered an absolute contraindication [12]. Age is not an absolute contraindication for PFAs, but in very young patients, younger than 40 years, it seems reasonable to try other surgical treatments, while in elderly patients, older than 70 years, it seems reasonable to opt for a TKA, because of its more predictable results.
598 P. Hinarejos Although there is no evidence that a previous meniscectomy or ligament injuries can lead to worse results, it is better not to indicate this partial replacement in cases of meniscal or ligament lesions, which are conditions that can accelerate osteoarthritis of the femoro-tibial joint. 6 on palpation of the lateral aspect of the patella is very common [3]. Patients also complain of pain when a direct pressure is applied on the patella against the femur. Significant pain in the medial or lateral joint lines, signs of knee instability in the saggital plane or pain with meniscal maneuvers should make us suspect of other knee lesions. Diagnosis of PF-OA: Patient Selection 6.3 Preoperative Radiology 6.1 Anamnesis Pain is the main symptom of patients with PFOA. Usually the pain is referred in the anterior aspect of the knee. A differential diagnosis with anterior knee pain from other causes (tendinitis, synovitis, etc.), or referred pain of spinal or hip joint origin, must be done. Usually the pain produced by PF-OA increases in closed chain movements with knee flexion and the foot on the ground, such as when getting up from a chair, squatting, rising up and down stairs. In all these situations the contraction of the extensor mechanism combined with the flexion of the knee greatly increases the pressure supported by the articular surfaces of the patella and trochlea, causing pain. The pain when walking on flat surfaces is much lesser. Another frequent symptom in PF-OA is the presence of crepitus on the anterior aspect of the knee. Recurrent joint effusions are frequent and feeling of locking in the anterior aspect of the knee can also occur. 6.2 Physical Examination On inspection, rotational abnormalities of the lower extremities during standing and walking should be examined, as they cause a medial situation of the patella when the patient places the feet facing forward. The alignment of the extremities in the coronal plane must also be explored, since a significant genu varum or genu valgum should contraindicate the use of a PFA. Pain and crepitus are frequent when the patella is mobilized in the longitudinal axis. Pain For the diagnosis of isolated PF-OA and surgical planning of PFA the following X-rays are recommended [13]: – Anterior–posterior weight-bearing view: It must show the medial and lateral joint lines preserved. This view is not necessary if a good quality weight-bearing long X-ray centered on the knee is available. – Rosenberg (or schuss) view: Posterioranterior projection made with weight-bearing at about 40° of flexion. If an impingement of the joint line height is observed, degenerative changes in the posterior aspect of the knee should be suspected. – True lateral view (both femoral condyles must be seen aligned) (Fig. 7). A decrease in the patello-femoral joint line height can be seen, with preservation of the femoro-tibial joint line. On this view, the presence of a trochlear dysplasia, common in PF-OA, can be analysed. On this view, an assessment of the height of the patella should be done, usually using the Caton-Deschamps index (CDI). The presence of a high-riding patella or patella alta (CDI > 1.2) may advise us to add a distalization of the anterior tibial tuberosity (TT), while the presence of a low-riding patella or patella baja (CDI < 0.8) is a contraindication, at least relative, for a PFA. – Patellar axial view (Fig. 8): with a knee flexion of about 30°. It allows us to observe the involvement of the lateral and medial patellar facets, as well as indirect signs of instability of the extensor mechanism, like a lateral subluxation of the patella or an excessive tilt.
Patellofemoral Arthroplasty. Pearls and Pitfalls 599 considered a contraindication for PFA (Remy), since it increases the risk of progression of osteoarthritis to the other compartments, and therefore the need for surgical revision of a PFA. 6.4 Other Examinations Fig. 7 True lateral view: significant decrease in the patello-femoral joint line, with the femoro-tibial joint line preserved. A trochlear dysplasia can be seen and the patella height measured – Full-limb length weight bearing view: It is advisable to measure the hip-knee-ankle angle, which is the angle that connects the mechanical axes of the femur and the tibia. A varus or valgus deformity greater than 5° is Fig. 8 Patellar view: Made at 30° of flexion it shows the impingement of the joint line and signs of lateral instability of the extensor mechanism – Magnetic resonance imaging (MRI) (Fig. 9): If there are concerns about the femoro-tibial compartments condition, or about the association with meniscal or ligament pathology, it can be studied by MRI. MRI would not be routinely indicated in the preoperative evaluation of all PFA. If patellar instability is suspected, MRI (or computerized tomography) can show the alignment of the extensor mechanism, and the patellar tilt or subluxation and the tibial tuberosity-trochlear groove distance (TT-TG) can be measured. – Bone scintigraphy: In a recent study, Baker et al. recommend the use of preoperative bone scintigraphy to ensure that tracer uptake is limited to the patello-femoral joint, and this reduces the risk of progression of osteoarthritis to the other compartments during follow-up [14], but it is not used in our routine protocol.
600 P. Hinarejos 7.2 Medialization and Anteriorization Osteotomy of the Tibial Tuberosity Fig. 9 Magnetic nuclear imaging showing severe patellofemoral osteoarthritis with joint effusion and lateral subluxation of the patella in a patient with trochlear dysplasia This technique, described by Fulkerson [15], consists of an oblique osteotomy (from anteromedial to postero-lateral) of the TT, which is mobilized in a medial direction, achieving its anteriorization (Maquet effect) in addition to the medialization. Subsequently, the TT is fixed with two compression screws in its new position. This surgery would be indicated only in cases in which osteoarthritis is isolated in the lateral facet of the patella and there is an increased distance TT-GT, especially if the cartilage lesions are not full-thickness. The most frequently reported complications after TT osteotomy are nonunion, shaft fractures of the tibia distal to the osteotomy, or discomfort caused by screw heads [3]. 7.3 Patellectomy 7 Treatment Alternatives When an isolated PF O-A is diagnosed, several treatment alternatives to PFA have been proposed. 7.1 Conservative Treatment The initial treatment for any patient with isolated PF-OA should be conservative: activity modification (avoiding squatting positions and the use of stairs as much as possible), and overweight control must be recommended in case of obesity. Physical therapy should aim to strengthen the thigh and gluteal muscles, as well as stretching the contracted structures, especially the hamstrings. For pain control, the use of analgesics is recommended, and the use of injections for viscosupplementation may be indicated [3]. If knee braces are used, it is recommended to use those with a hole in the anterior part to minimize direct pressure on the patella. Resection of the patella and secondary reconstruction of the extensor mechanism was a widely used technique for the treatment of isolated PF O-A in the past. However, this technique was associated with loss of strength, as well as a feeling of instability and pain in a significant number of patients. In 50% of the cases in which the patellectomy was performed as a treatment for osteoarthritis they were considered failures [16]. These poor results, associated with the rise of the prosthetic surgery, have caused that this technique has been almost given up for the treatment of PF O-A. 7.4 Partial Lateral Patella Facetectomy This technique has been used in short series of patients with PF O-A with satisfactory results [17]. It consists in a resection by vertical osteotomy of the most lateral part of the lateral patellar facet, with its corresponding osteophyte,
Patellofemoral Arthroplasty. Pearls and Pitfalls leaving the lateral retinaculum open to reduce the pressure on the lateral facet. It should only be indicated if the osteoarthritis is limited to the lateral facet and it is associated with a lateral subluxation of the patella with an increase in its tilt. Its results are more predictable when the cartilage lesions of the lateral facet are not full thickness. 601 meta-analysis [21] TKAs have a significant lower revision rate than PFAs. For this reason, in elderly patients, for whom a TKA has a high chance of being a single surgery that does not require further revisions, it is the preferred indication. 8 7.5 Total Knee Arthroplasty (TKA) Although the majority of TKAs are used for the treatment of bi- or tricompartmental osteoarthritis of the knee, several authors have reported good results in the use of TKAs for the treatment of isolated PF O-A, similar to those obtained with TKAs for tricompartmental osteoarthritis [18, 19]. However, these cases often require a section of the lateral retinaculum to achieve a good patellar tracking [19]. TKA is probably still the best treatment for isolated PF O-A in very advanced stages in older patients, from 65 or 70 years of age. In studies based on National Registries [20], and also in Fig. 10 Preservation of bone, ligaments and menisci during implantation of a left patello-femoral arthroplasty Advantages of PFAs Compared to the alternative of a TKA (which probably remains the gold standard for the elderly patients), PFAs have several advantages: – Greater bone preservation (Fig. 10). This allows the revision of a PFA to be performed with a primary TKA, without the need for metallic augments or stems (unlike TKAs, that frequently need these elements and a greater degree of constriction in their revision). – More normal kinematics: By preservation of all knee ligaments and both menisci, in addition to the preservation of the femoro-tibial joint. – Lower risk of perioperative complications (infection or deep vein thrombosis)
602 P. Hinarejos – – – – Less perioperative bleeding [22] Less hospital stay Faster postoperative rehabilitation Better functional results: In a randomized study with 100 knees with isolated PF-OA, a higher score in the KOOS-Symptoms, less pain in the SF-36 and a better range of motion was observed in the PFA group than in the TKA group [23] – Greater possibility to return to sports activity [22] All the aforementioned advantages make PFAs an alternative to be seriously taken into account in young patients. 9 Surgical Technique After an anterior longitudinal incision, a medial parapatellar arthrotomy is usually performed (although some authors recommend a lateral arthrotomy) [13], taking special care not to injure the medial meniscus anterior horn (Fig. 11). Injury to cartilage in preserved areas must also be avoided. Fig. 11 Medial knee arthrotomy, preserving the anterior horns of both menisci and the intermeniscal ligament A partial excision of retropatellar fat pad and a synovectomy of the subquadricipital area are performed. Intraoperatively, the indemnity of the femoro-tibial joints must be verified. In onlay prostheses (the most frequently used today) an anterior cut of the femur is performed, looking for an external rotation with respect to the posterior bicondylar line to improve the patellar tracking, trying to make this cut parallel to the transepicondylar axis and perpendicular to the Whiteside’s line [24] (Fig. 12). This cut must end at the level of the anterior cortex of the femoral shaft, avoiding a trochlear component overstuffing that cause an increase in the anterior space of the knee. The size of the component must be adjusted to the size of the bone (Fig. 13), trying to avoid an abrupt transition between the metal component and the bone that can cause an impingement of the patella. If we use a symmetrical trochlear component, we must seek to align it in a certain valgus (usually 7–10°) with respect to the joint line to improve the patellar tracking centered on the trochlea. In the case of third-generation, anatomical PFA, the valgus is already incorporated into the implant [24].
Patellofemoral Arthroplasty. Pearls and Pitfalls Fig. 12 Anterior cutting guide of the trochlea in a left PFA, oriented in external rotation respect to the posterior condyles, taking as reference the epicondylar line (and the Whiteside line) Fig. 13 Trochlear component should not be raised with respect to the anterior cortex or in flexion to avoid protrusion of the patella with the edge of the trochlea 603
604 P. Hinarejos Fig. 14 Medialization of the cemented symmetric patellar component in the patellofemoral arthroplasty The patella will be replaced trying to reproduce the thickness of the original patella and trying to medialize the patellar component to improve patellar tracking (Fig. 14), although this medialization should not be excessive. Very frequently the wear of the patella is not only from the cartilage, but also from the bone, and this can create a mistake about the previous thickness of the patella. In any case, a minimum thickness of 12 mm in the bone remnant of the patella must be tried to be mantained, since a smaller thickness increases the risk of patellar fracture [13]. Some authors have used PFAs without patellar replacement, but in some cases thet have had to perform a patellar resurfacing in a second surgery in a subgroup of patients [25]. The systematic replacement of the patella is widely recommended. With the trial components, the correct patellar tracking must be assessed (Fig. 15), and the lateral tilt or subluxation of the patella should be corrected. If these signs of patellar instability are found, a lateral patellar release must be performed. The rate of patients who required a lateral patellar release is highly variable between series, reaching up to 82% in some of them [22]. Other authors suggest performing a vertical patellectomy of 10–15 mm including the lateral osteophyte of the patella [6], avoiding the lateral patellar soft tissue release. The absence of impingement between the patella and the superior edge of the trochlea during the range of motion must also be checked [26]. Associated procedures – In cases of severe patella alta, a distalization osteotomy of the TT may be associated to ensure that the patella articulates with the trochlea when the knee is in full extension [9]. Not treating a patella alta when implanting a PFA has been associated with lower postoperative outcomes in some series [27], but not in some others [28]. – In cases of severe instability with lateralization of the TT (high distance TT-GT), it may be necessary to associate a medialization of the TT to ensure that the patella moves centered on the trochlea. – In cases of significant low patella, a proximalization osteotomy of the TT or lengthening of the patellar tendon may be indicated.
Patellofemoral Arthroplasty. Pearls and Pitfalls 605 Fig. 15 Checking of the patellar tracking along the flexion–extension range of motion, without patellar subluxation or excessive tilt 10 Postoperative Treatment and Rehabilitation Although the incidence of infectious or thromboembolic complications is lower than that of TKAs, the use of antibiotic and antithrombotic prophylaxis similar to that used in TKAs is recommended. The analgesic guidelines in the postoperative period are also similar to those of the TKAs, but the need for opioids after surgery is frequently lower than after TKAs. In the postoperative period, knee mobilization and weight bearing should begin immediately. Physiotherapy protocols after PFAs are usually almost identical to those for TKAs. 11 PFAs Results With first-generation PFAs, the percentage of good and excellent results at 5–10 years was highly variable: from just 45% with the Lubinus prosthesis [4] to around 85% with the Richards prosthesis, highly depending on the specific implant design. With these models, a frequent cause of revision was patella instability, up to 43% in some series [29]. With second-generation PFAs, designed with a wider trochlear angle and less constriction, the percentage of good and excellent results in the short and mid term has increased to 85–94% [2, 8]. With these models, the need for revision due
606 to mechanical problems (patella instability) has greatly decreased and the main cause of revision is disease progression to the femoro-tibial compartments. A systematic review comparing the functional outcomes (measured with KSS, OKS, and WOMAC) of second-generation PFAs to TKAs for the treatment of isolated PF O-A concluded that there is no difference between both treatments in terms of function [30]. Ackroyd reported in a 5.2 years follow-up study with Avon PFA a revision rate of 15% and progression of osteoarthritis to the other compartments was the main cause of revision [8]. Some series of second-generation inlay PFAs, with a 5-year follow-up reported a similar revision rate of 17%, but in the case of inlay PFAs the main cause of revision was persistent pain [31]. When inlay PFAs were compared to onlay PFAs in the Australian Registry, the 5-year revision rate was higher than 20% for the former and lower than 10% for the latter [2]. Leadbetter et al., in a multicenter study with the Avon PFA and a follow-up of 2–6 years, reported a 90% rate of patients without pain in daily life activities, with an improvement in the KSS from 56 to 83 points [10]. The results of PFAs seem to be better in the group of patients whose diagnosis was trochlear dysplasia than in the group with primary osteoarthritis [27]. In a comparative study between PFAs and TKAs in young patients, it was concluded that the improvement in symptoms and functionality assessed by different scores is similar between both groups at 2-years [32]. In a longer-term series, van Jonbergen et al. reported a series of 185 Richards II type PFAs with a survival rate of 84% at 10 years and 69% at 20 years [33]. Survival was not influenced by age, gender, or primary diagnosis, but it decreased in obese patients. Femoro-tibial osteoarthritis was observed in 45% of patients in the long term, but had only required conversion to TKAs in 13% of them. There are few publications of the third generation of PFAs, with an anatomical trochlear component, but some of them suggest a low revision rate (around 5%) in the short to medium P. Hinarejos term (5 years) [34, 35]. Nevertheless, the revision cumulate rates of PFAs from several National Registries remain higher than those of TKAs [36]. In addition to an improved survival rate in recent decades, the functional result is similar to or better than that of TKAs [23, 37, 38] and the satisfaction rate is high, with 78% having no residual postoperative symptoms. 80% of patients would recommend this type of surgery to others [34], and the rate of satisfied and very satisfied patients exceeds 90% [35]. Moreover, from an echonomical point of view, PFAs are more cost-effective than TKAs, at least in the short term [39]. The reported results of PFAs in the last decade have encouraged some authors to expand the indications, combining its use with unicompartmental prosthesis if it is associated with femorotibial osteoarthritis in only one of its compartments [25, 35]. 12 Complications of PFAs 12.1 Early Complications The incidence of readmissions after PFAs at 30 days (4.3%) is similar or slightly lower than that of TKAs [11], and most of the causes that require readmission are related to medical complications such as bleeding requiring transfusion, urinary tract infections or deep vein thrombosis. The reoperation rate at 30 days is 1.5% [11]. Most early complications (excluding infections) are secondary to poor surgical technique. – Patellar instability: This complication was much more frequent in first-generation PFAs, with inlay components, in which the trochlea had to be accommodated to the patient’s anatomical trochlea. If a previous trochlear dysplasia is present, it is not corrected with an inlay component and a postoperative subluxation or excessive tilt of the patella could remain if it is not diagnosed and corrected in the same surgical act. With onlay
Patellofemoral Arthroplasty. Pearls and Pitfalls components, a mistake to achieve a proper external rotation of the trochlea can also cause lateral instability of the extensor mechanism. If patellar instability is observed during surgery, it must be corrected by adjusting the rotation of the trochlear component and associating lateral patellar release. When necessary, a medialization osteotomy of the TT should be added. – Protrusion of the patella: Placing the trochlear implant in flexion can cause a patellar clunk when the patella engages with the elevated trochlear component (Fig. 16). – Perirpatellar pain: It may be the consequence of an increase in the anterior space of the knee, due to an insufficient cut or a too thick component, either in the trochlea or in the patella [40]. This pain can also appear if a trochlear component that is too large is used, protruding medially or laterally and irritating the synovium at this level. – Postoperative stiffness: A percentage of 3– 14% of patients may require a manipulation under anesthesia to improve postoperative knee flexion if postoperative flexion is less Fig. 16 Excessive elevation of the trochlear component over the anterior cortex of the patella. It can cause anterior pain due to thickening of the anterior knee space, or protrusion of the patella when beginning knee flexion 607 than 90° [8, 33]. This complication is more frequent if the trochlear component is too thick or it is implanted in a too anterior position, or if a too thick patella is mantained, causing excessive tension in the anterior space of the knee. 12.2 Late Complications – Prosthetic loosening and wear of the patellar button: These are rare complications, but they can be treated with an isolated revision of the patellar component. Loosening rate is < 1% at mid term follow-up [2]. – Persistent pain: The presence of persistent pain, without evidence of any other complication, is the cause of revision of PFAs in up to 16% of cases [41], and even higher in inlay PFAs [31]. – Chronic effusions: It is not uncommon to observe long-term joint effusions, especially if there are technical errors like placement of the trochlear component in internal rotation [10]. – Progression of degenerative disease to the femoro-tibial compartments: It is the most frequent cause of PFA revision in almost all case series and all national registries [42]. In the Australian Registry, the progression of osteoarthritis to the other compartments is the cause of the revision of PFAs in 56% of cases [36]. For this reason, the proper selection of PFA candidates is very important, as they must not have degenerative femoro-tibial changes at the time of surgery, morbide obesity, or varus or valgus malalignment, conditions that can make the evolution of the disease easier. The progression of the disease to the femoro-tibial joint (Fig. 17) seems to be more frequent in cases of primary osteoarthritis than in those cases with trochlear dysplasia or post-traumatic osteoarthritis [22]. A case–control study suggested that the use of second-generation inlaytype PFA (the Hemicap Wave from Arthrosaurace, USA) seems to be associated with a lower rate of disease progression to other
608 P. Hinarejos 13 Fig. 17 Rosenberg view at long-term follow-up of PFA (14 years): Progression of the degenerative disease to the lateral femoro-tibial compartment compartments in the short term (2 years) than the use of an onlay-type PFA, and the cause could be that a significant percentage of patients after an onlay PFA have synovitis and persistent effusions, with cytokines which cause the evolution of degenerative changes to the other compartments [43]. Fig. 18 Appearance of the trochlea after removal of the component during a revision to a total knee arthroplaty: Almost complete preservation of the bone remnant PFA Revision Despite the progressive improvement in PFAs results in the last four decades, the revision rate of PFAs is still significantly higher than that of TKAs, around 10% at 6 years and above 15% at 10 years follow-up [36]. There is a series of 14 first-generation Lubinus PFAs, which were revised to new Avon secondgeneration PFAs, with clinical improvement [44], but in these cases the revision was due to patellar instability and wear of polyethylene. A revision of a PFA to another PFA should only be considered in the presence of a well-known cause and in the presence of femoro-tibial compartments without any arthritic involvement. In all other cases, the failure of a PFA must be treated with a revision to a TKA [9]. The revision of a PFA to a TKA is usually a simple surgery, similar to the implantation of a primary TKA, since there are no significant bone defects (Fig. 18) or problems with the ligament balance. The TKA used in the PFA revision can be performed with retention or with sacrifice of the posterior cruciate ligament, and both strategies appear to give similar results [36].
Patellofemoral Arthroplasty. Pearls and Pitfalls 609 Fig. 19 Checking during a revision of the PFA (due to disease progression): Adequate fixation and absence of wear of the patellar component of the PFA As said before, the most common cause of revision of PFAs is disease progression to the femoro-tibial compartments [42]. Except when there is an excessive wear or loosening of the patellar component, the patellar button can be preserved (Fig. 19). In a large series based on the Australian registry only 42% of the patellar components were revised during revision from a PFA to a TKA [36]. One case series found that the results of revision of PFA to a TKA are similar to those of a primary TKA [45]. However, data from the Australian Registry suggest that the survival of TKAs after a PFA could be lower than that of primary TKAs [36]. 14 Take-Home Messages 1. Adequate patient selection is essential in the use of PFAs. The preoperative study of the patient must confirm that femoro-tibial compartments are undamaged and it should rule out the presence of severe limb malalignment. 2. Careful surgical technique is also fundamental to obtain satisfactory results. Contemporary PFAs have instruments that make the technique more reproducible, but attention must be paid to some technical details, such as the correct choice of the size, the placement of the correct degree of flexion of the trochlear component, and avoiding to increase the anterior space of the knee. 3. The results of contemporary PFAs appear to be clearly superior to those of the models used 2–3 decades ago. Although the survival rate of PFAs is not yet the same as that of TKAs, the fact that they have some advantages such as a faster postoperative recovery and slightly superior functional results, the use of PFA is recommended in young patients with isolated PF-OA. 4. The most common cause of PFAs failure is the progression of osteoarthritis to the other compartments, but revision of the PFA is in most cases a simple surgery with reproducible results. 5. The use of PFAs is a useful treatment in isolated PF-OA, especially in relatively young patients, but in patients older than 70 years, the use of TKAs is recommended because of their more reproducible results.
610 15 P. Hinarejos Key Message PFA is a useful treatment of isolated PF-OA in relatively young patients, but an adequate patient selection and careful surgical technique are essential factors to achieve satisfactory results. References 1. Davies AP, Vince AS, Shepstone L, Donell ST, Glasgow MM. The radiologic prevalence of patellofemoral osteoarthritis. Clin Orthop Relat Res. 2002;402:206–12. 2. Lonner JH, Bloomfield MR. The clinical outcome of patellofemoral arthroplasty. Orthop Clin North Am. 2013;44:271–80. 3. Grelsamer RP, Stein DA. Patellofemoral arthritis. J Bone Joint Surg Am. 2006;88:1849–60. 4. Tauro B, Ackroyd CE, Newman JH, Shah NA. The Lubinus patellofemoral arthroplasty. A five to ten year prospective study. J Bone Joint Surg Br 2001;83-B:696–701. 5. Amis AA, Senavongse W, Darcy P. Biomechanics of patellofemoral joint prostheses. Clin Orthop Relat Res. 2005;436:20–9. 6. Dejour D, Saffarini M, Malemo Y, Pungitore M, Valluy J, Nover L, Demey G. Early outcomes of an anatomic trochlear-cutting patellofemoral arthroplasty: patient selection is key. Knee Surg Sports Traumatol Arthrosc. 2019;27:2297–302. 7. Borus T, Brilhault J, Confalonieri N, Johnson D, Thienpont E. Patellofemoral joint replacement, an evolving concept. Knee. 2014;21(Suppl 1):S47-50. 8. Ackroyd CE, Newman JH, Evans R, Eldridge JD, Joslin CC. The Avon patellofemoral arthroplasty: five-year survivorship and functional results. J Bone Joint Surg Br. 2007;89:310–5. 9. Lustig S, Magnussen RA, Dahm DL, Parker D. Patellofemoral arthroplasty, where are we today? Knee Surg Sports Traumatol Arthrosc. 2012;20:1216–26. 10. Leadbetter WB, Seyler TM, Ragland P, Mont MA. Indications, contraindications and pitfalls of patellofemroal arthroplasty. J Bone Joint Surg (Am) (Suppl 4) 2006;88: 122–137. 11. Rezzadeh K, Behery OA, Kester BS, Dogra T, Vigdorchik J, Schwarzkopf R. Patellofemoral arthroplasty: short-term complications and risk factors. J Knee Surg. 2020;33(9):912–8. 12. Tishelman JC, Pyne A, Kahlenberg CA, Gruskay JA, Strickland SM. Obesity does not affect patientreported outcomes following patellofemoral arthroplasty. J Knee Surg. 2020. https://doi.org/10.1055/s0040-1713862. Online ahead of print. 13. Remy F. Surgical technique in patellofemoral arthroplasty. Orthop Traumatol Surg Res. 2019;105(1S): S165–76. 14. Baker JF, Caborn DN, Schlierf TJ, Fain TB, Smith LS, Malkani AL. Isolated patellofemoral joint arthroplasty: can preoperative bone scans predict survivorship? J Arthroplasty. 2020;35:57–60. 15. Fulkerson JP, Becker GJ, Meaney JA, Miranda M, Folcik MA. Anteromedial tibial tubercle transfer without bone graft. Am J Sports Med. 1990;18:490–6. 16. Lennox IA, Cobb AG, Knowles J, Bentley G. Knee function after patellectomy. A 12- to 48-year followup. J Bone Joint Surg Br. 1994;76:485–487. 17. Yercan HS, Ait Si Selmi T, Neyret P. The treatment of patellofemoral osteoarthritis with partial lateral facetectomy. Clin Orthop Relat Res. 2005;436:14–19. 18. Mont MA, Haas S, Mullick T, Hungerford DS. Total knee arthroplasty for patellofemoral arthritis. J Bone Joint Surg Am. 2002;84:1977–81. 19. Parvizi J, Stuart MJ, Pagnano MW, Hanssen AD. Total knee arthroplasty in patients with isolated patellofemoral arthritis. Clin Orthop Relat Res. 2001;392:147–52. 20. National Joint Registry for England and Wales. 15th Annual Report 2018. https://www.hqip.org.uk/resource/ national-joint-registry-15th-annual-report-2018. 21. Dy CJ, Franco N, Ma Y, Mazumdar M, McCarthy MM, Gonzalez Della Valle A. Complications after patello-femoral versus total knee replacement in the treatment of isolated patello-femoral osteoarthritis. A meta-analysis. Knee Surg Sports Traumatol Arthrosc. 2012;20:2174–2190. 22. Dahm DL, Al-Rayashi W, Dajani K, Shah JP, Levy BA, Stuart MJ. Patellofemoral arthroplasty versus total knee arthroplasty in patients with isolated patellofemoral osteoarthritis. Am J Orthop (Belle Mead NJ). 2010;39:487–91. 23. Odgaard A, Madsen F, Kristensen PW, Kappel A, Fabrin J. The mark coventry award: patellofemoral arthroplasty results in better range of movement and early patient-reported outcomes than TKA. Clin Orthop Relat Res. 2018;476:87–100. 24. Thienpont E, Lonner JH. Coronal alignment of patellofemoral arthroplasty. Knee. 2014;21(Suppl 1):S51–7. 25. Benazzo F, Rossi SM, Ghiara M. Partial knee arthroplasty: patellofemoral arthroplasty and combined unicompartmental and patellofemoral arthroplasty implants–general considerations and indications, technique and clinical experience. Knee. 2014;21(Suppl 1):S43–6. 26. Lonner J. Patellofemoral arthroplasty. Pros, cons, design considerations. Clin Orthop. 2004;428:158–165. 27. Dai Y, Diao N, Lin W, Yang G, Kang H, Wang F. Patient-reported outcomes and risk factors for decreased improvement after patellofemoral arthroplasty. J Knee Surg. 2021. https://doi.org/10.1055/s0041-1735159.
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Clinical Cases—Primary and Revision Patellofemoral Surgery Patellofemoral Joint Preservation Surgery A Case-Based Approach In this section of the book, 11 clinical cases that represent real situations that we encounter in our daily clinical practice are presented. The goal of case-based teaching is to engage the reader in real-world decision making. This pedagogical approach aims to apply the knowledge acquired by the reader in the two previous sections of this book to solve the clinical cases presented. Another objective of this section is to emphasize that prosthetic surgery is not necessarily the first option for treating patients with severe patellofemoral chondropathies. This clinical entity is typical of active young people. Therefore, all our efforts must be focused on performing joint preservation surgery and avoiding prosthetic surgery. In the cases that are presented in this section, the importance of torsional abnormalities in the treatment of patients with patellofemoral pain is emphasized. In addition, the cases presented show that the etiology of patellofemoral disorders is multifactorial. Therefore, a complete physical examination and imaging studies to discover all the anatomical abnormalities that the patient presents, of which there are often many, is crucial. We must strive to restore normal anatomy, because that will create a better biomechanical environment for the repaired tissue. We must understand biomechanics because orthopedic surgery is a mechanical engineering discipline. I believe that these cases are a good stimulus for our intellectual activity and will make us forget many of the dogmas that we have been taught. These cases will provide us with the opportunity to learn something new.
Case # 1: Disabling Anterior Knee Pain After Failed MPFL Reconstruction in a Patient with Patellar Chondropathy, Femoral Anteversion and External Tibial Torsion Vicente Sanchis-Alfonso and Alejandro Roselló-Añón 1 Clinical Case This is the case of a 22 years-old female (163 cm in height and 51 kg, BMI 19.2) who came to our office for a second opinion for disabling longlasting right anterior knee pain (AKP) since the age of 16. It had shown itself resistant to conservative treatment. She also had right patellar instability, but it was not her main complaint. She had previously undergone a bilateral medial patellofemoral ligament reconstruction (MPFLr). The proposal made by the previous orthopedic surgeon to solve the problem of her right knee was a Tibial tubercle osteotomy (TTO). Upon her visit to my office, the patient had severe right AKP (VAS 7) despite her taking medication (paroxetine, trazodone and tapentadol), and central sensitization (CSI 63). She experienced quite significant limitations in her daily living activities (Kujala score 36; IKDC 16.1) as well as a consequential decrease in her Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/978-3-031-09767-6_42. V. Sanchis-Alfonso (&) A. Roselló-Añón Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com quality of life (EuroQol 5D 2–2-2–2-2 [0.493]). She had depression (HAD 11), catastrophizing (PCS 30) and kinesiophobia (TSK 49). She also had pain in the anterior aspect of her left knee. But the knee that caused serious problems was the right one and she wanted a resolution. For her, the left knee was the good one. 2 Physical Examination In the examination, we asked her to locate the pain. She placed her hand over the anterolateral aspect of the knee (see video). There was tenderness over the lateral retinaculum, pain with the patellar glide test and with the axial compression test. Moreover, there was pain with palpation of the inferior pole of the patella. The patella could not be laterally dislocated but there was a positive apprehension test with the lateral displacement of the patella (see video). Patellofemoral tracking was normal (negative J-sign). From a clinical standpoint, there was a right femoral anteversion given that internal rotation of the right hip exceeded external rotation by more than 30 degrees (Fig. 1). Moreover, there was excessive external tibial torsion on the right side (Fig. 2). However, there was no squinting patella despite the presence of femoral anteversion and external tibial torsion. In this patient, the foot was externally rotated during the swing phase of gait (see video). © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_42 615
616 V. Sanchis-Alfonso and A. Roselló-Añón Fig. 1 During physical examination, the patient was seen to exhibit right femoral anteversion Fig. 2 During physical examination, the patient was seen to exhibit right external tibial torsion
Case # 1: Disabling Anterior Knee Pain After Failed MPFL Reconstruction … 617 Fig. 3 CT—patellar tunnels for MPFLr. Arthroscopy— Severe patellar chondropathy Nobody had ever evaluated torsional anomalies in this patient previous to visiting with me. Femoral and tibial rotational abnormalities are the most ignored factors in the diagnosis and treatment of AKP patients. right 15 mm/left 14 mm; patellar tilt, right 3º/left 3º; femoral anteversion (Murphy´s method), right 39º/left 22º; external tibial torsion, right 43º/left 23º). Bone overload was detected using a SPECT-CT scan (Fig. 4). 4 3 Imaging Studies Plain radiographs were normal. There was no lower-limb malalignment on the coronal plane. In Fig. 3, one can see the patellar tunnels performed during MPFLr. The patellar tunnels penetrate the articular face of the patella. A CT scan was done to evaluate the patella and the torsional abnormalities (TT-TG distance, What to Do in Such a Situation? The only objective pathological finding in this patient was the torsional abnormality of both femur and tibia. Therefore, our proposal was a double level osteotomy, an intertrochanteric external rotational femoral osteotomy of 20º (39–20 = 19) and internal rotational tibial osteotomy of 15º (43–15 = 28) just distal to the tibial tuberosity. Since the proposed tibial derotation was less than 20º, the association of a fibular osteotomy and the release of the peroneal nerve were not considered.
618 V. Sanchis-Alfonso and A. Roselló-Añón Fig. 4 The SPECT-CT scan showing an uptake increment in the lateral aspect of the patellofemoral joint (PFJ). The SPECT-CT scan can reveal the metabolic and geographic characteristics of bone homeostasis, which is the normal osseous metabolic status of a living joint 5 7 Why not the Tibial Tubercle Osteotomy? First, the TTO is not done when the TT-TG distance is < 20 mm. Moreover, TT medialization increases tibial external rotation, [1] which might trigger more AKP. Lastly, femoral anteversion is a poor prognostic factor in patients undergoing a TTO. That is, the TTO does not prevent the negative effect of femoral anteversion on the PFJ [2]. 6 Why Rotational Osteotomy? Rotational osteotomy is the most powerful treatment for the AKP patient with torsional abnormalities. The quadriceps, is responsible for the force acting on the patella. Osteotomy changes the quadriceps direction and therefore the force acting on the patella. Special Considerations. Why Double Level Rotational Osteotomy? This clinical case raises several questions. What is more important in the genesis of AKP, femoral anteversion or external tibial torsion? What would be the ideal indication? Femoral osteotomy? Tibial osteotomy? Maybe both? From an anatomical standpoint, the best option to treat this patient would be a combination of the femoral and tibial osteotomy. Another option would be to operate on the bone with the greatest variance from normal. In this case, both the torsional alteration of the femur and of the tibia were of similar pathological magnitude. Moreover, the foot was externally rotated during the swing phase of gait in this patient. For this reason, we decided on a double level (femoral and tibial) osteotomy.
Case # 1: Disabling Anterior Knee Pain After Failed MPFL Reconstruction … 8 Follow-Up In this case, the result was immediate relative to the elimination of pain. Furthermore, twelve months after surgery, the patient has no knee pain at all and was able go up and down the stairs in a natural way with no problem (see video). Additionally, there is no apprehension. In Figs. 5 and 6, one can see the before and after of the double level osteotomy. The X-rays at the 4month follow-up can be seen in Fig. 7. The pattern of descending and ascending stairs has been completely normalized. In the attached video we can see how she went up and down the stairs before the surgery, and at 3, 6, 9 and 12 months post-surgery. Moreover, in the attached video you can hear the mother's testimony, which is sometimes more demonstrative than the scores. 9 619 What Has This Case Taught Us? Key Points In the AKP patient, think about limb alignment, not patellar alignment. Limb alignment is crucial, especially torsional alignment. Skeletal torsional abnormalities are the most ignored factors in the diagnosis of AKP. Not all patients with femoral anteversion have squinting patella. In some patients with torsional abnormalities, as in the case presented here, the SPECT-CT study reveals an uptake increment in the lateral aspect of the PFJ that allows us to justify the pain in these patients. Therefore, the SPECT-CT scan helps to make a correct surgical indication. Osteotomy is the most powerful and underutilized treatment for the AKP patient with torsional abnormalities. Fig. 5 Correction of femoral anteversion after femoral rotational osteotomy
620 V. Sanchis-Alfonso and A. Roselló-Añón Fig. 6 Correction of external tibial torsion after tibial rotational osteotomy Fig. 7 X-rays at the 4-month follow-up In this case, the patient is pain-free even though the iatrogenic patellar chondropathy presented was left alone. In the PFJ, patellofemoral congruence and smooth kinematics are much more important than normal articular cartilage. The presence of a psychological affectation, as in the case at hand, should not be the excuse to stop analyzing possible mechanical causes that justify the pain of our patient and only send her to a psychiatric unit. Even if it takes more patience and tender loving care from the provider, we need to look hard for pathology and help patients with psychological impairment. In the same way, the presence of central sensitization (CS) should not be the excuse to stop analyzing possible mechanical causes that justify the pain in our patient and send her to a “Pain Unit”. There are patients with high values in the CS score who have objective structural causes that provide an explanation for the pain
Case # 1: Disabling Anterior Knee Pain After Failed MPFL Reconstruction … that had gone undetected. Once the structural cause is treated to improve or eliminate it, it causes the CS score to drop drastically. 10 Conclusion In the clinical case presented here, the restoration of stability did not relieve the AKP, but it did disappear after correction of femoral and tibial maltorsion. 621 References 1. Mani S, Kirkpatrick MS, Saranathan A, et al. Tibial tuberosity osteotomy for patellofemoral realignment alters tibiofemoral kinematics. Am J Sports Med. 2011;39(5):1024–31. 2. Franciozi CE, Ambra LF, Albertoni LJ, et al. Increased femoral anteversion influence over surgically treated recurrent patellar instability patients. Arthroscopy. 2017;33(3):633–40.
Case # 2: Disabling Anterior Knee Pain Recalcitrant to Conservative Treatment in a Patient with Patellofemoral Osteoarthritis and Structural Femoral Retrotorsion and Genu Varum Vicente Sanchis-Alfonso and Alejandro Roselló-Añón 1 Clinical Case This is the case of a 55 years-old female with seriously disabling left anterior knee pain (AKP), which was her main complaint, recalcitrant to conservative treatment. Her VAS score stood at between 6 and 7 almost every day. The VAS score rose to 10 on various occasions throughout the month. Moreover, she had pain in the left groin area as well as ankle pain. It all started when she was 48 years-old after a traffic accident. As a result of the accident, she suffered a femur and tibia fracture that were not treated adequately because the treating physicians thought she was going to die. The injuries significantly limited her daily living activities (Kujala score 31, IKDC 27). X-rays showed lower left limb malalignment on the coronal plane (genu varum of 4º) (Fig. 1). Computed tomography (CT) showed patellofemoral osteoarthritis (PFOA), left femoral retroversion of 13º, measured with Murphy´s method (the right side presented with a normal femoral anteversion of 16º), left external tibial torsion of 25º (right side 18º) and a left knee rotation angle of 7º (right side 4º). The diagnosis was left V. Sanchis-Alfonso (&) A. Roselló-Añón Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com PFOA, a left femur fracture and a left tibia fracture with a vicious consolidation (Figs. 1 and 2). 2 What to Do in Such a Situation? She had visited various orthopedic surgeons that had recommended different treatment options like physical therapy, Fulkerson s osteotomy or a patellofemoral replacement. However, all of them said that her best option would be to handle the pain and wait for a knee replacement. The main problem in this case was the disabling AKP. Of course, the varus can contribute to patellofemoral pain. Varus-valgus malalignment has been shown to influence the progression of PFOA [1]. Varus alignment increases the likelihood of medial PFOA progression. In a cadaveric study, Fujikawa and colleagues [2] found an important alteration of the patellofemoral contact areas with the introduction of an increment of varus alignment brought on by a varus osteotomy. Nevertheless, it is our opinion that the retroversion has more influence on her knee pain. Moreover, we think that knee surgery on a crooked skeleton is not what one would call a good plan. Our surgical plan was to perform a femoral intertrochanteric internal de-rotational osteotomy (25º) and a valgus opening wedge proximal tibial © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_43 623
624 V. Sanchis-Alfonso and A. Roselló-Añón Fig. 1 Femur fracture with a vicious consolidation. Genu varum in the left side Fig. 2 Bilateral tibial fracture with a vicious consolidation
Case # 2: Disabling Anterior Knee Pain Recalcitrant … 625 Fig. 3 Tibial osteotomy osteotomy (Figs. 3, 4 and 5). Both surgeries were performed in the same surgical time with a satisfactory clinical result. 3 The Conventional Thinking is ... The association between femoral anteversion and AKP or patellar instability has been welldocumented in the medical literature, but very few clinical studies have looked at femoral retroversion and AKP. Lee and colleagues [3, 4] performed the most cogent study that demonstrated the importance of femoral rotation in the genesis of AKP. They found that an external rotational deformity of the femur augments patellofemoral contact pressure on the medial facet of the patella. External rotation has been related to medial PFJ pain due to a nonlinear increase in the patellofemoral contact pressures on the contralateral facets of the patella [3]. A few authors have confirmed the importance of external femoral rotation in the genesis of AKP. Cibulka and Threlkeld-Watkins [5] reported an unusual case of patellofemoral pain in a patient with excessive asymmetric external hip rotation. Yildirim and colleagues [6] observed that an external rotation deformity of the femur greater than 10° could cause a deterioration in the patellofemoral scores and provoke AKP. Karaman and colleagues [7] showed that both external and internal rotational malalignment, greater than or equal to 10° after closed intramedullary nailing of femoral shaft fractures, caused AKP while climbing stairs. Finally, Jaarsma and colleagues [8] found that patients with a torsional deformity after femoral nailing due to shaft fractures had difficulty with more demanding activities like practicing sports activities and climbing stairs. External rotational malalignment caused more
626 Fig. 4 Double level osteotomy Fig. 5 Double level osteotomy in the left side. Physical examination. Preop (above). Postop (below) V. Sanchis-Alfonso and A. Roselló-Añón
Case # 2: Disabling Anterior Knee Pain Recalcitrant … 627 functional problems than internal rotational malalignment in that series. The ideal osteotomy site after post-fracture deformity would be at the fracture site. Double-level osteotomy surgery is an aggressive approach prone to major complications. results in a resolution of pain. The patient noticed an immediate improvement after the surgery. The knee pain as well as the ankle and hip pain completely disappeared. References 4 What Has This Case Taught Us? This Case Shows ... Retroversion can cause AKP. Moreover, retroversion can be more symptomatic than anteversion. Of course, correction at the fracture site is preferable. The ideal osteotomy site to correct retroversion would be at the fracture site. But the risk of pseudoarthrosis and the important deformity at the fracture site, makes the surgery more aggressive and difficult. Moreover, if we correct the varus deformity at the fracture site, the correction would be very good, and the joint line would not become oblique. However, we were afraid of pseudoarthrosis. In this case, the correction away from the fracture site has given good results. There is not greater risk of DVT with doublelevel osteotomy surgery [9]. The key is an “atraumatic surgery” that is a surgery without excessive tissue trauma, without a tourniquet and immobilization. CPM must begin immediately after surgery. 5 Conclusion Femoral retroversion should be considered in the evaluation of the mechanical causes of AKP. Restoring the normal rotational alignment 1. Elahi S, Cahue S, Felson DT, et al. The association between varus-valgus alignment and patellofemoral osteoarthritis. Arthritis Rheum. 2000;43:1874–80. 2. Fujikawa, K, Seedhom BB, Wright V. Biomechanics of the patellofemoral joint. Part II: a study of the effect of simulated femoro-tibial varus deformity on the congruity of the patellofemoral compartment and movement of the patella. Eng Med. 1983;12: 13–21 3. Lee TQ, Anzel SH, Bennett KA, et al. The influence of fixed rotational deformities of the femur on the patellofemoral contact pressures in human cadaver knees. Clin Orthop. 1994;302:69–74. 4. Lee TQ, Morris G, Csintalan RP. The influence of tibial and femoral rotation on patellofemoral contact area and pressure. J Orthop Sports Phys Ther. 2003;33:686–93. 5. Cibulka MT, Threlkeld-Watkins J. Patellofemoral pain and asymmetrical hip rotation. Phys Ther. 2005;85 (11):1201–7. 6. Yildirim AO, Aksahin E, Sakman B. The effect of rotational deformity on patellofemoral parameters following the treatment of femoral shaft fracture. Arch Orthop Trauma Surg. 2013;133(5):641–8. 7. Karaman O, Ayhan E, Kesmezacar H, et al. Rotational malalignment after closed intramedullary nailing of femoral shaft fractures and its influence on daily life. Eur J Orthop Surg Traumatol. 2013;24(7):1243–7. 8. Jaarsma RL, Pakvis DFM, Verdonschot N, et al. Rotational malalignment after intramedullary nailing of femoral fractures. J Orthop Trauma. 2004;18 (7):403–9. 9. Sanchis-Alfonso V, Domenech J, Ferras-Tarrago J, et al. The incidence of complications after derotational femoral and/or tibial osteotomies in patellofemoral disorders in adolescents and active young patients. A systematic review with meta-analysis. Knee Surgery Sports Traumatol Arthrosc (In press).
Case # 3: Severe Anterior Knee Pain Recalcitrant to Conservative Treatment in a Patient with Functional Femoral Retrotorsion Vicente Sanchis-Alfonso, Marc Tey-Pons, and Joan Carles Monllau 1 Clinical Case A 28-year-old female who practiced athletics came to our office with a history of severe left anterior knee pain (AKP) (VAS 8) of 1 year of evolution. Pain onset was secondary to a direct traumatism of the knee from playing football. She had great difficulty driving because of the pain caused upon engaging the clutch, going downstairs, wearing high heels, and sitting with the knee bent for a long period of time (positive “movie sign”). The psychological evaluation that we routinely perform on our patients with AKP did not indicate anxiety or depression. She had kinesiophobia, catastrophizing and central sensitization. Imaging studies of the knee (X-rays, CT and MRI) were normal. The mechanical axis V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com M. Tey-Pons J. C. Monllau Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain J. C. Monllau Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain Universitat Autònoma de Barcelona (UAB), Barcelona, Spain of the lower limb was normal. There were no torsional abnormalities. The physical therapy program performed in our institution over 6 months was unsuccessful in improving her symptoms. This pain forced her to give up sports activities but she kept going to the gym. Ten months later, she came back to our office due to severe left hip pain (VAS 8) with no history of traumatism to justify it. The hip pain was so significant that it not only forced her to leave the gym but also made for significant limitations in her regular daily activities. Moreover, she continued to suffer from knee pain (VAS 8). The Kujala Knee Score was 22 and the Non-arthritic Hip Score was 28.75. During physical examination of the hip, there was a positive impingement test and a positive decompression test. A Dunn radiograph view showed an alpha angle of 58º in both hips. An angle of > 55º is considered pathological. However, the right hip was completely asymptomatic. A study by means of an arthro-MRI of the left hip showed a Cam lesion and a detachment of the anterior labrum. The final diagnosis was Cam femoroacetabular impingement (Cam-FAI). Prior to hip surgery, she was evaluated using kinetic and kinematic analyses during gait and stair ascent as the latter activity was the one that brought about a major limitation in her daily life. A pathway with two extensometric force plates on its surface was used to carry out the gait analysis. She was asked to walk at a high © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_44 629
630 cadence rate because the faster the subject walks, the more evident the functional impairment becomes. Before the data were collected, she walked on the pathway several times until she was able to walk with a natural and constant gait. A portable two-step wooden staircase and two independent dynamometric platforms, placed as indicated in (Fig. 1), were used to perform the kinetic analysis during the stair ascent test. An eight-camera computer-aided video motion analysis system and reflective passive markers that determined the spatial position of the segments of the lower limb were used to carry out the kinematic analysis (Fig. 2). All the markers were placed on the lateral aspect of the leg to allow for a correct visualization by the cameras (Fig. 2). The kinetic and kinematic parameters were analyzed using the NedRodilla/IBV software (Instituto de Biomecánica de Valencia, Valencia, Spain). Preoperative gait analysis showed an altered gait pattern (Fig. 3). Preoperative kinematic analysis showed a gait (Fig. 4A) and stair ascent (Fig. 5A) pattern with external rotation of the involved hip. Moreover, the hip external rotation torque of the involved hip increased significantly during stair ascent (Fig. 5C). Fig. 1 Portable two-step wooden staircase and two independent dynamometric platforms were used to perform the kinetic analysis during the stair ascent test. (Reused from Hindawi Publishing Corporation. SanchisAlfonso V, Tey M, Monllau JC. Cam femoroacetabular V. Sanchis-Alfonso et al. 2 What to Do in Such a Situation? Our Surgical Treatment We performed a femoral neck osteoplasty and reattachment of the labrum. During arthroscopy, we confirmed the impingement mechanism with the hip at 90º of flexion and maximum internal rotation. With external femoral rotation, we prevent the impingement and, in theory, the hip pain. After hip surgery, no specific physiotherapy treatment for the AKP was performed. 3 Follow-Up At 6 months after surgery, the patient had no discomfort in the hip, and knee pain had completely disappeared. At 7 months, kinetic and kinematic analyses were performed to evaluate the effects of hip surgery on the preoperative biomechanical parameters. They showed a normal gait pattern (Fig. 3B) and a symmetric pattern between both hips (Figs. 4B and 5B,D). At final follow-up (7.5 years), the patient is completely asymptomatic. With reference to both the hip and knee, activities that previously could impingement as a possible explanation of recalcitrant anterior knee pain. Case Rep Orthop. Vol 2016, Article ID 2,064,894, https://doi.org/10.1155/2016/2064894. Copyright © 2016 Vicente Sanchis-Alfonso et al.)
Case # 3: Severe Anterior Knee Pain Recalcitrant to Conservative … 631 Fig. 2 Subject with reflective markers used for kinematic analysis. (Reused from Hindawi Publishing Corporation. Sanchis-Alfonso V, Tey M, Monllau JC. Cam femoroacetabular impingement as a possible explanation of recalcitrant anterior knee pain. Case Rep Orthop. Vol 2016, Article ID 2,064,894, https://doi.org/10. 1155/2016/2064894. Copyright © 2016 Vicente Sanchis-Alfonso et al.) not be done or had been done with much difficulty like walking at a high cadence rate, going up or down stairs, squatting, making turns with the hip or using a car with a clutch were done without any problem. Moreover, she runs without any limitation. A Dunn radiograph view showed an alpha angle of 32º. At 7.5-years, the postoperative Kujala Knee Score was 99 and the postoperative Non-arthritic Hip Score was 91.25. Postoperative pain intensity on the VAS was 0 for the knee and 0 for the hip. 4 What Does the Medical Literature Tell Us About the Association Between External Rotational Femoral Deformity and AKP? Lee and colleagues [1, 2] demonstrated the importance of femoral rotation in the genesis of AKP. They found that an external rotational deformity of the femur increases patellofemoral contact pressure on the medial facet of the patella. Karaman and colleagues [3] showed that both external and internal rotational malalignment greater than or equal to 10° after closed intramedullary nailing of femoral shaft fractures provoked AKP while climbing stairs. Jaarsma and colleagues [4] found that patients with a torsional deformity after femoral nailing due to shaft fractures had difficulty with more demanding activities like running, sports, and climbing stairs. External rotational malalignment caused more functional problems than internal rotational malalignment in this series. Other authors have confirmed the importance of external femoral rotation in the genesis of AKP. Cibulka and Threlkeld-Watkins [5] reported an unusual case of AKP in a patient with asymmetric excessive hip external rotation. Finally, Yildirim and colleagues [6] observed that an external rotation deformity of the femur greater
632 V. Sanchis-Alfonso et al. Fig. 3 Gait analysis. A Preoperative. B Postoperative. Red line, right lower limb. Blue line, pathologic lower left limb. The preoperative study showed a decrease of the vertical heel contact force that could be a defense mechanism to avoid the load on the pathologic limb. Notice the gait pattern normalization after surgery. (Reused from Hindawi Publishing Corporation. SanchisAlfonso V, Tey M, Monllau JC. Cam femoroacetabular impingement as a possible explanation of recalcitrant anterior knee pain. Case Rep Orthop. Vol 2016, Article ID 2,064,894, https://doi.org/10.1155/2016/2064894. Copyright © 2016 Vicente Sanchis-Alfonso et al.) Fig. 4 Kinematic gait analysis. Hip external rotation angle. A Preoperative. B Postoperative (at the 7-month follow-up). Red line, right hip. Blue line, pathological left hip. Blue band, band of normality. Notice how the preoperative non-pathological hip values differ from those of the postoperative ones of the same hip. This is because the pathological limb influences the healthy limb in the kinematic and kinetic studies. What is relevant is that after surgery, the values of both hips are in the normality band. Furthermore, the external rotation of the hip that has been operated on has decreased relative to the preoperative status. (Reused from Hindawi Publishing Corporation. Sanchis-Alfonso V, Tey M, Monllau JC. Cam femoroacetabular impingement as a possible explanation of recalcitrant anterior knee pain. Case Rep Orthop. Vol 2016, Article ID 2,064,894, https://doi.org/10.1155/2016/ 2064894. Copyright © 2016 Vicente Sanchis-Alfonso et al.)
Case # 3: Severe Anterior Knee Pain Recalcitrant to Conservative … 633 Fig. 5 Kinematic analysis during stair ascending test. (A and B−Hip external rotation angle) A Preoperative. B Postoperative (at the 7-month follow-up). Red line, right hip. Blue line, pathological left hip. Kinetic analysis during stair ascending test. (C and D−Hip external rotation moment) C Preoperative. D Postoperative (at the 7-month follow-up). Red line, right hip. Blue line, pathological left hip. On the x-axis, one can note the stance phase percentage. The stance phase begins with the heel strike and ends with the toe off. The normalization of the kinematic and kinetic parameters can be seen after cam-FAI resolution. (Reused from Hindawi Publishing Corporation. Sanchis-Alfonso V, Tey M, Monllau JC. Cam femoroacetabular impingement as a possible explanation of recalcitrant anterior knee pain. Case Rep Orthop. Vol 2016, Article ID 2,064,894, https://doi.org/ 10.1155/2016/2064894. Copyright © 2016 Vicente Sanchis-Alfonso et al.) than 10° could cause a deterioration in the patellofemoral scores and provoke AKP. mechanism to avoid hip impingement and the associated hip pain [7]. Therefore, cam-FAI may be responsible for functional femoral retroversion. Functional femoral retrotorsion may eventually provoke a patellofemoral joint imbalance that in turn might be responsible for AKP [7, 8]. A Cam resection normalizes hip biomechanics in the same way that the derotational osteotomy does in structural retroverted femora. This case highlights the importance of torsional abnormalities, a functional torsional abnormality in this case, in the genesis of AKP. 5 What Has This Case Taught Us? This Case Shows … External hip rotation conditioned by the cam morphology of the femoral head to avoid hip impingement and pain behaves from a functional point of view as a femoral retrotorsion [7]. In this case, external hip rotation is a defense
634 6 V. Sanchis-Alfonso et al. Conclusion Femoral osteoplasty eliminated hip impingement and therefore hip pain and normalized lower extremity biomechanics. This could be responsible for the knee pain going away. 4. 5. 6. References 1. Lee TQ, Anzel SH, Bennett KA, et al. The influence of fixed rotational deformities of the femur on the patellofemoral contact pressures in human cadaver knees. Clin Orthop. 1994;302:69–74. 2. Lee TQ, Morris G, Csintalan RP. The influence of tibial and femoral rotation on patellofemoral contact area and pressure. J Orthop Sports Phys Ther. 2003;33:686–93. 3. Karaman O, Ayhan E, Kesmezacar H, et al. Rotational malalignment after closed intramedullary nailing of 7. 8. femoral shaft fractures and its influence on daily life. Eur J Orthop Surg Traumatol. 2013;24(7):1243–7. Jaarsma RL, Pakvis DFM, Verdonschot N, et al. Rotational malalignment after intramedullary nailing of femoral fractures. J Orthop Trauma [Internet]. 2004;18(7):403–9. Cibulka MT, Threlkeld-Watkins J. Patellofemoral pain and asymmetrical hip rotation. Phys Ther. 2005;85 (11):1201–7. Yildirim AO, Aksahin E, Sakman B. The effect of rotational deformity on patellofemoral parameters following the treatment of femoral shaft fracture. Arch Orthop Trauma Surg. 2013;133(5):641–8. Sanchis-Alfonso V, Tey M, Monllau JC. Cam femoroacetabular impingement as a possible explanation of recalcitrant anterior knee pain. Case Rep Orthop. 2016. https://doi.org/10.1155/2016/2064894. Sanchis-Alfonso V, Tey M, Monllau JC. A novel association between femoroacetabular impingement and anterior knee pain. Pain Res Treat. 2015;2015. https://doi.org/10.1155/2015/937431.
Case # 4: Disabling Anterior Knee Pain in a Multi-operated Young Patient with Severe Patellofemoral Osteoarthritis and Medial Patellar Instability Vicente Sanchis-Alfonso 1 Clinical Case A 41-year-old woman came to our institution complaining mainly of disabling right patellar instability and severe right anterior knee pain (AKP) that had not improved with appropriate physical therapy. It is worth mentioning that she had serious psychological problems. The Kujala score was of 24 points. The contralateral knee was completely asymptomatic. She had visited 5 doctors before coming to us. This patient had undergone surgery 3 years earlier due to lateral patellar instability, being instability the main symptom. Moreover, there was a secondary symptom of mild occasional pain during physical activity. An Insall’s proximal realignment and lateral retinaculum release (LRR) were performed. After the surgery, the patient indicated that the patellar instability had increased. She also stated that it was different and more incapacitating than the one she had before surgery. Moreover, there was a severe pain with day-to-day activities. Both instability and pain were much worse than the ones prior to the realignment surgery. One year and a half after her realignment surgery, another surgeon suggested a knee arthroscopy to which the patient agreed. With this second procedure (partial syn- V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com ovectomy and denervation), the patient did not see any improvement. A physical examination of the knee showed a positive apprehension sign when pressing the patella medially and a positive Fulkerson’s relocation test. Additionally, there was an apprehension sign when pressing the patella laterally. The rest of the physical examination was completely normal. Conventional radiography showed patellofemoral osteoarthritis (PFOA) (Fig. 1). The radiographs prior to the first surgery had shown no degenerative changes. An MRI examination showed a lateral subluxation of the patella and severe patellar chondropathy. A CT examination at 0° of extension and with a relaxed quadriceps showed mild lateralization of the patella. The TT-TG index was 10 mm. There were no torsional abnormalities. The stress CT of the patellofemoral joint (PFJ) in extension revealed medial patellar instability and a lateral patellar displacement that was significantly greater in the right knee in comparison to the left knee (Fig. 2). A bone scan with Tc-99 m showed increased pathologic uptake only in the patella (Fig. 3). Kinetic and kinematic analyses were performed during stair descent (Fig. 4). They showed that the patient had a stair descent pattern with knee extension, which is a strategy to avoid instability and the subsequent pain. A decrease in the stance phase duration on the platform was also seen. It is a strategy to reduce the extensor moment. There were also reduced values of the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_45 635
636 V. Sanchis-Alfonso Fig. 1 Patellofemoral osteoarthritis Fig. 2 Multidirectional patellar instability as is seen in the stress CT. Arrows indicate the direction of the stress applied to the patella during stress CT. Lateral stress causes an upward tilt. The lateral retinaculum prevents the upward tilt with lateral stress Fig. 3 Increased scintigraphic uptake in the patella that may explain the AKP in this patient extensor moment with the subsequent reduction in quadriceps contraction and, therefore, a reduction of the PFJ reaction force, being the final goal to reduce pain. Furthermore, the analyses showed reduced values of the abduction moment that provokes, a reduction of the lateral tibiofemoral compression force on one hand and a reduction of the force exerted proximally by the
Case # 4: Disabling Anterior Knee Pain in a … 637 A B C D Fig. 4 Knee kinetics and kinematics during stair descent. A Knee joint angles during stair descent. B Ground force reactions during stair descent. C Flexion–extension knee moments during stair descent. D Abduction–adduction knee moments during stair descent medial collateral ligament on the other hand. Here, the result is the reduction of the lateral and medial tibiofemoral compression forces. 2 Diagnosis Iatrogenic medial patellar instability and PFOA. 3 Our Surgical Treatment Before reconstruction of the lateral retinaculum, arthroscopy was performed. A severe PFOA was noted but not treated. The rest of the findings were normal. A reconstruction of the lateral retinaculum, using the fascia lata, was performed following the technique described by Jack Andrish (Fig. 5) [1]. Fig. 5 Deep transverse lateral retinaculum reconstruction following Andrish’s technique [1]
638 4 V. Sanchis-Alfonso Follow-Up Twelve months after surgery, the patient was asymptomatic and was able to go down the stairs in a natural manner without any problem. The current follow-up of this patient comes to 12 years, and she is now completely asymptomatic. She carries on a normal life and is fully satisfied with the surgery. The Postop Kujala score was 94 (24 in the preop). Kinetic and kinematic analyses during stair descent were performed at 6 months and 12 months after surgery and showed a progressive recovery of the kinetic and kinematic parameters (Fig. 4). She is pain free despite the severe PFOA and the increment of the extensor moment and, therefore, the increase in the PFJ reaction force after surgery. should be suspected in a patient who has undergone previous patellar realignment surgery that has made the pain worse [2, 3]. – Take special care with the “extensive” LRR because it could provoke a medial patellar instability [3]. – This patient had to go to 5 doctors before obtaining a diagnosis and an appropriate treatment. This demonstrates that medial patellar instability is a clinical condition that most orthopedic surgeons do not know about. Therefore, our belief is that there is a need to make the diagnostic procedures for recognizing this clinical condition more widely known. 6 5 What Has This Case Taught Us? This Case Shows … – Not all PFOA are associated with severe pain. There is poor evidence that all cartilage lesions are painful. The mere presence of a cartilage lesion does not mean it is the source of pain. In other words, structural damage of the patellar articular cartilage does not always result in AKP. In this case, the patellofemoral imbalance (medial patellar instability) was responsible for the pain. – In the PFJ, patellofemoral congruence and smooth kinematics are much more important than normal articular cartilage. – Iatrogenic medial patellar instability is a specific condition that frequently causes incapacitating AKP, severe disability, and serious psychological problems. The diagnosis Conclusion This is an example of PFJ preservation surgery. This begs the question as to whether articular cartilage is essential in the PFJ. In other words, does the PFJ in fact need articular cartilage? [4]. References 1. Sanchis-Alfonso V, Montesinos-Berry E, Monllau JC, Andrish J. Deep transverse lateral retinaculum reconstruction for medial patellar instability. Arthrosc Tech. 2015;4(3):e245–9. 2. Sanchis-Alfonso V, Montesinos-Berry E, Monllau JC, Merchant AC. Results of isolated lateral retinacular reconstruction for iatrogenic medial patellar instability. Arthroscopy. 2015;31(3):422–7. 3. Sanchis-Alfonso V, Merchant AC. Iatrogenic medial patellar instability: an avoidable injury. Arthroscopy. 2015;31(8):1628–32. 4. Blønd L, Donell S. Does the patellofemoral joint need articular cartilage? Knee Surg Sports Traumatol Arthrosc. 2015;23(12):3461–3.
Case # 5: Multidirectional Patellar Instability After Over-Medialization of the Tibial Tubercle in a Patient with Severe Trochlear Dysplasia and Patella Alta Vicente Sanchis-Alfonso 1 Clinical Case This is the case of a 43-year-old woman who came to my office for a second opinion for right patellar instability and severe anterior right knee pain. Instability was the main complain. She had undergone an operation on both knees in which a bilateral medialization of the tibial tubercle associated to lateral retinaculum release was performed. She experienced very significant limitations in her daily life activities as well as a quite notable decrease in her quality of life. Physical examination demonstrated multidirectional (lateral and medial) patellar instability. 2 Imaging Studies Imaging studies of the right knee showed pseudoarthrosis at the level of tibial tubercle osteotomy, knee osteoarthritis, a patella alta and trochlear dysplasia (Figs. 1 and 2). Computed Tomography showed: (1) Femoral anteversion Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/978-3-031-09767-6_46. V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com according to Murphy’s method, right 26°/left 29°; (2) Knee rotation, right 10°/left 12°; (3) External tibial torsion, right 33°/left 25°; (4) TT-TG distance, right −8 mm/left 7 mm. 3 What to Do in Such a Situation? As can be seen in the video of this case, the patient had a clear alteration of patellofemoral tracking (J-sign+). Prior to surgery and with the patient under general anesthesia, axial stress radiographs of the patellofemoral joint (PFJ) were performed. They demonstrated a complete medial patella dislocation when a force was applied to the lateral side of the patella to displace it medially (Fig. 3). Moreover, a lateral displacement of the patella of more than 50% was observed when a force was applied to the medial side of the patella to displace it laterally (Fig. 3). Moreover, lateral stress caused an upward tilt of the patella. At this point, it is interesting to note that the lateral retinaculum prevents the upward tilt of the patella with lateral stress, which is also why it adds resistance to a lateral displacement force. My therapeutic proposal was: 3.1 Surgical Approach – Elevate the tibial tuberosity to improve the exposure of the trochlea. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_46 639
640 V. Sanchis-Alfonso Fig. 1 Normal lower-limb alignment can be seen on the coronal plane, as well as bilateral knee osteoarthritis Fig. 2 Pseudoarthrosis at the level of the tibial tubercle osteotomy, a patella alta and trochlear dysplasia
Case # 5: Multidirectional Patellar Instability After Over-Medialization of the Tibial Tubercle … 641 Fig. 3 Axial stress radiographs of the PFJ. The red arrow shows the force applied to the patella to displace it laterally or medially. In the image on the left, how the patella is displace medially without applying stress to it can be seen 3.2 Correction of Patellofemoral Maltracking – A deepening trochleoplasty because the trochlear dysplasia is a major factor for patellar instability. – A lateralization and distalization of the tibial tubercle because there is a patella alta and an over-medialization of the tibial tubercle. 3.3 Stabilization of the PFJ: Ligament Reconstruction – MPFL and LPFL reconstruction if the patella can be dislocated in both directions in spite of maltracking correction. Finally, we only carried out a trochleoplasty and lateralization and distalization of the tibial tubercle (Figs. 4 and 5), because instability completely disappeared after the maltracking correction (see video). 4 Follow-Up 12 months after the surgery, the patient had no pain or instability and can go up and down the stairs in a natural way with no problem. In addition, she discharges her physically demanding work activity without problems. 5 Key Points – The common belief that the presence of osteophytes, that are a common radiographic finding (Fig. 1), is pathognomonic for the presence of osteoarthritis and that it is predictive of its progression is foolish [1]. In Fig. 6, severe chondropathy with exposed
642 A V. Sanchis-Alfonso B C Fig. 4 A Tubercle sulcus angle. B Over-medialization of the tibial tubercle. C Re-osteotomy of the tibial tubercle (tubercle sulcus angle of 0°) Fig. 5 Postop X-ray bone in the patella can be observed. However, there are no gross signs of osteoarthritis in the femoral condyles. – Not all PFOA are associated with severe pain. In the PFJ, patellofemoral congruence and smooth kinematics are much more important than normal articular cartilage [2]. – Over-medialization of the tibial tubercle can be avoided by means of an intraoperative evaluation of the tubercle sulcus angle (Fig. 4A). The intraoperative goal should be a tubercle sulcus angle of 0° (Fig. 4C). – In cases of multidirectional patellar instability with patellofemoral maltracking, the first step is always to correct the maltracking. Once the maltracking has been corrected, we must explore the stability of the PFJ again. If the instability has disappeared, we should not do a ligamentous reconstruction. If the instability persists, despite correcting the maltracking, the next step will be to reconstruct the MPFL. If there is still medial instability afterwards, the last step is to reconstruct the lateral patellofemoral ligament. – The medial transfer of the tibial tubercle has been commonly used for the treatment of a recurrent dislocation of the patella and patellofemoral malalignment. Kuroda and colleagues [3] have shown that tibial tubercle medialization significantly increases both the patellofemoral contact pressure and the contact pressure in the medial tibiofemoral compartment. Therefore, over-medialization of the tibial tuberosity should be avoided in the varus knee, the knee after medial meniscectomy, and the knee with preexisting degenerative arthritis of the medial compartment.
Case # 5: Multidirectional Patellar Instability After Over-Medialization of the Tibial Tubercle … 643 Fig. 6 Exposure of the surgical field after a tibial tubercle osteotomy References 1. Teitge RA. CORR Insights®: Lateral-compartment osteophytes are not associated with lateralcompartment cartilage degeneration in arthritic varus knees. Clin Orthop Relat Res. 2017;475(5):1393–4. 2. Blønd L, Donell S. Does the patellofemoral joint need articular cartilage? Knee Surg Sports Traumatol Arthrosc. 2015;23(12):3461–3. 3. Kuroda R, Kambic H, Valdevit A, et al. Articular cartilage contact pressure after tibial tuberosity transfer: A cadaveric study. Am J Sports Med. 2001;29 (4):403–9.
Case # 6: Failed MPFL Reconstruction in a Patient with Severe Trochlear Dysplasia and Malpositioning of the Femoral Attachment Point Vicente Sanchis-Alfonso 1 Clinical Case This is the case of a 35-year-old female (171 cm in height and 53 kg, BMI 18.1) who came to my office for a second opinion for right anterior knee pain (AKP) after having undergone a previous medial patellofemoral ligament reconstruction (MPFLr). The AKP was the main complaint and the secondary complaint was patellar instability. Upon her visit to my office, the patient had severe AKP in the right knee (VAS 8). She experienced significant limitations in her daily life activities (Kujala score 42; IKDC 40.2) as well as a noteworthy decrease in her quality of life (EuroQol 5D 2-1-2-2-2). She had a diagnosis of anxiety (HAD 12), catastrophizing (PCS 40) and kinesiophobia (TSK 58). She also had lateral patellar instability and pain in the anterior aspect of her left knee. However, it was the right knee that caused serious problems and she wanted a resolution. Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/978-3-031-09767-6_47. V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com 2 Physical Examination—Key Points At rest with the knee in extension, the patella is located excessively lateral (Fig. 1) and she needs to flex and to rotate the limb for the patella to line up with the trochlea. Then, she is able to function when the patella is in the trochlea (see video). She must keep the knee flexed to function and to prevent the excessive lateral position in extension. This is why she keeps her knee bent while coming downstairs (see video). With knee flexion, the patella is centered. She can then walk safely in flexion. Moreover, she has evident bilateral patellofemoral maltracking (evident J-sign). 3 Imaging Studies X-rays demonstrated a minor degree of valgus of the right limb, a misplaced MPFLr (a femoral tunnel very proximal and anterior) and severe trochlear dysplasia (Grade D) (Figs. 2 and 3). Computed tomography showed: Patellar tilt, right 44°/left 40°; TT-TG distance, right 22 mm/left 20 mm; Femoral anteversion according to Murphy’s method, right 19°/left 8°; Knee rotation, right 5°/left 8°; External tibial torsion, right 31°/left 31°. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_47 645
646 V. Sanchis-Alfonso Fig. 1 Significant lateral dislocation in extension and severe trochlear dysplasia 4 Questions Raised by This Case In the medical literature, it is accepted that valgus is a predisposing factor for lateral patellar instability [1]. This patient has a very discreet valgus. Normally, the mechanical axis is near the medial tibial spine. Could that degree of valgus be considered pathological? In theory, coronal alignment is more significant with height. This patient is tall, and this makes the valgus vector that displaces the patella laterally greater than that of a shorter person who has the same valgus (Fig. 4). Body weight has to be transferred through the knee to the ground. We assume weight transfer is “normalized” when the mechanical axis is near the medial tibial spine, about 1–2° varus. If there is a valgus (or varus) deformity, the mechanical axis is shifted. The longer the tibia and femur, the further the mechanical axis is shifted. We often see no pain or disability in children with limb deformity, but pain often develops in adolescence. We assume this is because of growth. The growth leads to lengthening of the lever arms as well as increased weight that is transferred to the ground. We assume the long bones act as long lever arms. In Fig. 4, the length of the limb on the left is ½ of the length on the right. A tibiofemoral angle of 10° has been drawn. The mechanical axis deviation is almost double. Therefore, the mechanical axis deviation is lateralized relatively more on the longer limb. Of course, adding abnormal torsion probably multiplies this effect. Could the combination of a small degree of valgus and a small degree of patella alta and some external tibial rotation be enough to
Case # 6: Failed MPFL Reconstruction in a Patient with … 647 Fig. 2 Lower-limb alignment on the coronal plane. Minor degree of valgus provide a lateral vector to the quad so the patella will sit so far lateral? Wilson and colleagues [1] observed a disappearance of the lateral patellar instability after an isolated osteotomy of the distal femur, that is to say, without any more associated surgical procedures. This shows how important genu valgum is in the etiopathogenesis of lateral patellar instability. Therefore, a logical approach would be to treat genu valgum if a significant genu valgum is present. If necessary, do an MPFLr in a second procedure. However, our patient has a very discreet valgus. Could a Trochleoplasty Be Sufficient to Keep the Patella Centered? Trochlear dysplasia seems to be the most important of all the main risk factors for the development of chronic lateral patellar instability [2–5]. Trochlear dysplasia is a recognized factor that favors lateral patella instability. The trochlear dysplasia of this patient is very severe (Fig. 5). In theory, we should act on the most serious one when there are many predisposing factors for instability. In this case, we should possibly act only on trochlear dysplasia. In a consensus statement from the AOSSM/PFF about patellar instability, the Deepening trochleoplasty is considered when several factors are present at the same time. They are a J-sign, a boss or 5 mm supratrochlear spur, and a convex proximal trochlea [6]. Our patient met all these requirements. 5 What to Do in Such a Situation? My proposal was: First Step—Arthroscopy to rule out other pathological conditions, a chondral evaluation (Fig. 6) and resection of the previous MPFLr. Second Step—Correct patellofemoral maltracking (J-sign) by means of a Deepening trochleoplasty to keep the patella centered.
648 V. Sanchis-Alfonso Fig. 3 Femoral tunnel very proximal and anterior. Severe trochlear dysplasia Third Step—Stabilize—Balance. Revision MPFLr using a medial quadriceps tendon autograft. 6 What Has This Case Taught Us? This Case Shows … – Not all PFOA are associated with severe pain. There is poor evidence that all cartilage lesions are painful. The mere presence of a cartilage lesion does not mean it is the source of pain. In other words, structural damage of the patellar articular cartilage does not always result in AKP. In this case, the patellofemoral imbalance (lateral patellar instability) was responsible for the pain. – In the PFJ, patellofemoral congruence and smooth kinematics are much more important than normal articular cartilage [7]. 7 Conclusion In the case presented here with trochleoplasty, we have completely corrected the patellofemoral maltracking. In addition, with the stabilization of the patella, we have eliminated the AKP even though we have not acted on the severe cartilage injury. Now, at rest with the knee in extension, she does not need to flex and rotate the limb for the patella to line up with the trochlea (see video).
Case # 6: Failed MPFL Reconstruction in a Patient with … Fig. 4 Variation of the valgus vector as a function of the length of the femur and tibia Fig. 5 Severe trochlear dysplasia 649
650 V. Sanchis-Alfonso Fig. 6 Severe chondropathy on the medial facet of the patella References 1. Wilson PL, Black SR, Ellis HB, et al. Distal femoral valgus and recurrent traumatic patellar instability: is an isolated varus producing distal femoral osteotomy a treatment option? J Pediatr Orthop. 2018;38:e162-7. 2. Nelitz M, Theile M, Dornacher D, et al. Analysis of failed surgery for patellar instability in children with open growth plates. Knee Surg Sports Traumatol Arthrosc. 2012;20:822–8. 3. Wagner D, Pfalzer F, Hingelbaum S, et al. The influence of risk factors on clinical outcomes following anatomical medial patellofemoral ligament (MPFL) reconstruction using the gracilis tendon. Knee Surg Sports Traumatol Arthrosc. 2013;21(2):318–24. 4. Kita K, Tanaka Y, Toritsuka Y, et al. Factors affecting the outcomes of double-bundle medial patellofemoral ligament reconstruction for recurrent patellar dislocations evaluated by multivariate analysis. Am J Sports Med. 2015;43(12):2988–96. 5. Dejour D, Byn P, Ntagiopoulos PG. The Lyon’s sulcus-deepening trochleoplasty in previous unsuccessful patellofemoral surgery. Int Orthop. 2013;37 (3):433–9 [PMID: 23275080]. https://doi.org/10.1007/ s00264-012-1746-8. 6. Post WR, Fithian DC. Patellofemoral instability: a consensus statement from the AOSSM/PFF patellofemoral instability workshop. Orthop J Sports Med. 2018;30;6(1):2325967117750352. https://doi.org/10. 1177/2325967117750352.eCollection, January 2018. 7. Blønd L, Donell S. Does the patellofemoral joint need articular cartilage? Knee Surg Sports Traumatol Arthrosc. 2015;23(12):3461–3.
Case # 7: Lateral Patellar Instability in a Multi-operated Young Patient with Severe Patellofemoral Osteoarthritis and Severe Trochlear Dysplasia Vicente Sanchis-Alfonso and Joan Carles Monllau 1 Clinical Case This is the case of a 29-year-old female (178 cm in height and 54 kg, BMI 17) who came to the office due to severe long-lasting left lateral patellar instability. She had had two left patellar dislocations and 4 recurrent right patellar dislocations. She also suffered from anterior left knee pain, but it was not her main complaint. She had been putting up with the pain but not with the instability. She was a physiotherapist. She practised paddle, swimming, Pilates and went to the gym despite her instability. Using the terminology of the ACL deficient knee, we would classify this patient as a copper. On several occasions, surgery was performed on her left knee with less than satisfactory results (medial retinacular plication—2001—, Albee’s osteotomy + TT osteotomy (Emslie) + open-wedge patellar osteotomy—2002—, medial patellar tendon transfer—2006—). Physical examination showed evident patellofemoral maltracking (positive J-sign). The patella dislocated laterally with knee flexion. X-rays showed no lower-limb malalignment on the coronal plane but there was evidence of tricompartmental knee osteoarthritis (Fig. 1). In axial views, one can observe how the patella dislocates with knee flexion (Fig. 2). You can also note a half-moon patella. The CT image reveals a patella magna and a severe trochlear dysplasia (Fig. 3). No torsional abnormalities were found in the lower extremities. In short, the patient is looking for a solution to her instability, which is what limited her in sports activities. It would never have occurred to her to go to the doctor because of knee pain as she was able to live with it. 2 V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com J. C. Monllau Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain Universitat Autònoma de Barcelona (UAB), Barcelona, Spain What to Do in Such a Situation? Obviously, the easiest thing to do is to indicate total knee arthroplasty (TKA). However, there is a question to be answered. Is this the best choice for a young patient who is consulting mainly due to instability but not severe pain? Another option would be patellofemoral arthroplasty or a bipolar patellofemoral fresh allograft, but they are not options if tricompartmental knee osteoarthritis is observed in the X-ray. Moreover, the pain the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_48 651
652 V. Sanchis-Alfonso and J. C. Monllau Fig. 1 Normal lower-limb alignment can be seen on the coronal plane, as well as the tricompartmental knee osteoarthritis Fig. 2 Left patella dislocates with knee flexion. Severe trochlear dysplasia can be observed in the left knee. Some hardware from prior surgeries (namely, the lateral facet elevating trochleoplasty as well as the anterior tibial tuberosity transposition) (Reprinted with permission from Am J Orthop. 2017; 46:139–145. ©2017, Frontline Medical Communications Inc.) patient has is bearable and the main indication for arthroplasty or an osteochondral allograft procedure is severe pain recalcitrant to conservative treatment. Another option would be to tell her to give up sport. That would be inconceivable as the practice of sport is this patient’s profession and passion. There is yet another option even though it may seem rather far-fetched. We can simply advise the patient to stop living her life and wait until she is of an age suitable for TKA. Prior to moving forward with our treatment plan, the objectives were thoroughly discussed with the patient. Keep in mind that the patient was quite familiar with the subject because she is physiotherapist and is used to dealing with patients who have undergone knee operations. It should be remembered that the patient’s values and preferences are one of the three legs of Evidence Based Medicine. The first step in the treatment plan was to correct the maltracking by means of a sulcus deepening trochleoplasty and a patellar osteotomy to obtain smooth PFJ kinematics. The second step called for stabilization of the patella with an MPFL reconstruction. The patient knew that the aim of preserving-joint surgery is to delay arthroplasty for as long as possible. Our treatment does not close the doors to a possible future arthroplasty.
Case # 7: Lateral Patellar Instability in a Multi-operated Young … 653 Fig. 3 Preoperative CT imaging showing severe trochlear dysplasia and a concave patella magna 3 Our Surgical Treatment The patient has both severe patellofemoral osteoarthritis (PFOA) and trochlear dysplasia (Fig. 4). Therefore, it is difficult to cause more damage. In this case, maltracking can be reproduced passively. With knee flexion, we can reduce the patella. This marks the difference between true fixed lateral patellar instability in flexion due to a retraction of the extensor mechanism of the knee and patellofemoral maltracking due to severe trochlear dysplasia. A Dejour’s sulcus deepening trochleoplasty, associated with a closed-wedge patellar osteotomy, was indicated (Figs. 5 and 6). To that end, A a periosteal patella sleeve was elevated from the midline, and a longitudinal dorsally closing wedge osteotomy was performed down to the subchondral bone using a small oscillating saw. Care was taken not to disturb the remnant articular cartilage. The wedge was carefully closed with a clamp and then the osteotomy was fixed with two 3.5 mm cannulated screws entering medially. After that, patellar tracking was reassessed. Then, a reconstruction of the MPFL using a semitendinosus tendon autograft was performed. Due to the abnormally thin patella, the reconstruction was performed using a method that does not require anchoring bone tunnels at this level (i.e. the medial quad tendon). In this case, avoiding patellar bone tunnels was B Fig. 4 A Note the severe convex dysplastic trochlea. B The concave patella has lost all the cartilage (Reprinted with permission from Am J Orthop. 2017; 46:139–145. ©2017, Frontline Medical Communications Inc.)
654 V. Sanchis-Alfonso and J. C. Monllau A B Fig. 5 A burr, starting from the medial proximal part of the joint, is used to remove the cancellous bone from the under surface of the femoral trochlea. B Final result after A molding the flap to the underlying cancellous bone bed and fixation with a resorbable anchor device and sutures B Fig. 6 A follow-up CT scan image after the combined sulcus deepening trochleoplasty and patellar osteotomy. A Note the supratrochlear spur resection in the lateral view as well as B the new shape of the patella in the axial view particularly safer since a patellar osteotomy was also performed. For the graft femoral fixation, a technique that uses the Adductor Magnus tendon as a dynamic post was preferred. 4 Follow-Up Six years have passed since the surgery and the patient has fulfilled her goal of being able to practice recreational sports. She is pain-free and has no instability. 5 The Conventional Thinking Is … Trochleoplasty is contraindicated in high-grade trochlear dysplasia with instability associated with PFOA [1]. Dejour and Le Coultre [2], considered the patellar osteotomy an attractive surgical technique when associated with trochleoplasty in cases with a flat patella, but did not recommend it for several reasons. They determined that there is a significant risk of non-union and necrosis and it
Case # 7: Lateral Patellar Instability in a Multi-operated Young … is difficult to determine the amount of articulation for each facet and exactly where the ridge is to be placed. 6 Is There an Indication for Patella Osteotomies? The indication for patella osteotomy is exceptional. We should only perform it in cases of an important patellofemoral mismatch after performing a trochleoplasty, as occurs in the clinical case that we have presented. The goal is that the congruence between the patella and the newly formed sulcus angle is the best possible. The final decision for patella osteotomy is taken during surgery by means of direct observation of the tracking of the PFJ after trochleoplasty. The Patellar closing wedge osteotomy was first reported by Griss [3]. Koch and colleagues [4] presented 2 patients out of 85 trochleoplasties performed. At 2 years follow-up, both patients showed a stable patella with correct tracking. Both patients considered their functional result excellent. However, Badhe and Forster [5] presented 4 patients suffering from patellar instability due to an underlying trochlea dysplasia and treated it with elevation of the lateral femoral condyle according to Albee in combination with a Dorsal closing wedge patellar osteotomy. The result was fair. The patella was stable but patients experienced residual patellofemoral pain in the absence of necrosis or non-union. Elevation of the lateral condyle as described by Albee provokes and increment in PFJ pressure. Dejour does not recommend this technique. 7 What Has This Case Taught Us? This Case Shows – Not all PFOA are associated with severe pain. – TT-TG distance cannot be calculated in all the cases, especially in those in which there is a severe trochlear dysplasia, as in this case. 655 – This case calls into question the necessity of performing patellar osteotomies to fit the patella into the new trochlea. The Closing wedge patellar osteotomy can be helpful in combination with trochleoplasty in patients with patellofemoral instability due to trochlear and patellar dysplasia. – In the patellofemoral joint, patellofemoral congruence and smooth kinematics are much more important than normal articular cartilage [6]. – Caution must be exercised when performing a surgical indication in a patient with patellofemoral instability. This patient had been operated on several times without any improvement and the result was patellar instability along with PFOA. The patient had gone through several episodes of instability of the contralateral knee, but it has not been operated on and there is no osteoarthritis (Fig. 2). This case should serve as a warning of the damage that inappropriate surgery can cause. 8 Conclusion This is an example of the challenging PFJ preservation surgery in a borderline case. This case asks us to question whether articular cartilage is in fact essential in the PFJ. In other words, does the PFJ truly need articular cartilage? References 1. Vasta S, Castelhanito P, Dejour D. Trochleoplasty techniques: deepening Lyon. In: Dejour D, et al. editor. Patellofemoralpain, instability and arthritis. Springer;2020. 2. Dejour D, Le Coultre B. Osteotomies in patellofemoral instabilities. Sports Med Arthrosc. 2007;15:39–46. 3. Griss P. Modification of sagittal osteotomy of the patella as treatment of excentric chondromalacia or retropatellar arthrosis. Preliminary communication.] (in German). Z Orthop Ihre Grenzgeb. 1980;118: 822–4.
656 4. Koch PP, Fuchs B, Meyer DC, et al. Closing wedge patellar osteotomy in combination with trochleoplasty. Acta Orthop Belg. 2011;77(1):116–21. 5. Badhe NP, Forster W. Patellar osteotomy and Albee’s procedure for dysplastic patellar instability. Eur J Orthop Surg Traumatol. 2003;13:43–7. V. Sanchis-Alfonso and J. C. Monllau 6. Blønd L, Donell S. Does the patellofemoral joint need articular cartilage? Knee Surg Sports Traumatol Arthrosc. 2015;23(12):3461–3.
Case # 8: Extensor Mechanism Reconstruction After Resection of a Soft Tissue Sarcoma that Infiltrates the Patellar Tendon Vicente Sanchis-Alfonso, Alejandro Roselló-Añón, Eloisa Villaverde-Doménech, Onofre Sanmartin, and Juan Pablo Aracil-Kessler 1 Clinical Case A 65-year-old woman with a painless subcutaneous mass in the anterior aspect of the knee was referred to our hospital for a second opinion. The lesion had recurred twice. The pathological diagnosis was glomangiosarcoma. It is a rare malignant tumor with a tendency to local invasion and recurrence after excision. The tumoral extension evaluation revealed no other lesions. Physical examination showed a transverse excision scar of 10 cm along with a palpable mass adhered to the skin. Magnetic resonance imaging (MRI) showed a mass adjacent to the patellar tendon with both cutaneous and patellar tendon infiltration (Fig. 1). 2 What to Do in Such a Situation? Obviously, limb-sparing surgery is indicated. There are 3 steps in this type of surgery. V. Sanchis-Alfonso (&) A. Roselló-Añón Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com E. Villaverde-Doménech J. P. Aracil-Kessler Plastic and Reconstructive Surgery Department, Hospital Provincial de Castellón, Castellón, Spain O. Sanmartin IVO’s Dermatology Department, Instituto Valenciano de Oncología (IVO), Valencia, Spain 2.1 First Step—Tumor Resection (Fig. 2) The tumor was removed with wide surgical margins. A wide resection of the tissues surrounding the tumor including the skin, patellar tendon (resected transversely from the inferior pole of the patella), Hoffa fat pad and pes anserinus was performed. Biopsy detected negative margins. The definitive diagnosis was a subcutaneous GLI1-amplified neoplasm. 2.2 Second Step—Reconstruction of the Extensor Mechanism (Fig. 3) Extensor mechanism disruption is a devastating lesion. Several techniques for reconstruction have been published. However, few techniques adequately restore the function of the extensor mechanism. In many surgical techniques, appears a persistent extension lag. Furthermore, there is a deficit in flexion in many cases. In our patient, a reconstruction using an allograft (tibial bone— patellar tendon—patella—quadriceps tendon) was performed in accordance with the technique described by Fiquet and colleagues in 2019 [1]. The postoperative care and rehabilitation protocols proposed by Burnett and colleagues [2] after massive extensor mechanism allograft reconstruction were followed. The knee is not flexed intraoperatively to evaluate flexion after © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_49 657
658 Fig. 1 Preoperative MRI Fig. 2 Tumor resection V. Sanchis-Alfonso et al.
Case # 8: Extensor Mechanism Reconstruction After Resection … Fig. 3 Reconstruction of the extensor mechanism (Drawing by Noelia Bonet-Miralles) 659
660 V. Sanchis-Alfonso et al. Fig. 4 Skin coverage the reconstruction. A knee orthosis in full extension was put in place for 8 weeks, and then rehabilitation began. We did not allow any flexion during that period. 2.3 Third Step—Skin Coverage (Fig. 4) Adequate soft tissue coverage is necessary for a successful extensor mechanism allograft reconstruction. Although most wounds around the knee can be managed by medial gastrocnemius muscle flap, we opted for a free flap in this case. A perforator anterolateral thigh (ALT) free flap from the contralateral thigh was chosen [3]. We prefer the free graft for various reasons. One of them is that the skin defect that we must close is very large because we must resect 2 cm at least of skin per side. We must also consider that the female gastrocnemius is shorter and more atrophic than that of the male. Therefore, it may not be sufficient to close the skin defect in our case. Another advantage is that a free flap heals sooner. That being the case, radiotherapy could be done in the third or fourth week after surgery if it were necessary. Furthermore, the free flap is less aggressive than the gastrocnemius flap and, there is a minimal donor site morbidity. The main difficulty with this case was performing the anastomosis with total knee extension as the knee is not flexed intraoperatively after the extensor mechanism reconstruction according to the surgical protocol published by Burnett and colleagues [2]. For this reason, we performed the arterial anastomosis end-to-end to the posterior tibial artery (instead of end-to-side). 3 Outcome—The Key for a Successful Reconstruction of the Extensor Mechanism of the Knee At the 6-month follow-up, she had functionally adequate knee flexion (Figs. 5 and 6). More importantly, she can raise her leg without an extension lag. Burnett and colleagues evaluated two techniques of reconstruction of the extensor mechanism of the knee using an extensor mechanism allograft [4]. They described Group I with the allograft minimally tensioned and Group II with the allograft
Case # 8: Extensor Mechanism Reconstruction After Resection … 661 Fig. 5 Clinical aspect at the 6-month follow-up Fig. 6 X-rays at the 6-month follow-up tightly tensioned in full extension. They demonstrated that the results of surgery depend on the initial tensioning of the allograft. The loosely tensioned allograft results in a persistent extension lag and clinical failure. Allografts that are tightly tensioned in full extension can restore active knee extension and result in clinical success. They concluded that an extensor mechanism allograft transplantation will be successful only if the graft is initially tensioned tightly in full extension.
662 References 1. Fiquet C, White N, Gaillard R, et al. Combined patellar tendon lengthening and partial extensor mechanism allograft reconstruction for the treatment of patella infera: a case report. Knee. 2019;26(2):515–20. 2. Burnett RS, Berger RA, Della Valle CJ, et al. Extensor mechanism allograft reconstruction after total knee arthroplasty. J Bone Joint Surg Am. 2005;87(Suppl 1):175–94. V. Sanchis-Alfonso et al. 3. Philandrianos C, Mattei JC, Rochwerger A, et al. Free antero-lateral thigh flap for total knee prosthesis coverage after infection complicating malignant tumour resection. Orthop Traumatol Surg Res. 2018;104(5):713–7. 4. Burnett SJ, Berger RA, Paprosky WG, et al. Extensor mechanism allograft reconstruction after total knee arthroplasty. A comparison of two techniques. J Bone Joint Surg Am. 2004;86(12):2694–9.
Case # 9: Severe Patellofemoral Chondropathy in an Active 47-Year-Old Patient Erik Montesinos-Berry 1 Clinical Case A 47-year-old male came to our institution complaining mainly of disabling left anterior knee pain. He works as a police officer, now doing mostly desk work because of his disability, he also walks with a cane because of it. The pain was located on the anterolateral aspect of the knee. The inferior pole of the patella was not painful upon examination. The pain was recalcitrant to an appropriate conservative treatment for more than two years. The patient was hesitant to undergo a surgical procedure on his knee because he was not completely satisfied with the results of a tibial tubercle medialization osteotomy performed on his right knee in 2011. The imaging study showed no malalignment in the coronal plane or any torsional abnormalities. The CT-scan showed a TT-TG distance of 21 mm. MRI exam showed a stage IV lateral facet chondropathy. 2 What to Do in Such a Situation? When we need to unload lateral and/or distal painful chondral lesions, even in advanced isolated patellar lateral facet arthrosis, in cases with a lateral patellar subluxation and a TT-TG distance of more than 20 mm, a Fulkerson’s osteotomy might be a good solution (Fig. 1). Obviously, proximal and medial healthy cartilage onto which to transfer load is mandatory. Diffuse, proximal or medial patellar lesions or central trochlear lesion are contraindications for Fulkerson’s osteotomy. In our case, during the arthroscopic examination, a severe lateral facet chondropathy and a mild medial facet chondropathy was confirmed (Fig. 2). Therefore, a tibial tubercle anteromedialization osteotomy (Fulkerson’s osteotomy) was performed. 3 Outcome The patient is now pain-free, his left knee no longer hurts. In fact, he is happier with the result of his left knee than with his right knee, and now he wants the same type of surgery that was performed on the left knee to be performed on the right one. E. Montesinos-Berry (&) ArthroCentre—Agoriaz, Riaz & Clinique CIC Riviera, Montreux, Switzerland e-mail: erik.montesinos@gmail.com © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_50 663
664 E. Montesinos-Berry Fig. 1 Left knee postoperative radiographs and CT scan. The inferior pole of the patella was not painful Fig. 2 During arthroscopic examination. Severe chondropathy of the lateral facet, and mild chondropathy of the medial facet 4 What Has This Case Taught Us? This Case Shows … The clinical examination is still our most important tool to identify the origin of pain. Most surgeons would have considered a resection of the inferior pole of the patella just by looking at the X-rays, when in fact the inferior pole was not painful. The pain was located on the lateral aspect of the knee. This case really emphasizes the importance of unloading. The biomechanical effect we get from a medialization is not same one we get from a anteromedialization. The pressure reduction in the lateral facet is greater with an anteriomedialization [1]. Our patient would agree with this since his subjective feeling is of a great improvement with an anteromedialization in the left knee, and only a mild improvement with a medialization in the right knee, to the point of wanting to undergo surgery again on his right knee to have the same procedure as on his left knee. Kuroda and colleagues [2] have shown that tibial tubercle medialization significantly increases both the patellofemoral contact pressure and the contact pressure in the medial tibiofemoral
Case # 9: Severe Patellofemoral Chondropathy in an Active … Fig. 3 Radiographs of the right knee operated in 2011. Medialization of the tibial tuberosity. Degenerative changes in the medial compartment can be observed compartment. Therefore, over-medialization of the tibial tuberosity should be avoided in the varus knee, the knee after medial meniscectomy, and the knee with preexisting degenerative arthritis of the medial compartment. Interestingly, degenerative changes in the medial compartment on the right knee have been observed in our patient (Fig. 3). 5 The Key for a Successful Fulkerson’s Osteotomy Fulkerson’s osteotomy is indicated when we need to realign the patella, that is when we need to restore central tracking. Therefore, the presence of a lateral patellar subluxation and a TTTG distance of more than 20 mm, is mandatory. The results of Fulkerson’s osteotomy depend on the location of the chondral lesion. The location of the chondral lesion is essential to 665 indicate an anteromedialization osteotomy of the tibial tubercle (Fulkerson’s osteotomy). Pidoriano and colleagues [3] reported a higher number of successful results when the lesion was only on the lateral aspect of the patella. An MRI mapping of the chondral lesion of the patella and/or an arthroscopic examination of the cartilage of the patella, confirming the lateral facet damage, and the medial facet preserved cartilage, are mandatory before performing this type of osteotomy. In the paper published by Pidoriano and colleagues ten patients with type I (distal) patellar lesions and thirteen with type II (lateral facet) patellar lesions showed 87% good to excellent subjective results [3]. Every single one of these patients indicated he/she would undergo this procedure again. Nine patients with type III (medial facet) lesions showed 55% good to excellent results [3]. Five patients with type IV (proximal or diffuse) lesions barely showed 20% good to excellent results [3]. In short, patients with type I or II lesions were considerably more inclined to show good or excellent results compared to those with type III or IV lesions. They observed that central trochlear lesions were involved in medial patellar lesions and that the results were poor for all the patients with central trochlear lesions [3]. No significant correlation was detected between the Outerbridge grading of the patellar lesion and the overall results [3]. We must avoid an over-medialization. Our goal is a TT-TG distance of 10–15 mm. In our patient the postoperative TT-TG distance was 14 mm. 6 Conclusions – In patients with a lateral facet chondropathy, and a TT-TG distance over 20 mm a Fulkerson’s osteotomy can be considered as long as the medial facet cartilage is in good condition. An arthroscopic examination will allow us to determine this.
666 – Even in cases of severe chondropathy including bone on bone, a Fulkerson’s osteotomy could be better than patellofemoral arthroplasty. – In this case, since both knees have been operated on, with different techniques, the feedback we get from the patient is very valuable. The patient had been reluctant to have surgery on the left knee for over two years, but now he did not hesitate and had the operation on his right knee within the year. E. Montesinos-Berry References 1. Elias J, Jones KC, Copa AJ, et al. Computational simulation of medial versus anteromedial tibial tuberosity transfer for patellar instability. J Orthop Res. 2018;36(12):3231–8. 2. Kuroda R, Kambic H, Valdevit A, et al. Articular cartilage contact pressure after tibial tuberosity transfer: A cadaveric study. Am J Sports Med. 2001;29 (4):403–9. 3. Pidoriano AJ, Weinstein RN, Buuck DA, et al. Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer. Am J Sports Med. 1997;25(4):533–7.
Case # 10: Dislocated Patella After Revision Total Knee Arthroplasty. Case # 11: Patella Baja and Valgus Limb 56 Years After Tibial Tubercle Transfer Robert A. Teitge 1 Clinical Case 76 year-old-male presented on referral from treating orthopaedic surgeon 30/09/2008. Chief complaint: recurrent dislocation of patella post-revision of tibial component right total knee. TKA right knee in 1992 no complaints until 2007 when the knee felt unstable. Progressive laxity of the right knee with increased valgus. Laxity and valgus felt to be due to lateral polyethylene insert wear. Replacement of Poly insert with 25 mm spacer reduced valgus and provided stability under anesthesia. At 3-month post-op the knee gave way while going up stairs followed by recurrent dislocation in which the knee suddenly gives way with no power. The knee is weak on stairs. The kneecap “pops out of place” without warning frequently and he has fallen a number of times. He underwent arthroscopy with lateral retinacular release with no change. Patient is unable to walk on uneven ground like the beach or climb stairs or ride a bicycle. Examination: 180.3 cm, 109 kg. Alignment clearly valgus compared with minimal valgus on the left. Feet, heels and patella straight. Going on toes and heels normal but cannot do minimal squat as the patella dislocates. Motion 0–130°. Straight leg raising to 90°. A small effusion is present with no heat, swelling, bursitis or synovitis. No crepitation with extension from 40° but the patella dislocates when flexion is more than 40°. There is clinically increased mobility of the patella in both the medial and lateral direction with no apprehension or discomfort. Manual pressure on the lateral side of the patella cannot prevent dislocation with knee flexion. Q angle is 15°. There is visible and palpable atrophy in the right quadriceps compared with the left. Thigh circumference is 49.5 cm on the right and 53.3 on the left. Varus-Valgus stress and Anterior– Posterior drawer test appear normal bilateral. There is no pain at any location with palpation. The Ober test is 0 but with 40° of knee flexion the patella dislocates. In the prone position hip Internal/External rotation is 30°/45° on the right and 45°/15° on the left. Radiological evaluation: Radiographs reveal what appears as well fixed femoral, tibial and patellar components (Fig. 1). The whole limb standing film reveals a valgus limb alignment of 15° (Fig. 2). There is a valgus of the tibia. The femoral component is in 9° of valgus compared with normal alignment, The tibial component is R. A. Teitge (&) Wayne State University, Detroit, MI, USA e-mail: rteitge@med.wayne.edu © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_51 667
668 Fig. 1 Well-fixed femoral, tibial and patellar components Fig. 2 Valgus limb alignment of 15°. The angle of medial femur joint line to mechanical axis is 93°. The angle of medial tibial joint line to mechanical axis is 87° R. A. Teitge
Case # 10: Dislocated Patella After Revision Total … in 6° of valgus compared with normal. The mechanical axis was tilted medially a normal 3°. First question: Is there an alignment deformity? Answer: Yes. Knee valgus Second question: How much? Answer: 15° Valgus deformity Third question: Where is the deformity? Answer: 15° valgus deformity could be at 3 sites: femur, joint and tibia. In this case: femur = 9° (102−93 = 9); joint = 0°; and tibia 6° (93−87 = 6). The mechanical axis is inclined 3°. The joint line is horizontal. 2 What to Do in Such a Situation? Options (1) Revision of femoral and tibial components will require resection of more femur and 669 tibia or require addition of femoral and tibial component augments. (2) Medial patellofemoral ligament reconstruction. (3) Coronal plane osteotomy will require 15° correction. Decision Making (see Figs. 3 and 4). (1) Revision of well-fixed components will likely result in greater bone loss and still present the challenge of making perfect femoral and tibial cuts. The possibility of creating varus-valgus instability will increase. (2) MPFLR is not guaranteed to prevent further dislocation in the presence of genu valgum. (3) Osteotomy of just the femur or tibia will create an undesirable joint line obliquity. (4) Osteotomy of the femur and tibia will maintain a horizontal joint line. (5) Closing wedge osteotomy of femur and tibia should not create varus-valgus instability. Fig. 3 Clinical pictures after double level osteotomy. Valgus correction
670 R. A. Teitge Fig. 4 Radiological evaluation after double level osteotomy (6) Closing wedge osteotomy of femur and tibia with compression should yield rapid bone healing. (7) MPFLR was probably unnecessary as the observed patellar tracking after osteotomy remained midline with no tendency to dislocate, but it was added rather as an “insurance” policy. 3 Outcome Patient was progressed to full weight bearing at 4 weeks. At 1 year follow-up he was comfortable walking on a beach, riding a bicycle and walking up 4 flights of stairs. He had no sense of instability, insecurity or weakness of the patella and knee. He was delighted with the outcome. 4 What Has This Case Taught Us? This Case Shows … Limb Alignment is Very Important in the Resolution of Patellofemoral Disorders. The case presented below further emphasizes the great importance of limb alignment in the resolution of patellofemoral pain. 68-year-old female. Right Incapacitating knee pain. She has been in a wheelchair for the past 2 years. History: TTO at age 12; fractured distal tibia at age 40 (Fig. 5).
Case # 10: Dislocated Patella After Revision Total … Fig. 5 Patella infera, valgus limb alignment, lateral compartment osteoarthritis. The knee points forward, with the foot pointing outward indicates an external tibial 671 rotational deformity, there is evidence of prior tibial tubercle osteotomy and tibial diaphyseal fracture 5 Diagnoses Right tibial mal-union " Femoral anteversion " External tibial torsion Recurrent dislocation Patella Baja Tibia valgus growth Tibia valgus congenital Lateral compartment OA Valgus joint convergence Fig. 6 The post-operative radiographs after tibial varus internal rotation osteotomy + proximal transfer of the tibial tuberosity show a neutral mechanical axis, the knee joint and ankle joint appear to be normally aligned in rotation. The patellofemoral joint is congruent Right (37°) and Left (39°) Right (54°) and Left (36°) Left patella Right Right Left Right Right
672 6 R. A. Teitge Options • Total Knee? • Tibial Osteotomy? – Rotation – Varus Proximal Mid Distal • Femoral Osteotomy? • Lengthen patellar tendon? 7 Surgery The arthroplasty surgeon did not want to do TKA unless the patella baja was corrected and the quadriceps was functionally normally. I thought it was foolish to consider a proximal tuberosity transfer and leave the tibia with the valgus and external rotation deformity. I elected pre-op to accept the joint line obliquity post-op rather than add femoral osteotomy. Tibia: Varus + Rotation at Diaphysis + Tibial Tuberosity Osteotomy Moved Proximal (Fig. 6). 8 Outcome 2 years. postop. She is walking. “I don’t need a total knee, right is better than left with recurrent patellar dislocation”.
New Frontiers in Anterior Knee Pain, Patellar Instability and Patellofemoral Osteoarthritis Evaluation and Treatment
Kinetic and Kinematic Analysis in Evaluating Anterior Knee Pain Patients Vicente Sanchis-Alfonso and Jose María Baydal-Bertomeu 1 The Need for an Objective Measurement of Outcomes Given that clinical practice modification is based on outcome studies, the ability to evaluate and quantify the effects of treatment in anterior knee pain (AKP) patients is vital. Due to the limitations of the current methods like the Visual Analog Scale (VAS) and functional scores such as the Kujala score and IKDC, new technologies are needed to measure the benefits of AKP treatment and to compare different methods of treatment. The final objective should be measurement during dynamic activities that cause or aggravate the symptoms. This objective might be achievable by means of kinetic and kinematic analysis given that both are useful in the objective measurement of lower limb function. The application of kinetic and kinematic analysis in the objective assessment of AKP patients is discussed in this chapter. Moreover, kinetic and kinematic analyses can also be useful to help us to understand the knee osteoarthritis mechanisms in this population group. V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com 2 What Provoking Activity is the Best to Evaluate AKP? The Rationale Stair climbing is a demanding locomotor task that is frequently performed during daily activities. From a functional point of view, it is wellknown that going up and down stairs requires high levels of quadriceps activity and is one of the most painful and challenging activities of daily living for subjects with AKP. Moreover, going downstairs is more challenging than going up stairs due to the level of eccentric control required during step descent. In fact, Costigan and colleagues [1] have reported that during stair descent there is an increment in the patellofemoral joint reaction force (PFJRF), being eight times greater compared to level walking. Therefore, stair descent is demanding enough from a biomechanical standpoint to not only aggravate pain in those patients with AKP, but also to trigger the use of defense strategies. Therefore, we propose the stair descent test to evaluate and to quantify the effects of both surgical and nonsurgical treatment in AKP patients. Another interesting aspect that will be analyzed in this chapter are the compensating strategies to reduce load and the resulting pain that, in theory, an AKP patient may develop during the stair descent test. Those strategies that J. M. Baydal-Bertomeu Instituto de Biomecánica de Valencia (IBV), Valencia, Spain © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_52 675
676 V. Sanchis-Alfonso and J. M. Baydal-Bertomeu may seem good at reducing pain might have an adverse mid-term and long-term effect on the knee joint (knee osteoarthritis). 3 Kinetic and Kinematic Analysis in Evaluating AKP To evaluate the way the stair descent is performed we use kinematic information, registered through photogrammetric instruments and kinetic information, picked up on dynamometric platforms. Both systems are combined to determine the most relevant variables that characterize going down stairs. 3.1 Instruments—Motion Analysis System—Dynamometric Platforms A four-camera computer-aided video motion analysis system1 and two independent dynamometric platforms that register the force exerted by the foot on the floor in the three directions of space are used for this test. Dynamometric platforms are placed as indicated in Fig. 1. To carry out the test, a portable two-step wooden staircase, and passive markers2 are needed. Three boxes with the following dimensions are used: 20 cm high step riser and 40 cm footprint, forming a two-step staircase (Fig. 1). The box that serves as the first step was built to adapt perfectly to the dynamometric platform to avoid vibrations when stepping on it. Sixteen reflecting markers are used, eight for each leg. They determine the spatial position of the segments of the lower limb. The markers are placed tracing two triangles in each segment (leg and thigh), with the apex in opposing directions in each of the segments (Fig. 2). All the markers are placed on the lateral aspect of the leg to allow for a 1 Motion analysis. Interpretation of computerized data that documents an individual’s lower and upper extremities, pelvis, trunk, and head motion during ambulation. 2 Passive markers. Joint and segment markers used during motion analysis that reflect visible or infrared light in contrast with active markers that emit a signal. correct visualization by the cameras. Two of the markers are placed on the lateral condyle and on the lateral malleolus respectively to determine the position of the knee and ankle joints. 3.2 Laboratory Protocol To do the test, the subject starts in a standing position with both arms crossed over the chest for the first step. The test involves descending the two steps of the staircase. First, the subject puts one foot on the first step, which has one of the platforms underneath it. Then, the other foot is placed on the floor where the other platform is. The test is repeated four times (two with each leg) for this analysis. Participants are given a visual demonstration of the task prior to testing. Following a verbal cue, the participants perform the task (Fig. 3). To ensure that the task is always performed in the same fashion, we always position some examiners beside the subject to instruct him/her on how to perform the task correctly and to make sure he/she follows the instructions while carrying out the task. We also have a video camera recording our patients to confirm that it is performed correctly. To avoid the possible effects of footwear on gait when descending stairs, all subjects undergo data collection in their barefeet. Apart from standardized stair descent, the patient performs a free one, meaning going down the stairs the way he/she feels more comfortable. 3.3 Kinematic and Kinetic Variables The video-photogrammetric system provides the coordinates of the markers. From this raw data, the finite displacements from the body-reference position were computed using an in-house developed software based on the algorithms described by Woltring [2]. This software provides angular displacements expressed as the attitude vector. The projection of the attitude vector on the medio-lateral and antero-posterior axis provides an estimation of the flexionextension and abduction-adduction angle based on the procedure described by Page and
Kinetic and Kinematic Analysis in Evaluating Anterior Knee … 677 Fig. 1 How the step is adapted to the platform: step disposition Fig. 2 Marker disposition. A With calibration markers. B, C Without calibration markers A colleagues [3]. Using the spatial position and the forces registered with the dynamometric platform, the knee joint moments were calculated. We have used a smoothing technique based on a local polynomial-fitting. The width of the window was optimized in each measurement for the minimum self–correlation of the residuals [3]. The variables specific to the test are (Table 1): (1) knee flexion angle—measured in degrees; B C (2) stance phase duration—time during which the subject is in contact with the first step and is measured in seconds; (3) normalized3 heel contact force—ground reaction force (GRF) that appears on the platform when the heel strikes on 3 The forces are measured in N and they have been normalized for subject weight; therefore, it is a dimensionless magnitude.
678 V. Sanchis-Alfonso and J. M. Baydal-Bertomeu Fig. 3 Photographic sequence of the stair descent test Table 1 Variables specific to the test in a control group Control group Knee flexion angle Average SD Max Min 99.12 7.54 63.45 121.23 Stance phase duration 0.88 0.12 0.62 1.24 Heel contact GRF 1.45 0.15 1.16 1.76 Oscillation GRF 0.75 0.07 0.54 0.94 Toe-off GRF 0.95 0.08 0.75 1.14 Heel contact A/A moment 0.20 0.05 0.12 0.33 Toe-off A/A moment 0.16 0.04 0.08 0.26 −0.13 0.07 −0.54 −0.02 0.29 0.05 0.18 0.42 Heel contact F/E moment Toe-off F/E moment the first step; (4) normalized oscillation force— GRF that appears on the platform when the contralateral leg is oscillating; (5) normalized toe-off peak force—GRF that appears on the platform when the foot steps off of it; (6) heel contact abduction-adduction moment4—maximum torque on the coronal plane5 that is produced during the foot-strike phase on the platform; (7) toe-off abduction-adduction moment—maximum torque on the coronal plane that is produced during the foot take-off phase on the platform; (8) heel contact flexion- extension moment—maximum torque on the sagittal plane6 that is produced during the foot heel-strike phase on the platform; and (9) toe-off flexion-extension moment—maximum torque on the sagittal plane that is produced during the foot take-off phase on the platform. Kinetic and kinematic variables are expressed on a curve. In each graphic, a band of normality (color, light blue), the control group’s mean value (a dotted line) and the mean value of our patients (a black line) are presented (Figs. 4, 5, 6, 7, 8, 9, 10 and 11). 4 The moment is measured in Nm, it has been normalized for subject weight and knee height; therefore, it is a dimensionless value. 5 Coronal plane. The plane that divides the body or body segment into anterior and posterior parts. 6 Sagittal plane. The plane that divides the body or body segment into the right and left parts.
Kinetic and Kinematic Analysis in Evaluating Anterior Knee … 4 Clinical Relevance: Understand the Knee Osteoarthritis Mechanisms in the AKP Patient It is well known that the moments that act upon a joint must be balanced by an equal and opposite muscle force to maintain joint equilibrium. In the healthy subject, the knee joint starts from a relatively stable extended position and flexes towards an increasingly unstable position while going downstairs. The increased joint flexion causes a progressive increment in the external flexion moment7, which is matched by progressively increasing eccentric quadriceps contraction to prevent collapse. In doing so, the internal (muscle) extensor moment8 increases during stair descent as knee flexion occurs. As the PFJRF is dependent on the magnitude of the quadriceps force and knee flexion angle [4], the compressive force acting between the patella and femoral trochlea during stair descent would be expected to be significant. It would also increase the patellofemoral joint (PFJ) stress (force per unit contact area), which is a factor responsible for the PFJ cartilage degeneration. Although articular cartilage is aneural, it has been proposed that articular cartilage degeneration renders the subchondral bone susceptible to pressure variations that would normally be absorbed by healthy cartilage. Although the knee abduction-adduction moment (valgus-varus moment) is not on the primary plane of motion (the primary plane is the sagittal plane), its magnitude should not be ignored when trying to understand the stability and function of the knee during stair climbing and the future life of the knee. Kowalk and colleagues [5] have demonstrated that coronal plane moment patterns are exclusively abductor throughout stance. When an external knee valgus moment occurs, an internal (muscle) joint moment will be generated by the medial muscles 7 External moment. The load applied to the human body due to ground reaction forces, gravity and external forces. 8 Internal joint moment. The net result of all the internal forces acting about the joint which include moments due to the muscles, ligaments, joint friction and structural constraints. 679 (pes anserinus) to balance the joint. An abduction moment will induce a valgus rotation of the tibia. This rotation is limited by two forces, the MCL force, a proximally oriented force at the medial aspect of the knee joint, and a joint contact force acting distally on the lateral tibial plateau [6]. In the young patient with AKP, we and other authors [7, 8] have observed a significant reduction in the knee extensor moment while going downstairs when compared to healthy control group subjects (Fig. 4), which is generally reversed after pain relief with physiotherapy treatment. However, in some cases, Grenholm and colleagues [9] have demonstrated that these compensatory strategies may remain even after the pain has disappeared. This finding goes against the use of this test as a patient evolution control system. The reduction of the knee extensor moment, which is suggestive of a quadriceps avoidance gait pattern [10], could be a primary compensatory strategy used by patients with AKP to reduce the muscle forces acting across the PFJ. Doing so, pain aggravation during walking downstairs is minimized. The reduction of the knee extensor moment with the subsequent smaller quadriceps contraction, will cause a decrease in the PFJR force and a decrease in PFJ loading while going downstairs. In this sense, Brechter and Powers [7] have demonstrated that subjects with AKP did not show increased PFJ stress during stair descent in comparison to a pain-free control group. We have found that when a patient goes down the stairs using his/her strategy for maximum comfort, the extensor moment is lower than when the stair descent is performed following the standard protocol. This confirms the fact that we have discovered a defense strategy (Fig. 5). One factor that may contribute to the knee extensor moment reduction is the decrease of knee flexion angle during the stance phase9 of stair ambulation when compared to control healthy subjects (Fig. 6). It is a strategy to reduce the extensor moment and therefore pain during stair descent. With less knee flexion, the lever 9 Stance phase. Period of time when the foot is in contact with the first step.
680 V. Sanchis-Alfonso and J. M. Baydal-Bertomeu Fig. 4 Knee extension moment arm of the ground reaction force is shortened. Consequently, the knee extensor moment is reduced, with equilibrium being achieved by fewer quadriceps contractions. Although we have observed a decrease of the flexion angle in most of our cases, it has not been a uniform finding. In this sense, there are authors who have found a decrease in the flexion angle during stair descent [11, 12], while others have found no significant differences in the flexion angle during stair descent [7–9, 13, 14] in AKP patients. The decrease of the knee flexion angle during stair descent is therefore not a constant adaptive strategy or defense mechanism. It could be possible that the lack of a decrease of the flexion angle during stair descent is because this activity may not cause enough pain in some people to cause them to use compensatory strategies like knee flexion reduction. Another possible reason for this lack of knee flexion reduction with stair descent could be the activation instant of the VMO when compared to the VL. Crossley and colleagues [11] have demonstrated that those subjects with a higher deficit in the activation moment of the VMO when compared to that of the VL show a higher reduction in knee flexion during stair descent. This is because these patients show an increment in PFJ stress due to the altered patellar tracking. Finally, another fact to justify not finding a decrease of the flexion angle might be how long the pain has been felt. It makes sense to think that some time is required for the patient to develop adaptive measures like flexion reduction. Other strategies besides a decrease in knee flexion to reduce the extensor moment would be the decrease in the vertical ground reaction force in comparison to the healthy limb (Fig. 7). This may reflect an apprehension to load the knee joint at the beginning of the stance phase. According to Salsich and colleagues [8], other strategies employed to reduce the knee extension moment could be the decrease in the stance time duration and the pace. This way, the decrease in the vertical ground reaction force or the speed at which he/she performs the stair descent might contribute to the decrease in the PFJRF. Therefore, the patient may not need to reduce knee flexion during stair descent. According to Hinman and colleagues [15], quadriceps dysfunction may be important in the development and progression of structural changes in osteoarthritis. Quadriceps dysfunction may compromise the protective mechanisms of the knee. The decrease in the extensor moment, which
Kinetic and Kinematic Analysis in Evaluating Anterior Knee … Fig. 5 Knee extension moment. A Standard stair descending test. B Stair descending test following the comfort strategy 681 A B is a strategy to reduce pain, can have destructive long-term effects on the knee joint. In this sense, the decrease in active shock absorption10 during weight-bearing from the eccentric quadriceps muscle contraction [4, 11, 13] means greater shock absorption through the bone and cartilage that could explain tibiofemoral pain. It might also be a predisposing factor to tibiofemoral osteoarthritis of 10 Shock absorption. The progressive damping of an applied force. Damping is a complex, generally nonlinear, phenomenon that exists whenever energy is dissipated. the knee. There is growing evidence that subchondral bone and its turnover may play a causal role in the pathogenesis of osteoarthritis as well as its related symptoms, especially in the knee. This data supports the findings by Naslund and colleagues [16] using bone scintigrams in patients suffering from AKP. They found that tracer accumulation occurred as often in the proximal tibia as in the patella. We have been able to demonstrate a decrease in the knee abduction (valgus) moment while
682 Fig. 6 Knee flexion during stair descending test (A). B Stair descending with a severe knee extension pattern V. Sanchis-Alfonso and J. M. Baydal-Bertomeu A B walking downstairs in almost all cases in AKP patients when it is compared to a healthy painfree knee (Fig. 8). The decreased abduction moments around the knee seen on the coronal plane may help to reduce joint loading, which may be a mechanism that prevents degeneration. We have found that when the patient goes downstairs with his best comfort strategy, the abduction moment is lower than when it is done following a standard protocol. This is confirmation that the decrease in the abductor moment is a defense strategy. The increment in the knee abduction moment would cause a lateral tibiofemoral overload. In this way, Elahi and colleagues [17] correlate PFOA with increased valgus knee alignment.
Kinetic and Kinematic Analysis in Evaluating Anterior Knee … Fig. 7 Vertical ground reaction force during stair descending test Fig. 8 Knee abduction moment during stair descending test 683
684 5 V. Sanchis-Alfonso and J. M. Baydal-Bertomeu Case Studies: A “Snapshot” Case #1. Disabling AKP in a Multi-operated Young Patient With a Chronic Patellar Tendon Rupture and Loosening of the Femoral Component of the Patellofemoral Prosthesis Here, we cite a 29-year-old woman whose left knee was operated on 7 times beginning at the age of 20 (arthroscopic shaving, patella osteotomy, tibial tubercle anteromedialization with lateral patellar retinaculum release, and finally a patellofemoral arthroplasty with primary repair and augmentation of a chronic patellar tendon rupture). She had severe and constant left AKP even during rest (8 in the visual analog pain scale). She also had evident instability during activities of daily living. She went up and down the stairs one step at a time and was very limited in her activities of daily living. The patient even had difficulties getting up from a chair without using the armrest (Preoperative Lysholm 26, preoperative IKDC 25, preoperative Tegner activity scale of level 1). She used to work as a hairdresser but can no longer do it because she is unable to stand up for long periods of time. She only tolerates activities where she can sit. A kinetic and kinematic study during stair descent test revealed the following defense mechanisms: a reduction in the extensor moment (Fig. 9), a reduction of the ground reaction force (Fig. 10). We also found an increase in the abductor Fig. 9 Physical examination shows a patella alta. Lateral radiograph of the left knee showing a patella alta and a patellofemoral arthroplasty. Knee flexion-extension moment during stair descending test
Kinetic and Kinematic Analysis in Evaluating Anterior Knee … 685 Fig. 10 Vertical ground reaction force during stair descending test Fig. 11 Standard Technetium 99 methylene diphosphonate (Technetium-99m MDP) bone scan showing increased osseous metabolic activity in femoral condyles. Knee abduction moment during stair descending test moment, hence a tibiofemoral overload (Fig. 11). The extensor moment reduction entails the suppression of one of the impact absorption mechanisms of the knee. This is clearly going to favor the development a tibiofemoral osteoarthritis. Case # 2. Severe Patellofemoral Osteoarthritis and Medial Patellar Instability in a Multioperated Young Patient A 41-year-old female came to our institution complaining mainly of disabling right patellofemoral instability and of severe right AKP that had not improved with appropriate physical therapy. She had severe PFOA. A reconstruction of the lateral retinaculum using fascia lata was performed following the technique described by Jack Andrish. Kinetic and kinematic analyses were performed during stair descent (Fig. 12). They showed that the patient had: (1) a stair descent pattern with knee extension (strategy to avoid instability and therefore pain), (2) a decrease in the stance phase duration on the platform, (3) reduced values of the extensor moment (with the subsequent reduction in quadriceps contraction and therefore, a reduction of the PFJ reaction
686 V. Sanchis-Alfonso and J. M. Baydal-Bertomeu A B C D Fig. 12 Knee kinetics and kinematics during stair descent. A Knee joint angle during stair descent. B Ground force reactions during stair descent. force, being the final goal to reduce pain), and (4) reduced values of the abduction moment that provokes a reduction of the lateral tibiofemoral compression force on one hand and a reduction in the force exerted proximally by the medial collateral ligament on the other hand (the final result is the reduction of the lateral and medial tibiofemoral compression forces). Kinetic and kinematic analyses during stair descent were performed at 6 months and 12 months after surgery (Fig. 12) and showed a progressive recovery of the kinetic and kinematic parameters. She is pain-free despite the severe PFOA and the increment in the extensor moment. When this is the case, there is an increment in the PFJ reaction force after surgery. C Flexion-extension knee moments during stair descent. D Abduction-adduction knee moments during stair descent 6 Take Home Messages – Most assessments of AKP treatment progression are made using subjective measurements. Kinetic and kinematic analyses would be appropriate to rovide the physician with an objective dynamic measurement of treatment progression. – However, we must insist that the kinetic and kinematic analysis of stair descent is not a diagnostic tool. – AKP patients use strategies to decrease PFJ loading while going downstairs when they are compared to a pain-free control group. The problem is that compensatory strategies
Kinetic and Kinematic Analysis in Evaluating Anterior Knee … require some time to develop and may remain even when pain disappears, which weakens the usefulness of this measurement technique as a treatment progression evaluation method. – Kinetic and kinematic analysis helps us to understand some of the mechanisms behind the development of knee osteoarthritis in AKP patients. References 1. Costigan PA, Deluzio KJ, Wyss UP. Knee and hip kinetics during normal stair climbing. Gait Post. 2002;16:31–7. 2. Woltring H. 3-d attitude representation: a standardization proposal. J Biomech. 1994;27:1399–414. 3. Page A, De Rosario H, Mata V, et al. Effect of marker cluster design on the accuracy of human movement analysis using stereophotogrammetry. Med Biol Eng Comput. 2006;44:1113–9. 4. Fulkerson JP. Disorders of the patellofemoral joint. Philadelphia: Lippincott Williams & Wilkins; 2004. 5. Kowalk DL, Duncan JA, Vaughan CL. Abductionadduction moments at the knee during stair ascent and descent. J Biomech. 1996;29:383–8. 6. Grood ES, Noyes FR. Diagnosis of knee ligament injuries: biomechanical precepts. In: Feagin JA, editor. The crucial ligaments. New York: Churchill Livingstone; 1988. pp 245–60. 7. Brechter JH, Powers ChM. Patellofemoral joint stress during stair ascent and descent in persons with and without patellofemoral joint. Gait Post. 2002;16: 115–23. 687 8. Salsich GB, Brechter JH, Powers ChM. Lower extremity kinetics during stair ambulation in patients with and without patellofemoral joint. Clin Biomech. 2001;16:906–12. 9. Grenholm A, Stensdotter AK, Hager-Ross CH. Kinematic analyses during stair descent in young women with patellofemoral pain. Clin Biomech. 2009;24:88–94. 10. Powers CM, Landel R, Perry J. Timing and intensity of vastus muscle activity during functional activities in subjects with and without patellofemoral pain. Phys Ther. 1996;76:946–55. 11. Crossley KM, Cowan SM, Bennell KL, et al. Knee flexion during stair ambulation is altered in individuals with patellofemoral pain. J Orthop Res. 2004;22:267–74. 12. Greenwald AE, Bagley AM, France EP, et al. A biomechanical and clinical evaluation of a patellofemoral knee brace. Clin Orthop. 1996;324:187–95. 13. Crossley KM, Cowan SM, McConnell J, et al. Physical therapy improves knee flexion during stair ambulation in patellofemoral pain. Med Sci Sports Exerc. 2005;37:176–83. 14. Powers CM, Perry J, Hsu A, et al. Are patellofemoral pain and quadriceps femori muscle torque associated with locomotor function? Phys Ther. 1997;77:1063– 75. 15. Hinman RS, Crossley KM, McConnell J, et al. Does the application of tape influence quadriceps sensorimotor function in knee osteoarthritis? Rheumatology. 2004;43:331–6. 16. Näslund J, Odenbring S, Näslund UB, et al. Diffusely increased bone scintigraphic uptake in patellofemoral pain syndrome. Br J Sports Med. 2005;39:162–5. 17. Elahi S, Cahue S, Felson DT, et al. The association between varus-valgus alignment and patellofemoral osteoarthritis. Arthritis Rheum. 2000;43:1874–80.
Patellofemoral Instrumented Stress Testing Ana Leal, Renato Andrade, Cristina Valente, André Gismonti, Rogério Pereira, and João Espregueira-Mendes 1 Background Patellofemoral disorders display a high incidence in the population and mostly affect the younger and more active population. There is a wide spectrum of presentation of patellofemoral disorders, and may include anterior knee pain, potential patellar instability (PPI) and objective patellar instability (OPI). These conditions are associated with a higher risk to develop joint osteoarthritis, which will have an important and negative long-term both life-quality and A. Leal CMEMS—Center for MicroElectroMechanical Systems, University of Minho, Campus Azurém, Guimarães, Portugal R. Andrade C. Valente R. Pereira J. Espregueira-Mendes (&) Dom Henrique Research Centre, Porto, Portugal e-mail: espregueira@dhresearchcentre.com R. Andrade C. Valente A. Gismonti R. Pereira J. Espregueira-Mendes Clínica Espregueira - FIFA Medical Centre of Excellence, Porto, Portugal R. Andrade Porto Biomechanics Laboratory (LABIOMEP), Faculty of Sports, University of Porto, Porto, Portugal socioeconomic impact. An accurate and early diagnosis of the patellofemoral abnormalities has the potential to indicate the most adequate treatment approach and implement secondary prevention strategies which will positively impact the long-term health-related quality of life of these patients, as well as their socioeconomic status. The risk for patellofemoral instability is usually determined using four anatomical risk factors initially defined by Dejour et al. in 1994 [1]: (1) trochlear dysplasia, (2) quadriceps dysplasia R. Pereira Faculty of Sports, University of Porto, Porto, Portugal Health Science Faculty, University Fernando Pessoa, Porto, Portugal J. Espregueira-Mendes 3B’s Research Group–Biomaterials, Biodegradables and Biomimetics, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, Parque de Ciência e Tecnologia, Zona Industrial da Gandra, University of Minho, 4805-017 Barco, Guimarães, Portugal ICVS/3B’s–PT Government Associate Laboratory, Braga/Guimarães, Portugal School of Medicine, University of Minho, Braga, Portugal © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_53 689
690 (patellar tilt), (3) patellar subluxation as expressed as excessive distance between the tibial tubercle and the trochlear groove (TT-TG), and (4) patella alta. Although these risk factors show reasonable sensitivity, there are limited by poor specificity in patients with patellofemoral instability [2], compromising their discriminative capabilities. Moreover, trochlear dysplasia is usually considered the most reliable discriminator of patellofemoral instability [2], but patellar morphology and morphometry is highly variable in knees with and without patellofemoral instability and there is minimal association between morphometric measurement and trochlear dysplasia [3]. A myriad of other anatomical and biomechanical factors has been identified in the literature [2, 4–9], but most notably for patellofemoral instability is the insufficiency or rupture of structures of the medial patellofemoral complex: medial patellofemoral ligament (MPFL), medial quadriceps tendon femoral ligament (MQTFL), medial patellotibial ligament (MPTL) and medial patellomeniscal ligament (MPML) [10–13]. All these factors—isolated or combined—can lead to unbalanced biomechanical behaviour of the patellofemoral joint that promotes abnormal patellofemoral tracking and altered joint contact forces which can result in patellofemoral instability and/or joint degeneration [14, 15]. The etiopathogenesis of patellofemoral instability is thus multifactorial and complex. There are currently many limitations in the physical examination of patellofemoral instability that will underscore the capability of an accurate diagnosis. Most notably, the current techniques and tools to only provide an approximate and subjective estimation of patellofemoral joint laxity. The physical examination has poor reproducibility and reliability [16, 17] and the imaging techniques lack validity to measure joint laxity. Instrumented-assisted biomechanical testing of patellofemoral joint laxity contribute to better understand the dynamic role of the soft tissues and their active interplay on the pathomechanics of patellofemoral instability. Instrument-assisted examination emerges as a clinical solution to overcome the current limitations in measuring A. Leal et al. patellofemoral laxity. It has thus a crucial role in objectifying, quantifying and standardizing the assessment of individuals with patellofemoral disorders. 2 Instability Versus Laxity Joint instability is a symptom that the patient describes as the joint feeling unstable when moving, walking, running, jumping or twisting. Frequently, patients will refer that the joint “gives away”. Instability is subjective and only reported by the patient. Conversely, joint laxity is the passive response of joint movement as a result of an externally applied force or torque. Joint laxity is an objective and measurable parameter. Human joints may present physiological laxity (normal laxity) or pathological laxity (abnormal laxity). Physiological joint laxity is normal within any human joint as a result of joint movement. Abnormal joint laxity occurs when there is more joint movement than what can be considered as physiological laxity. Instability and laxity are thus different and not interchangeable clinical terms, which may or may not exist concomitantly—i.e., we may find a patient with feeling of instability without joint laxity, a patient with pathological laxity but without joint instability, or even a patient with both joint instability and pathological laxity. The joint laxity profile varies among individuals. Inter-individual differences in joint laxity can arise from differences related to age and sex, bone morphology and morphometrics, soft tissue insufficiency, and among other factors. 3 Clinical and Imaging Assessment of Patellofemoral Joint Instability Diagnosis of patellofemoral instability is firstly made through a clinical history survey and physical examination [18–20]. The clinical diagnosis is then reinforced by imaging exams, including radiography, magnetic resonance imaging (MRI) and/or computed tomography (CT) [19, 21]. The final diagnosis of patellofemoral instability is then
Patellofemoral Instrumented Stress Testing achieved by a correlation of clinical history, physical examination and imaging findings. During physical examination, there are many clinical static and dynamic physical tests available to assess the patellofemoral joint [16, 18, 20]. Most of these tests are assessed qualitatively (rather than quantitatively) and not supported accuracy and/or validity for the existent methods [17]. Whilst manual clinical examination is still paramount for an adequate diagnosis of patellofemoral instability, it is subjective both in the examiner’s technique and interpretation [19]. Manual examination of patellofemoral joint laxity is limited because it lacks precision (objective quantification) and reproducibility [16, 17, 19]. The examiner evaluates the patellofemoral joint laxity manually by pushing the patella medially and laterally and then subjectively quantifying the patellar movement in quadrants (0 to 4 quadrants). This measure lacks precision because it cannot ascertain how much millimeters the patella displaced, but only an approximation (in quadrants). Moreover, this measurement also fails to be reproducible because the amount of force applied and interpretation of movement can vary according the examiner’s experience and sensibility (either when comparing between different examiners, or the same examiner in different evaluations). With accumulated experience, the intra-rater reliability can achieve good results, but inter-rater reliability is poor when using manual tests to assess laxity in patellofemoral instability [16, 17]. Traditional and available physical examination methods to measure patellofemoral joint laxity are thus not suitable for universal application and can result inaccurate measurement of laxity and misdiagnosis of patellofemoral instability. The imaging findings play a crucial role in detecting any structural damage (e.g., MPFL damage) and identifying potential anatomical, morphological and morphometric factors that are associated with an increased risk for patellar dislocation and/or patellofemoral instability [1, 2, 4, 6, 9]. Although imaging has great clinical value to assess structural damage and anatomical risk factors, it is a static assessment and is not 691 capable to measure the biomechanical competence of soft tissue structures in restraining joint laxity. For the case of patellofemoral joint, imaging technique can identify an uninjured MPFL, but cannot ascertain if the MPFL is lax and if it is able to maintain joint stability while withstanding medio-lateral and tilt stress in the patella. Therefore, the currently available imaging methods do not provide a dynamic assessment of joint instability and lack an association with the injury pattern [22]. The poor reproducibility and reliability of physical examination allied to the lack of validity of imaging techniques to measure joint laxity clearly highlight the need for other tools that can provide an accurate, reliable and reproducible method to measure patellofemoral joint laxity. 4 Measurement of Joint Laxity Instrumented assessment has emerged as a potential solution to obtain a precise quantification of joint laxity, thus providing a more objective assessment of joint stability. Instrument-assisted tools to measure patellofemoral joint laxity aim to describe and quantify the bony displacement of the patella in relation to the femoral trochlea upon the application of an external force. Results of joint laxity measurement can then be used as cut-off values to serve as dichotomic screening tools to elicit one of two diagnostic results: biomechanically incompetent or competent ligaments. The diagnostic result of biomechanically incompetent (lax) ligaments will be linked to an increased risk of patellar dislocation. Results of joint laxity can be interpreted as unilateral or then compared by side-to-side difference (SSD). Beyond the dichotomous application, laximetry can become an important diagnosis and profiling tool of different patterns of patellofemoral ligament laxity (stiffness) and their interference in patellofemoral arthrokinematics, treatment decision-making and surgical planning, for prognostic purposes or to quantify post-operative joint laxity. There have been a few attempts to develop instrument-assisted methods to measure
692 patellofemoral laxity [23–31], but the currently available methods show high heterogeneity in the methods for assessing patellofemoral laxity and report variable measurement outcomes [32]. These existing instrument-assisted methods are additionally limited regarding its reproducibility as some of these methods apply the stress manually (subjective variability in the force applied), and all lack precision and accuracy as the measure the joint laxity is made externally to the joint (i.e., measured visually or using electronic tools), which only provides an approximation of the true (intra-articular) patellar displacement. Only one study [30] reported an arthrometer aided by radiography to measure the patellar displacement. However, stress radiographs imply exposure to radiation and are not able to concomitantly provide imaging evidence of structural damage. Safety, validity, reproducibility, precision and accuracy are key factors when developing a measuring device to enable a screening system with clinical usefulness that is supported by its sensitivity and specificity. We acknowledge that majority of clinical tests and testing principles yields value. Even that manual testing has its limitations and pitfalls, it still provides a safe and valid approximate estimation of joint laxity. However, if reproducibility, precision and accuracy are lacking, the outcome can be deceptive (misdiagnosis) and is not a reliable measure when comparing with the contralateral side, among different patients or assessors, and to use as a reference value for benchmarking during post-treatment assessments. The variability found in the literature [32] reinforces the need to develop a simple and universally applicable instrument that is able to reliably and objectively quantify the patellar mobility, and thus standardize the patellofemoral laxity assessment. The precision and accuracy of instrumented joint laxity measurements can be improved when it is combined with imaging assessment. Due to the limitations identified above for radiographs, the combination of laxity measurement with MRI or CT seems the obvious next step [19]. Moreover, by combining the instrument-assisted assessment with MRI, it is A. Leal et al. possible to assess, within the same exam, the joint laxity and any structural damage to the ligaments or cartilage. 5 Porto Patella Testing Device (PPTD) The Porto Patella Testing Device (PPTD) is an MRI-compatible laxity testing device, made of an inert polymer, for the measurement of patellofemoral joint laxity (Fig. 1). The PPTD operates through two modular components with movable activators that are triggered by air pump systems with compressed air cylinders to stress the patella in multiple directions. One activator induces a medio-lateral translation of the patella and the other an external tilt to the patella. The force is applied progressively and is usually up to a maximum of 0.5 Bar—converted to approximately 52.5 N load—which is a safe range to prevent damage to the MPFL (which has a tensile strength of 208 N [33]). The operator can manually control the magnitude of force transmission and the force applied is also subjectively controlled by feedback from patients or by noticing any signs of patient’s apprehension. After the movements are applied to the patella, by using anatomical landmarks at the MRI/CT images as reference points, it is possible to measure the patellar bony displacement (in relation to its resting position) and infer the joint laxity. 5.1 PPTD Operation Protocol The PPTD evaluation protocol starts with the patient positioning. The patient is placed in the device with the knee in full extension, without any rotation or flexion of the hip and ankle joints. All patients are instructed to avoid muscle guarding which could interfere with joint laxity. The patient’s anatomical axis (interline of the knee joint) is aligned with the mechanical axis of the PPTD and the modular components are adjusted to the size of the patient. The lower limb is then fixed to the PPTD using velcro straps at the thigh and foot to restrict lower limb movement.
Patellofemoral Instrumented Stress Testing 693 Fig. 1 Photograph of the Porto Patella Testing Device (PPTD) The first set of MRI/CT sequences are made after patient positioning, but without the application of any stress at the joint. These first sequence is made to set the resting position, which will be used latter for benchmarking when making the measurement of patellar displacement (Fig. 2A). Then, the second set of MRI/CT sequences is taken after being applied a mediolateral force to the medial border of the patella with the medial activator at 30 degrees (in relation to the patellar horizontal plane) to apply a lateral movement to the patella (Fig. 2B). Lastly, the medio-lateral stress is withdrawn and with the A B Fig. 2 Porto Patella Testing Device (PPTD) setup for stress-testing evaluation within imaging equipment: A initial setup without any stress to obtain the position of the PPTD lateral actuator is placed at 70 degrees (in relation to the patellar horizontal plane) and the patella is pushed in an oblique anteroposterior direction at the extreme of its anterolateral facet to apply an external tilt movement (Fig. 2C). 5.2 Measurement Protocol All MRI/CT sequences are taken in the axial plane. If using MRI, the measurements are done with sets of 1 mm spacing within the MRI slices. Patella position is calculated as the distance C patella at rest; B patella stressed on its medial facet for lateral translation; C patella stressed at the extreme of its anterolateral facet for external tilt
694 A A. Leal et al. B C Fig. 3 PPTD sequential stress testing of a patient with recurrent patella dislocations, with the left knee with an MPFL tear: A patella rest position (2 mm and 22°); B lateral transition, the patella displaced 16 mm and 8° (moved to 18 mm and 30°); C lateral tilt, the patella displaced 19 mm medially and increased 10° (moved to −17 mm and 32°) between two parallel lines—perpendicular to the tangential line of the posterior femoral condyles— one crossing the deepest point of the trochlear groove and other the center of the patellar ridge (Fig. 3). The lateral patellar angle is measured the angle formed by the line crossing the major transversal axis of the patella and the line tangential to the posterior femoral condyles. The patella position is firstly measured with the patella at rest (Fig. 3A) and then after stress is applied. The lateral patella displacement is measured by calculating the difference between the patella position after medio-lateral stress and the patella position at rest (Fig. 3B). The external tilt angle is measured by calculating the difference between the patella position after external tilt stress and the patella position at rest (Fig. 3C). The patella displacement can then be interpreted as a single unilateral displacement or as compared to the contralateral side by calculating the SSD of the bilateral assessment. Additionally, by using MRI/CT sequences of incremental force applied to the patella, it is also possible to calculate the force–displacement curves and relate it to the ligament stiffness of the patellofemoral joint. 5.3 PPTD Validity, Reliability and Outcomes The PPTD is a valid tool and reliable to assess patellofemoral joint laxity. The PPTD is a more valid tool to ascertain patellofemoral laxity than manual examination because it is able to produce a pre-determined and reproducible stress-force application to the patella. Conversely, the manual exam is imprecise stress-force application that is variable to the examiner sensibility. In patients that have withstand maximum translation force, the PPTD yields greater lateral patellar translation (converted in quadrants) as compared to manual exam. Measurement of patellar displacement using PPTD is thus more accurate and precise than the visual estimation of translated quadrants by manual exam. Moreover, the PPTD provide a reliable measurement of patellofemoral joint laxity with excellent intra-rater agreement (intraclass correlation coefficient 0.83–0.98) [34]. The PPTD is also a useful tool to discern between different patellofemoral disorders according to the profile of patellofemoral joint stiffness (Fig. 4). The force–displacement curves of patients with PPI (those with risk factor for
Patellofemoral Instrumented Stress Testing 695 Fig. 4 Graphical illustration of force–displacement curves (stiffness) for a representative case of a patient with AKP (green line), PPI (blue line) and OPI (orange line) patellofemoral instability, but without any dislocation episode) and patients with OPI (those with clinical history of patellar dislocation) display a similar stiffness pattern, which differs from the stiffness pattern seen in patients with anterior knee pain. When comparing both types of patellofemoral instability (PPI and OPI), those with PPI display greater stiffness (a higher force was required to displace the patella) than those with OPI [35]. The stiffness pattern can also be useful to compare with the contralateral uninjured side (Fig. 5) or after MPFL reconstruction (Fig. 6) or any patellofemoral joint corrective surgery. Fig. 5 Graphical illustration of force–displacement curves (stiffness) for a representative case of a patient with OPI (recurrent dislocations), showing the curve for the knee with OPI (red line) and the asymptomatic contralateral knee (green line)
696 A. Leal et al. Fig. 6 Graphical illustration of force–displacement curves (stiffness) for a representative case of a patient after MPFL reconstruction at follow-up, showing the curve for the MPFL-reconstructed knee (red line) and the asymptomatic contralateral knee (green line) Besides patellofemoral instability, the PPTD can be used to assess any ligament insufficiencies in other patellofemoral disorders. We have previously found that patients with idiopathic unilateral anterior knee pain and with morphologically equivalent knees display greater lateral patellar translation in the painful knee [36], suggesting a potential insufficiency or imbalance of the medial static patellar stabilizers. 5.4 PPTD Possible Clinical and Research Applications The ability of the combined evaluation of the PPTD with the MRI to visualize the soft tissues concomitantly with the accurate and precise measurement of joint laxity allows to correlate the structural integrity of the ligaments with its functional competence. Moreover, it allows within the same evaluation to identify any damage to other structures, such as the articular cartilage, as also to correlate with bony morphological and morphometric features (such as, trochlear dysplasia and patella alta or baja). Ultimately, this combined evaluation provides a precise and complete assessment of the patellofemoral status that will be helpful for diagnostic purposes of patellofemoral disorders. Therefore, the PPTD adds diagnostic value and contributes in the therapeutic decision-making and surgical planning. The PPTD can play an important role in establishing cluster profiles of patellofemoral joint laxity as it combines the assessment of both “anatomy” and “function”. For example, the MRI exam might identify absence of MPFL tear after a patellar dislocation, but the addition of the PPTD assessment can reveal incompetent MPFL to provide stability to the patellofemoral joint that warrants conservative or surgical intervention. Using the PPTD, we may identify subclinical groups of patellofemoral instability that may require differentiated or additional surgical interventions and thus refine our surgical indications and individualize the treatment. For example, we may identify a patient with extensive patellofemoral joint laxity that may benefit from combined reconstruction of the MPFL with the MQTFL [10] or with the MPTL [37]. Eventually, we may establish joint laxity cluster profiles that are able to provide prognostic value for each subclinical group with patellofemoral instability. The PPTD can also have clinical value to evaluate the joint laxity outcomes of patients with patellofemoral instability that underwent ligament reconstructive surgery. With the PPTD, we can prospectively monitor the patellofemoral joint laxity and evaluate if there is any residual
Patellofemoral Instrumented Stress Testing laxity in the operated knee by comparing to the pre-surgery laxity profile of the operated knee and to the non-operated contralateral side. It can also be useful to compare the joint laxity outcomes between different surgical techniques (with or without concomitant surgeries) and any conservative approaches. Lastly, by providing information about the potential presence of residual laxity, the PPTD can be useful for the decision to clear athletes to unrestricted sporting activities or pinpoint those that may require further rehabilitation or surgical reintervention. 697 4. 5. 6. 7. 8. 6 Conclusions The PPTD is an MRI/CT compatible testing device to evaluate patellofemoral joint laxity. It provides a valid, reliable, accurate and precise measurement of patellar displacement under applied stress to the patella and thus identify patients with pathological patellofemoral joint laxity. By analyzing the joint laxity and stiffness profile, this instrument-assisted MRI evaluation can identify subclinical cluster groups of patients with patellofemoral instability and thus personalize the treatment to the patient’s individual needs. The use of the PPTD can thus be very useful in the clinical practice to support diagnostic decisions, customize the therapeutic decision-making and surgical planning, and follow the joint laxity profile outcomes after conservative or surgical interventions. References 1. Dejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994;2:19–26. 2. Ridley TJ, Hinckel BB, Kruckeberg BM, Agel J, Arendt EA. Anatomical patella instability risk factors on MRI show sensitivity without specificity in patients with patellofemoral instability: a systematic review. J ISAKOS. 2016;1:141–52. 3. Jimenez AE, Levy BJ, Grimm NL, Andelman SM, Cheng C, Hedgecock JP, Cohen A, Pace JL. Relationship between patellar morphology and known 9. 10. 11. 12. 13. 14. 15. 16. anatomic risk factors for patellofemoral instability. Orthop J Sports Med. 2021;9:2325967120988690. Arendt EA, England K, Agel J, Tompkins MA. An analysis of knee anatomic imaging factors associated with primary lateral patellar dislocations. Knee Surg Sports Traumatol Arthrosc. 2017;25:3099–107. McCarthy MI, Hinckel BB, Arendt EA, Chambers CC. Putting it all together: evaluating patellar instability risk factors and revisiting the “Menu.” Clin Sports Med. 2022;41:109–21. Diederichs G, Issever AS, Scheffler S. MR imaging of patellar instability: injury patterns and assessment of risk factors. Radiographics. 2010;30:961–81. Neyret P, Robinson AH, Le Coultre B, Lapra C, Chambat P. Patellar tendon length–the factor in patellar instability? Knee. 2002;9:3–6. Escala JS, Mellado JM, Olona M, Giné J, Saurí A, Neyret P. Objective patellar instability: MR-based quantitative assessment of potentially associated anatomical features. Knee Surg Sports Traumatol Arthrosc. 2006;14:264–72. Kaiser P, Schmoelz W, Schoettle P, Zwierzina M, Heinrichs C, Attal R. Increased internal femoral torsion can be regarded as a risk factor for patellar instability-a biomechanical study. Clin Biomech (Bristol, Avon). 2017;47:103–9. Espregueira-Mendes J, Andrade R, Bastos R, Joseph S, Fulkerson JP, Silva LD. Combined soft tissue reconstruction of the medial patellofemoral ligament and medial quadriceps tendon-femoral ligament. Arthrosc Tech. 2019;8:e481-8. Hinckel BB, Gobbi RG, Demange MK, Pereira CAM, Pécora JR, Natalino RJM, Miyahira L, Kubota BS, Camanho GL. Medial patellofemoral ligament, medial patellotibial ligament, and medial patellomeniscal ligament: anatomic, histologic, radiographic, and biomechanical study. Arthroscopy. 2017;33:1862–73. Hinckel BB, Gobbi RG, Kaleka CC, Camanho GL, Arendt EA. Medial patellotibial ligament and medial patellomeniscal ligament: anatomy, imaging, biomechanics, and clinical review. Knee Surg Sports Traumatol Arthrosc. 2018;26:685–96. Tanaka MJ, Chahla J, Farr J 2nd, LaPrade RF, Arendt EA, Sanchis-Alfonso V, Post WR, Fulkerson JP. Recognition of evolving medial patellofemoral anatomy provides insight for reconstruction. Knee Surg Sports Traumatol Arthrosc. 2019;27:2537–50. Mäenpää H, Lehto MU (1997) Patellofemoral osteoarthritis after patellar dislocation. Clin Orthop Relat Res. 156–62. Elliott CC, Diduch DR. Biomechanics of patellofemoral instability. Op Tech Sports Med. 2001;9:112–21. Smith TO, Clark A, Neda S, Arendt EA, Post WR, Grelsamer RP, Dejour D, Almqvist KF, Donell ST. The intra- and inter-observer reliability of the physical examination methods used to assess patients with patellofemoral joint instability. Knee. 2012;19:404–10.
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Anterior Knee Pain and Functional Femoral Maltorsion in Patients with Cam Femoroacetabular Impingement Marc Tey-Pons, Vicente Sanchis-Alfonso, and Joan Carles Monllau 1 Introduction Previous chapters have shown how anterior knee pain, with an estimated prevalence between 12 and 25% of the population in the 2nd to 4th decade of life, is a common reason for consultation in orthopedic surgery and frequently has no clear cause to justify it [1, 2]. Anatomical alterations and biomechanical imbalances of the knee are usually studied to rule out mechanical overload, secondary patellar cartilage alteration and pain as the ultimate consequence. However, anatomical and biomechanical studies of the knee frequently do not identify an obvious patellofemoral disorder. It is in this context that the differential diagnosis should M. Tey-Pons (&) Department of Orthopaedic Surgery, iMove orthopaedics, Hospital Mi Tres Torres, Barcelona, Spain e-mail: mtey@imovetrauma.com V. Sanchis-Alfonso Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain J. C. Monllau Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain Universitat Autònoma de Barcelona (UAB), Barcelona, Spain focus on proximal or distal causes of patellar pain [3]. Torsional disorders, discussed in chapters “Femoral and Tibial Rotational Abnormalities Are the Most Ignored Factors in the Diagnosis and Treatment of Anterior Knee Pain Patients. A Critical Analysis Review”, “Why is Torsion Important in the Genesis of Anterior Knee Pain?” and “Rotational Osteotomy. Principles, Surgical Technique, Outcomes and Complications”, are an important element in this biomechanical imbalance of the proximal knee musculature. Other alterations in the morphology of the proximal femur, such as cam-type morphology of the femoral head, which causes femoroacetabular impingement syndrome (SFAI), have been related to the manifestation of anterior knee pain [4]. A distinct morphological alteration with an adaptive process with similar consequences could be termed a functional torsional disorder. 2 Proximal Causes of Anterior Knee Pain The most current evidence suggests that patients with patellofemoral pain (PFP) have altered neuromuscular activity in the proximal musculature during various activities such as running, jumping or stair climbing [5–7]. Weakness of the Gluteus Medius [8] but also of the vastus medialis obliquus [5], an important medial stabilizer of the patella, has been widely studied. The result of this muscular imbalance is an increase in the abductor © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_54 699
700 moment of the knee, with an overload on the external patellofemoral joint that initiates the pathophysiological process that will lead to pain, as has been amply explained in previous chapters. There is a broad consensus on the association of PFP with Gluteus Medius weakness and hip external rotation deficit. Meira et al. in an exhaustive review conclude that the relationship between hip position and anterior pain is clear, finding several references to increased hip adduction and internal rotation in relation to anterior pain [9], despite the bias since most of the studies have been carried out in a female population and runners and the causal relationship is not established. Other studies, such as that of Boling, identify increased external rotation strength in runners with anterior knee pain compared to controls. Therefore, the question arises as to whether patients with abductor weakness have greater patellar pain or whether patellar pain generates more abductor muscle exhaustion. Tibial torsional disorders involve a rotational disturbance in the frontal plane of the patella [10], which is radically different from rotational disorders of the femur in which the patella undergoes a translational disturbance [10]. Rotational disorders result in joint pressure increases at the patella, while patients with femoral torsional disorders experience an adaptive disorder, whereby they alter limb rotations at the hip to compensate for the rotational disturbance, thereby altering the relationship between hip position and patella, related to anterior knee pain. Alterations of the hip and proximal femur may favor some of the force balance disorders responsible for the increased abductor moment of the knee, causing the onset of patellar pain. One could think of the proximal femur as a distant cause of the PFP, or of anterior knee pain as a distant symptom of proximal femoral imbalances. In the approach to hip pathology proposed by Kelly, in which a layered analysis is established, the last layer is the kinematic chain [11]. According to this, the semiology at a distance from the original problem is analyzed, and anterior knee pain should be recognized as a symptom of the pathology of the proximal femur. This could be presented as a purely semantic discussion, but it has important clinical implications that M. Tey-Pons et al. should be carefully analyzed. This chapter will analyze how these morphological variations of the hip alter the biomechanics of the limb, in the same way as torsional changes, so we call them functional torsional alterations, having as clinical manifestation some local signs at the hip level, and some distal signs at the knee level. 3 Biomechanical Conflicts of the Hip Osteoarthritis of the hip is a highly prevalent pathology, classically labeled as primary or of idiopathic etiology. With very well-known exceptions, such as avascular necrosis, posttraumatic deformity, rheumatic or depositional diseases, and some systemic diseases with joint involvement, hip osteoarthritis has been considered linked to aging, but without a clear cause to justify it. The Stolzalpe school represents a paradigm shift, since it defines osteoarthritis of the hip in young adults, that which occurs before the age of 50–55 years, as secondary to identifiable processes in 95% of the cases. Among the identifiable causes, mechanical conflicts play a prominent role, accounting for 70% [12]. The progressive development of hip preservation surgery techniques led by the Bern school has increased the interest and study of biomechanical conflicts, as they represent a potentially treatable pathology that could change the natural history of osteoarthritis. These biomechanical conflicts are divided into two large groups, according to the alteration of joint kinematics, although with important kinetic implications, ultimately responsible for favoring and initiating joint degeneration. On the one hand, we find the dynamic conflicts of space, where the articular kinematic excursion is diminished by alteration of the femoroacetabular relationship, or by morphological alteration of one or both parts. On the other hand, dynamic stability conflicts are described, where the joint loses its congruence during movement, due to a lack of hip stabilizing mechanisms, favored by an alteration in the joint contact area or in the acetabular coverage of the femoral head. These conditions imply an alteration in the articular kinematics, with the alteration of the normal articular mobility and
Anterior Knee Pain and Functional Femoral Maltorsion … conflict of the periarticular soft tissues, and of the articular kinetics, with an abnormal distribution of articular loads. This alteration of loads, together with the lesion of periarticular soft tissues, will be responsible for initiating the joint degenerative process, the ultimate evolution of these conflicts as we announced [13]. Dynamic space conflicts have been grouped under the SFAI, in which the patient experiences groin pain associated with a conflict between the femur and acetabulum. Initially described by Ganz as a biomechanical imbalance attributed to a morphological alteration of the femoral head (cam-type SFAI) and/or an alteration of the acetabular coverage (pincer-type SFAI) [14], but later extended to other causes of mechanical hip space conflict, either intra- or extra-articular causes such as Subspine Impingement, Ischiofemoral Impingement or torsional disorders [15]. 4 Anterior Knee Pain in Biomechanical Conflicts of the Hip Morphological alterations of the proximal femur can favor a biomechanical conflict in the hip as explained. The clinical picture is determined by the joint impingement, such as the alteration of the normal range of motion, the suffering of articular tissues such as the acetabular labrum or the articular cartilage, but also by the adaptive mechanisms that are put in place to compensate for the conflict. Thus, in patients with hip dysplasia, with insufficient anterolateral femoral coverage, the gait pattern is altered [16] unbalancing the normal biomechanical functioning, responsible for the appearance of pain due to overload or misuse in the groin, but also in the posterior and lateral aspect of the hip [17]. Similarly, patients with SFAI have groin pain due to anterior joint impingement but may also experience pain in the gluteal region or on the lateral aspect of the hip [18]. The impact of torsional disturbances on hip muscle balance and thus on the imbalance of the knee extensor apparatus, with increased knee abductor moment and the occurrence of PFP is well demonstrated 701 by biomechanical studies [10] and proven in routine clinical practice. Biomechanical conflicts of the hip may be responsible for the occurrence of anterior knee pain by several mechanisms. Femoral internal rotation (or increased femoral antetorsion) leads to mechanical disadvantage for the abductor musculature, which loses leverage and increased internal rotation of the hip as a compensatory mechanism for muscle fatigue to increase the moment of force. The alteration of the sphericity of the femoral head, called cam morphology due to the kinematic alteration it produces, responds to a particular type of morphology of the proximal femur which in biology is called coxa recta. It is the hip presented by mammals adapted to the savannah, with a powerful hip for running, in which there is a decreased cervical-cephalic offset or a loss of sphericity of the femoral head, with an increased radius in the anterior and lateral region of the femoral head [19]. However, this powerful proximal femur has a more limited range of motion, and impinge with the anterior acetabular rim at flexion with internal rotation. Damage to the soft tissues may start pain and it is known as SFAI. Image 1 shows a patient with cam-type femoral head during hip arthroscopy before and after osteochondral resection. Damage to femoral cartilage explains how impingement limits flexion and why external rotation is needed to increase flexion without impinging. An abnormal gait with increased external rotation, similar to patients with femoral retrotorsion can be observed. The cam-type morphology of the proximal femur may not only be responsible for an alteration in hip joint kinematics but produces an adaptive disorder of the entire lower extremity, as has been demonstrated by gait studies. The alteration in gait produced by FAI cam leads to an increase in external rotation, similar to femoral retrotorsion [20–22]. Therefore, when analyzing the muscle imbalance produced by cam-type SFAI and the subsequent increased abductor moment of the knee, it can be assumed as a functional femoral retrotorsion. If we understand anterior knee pain as a distant symptom of cam-type SFAI, in the same way as
702 M. Tey-Pons et al. A B Image 1 A Cam-type femoral head with damaged cartilage (black arrow) due to impingement with the acetabular rim. View of peripheral compartment of right hip from anterolateral portal. B Osteochondroplasty is performed and impingement has been eliminated it is in femoral retrotorsion, SFAI should be considered in patients with cam morphology, without groin pain but with anterior knee pain. Cam-type femoral head may produce SFAI because of anterior impingement. Cam-type femoral head may produce external rotation to avoid impingement, with secondary muscle imbalance similar to that produced by retrotorsion. 5 Take-Home Messages Proximal ethiology of anterior knee pain is well known, and it is related to imbalance of proximal muscles. Abnormal torsions have been related to that imbalance. 6 Key-Message PFP can be a distant symptom of cam-type FAI.
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Finite Element Technology in Evaluating Medial Patellofemoral Ligament Reconstruction Vicente Sanchis-Alfonso, Diego Alastruey-López, Cristina Ramirez-Fuentes, Erik Montesinos-Berry, Gerard Ginovart, Joan Carles Monllau, and María Angeles Perez 1 Introduction Finite element (FE) analysis originated as a method for structural analysis in the British aerospace industry. This methodology made it possible to perform multiple simulations with the computer to avoid numerous experimental tests with the consequent savings in material, equipment and resource consumption. There are two types of modelling that use FE technology, real models and parametric models (PM) (Fig. 1). A PM is a generic model, a simplified model of reality, valid in our specific case for any knee, in which we can introduce the patient-specific knee variables that we want to evaluate. On the contrary, a real model is complex, expensive and Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/978-3-031-09767-6_55. V. Sanchis-Alfonso (&) Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain e-mail: vicente.sanchis.alfonso@gmail.com time-consuming. It also requires the work of several engineers and a system of computers connected in series. A PM is quite the opposite. The use of a PM can be seen in the making of mechanical simulations in many aspects of architecture. Our work group has developed a PM of the patellofemoral joint (PFJ) that makes it possible to evaluate the reconstruction of the medial patellofemoral ligament (MPFL) [1]. This model has already been clinically validated in a previous study in which we evaluated different MPFL reconstruction (MPFLr) techniques [1]. With this technology, different MPFL surgical reconstruction techniques for a specific patient can be simulated with the appropriate software on our laptop [1, 2]. Moreover, different associated E. Montesinos-Berry ArthroCentre - Agoriaz, Riaz and Clinique CIC Riviera, Montreux, Switzerland G. Ginovart Department of Orthopaedic Surgery, Hospital Terres de l’Ebre, Tortosa, Spain D. Alastruey-López M. A. Perez Instituto de Investigación en Ingeniería de Aragón (I3A), Instituto de Investigación Sanitaria Aragón (IIS Aragón), Multiscale in Mechanical and Biological Engineering, University of Zaragoza, Zaragoza, Spain J. C. Monllau Department of Orthopaedic Surgery, Hospital del Mar, Barcelona, Spain C. Ramirez-Fuentes Medical Imaging Department, Hospital Universitario y Politecnico La Fe, Valencia, Spain Universitat Autònoma de Barcelona (UAB), Barcelona, Spain Catalan Institute of Traumatology and Sports Medicine (ICATME), Hospital Universitari Dexeus, Barcelona, Spain © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_55 705
706 V. Sanchis-Alfonso et al. Fig. 1 Real finite element A model (FEM) (A, B) and Parametric FEM (C, D) of the PFJ B C D surgical gestures, for example, a trochleoplasty can be added. This means that distinctly different surgical simulations can be performed for each patient. In this way, one can determine what the best surgical approach for a specific patient is, at least from the biomechanical point of view. The objective of this chapter is to analyze the role of a PM of the PFJ in evaluating MPFLr. 2 Parametric Model of the PFJ— Our Protocol (See Video) First, a reconstruction of the knee under study using MIMICS software (MIMICS, Materialise NV, Leuven, Belgium) is made. Next, the patella is isolated and its maximum mid-lateral and proximal–distal length as well as its thickness are measured. In addition, the geometry of the patella is also evaluated. That means the shape of the patella. The PM is developed using ABAQUS FEA, the model simulation software (Abaqus/CAE v.6.14 software, Dassault Systèmes, Suresnes, France). Initially, we simulate the patella as an elliptical disc. Subsequently, the specific parameters of the patella that are going to be analyzed (thickness and major and minor diameters) are introduced. Then, different cuts are made to give the patella the appropriate shape to obtain a geometry that is like the geometry of the patella that is going to be evaluated. Then, the patellar cartilage is created using the geometry of the patella. A fixed thickness of 3 mm is assumed. The femur geometry is based on four main elements: a revolution shape that defines the bottom geometry, a solid loft for the irregular section, a revolution shape in the posterior geometry and two revolution shapes that represent the femoral epicondyles. Then, the femoral cartilage consists of a revolution shape for the bottom geometry and a combination of elements that makes it possible to define the upper region. Again, a fixed thickness of 3 mm is assumed. Finally, the finite element mesh is created (Fig. 2). Next, the same process is repeated with the femoral trochlea. If, for example,
Finite Element Technology in Evaluating … 707 the patient has grade D dysplasia in conformity with the Dejour classification, it can be incorporated into the PM. In short, a PFJ like that of the patient for whom we want to simulate surgery is obtained. Besides the MPFLr, the model also permits the simulation of other procedures done in association with MPFLr like trochleoplasty. An important parameter to consider in the design of the model is the thickness of the cartilage because it can theoretically influence the contact pressure. In the present case, as previously indicated, a uniform cartilage thickness of 3 mm is considered as it is widely accepted in the specialized literature [3]. A prior sensitivity analysis, making simulations with thicknesses of 2, 2.5, 3, 3.5 and 4 mm, showed that the cartilage thickness did not significantly affect patellar contact pressure, the differences being less than 0.005 MPa [1]. The cartilage is a multiphasic, inhomogeneous and anisotropic structure. Due to the computational costs and the time required to perform modelling with 3D FE, the cartilage has been considered a homogeneous and isotropic material with linear elastic behavior from the computational point of view [4–8]. Interstitial fluid flow is not considered despite it being a poroelastic material. Once the bone structures (distal femur and patella) and the femur and patellar cartilage have been modelled, the ligaments (MPFL and lateral retinaculum-LR-) and the tendons that surround the patella (quadriceps and patellar tendons) are Fig. 2 Parametric geometry of the four main parts of the PFJ model: A Patellar cartilage; B patellar bone; C femoral bone; D femoral cartilage; E geometric parameters of the patellar bone; F geometric parameters of the femoral bone (Reproduced from Sanchis-Alfonso V, Alastruey-López D, Ginovart G, et al. Parametric finite element model of medial patellofemoral ligament reconstruction model development and clinical validation. J Exp Orthop. 2019; 6 (1), 32. © The Authors)
708 V. Sanchis-Alfonso et al. Fig. 3 Final model reconstruction including the joint ligaments and tendons. (Reproduced from SanchisAlfonso V, Ginovart G, Alastruey-López D, et al. Evaluation of patellar contact pressure changes after static versus dynamic medial patellofemoral ligament reconstructions using a finite element model. J Clin Med. 2019; 8 (12), pii: E2093. © The authors) introduced into the PM as beam elements (Fig. 3). The LR ligament has the same position in all the simulations. It is defined as a group of six beam elements that connect the patella and the femur through six of their nodes. The MPFL is defined as a group of two beam elements that connect the patella and the femur through two of their nodes. The femoral insertion of this ligament is different for each reconstruction technique. The quadriceps tendon (QT) and patellar tendon (PT) are modelled as a group of four and two truss elements, respectively. The material properties of these ligaments and tendons are sourced from the specialized literature [9–11]. The inclusion of the patellar tendon and the quadriceps tendon in the current model is crucial for two reasons. The first reason is because its presence helps stabilize the patella. If these tendons are not included in the model, it will cause excessive rotation of the patella when tension is applied to the ligaments. However, the rotational movement of the patella upon applying tension to the surrounding ligaments will be practically non-existent when the tendons are present. The second is because the presence of these two tendons aids in making patellar contact pressure distribution more uniform. In the FE models designed for the study of the PFJ, emphasis is placed on achieving an adequate orientation of the quadriceps and patellar tendons. This maneuver aims to prevent a valgus alignment that would result in a lateral displacement of the patella. From a mechanical point of view, valgus alignment increases lateral pressure in the patella due to the increase in the so-called Q angle. In the present model, uniform pressure distribution was achieved in the patella because the patellar and the quadriceps tendon were introduced. It ensures that there is no pathological valgus that can skew the results obtained. All the structures are in a situation of balance in our model. One of the most complex points in this kind of model with different parts (the patellar bone, patellar cartilage, femoral cartilage and femoral bone) is defining how all the parts interact. In this study, bone (patella and femur) is considered a rigid part. Therefore, its geometry remains nondeformable when loads and displacement are applied. On the other hand, the cartilages are deformable solids. When the interactions are defined, it is necessary to assign a master or slave behavior to each contact surface. Therefore, the
Finite Element Technology in Evaluating … 709 Fig. 4 Initial patellar cartilage contact pressure (MPa) (right)—Contact pressure after applying tension to the ligaments (middle)—Relative contact pressure (left) (L = lateral; M = medial) two main different interactions are patellar bone with patellar cartilage and femoral bone with femoral cartilage. The interactions are modelled as a tie constraint between bone and cartilage (a tie constraint implies the union of two regions without regard to whether the meshes created on their surfaces are similar or not). Patellar cartilage with femoral cartilage is modelled as a surface-to-surface contact with a friction coefficient of 0.02. We generate different models for each degree of knee flexion [1]. The first thing is to draw the patella to the femur to generate contact (initial contact pressure). Then, the ligaments and tendons are brought into play. Next, tension is slowly and progressively applied to the ligaments. Tension is applied according to the variation in graft length during knee flexion [12]. With this, the initial contact pressure is increased. To this final contact pressure value, we subtract the initial contact pressure. With that, we are really evaluating the relative contact pressure value (Fig. 4). Specifically, the pressures resulting from the incorporation of the MPFL to the model are evaluated. This is the reason negative pressures are found. In this way, different surgical techniques can be compared under the very same conditions. In a previous work, the changes in graft length used to reconstruct the MPFL with knee flexion were analyzed and it was shown to differ in each type of MPFLr [12]. Particularly, the static and the dynamic types of MPFLr were analyzed in prior studies done by our group [1, 2]. 3 The Clinical Problem—What is Going to Happen with the PFJ in the Long-Term After a MPFLr? Currently, MPFLr is the procedure of first choice for the treatment of patients with chronic lateral patellar instability (CLPI). An MPFLr technique is good when the clinical result is good, which is when pain and instability disappear and no new problems like patellofemoral chondropathy or even patellofemoral osteoarthritis (PFOA) develop over the long term. PFOA is the result of an excessive increase in PFJ pressure due to an inappropriate MPFLr. It has been shown that the femoral attachment point in MPFLr is of utmost importance for MPFL-graft length change during
710 knee flexion and relative graft length [12]. Both factors influence the long-term success and failure rate of the MPFLr surgery [12]. Graft overtensioning and/or non-anatomic positioning of the femoral attachment point during MPFLr increases PFJ contact pressures [13–15]. This increment in PFJ contact pressure might lead to joint degeneration [13, 16]. In the medical literature, there are many surgical MPFLr techniques published with different fixation points and different types of grafts that have shown good short-term clinical outcomes. It seems like they are all good, but they certainly are not. These techniques have noticeably short follow-ups and have been evaluated only by means of clinical tests that are not sensitive enough to evaluate a surgical technique. MPFLr assessment using FEM is more sensitive than evaluations using only clinical or radiological tools. FEM can demonstrate the validity of a surgical technique in the long term since it enables one to determine whether a specific technique will lead to an increase in PFJ contact pressure, which is closely related to the future development of PFOA. An important question arises here. What is going to happen with the PFJ in these MPFL reconstructions techniques in the long run? We do not know. To respond to this question, we could use the PM of the PFJ developed with FEM technology using the computed tomography images (CTs) of patients with patellar instability. Therefore, we would have those with the specific anatomical characteristics of a knee with a CLPI. This technology would give us the ability to evaluate PFJ pressures after an MPFLr in the entire range-of-motion of the knee (0120º). Additionally, we would be able to compare the new pressures with the ones found in a normal knee with a native MPFL (gold standard). This technology also provides the means to determine the maximum stress of the MPFL graft in all the knee flexion–extension positions. Our evaluation tool makes it possible for us to compare the maximum stress of the graft with the maximum stress of a native MPFL (gold standard). Our FE model of the PFJ predicts the V. Sanchis-Alfonso et al. stress distribution on the patellar cartilage and the MPFL stresses in their different configurations, depending on the different surgical techniques that can be simulated. Therefore, our simulations allow us to compare the different surgical techniques to evaluate a likely patellofemoral chondropathy or even PFOA in the long term. 4 Native MPFL Evaluation Using FEM Technology. The Ideal MPFLr from a Biomechanical Standpoint In a native knee with an intact MPFL, the maximum patellar cartilage contact pressures are 0.18 MPa at 0º and 0.016 MPa at 30°. The contact pressures at 60°, 90° and 120° are exceptionally low compared to those at 0° and 30°. The maximum MPFL stress at 0° is 8.85 MPa and at 30° it is 0.78 MPa. At 60°, 90° and 120°, the MPFL is loose. There is no tension. Therefore, we should reproduce both the patellar pressure and the graft tension behavior of a native knee when doing an MPFLr. Nevertheless, it is logical to think that we are risking a new rupture if we perform the reconstruction with a graft that has the same maximum stress as the one that just tore. Therefore, we should use a graft that is stronger than the native MPFL to compensate for the anatomical factors predisposing to patellar dislocation. Those factors include an increased tibial tuberosity-trochlear groove (TTTG) distance, patella alta, femoral anteversion, external tibial torsion and trochlear dysplasia. However, it is especially important not to increase the maximum MPFL-graft stress by increasing the patellar contact pressure, because it will result in an injury to the cartilage that would eventually cause PFOA in the long term. Patellar chondropathy is quite common in patients with CLPI. Therefore, it is particularly important not to increase the patellar contact pressure at high degrees of knee flexion after an MPFLr because it will aggravate the previous chondropathy. This chondropathy could be responsible for AKP after MPFLr. In short, an ideal MPFLr technique must combine a perfect
Finite Element Technology in Evaluating … A B 711 C Fig. 5 Static and anatomic MPFLr (A). MPFLr using the AMT as a pulley (B). MPFLr using the quadriceps tendon as soft attachment point (MQTFL reconstruction) (C). (Reproduced from Sanchis-Alfonso V, Ginovart G, Alastruey-López D, et al. Evaluation of patellar contact pressure changes after static versus dynamic medial patellofemoral ligament reconstructions using a finite element model. J Clin Med. 2019; 8 (12), pii: E2093. © The authors) balance between optimal patellar pressure and maximum graft stress, making a new tear less likely. 120° are very low. We must note that increased patellofemoral contact pressure helps to stabilize the patella. The objective would be not to exceed the safety levels for pressure so as not to induce patellofemoral chondropathy and finally PFOA. The problem is that we do not know the safety level for contact pressure in the PFJ. The maximum MPFL-graft stress at 0° and 30° is higher than in a native knee. Moreover, as occurs in a native knee, the MPFL-graft is loose at 60°, 90° and 120°. It has no tension. Many orthopedic surgeons recommend robust grafts to compensate for predisposing anatomical factors for a dislocation. If we use an anatomical technique with a semitendinosus autograft, the maximum patellar contact pressures at 0° and 30° are a bit greater than with using a gracilis autograft (Fig. 6). However, the contact pressures at 60°, 90° and 120° are quite low. The maximum MPFL stress at 0° and 30° is greater than when the gracilis is used. At 60°, 90° and 120° the MPFL is loose. In other words, the type of graft does matter, at least from a biomechanical point of view. In a number of cases, the static MPFLr is not anatomic because of a surgical mistake. In these cases, we can see two biomechanical patterns. Firstly, there is a non-anatomic but physiometric MPFLr. This type of reconstruction behaves kinematically, like a native ligament [12]. The clinical results of this type of reconstruction are 5 Analysis of the Types of MPFLr Using FEM Technology We have evaluated three types of fixation techniques: (1) Static and anatomic MPFLr in which both graft attachments are fixed rigidly to the bone; (2) Dynamic MPFLr using the adductor magnus tendon (AMT) as a pulley and (3) Dynamic MPFLr using the quadriceps tendon as one of the attachment points, medial quadriceps tendon-femoral ligament (MQTFL) reconstruction (Fig. 5) [1, 2]. 5.1 Static and Anatomic MPFLr—The Type of Graft Does Matter Currently, the most widespread surgical technique for MPFLr is the anatomical technique using a gracilis tendon autograft with bone anchoring in both the femur and patella. With this type of reconstruction, the patellar contact pressures at 0° and 30° are greater than in a native knee (Fig. 6). Likewise, as occurs in a native knee, the contact pressures at 60°, 90° and
712 Fig. 6 Contact pressure (MPa) on the patellar cartilage. A Intact knee. B Anatomic MPFLr with a semitendinosus autograft. C Anatomic MPFLr with a gracilis autograft. D MPFLr with a semitendinosus autograft using the AMT as a pulley. E MPFLr with a gracilis autograft using the AMT as a pulley. F MQTFLr with a semitendinosus autograft. G MQTFLr with a posterior tibial tendon V. Sanchis-Alfonso et al. allograft (M = Medial; L = Lateral). (Reproduced from Sanchis-Alfonso V, Ginovart G, Alastruey-López D, et al. Evaluation of patellar contact pressure changes after static versus dynamic medial patellofemoral ligament reconstructions using a finite element model. J Clin Med. 2019; 8 (12), pii: E2093. © The authors)
Finite Element Technology in Evaluating … good [12]. Second, we have a non-anatomic, non-physiometric reconstruction. This type of reconstruction behaves kinematically in a manner opposite to that of a native ligament [12]. This provokes high patellar contact pressures at high degrees of knee flexion that can lead to patellar chondropathy and finally PFOA. The clinical results of this type of reconstruction are quite bad [12]. 5.2 Dynamic MPFLr FEM validates using the AMT as a pulley in MPFLr in our clinical practice [2]. From a biomechanical point-of-view, it is a good technique. It does not increase patellar contact pressure when it is compared to the pressure in a native MPFL. Moreover, the maximum MPFL stress is like the native ligament. It is an exceedingly good technique in cases without severe predisposing factors to CLPI. Moreover, FEM also validates MQTFL reconstruction in our clinical practice [2]. From a biomechanical perspective, it is an excellent technique. It does not significantly increase patellar contact pressure when it is compared to the pressure in a native MPFL. Moreover, the maximum ligament stress is greater than that of the native ligament, which could compensate for the anatomical factors predisposing to patellar dislocation. In the MQTFLr, the posterior tibial allograft has a greater stress to failure relative to a semitendinosus graft without increasing the patellar contact pressure [2]. In theory, a new tear is less likely with a posterior tibial allograft. 5.3 Static Versus Dynamic MPFLr. Clinical Relevance The patellar contact pressures from 0° to 30° of knee flexion after a dynamic MPFLr were like those of the native knee, whereas the static and anatomic reconstruction resulted in greater pressures. This may eventually increase the risk of PFOA after a static MPFLr, at least from a 713 biomechanical standpoint, in the long term. In the static and anatomic technique, the maximum MPFL-graft stress at 0° and 30° was higher than in a native MPFL. However, at 60°, 90°, and 120° the MPFL-graft was loose, that is, it had no tension, like a native ligament. Then again, the maximum stress of the MPFL-graft at 0° was less than that of a native ligament in the dynamic MPFLr using the AMT as a pulley. However, at 30°, the maximum MPFL-graft stress was significantly more than in a native ligament. After 30° of flexion, the MPFL-graft loosened, like a native knee. In the dynamic MQTFL reconstruction, the maximum stress of the MPFL-graft was much greater at 0° and 30° than that of a native MPFL. After 30° of flexion, the MQTFL graft also loosened as does the native knee. The MPFLr using the AMT as a pulley is the most common dynamic MPFLr technique in current use [17–21] There are authors that have evaluated the validity of this surgical technique and found satisfactory clinical results in the short-term follow-up. From a biomechanical point of view, this is a good technique in cases without severe predisposing factors to patellar dislocation like severe trochlear dysplasia. Alm and colleagues [19] found an elevated redislocation rate after MPFLr in children and adolescents with this surgical technique. The authors concluded that this technique could only be recommended in the absence of additional patellofemoral maltracking, caused by an elevated tibial tuberosity-trochlear groove (TT-TG) distance (>15 mm), patella alta, or especially severe trochlear dysplasia. Monllau and colleagues obtained satisfactory results with this technique, but it was associated with realignment surgery in 56% of their cases [18]. This approach might explain their satisfactory clinical results. To obtain satisfactory results after an MPFLr using the AMT as a pulley, the associated risk factors for dislocation must be addressed during surgery. Otherwise, this technique as an isolated procedure should only be used in patients without severe trochlear dysplasia. Recently Marot and colleagues [21] have published a multicenter longitudinal prospective comparative study to
714 V. Sanchis-Alfonso et al. compare the functional outcomes after an isolated MPFLr using either a quasi-anatomical technique (elastic femoral fixation) or an anatomical MPFLr. Patients with trochlear dysplasia types C and D were excluded from this study. They concluded that an isolated quasianatomical MPFLr using a gracilis tendon autograft provides outcomes as good as the isolated anatomical MPFLr at the 2.5-year follow-up in a selected subgroup of patients with CLPI and with no severe trochlear dysplasia. MQTFLr described by Fulkerson and Edgar [22] fulfills all the criteria for an ideal MPFLr, biomechanically. It combines a perfect balance between optimal patellar contact pressure and maximum graft stress. While the MPFLr using the AMT as an elastic femoral fixation is a nonanatomic technique, the soft tissue technique using the quadriceps tendon as the soft tissue fixation point is an anatomic technique as it reconstructs the MQTFL. This technique also shows good clinical results in the short term [22]. The question is which surgical technique is better. Is it the static or dynamic? To definitively answer this question, we must consider not only biomechanical factors but also the number of redislocations with each technique as well as the functional results as well as the ability to return to sports practice. However, there are currently no high-quality clinical studies that allow us to conclusively answer this question. Well-designed prospective studies with a substantial number of patients and a longer follow-up are necessary to allow us to answer this question. 6 Examples Demonstrating the Good Correlation Between Computational Predictions and Clinical Evaluation In the case of Fig. 7 (case #1), the computational simulation projects high contact pressures at 60°, 90° and 120° of knee flexion compared with the native knee. In theory, this will lead to patellar chondropathy and finally AKP. In fact, our patient had disabling AKP and severe patellar chondropathy, as can be seen in the arthroscopic image. Moreover, the MPFL is tense at 60°, 90° and 120° of knee flexion and it is completely loose at 0° and 30° of knee flexion in this case. This tension pattern projects the presence of lateral patellar instability as was seen upon physical examination. This tension pattern is typical of a non-anatomic and non-physiometric MPFL reconstruction. In fact, in this case, we can observe a very incorrect femoral attachment point in the 3D-CT. In the case of Fig. 8 (case # 2), the computational simulation projects remarkably high contact pressures at 60°, 90° and 120°. In theory, this will lead to PFOA. During revision surgery, we observed an evident PFOA with exposed bone in the medial facet of the patella. Indeed, the maximum patellar contact pressure was in the medial facet of the patella. This patient complained of disabling AKP. Moreover, the tension pattern is typical of a non-anatomic and nonphysiometric MPFL reconstruction. You can observe a very anterior and superior femoral fixation point in the 3D-CT. Moreover, the tension pattern justifies the lateral patellar instability that we can see during physical examination (Fig. 8). 7 Clinical Relevance of FE Technology—Discussion FE technology shows that the native MPFL is more tense during the first 30° of knee flexion, and then loses a considerable amount of tension with higher degrees of knee flexion [1]. After 30°, the ligament loosens and the patellofemoral contact pressure, which also contributes somewhat to patellofemoral stability and is already low during the first 30 degrees (0.23 MPa), decreases considerably (0.0046 MPa) [1]. This indicates, as shown by previous studies [23–25], that the MPFL contribution to resisting lateral patellar dislocation is greatest during the first 30 degrees of knee flexion. Precisely after 30° of knee flexion, lateral patella stability depends more on the femoral trochlea than on the MPFL. The current tendency is to perform static anatomic MPFL reconstructions. Sanchis-
Finite Element Technology in Evaluating … 715 TENSION PATTERN Flexion Angle Maximum MPFL Stress (MPa) Maximum LR Stress (MPa) 60 90 120 59.03 119.2 252 1.62 5.38 7.06 Fig. 7 Case # 1. Surgical failure secondary to an anterior femoral attachment point. Contact pressure (MPa) on the patellar cartilage. L = lateral, M = medial (A). Parametric model of this patient (B). Femoral attachment point is too far anterior (black arrow) (C). Severe patellar chondropathy during arthroscopy (D). At 0° and 30° the ligament is loose. There is no tension. (Reproduced from SanchisAlfonso V, Alastruey-López D, Ginovart G, et al. Parametric finite element model of medial patellofemoral ligament reconstruction model development and clinical validation. J Exp Orthop. 2019; 6 (1), 32.© The Authors) Alfonso and colleagues [1] have demonstrated that there is an increase in patellar contact pressure at 0° and 30° of knee flexion after a static anatomic MPFLr (2.17 MPa at 0° and 0.14 MPa at 30° when using the semitendinosus as a graft) when compared to the pressure found in a nonoperated knee (0.18 MPa at 0° and 0.016 MPa at 30°). This leads us to consider the possible deleterious long-term effects from slightly greater patellar contact pressures. However, in theory, the patellar contact pressures found in the static anatomic MPFL reconstructions are not great enough to cause symptomatic PFOA since they are lower than those causing knee osteoarthritis [26]. The objective would be not to exceed safe levels of patellofemoral pressure so as not to induce patellofemoral chondropathy and, ultimately, PFOA. It should also be remembered that the increase in patellofemoral contact pressures helps to stabilize the PFJ. Therefore, this factor would be beneficial in the classic anatomic reconstruction. Thus, a discrete increase in contact pressure, as we have observed, is desirable. There is an ongoing debate about the exact clinical consequences of a non-anatomical MPFLr. There are only two papers that correlate the femoral fixation point with clinical results of MPFLr surgery [12, 27]. Servien and colleagues [27] found no negative effects on the clinical results from a non-anatomical femoral fixation point after a 2-year follow-up. A reason for this might be that the femoral fixation point was not so malpositioned from its ideal position to have a negative effect. In our series, we have only found clinical consequences with fixation points that were too anterior. Another reason for which Servien and colleagues justify the fact that no correlation was found between the nonanatomical femoral fixation point and the clinical result is because of the short follow-up of
716 V. Sanchis-Alfonso et al. TENSION PATTERN Flexion Angle Maximum MPFL Stress (MPa) Maximum LR Stress (MPa) 60 90 120 19.51 29.52 34.70 4.56 7.54 8.37 Fig. 8 Case # 2. Surgical failure secondary to anterior femoral attachment point. Contact pressure (MPa) on the patellar cartilage. L = lateral, M = medial (A). Parametric model of this patient (B). Femoral attachment point is too far anterior (black arrow). Severe grade D trochlear dysplasia according to the classification of Dejour (red arrow) (C). Severe PFOA during arthrotomy (D). At 0° and 30° of knee flexion, the ligament is loose. There is no tension. (Reproduced from Sanchis-Alfonso V, AlastrueyLópez D, Ginovart G, et al. Parametric finite element model of medial patellofemoral ligament reconstruction model development and clinical validation. J Exp Orthop. 2019; 6 (1), 32. © The Authors) their patients (2 years). This is particularly relevant relative to the risk of developing PFOA. Currently, what is being discussed is the precise clinical consequences of from the physiological point of view of the non-anatomical techniques for the MPFLr in which the MPFL-graft behaves like a native MPFL (physiometric behavior). Servien and colleagues [27] and Sanchis-Alfonso and colleagues [12] found no negative clinical effects after 2 years when using these reconstructions, which could be due to the short follow-up in both cases. In this type of reconstruction, the FEM shows an increase in patellofemoral contact pressure at 0° and 30° of knee flexion in comparison to these pressures in the native knee (2.77 MPa at 0° and 1.91 MPa at 30° vs 0.18 MPa at 0° and 0.016 MPa at 30°). This pressure increase mainly occurs on the medial patellar facet. What is not known is whether this increase in pressure results in chondropathy in the long run and ultimately in symptomatic PFOA. As far as we know, there is no study of the PFJ that has determined the contact stress threshold that is predictive of symptomatic PFOA. In 2009, Segal and colleagues [26] observed that a threshold of 3.42 to 3.61 MPa had a 73.3% sensitivity with specificity ranging from 46.7% to 66.7% for the prediction of symptomatic knee osteoarthritis. Obviously, these values cannot be extrapolated to the PFJ, which is the joint with the thickest cartilage in the human body. It is logical to think that the pressures causing symptomatic PFOA would be greater. In non-anatomical MPFL
Finite Element Technology in Evaluating … reconstructions, the maximum patellofemoral contact pressures are on the order of 2.77 MPa, values that are considerably below the cut-off point mentioned above. Therefore, it is likely that a non-anatomical but physiometric reconstruction would not have long-term negative effects on the PFJ. Consequently, it would seem more important for the ligament to be “physiometric” rather than perfectly anatomical. With the FEM, it is possible to predict which MPFLr has an increased risk of severe patellofemoral chondropathy resulting in symptomatic PFOA and requiring active treatment. In the cases in which PFOA occurred, it was because the MPFL-graft was loose, with knee flexion from 0° to 30°, and was tense from 60° onward. In these cases, the patellofemoral contact pressures were over 5 MPa from 60° onward, the femoral attachment point being extremely non-anatomical (too far anterior) and the MPFLr was not physiometric. The predictive value of the parametric model of the PFJ has made its clinical validation possible. Our findings could have meaningful potential implications for clinicians in terms of MPFLr surgery. In theory, a healthy knee with a native isometric MPFL during the knee’s entire rangeof-motion should have no negative repercussion on the PFJ, since the native MPFL is not a robust structure. A healthy PFJ shows no underlying chondropathy. However, a degree of chondropathy of the medial facet of the patella is frequently found in a knee with a chronic lateral patellar instability. If, on top of this, we consider that the graft we use to replace the MPFL is more robust and rigid than the native MPFL, we could expect that maintaining isometry during the entire range-of-motion of the knee would produce greater patellofemoral compression in a joint with a pre-existing medial patellar chondropathy, which would evidently worsen. Therefore, it would be desirable to have ligament isometry just from 0° to 30° in a knee with a chronic lateral patellar instability. It is what Thaunat and Erasmus [28] called a “favorable anisometry.” With it, we would achieve our goal 717 of stabilizing the patella in the 0° to 30° range, thusly avoiding the previously mentioned problems. Another interesting finding using FE technology is that the type of graft does matter, at least from a biomechanical perspective. Our FE parametric model study showed significant differences in terms of patellar contact pressure and the maximum MPFL graft stress. For example, the gracilis autograft has been recommended in the MPFLr using the AMT as a pulley because the gracilis tendon appears to be long and strong enough to duplicate the MPFL function [18]. However, based on the results found using the FE method, the semitendinosus tendon has greater stress to failure relative to the gracilis without significantly increasing the patellar contact pressure. In theory, a new tear is therefore less likely with a semitendinosus tendon autograft. 8 Take Home Messages – The use of a parametric finite element model of the PFJ enables us to evaluate different types of surgical techniques for MPFLr relative to the effect on patellofemoral contact pressure, the kinematic behaviour of the MPFL-graft with knee flexion and the maximum MPFL-graft stress with knee flexion. – The patellar contact pressures after dynamic MPFL reconstructions are like those in the intact situation. Therefore, a dynamic MPFLr may be a safer option than a static reconstruction, reducing the chance of PFOA in the long term. – From diagnostic images like a CT, for example, we can simulate different surgical treatments and choose the most optimal technique for each patient. That is, we can customize treatment for individual patients. – A PM of the PFJ is useful in predicting surgical outcomes and reducing complications after MPFLr surgery.
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Biomechanical Analysis of the Influence of Trochlear Dysplasia on Patellar Tracking and Pressure Applied to Cartilage John J. Elias 1 Trochlear Dysplasia During normal knee function, the patella has limited engagement with the trochlear groove with the knee extended, and becomes captured by the trochlear groove as the knee flexes to 30°. The patellar ridge is typically aligned with the deepest part of the trochlear groove during function. The resultant force applied to the patella by the quadriceps muscles and patellar tendon has a lateral component, and the lateral ridge of the trochlear groove provides an articular restraint to resist lateral patellar translation and maltracking. Trochlear dysplasia is characterized by a shallow trochlear groove providing limited articular constraints to resist lateral forces applied to the patella (Fig. 1). Supratrochlear spurs are also associated with trochlear dysplasia. Supratrochlear spurs refer to a protrusion of the femur at the proximal edge of the trochlear groove that can interfere with smooth entry of the patella into the groove. The groove can also extend more proximally than normal, which can induce interaction of the patella with the groove earlier in knee flexion [1]. J. J. Elias (&) Department of Health Sciences, Cleveland Clinic Akron General, 1 Akron General Ave, Akron, OH 44302, USA e-mail: eliasj@ccf.org Several measurement systems have been described to characterize anatomy of the trochlear groove. Lateral trochlear inclination and sulcus angle are commonly used to quantify depth of the trochlear groove. These measurements are based on axial slices from MRI or CT scans. Lateral trochlear inclination is quantified as the angle between a line along the lateral ridge of the trochlear groove and a line representing the posterior condylar axis of the femur, and increases with trochlear depth (Fig. 2). Sulcus angle is quantified as the angle between lines representing the medial and lateral ridges of the trochlear groove and decreases with trochlear depth. Trochlear dysplasia is also evaluated based on the Dejour classification system, including trochlear shape and prominence of a supratrochlear spur [2]. Dejour classification is determined from a lateral knee radiograph, along with axial CT or MRI imaging. A crossing sign is characterized by a curve along the deepest points of the trochlear groove crossing the anterior border of the femoral condyles, indicating a shallow proximal groove. Trochlear dysplasia is a primary anatomical feature of lateral patellar instability. Trochlear dysplasia has been identified in more than 60% of knees that have experienced a lateral patellar dislocation [3, 4]. While other anatomical features of patellar instability have been identified, such as patella alta and a lateral position of the tibial tuberosity, trochlear dysplasia has been consistently identified as a primary contributing © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_56 721
722 Fig. 1 A computational model representing a knee with trochlear dysplasia in the pre-operative condition and following groove-deepening trochleoplasty with removal of the supratrochlear spur. (Adapted with permission from Elias JJ et al. Groove-deepening trochleoplasty reduces lateral patellar maltracking and increases patellofemoral contact pressures: Dynamic simulation. J Orthop Res. 2021 Sep 24. https://doi.org/10.1002/jor.25181) J. J. Elias factor to initial patellar dislocations [3], dislocations following conservative treatment [5], and dislocations following surgical patellar stabilization [6–8]. Trochlear dysplasia, along with lateral patellar maltracking, also influences patellofemoral contact during function. Abnormal patellofemoral contact patterns can be related to degradation of patellofemoral cartilage. Trochlear dysplasia has been related to cartilage lesions associated with osteoarthritis (OA) [9] and shown to increase the risk of patellofemoral OA following patellar dislocation [10]. Trochlear shape can be surgically modified. Of the numerous surgical options available for patellar stabilization, trochleoplasty is the approach that directly addresses the constraint provided by the lateral ridge of the trochlear groove [11, 12]. The most common form is a groove-deepening trochleoplasty to address a flat or laterally convex trochlear groove [13, 14] (Fig. 1). The approach includes deepening and realigning the subchondral bone with the articular surface pressed into the gap. Groove deepening trochleoplasty has been shown to increase the average lateral trochlear inclination from 3° to 23° at the proximal groove and from 15° to 27° at the distal groove [15]. The deepest part of the groove is also typically lateralized by an average of 6 mm. A supratrochlear spur is also a characteristic of trochlear dysplasia, and is commonly flattened as part of groove-deepening trochleoplasty [16, 17]. 2 Fig. 2 An axial view of the knee showing measurements used to characterize trochlear depth (lateral trochlear inclination, sulcus angle) and patellar tracking (bisect offset index, lateral tilt) Biomechanical Analysis Numerous biomechanical studies have been performed to characterize how trochlear dysplasia influences knee function. Characterization of knee function has primarily focused on lateral patellar tracking during daily function or patellar stability in response to a laterally directed force. Some studies have included characterization of
Biomechanical Analysis of the Influence of Trochlear Dysplasia … contact pressure applied to patellofemoral cartilage. Most biomechanical studies have focused on trochlear depth as an anatomical factor influencing function. A few have represented trochleoplasty as a surgical option to correct trochlear dysplasia. Three primary techniques are used for biomechanical analysis of trochlear dysplasia. Mechanical rigs are commonly used to simulate function with cadaveric knees. Due to limited access to dysplastic knees, knees with normal anatomy are manipulated to represent trochlear dysplasia. The relationship between trochlear anatomy and patellar tracking is also commonly evaluated in patients being treated for patellofemoral disorders. Patellar tracking is quantified based on diagnostic imaging with the knee at multiple positions of flexion. To induce quadriceps activation, resistance is applied at the foot with a loading rig or an unsupported leg is elevated against gravity. Computational simulation models are also used to evaluate the influence of trochlear groove anatomy on patellofemoral function. Computational simulation allows controlled variation in anatomy like the in vitro studies, and also allows representation of pathological conditions that commonly accompany trochlear dysplasia. Fig. 3 Schematic representation of a knee attached to an in vitro testing frame to simulate knee function. (Adapted from Elias JJ et al. Computational assessment of the influence of vastus medialis obliquus function on patellofemoral pressures: model evaluation. J Biomech. 2010;43:612–7. https://doi.org/10.1016/j. jbiomech.2009.10.039) 723 2.1 In Vitro Simulation of Knee Function In vitro simulation represents knee function with cadaveric knees engaged with a mechanical simulator to induce motion (Fig. 3). The cadaveric knees are manipulated to vary the shape of the trochlear groove from normal to shallow. The advantages of in vitro simulation include controlled variation of patellofemoral anatomy, application of sensors to characterize patellofemoral kinematics, and control of applied muscle forces. Limitations include representation of a limited number of soft tissues and muscle forces, compromised strength of cadaveric tissues, and utilization of old knees to represent young subjects who are treated for patellar instability. Although the specimens can be manipulated to represent a shallow groove, the corresponding shape of the patella is not consistently represented. Other forms of pathologic anatomy, such as a lateral position of the patellar tendon and patella alta are also not consistently represented. Several studies focused on the influence of trochlear dysplasia on patellar tracking with muscle forces applied at multiple positions of knee flexion. One study manipulated the native trochlear groove to elevate the central anterior
724 trochlea to simulate dysplasia [18]. The study did not find a significant change in patellar kinematics related to representation of trochlear dysplasia. One study modeled a shallow trochlear groove and the corresponding change in the shape of the patella to represent trochlear dysplasia [19]. Articular surfaces of the patella and femur were replaced with 3D printed components to represent normal anatomy, Dejour type A trochlear dysplasia, and Dejour type B trochlear dysplasia. This study also did not find a variation in patellar kinematics related to trochlear dysplasia. Another study also used 3D printed components to represent a normal trochlear groove with Dejour types A through D included in representation of trochlear dysplasia [20]. The study represented two types of knee motion: knee squatting and open chain extension. For knee squatting over a range from 35° to 75°, patellar internal rotation and lateral tilt were larger for representation of trochlear dysplasia than for a normal trochlear groove. For knee extension over a range from 5° to 65°, patellar internal rotation, lateral tilt and lateral shift were larger for the trochlear dysplasia group than for representation of a normal trochlear groove. Overall, these studies indicate the influence of trochlear dysplasia on patellofemoral kinematics is limited, primarily noted for patellar rotation and tilt, with lateral shift also noted for representation of knee extension. Some studies focused particularly on patellar stability related to trochlear dysplasia. For a study that manipulated the trochlear groove to represent trochlear dysplasia, the lateral force required to shift the patella laterally decreased by approximately 50% with the knee at 30° of flexion, with smaller significant differences at lower and higher flexion angles [18]. Similar results were obtained for another study that quantified the translation in response to a 100 N lateral force [20]. Another study that also manipulated the trochlear groove to represent trochlear dysplasia similarly showed that representation of trochlear dysplasia decreased the force required to laterally displace the patella despite representation of reconstruction of the MPFL [21]. These studies show that trochlear J. J. Elias dysplasia limits patellar stability in response to a direct lateral force acting on the patella. Groove-deepening trochleoplasty has also been represented with cadaveric knees to determine the influence on patellar tracking and stability. Trochleoplasty was shown to restore the force needed to translate the patella 10 mm laterally to approximate the stability of a normal knee [18]. For patellar tracking with simulated muscle forces, however, position of the patella was unexpectedly more lateral following trochleoplasty than for the dysplastic condition. Some studies included pressure sensors to characterize patellofemoral contact pressures. Two studies measured contact pressures while using 3D printed surfaces to represent trochlear dysplasia. One study showed that trochlear dysplasia tended to shift patellofemoral contact forces from the medial facet of the patella to the lateral facet from 50°–70° of knee flexion, but the contact forces did not increase [19]. This study included variation in patellar shape while representing trochlear dysplasia. The other showed that trochlear dysplasia tended to decrease contact area and increase contact pressures, with the highest contact pressures noted for Dejour types B and D [20]. The changes were largest with the knee flexed for knee squatting and the knee extended for knee extension. This study did not vary the shape of the patella as the trochlear shape changed. Another study showed that anterior osteotomy of the lateral femoral condyle to deepen the trochlear groove increased patellofemoral contact pressures [22]. The cadaveric specimens used to deepen the trochlear groove were not dysplastic. Overall these studies seem to indicate that trochlear dysplasia influences the distribution of patellofemoral contact forces, but the primary factor that increases contact forces is altering the normal congruence between the patella and trochlear groove. 2.2 Functional Imaging Functional imaging characterizes patellar tracking and pathologic anatomy for patients being treated for patellar instability. Functional
Biomechanical Analysis of the Influence of Trochlear Dysplasia … imaging addresses several limitations of in vitro simulation. Functional imaging focused on patients being treated for patellofemoral disorders includes representation of pathologic anatomy, including trochlear dysplasia. Other forms of pathologic anatomy, including patella alta and a lateral position of the tibial tuberosity are also included. In vivo motion of the knee is also evaluated, without approximating muscle forces or orientations. Functional imaging studies are limited by the activities that can be performed by patients within a diagnostic scanner. Also, anatomy cannot be controlled, so studies rely on variations between subjects to relate anatomy to patellar tracking. Functional imaging studies have been based on dynamic CT, dynamic MRI, and static MRI at multiple flexion angles. Knee motion has been represented by knee extension against gravity or an MRI-compatible load frame has been used to apply resistance to knee extension at the foot. For functional imaging, trochlear dysplasia is characterized by a measure of trochlear depth determined from anatomical landmarks. The studies also typically utilize measures of patellar tracking characterized from anatomical landmarks. The most common measures used to characterize trochlear depth are lateral trochlear inclination and sulcus angle. The two primary parameters of patellar tracking are bisect offset index and patellar tilt (Fig. 2). Bisect offset index characterizes patellar tracking with respect to the trochlear groove. Bisect offset index is measured as the portion medial/lateral width of the patella lateral to the deepest part of the trochlear groove, measured in an axial plane at each position of knee flexion. The patella tends to be in the most lateral position with the knee extended, particularly for patients being treated for patellofemoral disorders. The average bisect offset index with the knee extended is 0.55 to 0.6 for healthy knees [23]. A bisect offset index of 0.75 is considered a cut-off between normal patellar tracking and maltracking [24]. Patellar tilt is measured as the angle between the medial/lateral axis of the patella and the posterior condylar axis. Patellar tilt on the order of 15° or higher is considered maltracking [25]. 725 Some functional imaging studies create computational models for 3D representation of the knee rather than identifying anatomical landmarks directly on slices from the acquired imaging [26–28]. A 3D model of the knee, including bones, cartilage surfaces and ligament attachments, is created from a high resolution MRI scan performed with the knee extended and unloaded. Computational models of the bones are also created from imaging performed with the knee at multiple flexion angles. One computational representation of the knee is developed including bones, cartilage, relevant soft tissue attachments, fixed anatomical landmarks, and reference axes. Shape matching techniques are used to align the model with the landmarks and reference axes to the bones at each position of knee flexion to represent each position of knee flexion with a consistent set of landmarks and axes. This approach eliminates potential error related to repeated identification of landmarks. The reference axes are used to measure patellofemoral and tibiofemoral kinematics, while the landmarks are used to characterize trochlear depth and patellar tracking. For patients being treated for patellar dislocations, multiple studies have shown that lateral patellar maltracking is correlated with a shallow trochlear groove. The relationships between patellar tracking and trochlear depth were primarily observed with the knee at low flexion angles [26–28]. The studies also showed that the strongest relationships were established between trochlear depth and patellar tilt. For the most recent study, with the knee at full extension, lateral trochlear inclination accounted for 46% of the variation in bisect offset index and 60% of the variation in patellar tilt [26]. For the vast majority of patients, bisect offset index and patellar tilt with the knee extended would be considered lateral maltracking. The study further showed that the influence of trochlear depth on patellar tracking was particularly prominent for knees without patella alta (Caton-Deschamps index < 1.2). In absence of patella alta, the patella is engaged with the trochlear groove at low flexion angles, so the depth of the trochlear groove plays a large role in resisting lateral forces applied to
726 J. J. Elias Fig. 4 Patellar tracking with the knee extended determined by functional imaging for two knees without patella alta. A shallow trochlear groove results in lateral maltracking while a deep trochlear groove provides normal patellar tracking. (Adapted with permission from Conry et al. Influence of tibial tuberosity position and trochlear depth on patellar tracking in patellar instability: Variations with Patella Alta. Clin Biomech. 2021;87:105,406. https://doi.org/10.1016/j.clinbiomech. 2021.105406) the patella (Fig. 4). For these subjects, lateral trochlear inclination accounted for 84% of the variation in bisect offset index between subjects. Studies focused on healthy control subject and subjects with patellofemoral pain have also identified relationships between lateral patellar tracking and a shallow trochlear groove. A study including subjects with and without patellofemoral pain found similar correlations between sulcus angle and both bisect offset index and patellar tilt at low flexion angles [29]. For this study, bisect offset index and patellar tilt would be considered lateral maltracking for a small minority of the subjects. The influence of sulcus angle on lateral patellar tracking was strongest with the knee at full extension, and generally stronger for patellar tilt than patellar shift. The results were similar for another study focused on healthy subjects and patients with patellofemoral pain [30]. The study used measurements of patellar lateral shift and tilt from six degree of freedom kinematics. For healthy control subjects and subjects characterized as lateral maltrackers, lateral trochlear inclination was significantly correlated with lateral patellar shift and tilt near full extension, with the relationships strongest for patellar tilt. Overall, these studies indicate that lateral patellar tracking increases as the depth of the trochlear groove decreases for healthy knees and knees being treated for patellofemoral pain and patellar instability. These relationships are observed with the knee at low flexion angles. The relationship between a shallow trochlear groove and patellar tracking is stronger for patellar tilt than patellar shift due to the lateral facet of the patella articulating along the lateral ridge of the trochlear groove. The relationships can also be influenced by other parameters, such as being stronger for knees with normal patella height, with the patella engaging the trochlear groove at low flexion angles. 2.3 Dynamic Simulation of Knee Function For dynamic simulation of knee function, computational models are also used to characterize the relationship between patellar tracking and trochlear depth, but the motion is simulated based on finite element analysis or multibody dynamic simulation. Dynamic simulation models can be made to represent patients being treated
Biomechanical Analysis of the Influence of Trochlear Dysplasia … Fig. 5 Computational model for dynamic simulation of knee function. The model is used to simulate a dual limb knee squat and is shown with the knee extended and at 50° of flexion. (Reprinted with permission from Elias et al. Allowing one quadrant of patellar lateral translation during medial patellofemoral ligament reconstruction successfully limits maltracking without overconstraining the patella. Knee Surg Sports Traumatol Arthrosc. 2018;26:2883–2890. https://doi.org/10.1007/s00167-0174799-9) for patellar instability to incorporate realistic pathologic anatomy (Fig. 5). Models can also be manipulated to vary the depth of the trochlear groove for individual subjects. Patellofemoral kinematics and patellar tracking can be quantified during the simulated motions. Computational models characterize reaction forces at the trochlear groove to drive patellofemoral motion. Patellofemoral contact pressures can be quantified based on the reaction forces. Computational models also allow representation of functional activities that patients cannot perform within a diagnostic scanner, incorporating higher muscle forces and deeper flexion angles. The primary limitation of dynamic simulation is that output data depends on mathematical representation of interactions between tissues and approximations of muscle forces and tissue properties. Rigorous validation of simulation models against data from in vitro simulation of function or functional 727 imaging should be performed to characterize accuracy of the simulated motion and loads applied to cartilage. Computational simulation studies have indicated that a shallow trochlear groove contributes to lateral patellar maltracking and reduces patellar stability. One study simulated knee squatting and knee extension as the depth of the trochlear groove was manipulated [31]. Lateral trochlear inclination was varied to represent a normal value (24°), borderline trochlear dysplasia (12°), and trochlear dysplasia (6°). During simulated knee extension, with the knee fully extended the average bisect offset values were 0.86 for a normal groove, 0.95 for borderline trochlear dysplasia, and 1.02 for trochlear dysplasia. For knee squatting, with the patella entering the trochlear groove at 15°, the average bisect offset index values were 0.57 for a normal groove, 0.64 for borderline dysplasia and 0.71 for trochlear dysplasia. Further, with representation of trochlear dysplasia, the peak bisect offset index during knee squatting was highly correlated with lateral position of the tibial tuberosity (r2 = 0.81, p = 0.006). Another computational study characterized patellar stability in response to a lateral force applied directly to the patella with models representing healthy knees and knees with trochlear dysplasia [32]. The force required to displace the patella laterally by 10 mm was approximately 30% larger for healthy knees than dysplastic knees with the knee at full extension, with the percentage change increasing as the knee was flexed. Simulation studies have indicated that trochleoplasty improves patellar constraint applied by the trochlear groove, but with an adverse influence on patellofemoral contact pressures. One simulation study represented knees with trochlear dysplasia and characterized the influence of groove-deepening trochleoplasty on the force needed to displace the patella laterally [32]. Trochleoplasty had minimal influence on patellar stability with the knee fully extended but restored stability similar to healthy knees with the knee flexed. A dynamic simulation study represented groove-deepening trochleoplasty performed to stabilize the patella,
728 and characterized the influence on patellar tracking and pressure applied to patellar cartilage [33]. The study was based on computational models representing patients treated for patellar instability with trochlear dysplasia categorized as Dejour type B or D. For all knees, the trochlear groove was manipulated to increase the lateral trochlear inclination to 23° at the proximal trochlear groove and 27° at the distal groove. Trochleoplasty significantly decreased lateral patellar tracking, particularly at low knee flexion angles. For simulated knee squatting, trochleoplasty decreased average bisect offset index with the knee extended from 0.87 to 0.75, representing a change from lateral maltracking to borderline normal patellar tracking [24]. Trochleoplasty also significantly decreased contact area and increased the maximum contact pressure at multiple flexion angles. Trochleoplasty decreased the average contact area by approximately 10% in mid-flexion, with a corresponding increase in the average maximum contact pressure of 13% to 23%. Decreased contact area and increased contact pressures were related to altered patellofemoral congruity due to reshaping the femur without a corresponding change to the patella. The simulation studies show that trochlear dysplasia compromises the ability of the trochlear groove to constrain the patella. For lateral forces directly applied to the patella and simulated knee motion, the patella is in a more lateral position for knees with trochlear dysplasia, placing the knee at risk of lateral patellar dislocation. A lateral position of the tibial tuberosity amplifies the influence of trochlear dysplasia on patellar tracking. Trochleoplasty to increase the depth of the trochlear groove helps to restore patellar stability, although the benefit is limited with the knee fully extended and the patella not captured by the trochlear groove. Trochleoplasty does alter patellofemoral congruity, however, which tends to elevate patellofemoral contact pressures during function. J. J. Elias 3 Discussion Trochlear dysplasia is associated with a shallow trochlear groove that limits articular resistance to the lateral force applied to the patella by the quadriceps muscles and patellar tendon, particularly with the knee extended. Although not consistently identified with in vitro studies, functional imaging and computational simulation indicate that limited articular resistance results in lateral patellar tracking during normal function, with the level of patellar tracking with the knee extended considered maltracking that can contribute to patellar dislocations. Patellar stability in response to a direct lateral force applied to the patella is also compromised for knees with trochlear dysplasia. Trochlear dysplasia acts in combination with other types of pathologic anatomy to influence patellar tracking. Lateral position of the tibial tuberosity influences patellar tracking in combination with trochlear dysplasia. Combination of a large lateral force applied to the patella by the patellar tendon and quadriceps and limited articular constraint is particularly problematic for maintaining patellar stability. Trochlear dysplasia has a greater impact on patellar tracking for knees with normal patellar height than patella alta due engagement of the patella with the trochlear groove at lower flexion angles. Lateral patellar maltracking and pathologic shape of the patella and femur associated with trochlear dysplasia do not necessarily increase the pressure applied to patellofemoral cartilage during stable functional activities. Dynamic activities that potentially induce instability may be associated with low contact area and elevated contact pressures for patients with trochlear dysplasia. Studies that included measurement of contact pressures generally showed that any change that alters natural patellofemoral congruity increases pressure applied to patellofemoral cartilage when the patella is captured by the trochlear groove. Potential for elevated post-operative contact pressures should be considered when performing a groove-deepening trochleoplasty.
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Brain Network Functional Connectivity Clinical Relevance and Predictive Diagnostic Models in Anterior Knee Pain Patients María Beser-Robles, Vicente Sanchis-Alfonso, and Luis Martí-Bonmatí 1 Background Anterior knee pain (AKP) is the most common reason young people consult with a knee orthopedic surgeon. However, despite its great prevalence and the abundance of research, the pathogenesis of AKP is still debated. AKP literature is dominated by local biomechanical models that attempt to explain the mechanisms of pain. However, the structural abnormalities analyzed in those biomechanical models, such as patellar tilt, patellar subluxation, chondropathy, and skeletal torsional abnormalities, may be present in the absence of AKP. The reasons of such clinic-morphological discrepancies remain unsettled. Another peculiar characteristic of AKP is the large variability regarding magnitude of pain, disability, and pain experience, despite the cause of pain being the same. Also, a great M. Beser-Robles (&) Biomedical Imaging Research Group at Health Research Institute, Valencia, Spain e-mail: marti_lui@gva.es V. Sanchis-Alfonso Department of Orthopaedic Surgery, Hospital Arnau de Vilanova, Valencia, Spain L. Martí-Bonmatí Medical Imaging Department and Biomedical Imaging Research Group at Hospital, Universitario y Politecnico La Fe and Health Research Institute, Valencia, Spain variability in the response to an adequate treatment is observed among different AKP patients with the same disease status. In addition, AKP patients might present different psychological impairments, from none to severe levels of involvement. Interestingly, catastrophizing is the most important aspect among the psychological factors presented in AKP patients, being significantly related to pain and disability. This spectrum of variability might reflect the existence of different other factors, in addition to biomechanical and structural alterations, to explain the origin of the pain and its clinical heterogeneity. As described, there are many questions that cannot be properly answer at this time. Why is there so much variability in the magnitude of pain and in the pain experience among AKP patients? Why do some individuals present AKP while others with similar pathological findings do not? Why does pain persist in some patients after the painful structural stimulus has been removed? Functional Magnetic Resonance Imaging (fMRI) analyses provides a better understanding of the mechanisms underlying the development of chronic pain by evaluating the brain resting state functional connectivity (rsFC) [1]. As AKP is a paradigm of chronic pain, we hypothesized that AKP is associated with functional interconnected brain networks changes, which may modulate the variable impairments that accompany this condition, explaining the different treatment responses. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_57 731
732 The first objective of this chapter is to show that rsFC networks are different in AKP patients compared with healthy subjects, mainly among those brain areas involved in affective and cognitive stimulus processing and in regions involved in pain modulation. Moreover, we will define the rsFC changes related to the feeling of catastrophizing. In addition, we will explore the predictive ability of fMRI analyses with a clinical decision support system (CDSS), providing a complementary tool to help clinicians in the clinical assessment of this condition. 1.1 Functional Magnetic Resonance Imaging Pain related changes can be captured by objective markers of functional brain activity. Blood oxygen-level-dependent imaging, or BOLDcontrast imaging, is a method used in fMRI to determine where and when brain activity occurs. The BOLD signal change is the keystone of fMRI, being used to construct spatial parametric maps indicating which brain regions are activated by certain tasks or react to specific stimulus. Neurons do not contain any internal stores of energy, either in the form of glucose or oxygen. Therefore, when a brain region is activated, adjacent capillaries provide it an increased regional blood flow through a hemodynamic response with a large increase in oxygen supply. This inflow causes a change in the level of oxyhemoglobin and deoxyhemoglobin balance that can be detected using their differential magnetic susceptibility, as deoxyhemoglobin is strongly paramagnetic. fMRI is a safe and noninvasive image technique able to map and measure regional brain activity. fMRI is used to determine which brain regions and networks are activated during different process by evaluating the increase in oxygen consumption. This technique improves our understanding of how the brain operates, which regions are activated during specific mental tasks or at rest, and how these regions are organized into networks [2]. M. Beser-Robles et al. fMRI has been widely used in patients with neurological or psychiatric disorders, to analyze the differences in synchronous and spontaneous fluctuations of various networks compared with healthy matched control subjects. Both taskbased and resting state studies have been performed for this purpose. In comparison to specific task-based fMRI, resting state fMRI (rsfMRI) is acquired in the absence of a stimulus or task, being therefore focus on the spontaneous alterations of the brain BOLD signal. The absence of a task makes rs-fMRI particularly attractive for understanding the inherent connectivity patterns of interoperable brain regions in patients suffering from neurological, neurosurgical, or psychiatric diseases and their differences with healthy controls, to improve the understanding of these diseases [3, 4]. 1.2 Pain Neuromatrix It has been shown that several functional brain regions are activated in a coordinated manner when pain occurs, constituting what is known as the “pain neuromatrix” [5]. This functional network is the basis of the multidimensional experience of pain. Specifically, under chronic pain conditions, the main regions being affected are the primary and secondary somatosensory cortex (S1 and S2), spinal cord, thalamus, insula, anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), the medial and dorsolateral prefrontal cortex (mPFC/dlPFC), amygdala, nucleus accumbens, and various mesencephalic areas such as the periaqueductal grey matter (PAG) and the cerebellum [6]. The human brain is intrinsically organized into dynamic, anticorrelated functional networks [5]. It has been found that there are four main brain networks whose dynamic interactions are related to chronic pain [7]. One of them, the Salience Network (SN), comprises the anterior insula and the ACC, and is responsible for the reception of sensory stimuli and the production of affective responses. The Default Mode Network (DMN) consists of the PCC and the mPFC
Brain Network Functional Connectivity Clinical Relevance … and it is mainly activated during resting state, as the “automatic pilot” of the brain, it is related with introspection. The third pain-related system is the antinociceptive system (AS), which is classically associated with pain modulation and includes a hub of multi-connected regions in the periaqueductal gray matter of the brainstem. Finally, the sensorimotor network (SMN), which consists of the basal ganglia, thalamus, posterior insula, SI and SII, relates to the awareness of bodily sensations and generation of appropriate motor responses. Although these are the most relevant, other functional networks such as limbic, attentional, and central executive, are also active during the processing of pain stimuli [8] (Fig. 1). Pain pathways comprise a complex sensory system, which is activated to provide protective responses to noxious stimuli. Inputs regarding noxious stimuli are transmitted from nociceptors via primary afferent fibers to the brain. When a Fig. 1 Overview of pain pathways and functionally altered areas in chronic pain, divided according to the neural networks to which they belong. Green = SMN; Blue = DMN; Copper = Cerebellar network; Dark blue = AS. Amy = amygdala; ACC = anterior cingulate cortex; Ins = insula; PAG = periaqueductal gray; mPFC = medial prefrontal cortex; BG = Basal ganglia; Thal = thalamus; PCC = posterior cingulate cortex; S1, S2 = primary and secondary somatosensory cortex 733 painful stimulus occurs, peripheral nociceptors are activated and ascending fibers transmit this stimulus to the spinal cord. Ascending pathways transmit the painful stimulus from the spinal cord to the brain carrying sensory information from the body to the brain. In addition, descending pathways are established in mesencephalic areas such as the PAG, descending down the spinal cord and has a role in the modulation of pain [9]. The mechanism of pain transmission can be oberved in Fig. 2. Patients with chronic pain have increased BOLD oscillations in DMN regions such as the mPFC and, to a lesser extent, the PCC [4, 10]. In addition, chronic pain has been shown to influence the functional connectivity of the ACC, insula and SII. These regions are known to receive nociceptive information from the periphery and are involved in pain perception and modulation [11]. Furthermore, it has been suggested that weaker communications appear
734 M. Beser-Robles et al. PFC A B S1/S2 ACC NAc Thalamus AMG Brain PAG LC Brain Stem RVM Spinal dorsal horn Dorsal Spine Nociceptor Painful sƟmulus Fig. 2 A Anatomical sites showing functional changes in patients suffering chronic pain. Sensorimotor, emotional/affective, cognitive/integrative, and modulatory regions are involved in the complex processing of pain, with some areas participating in more than one pain domain. An example is the thalamus, which contains a somatotopic representation of pain and processes the emotional aspects of the pain experience. B Ascending pathway (blue line): Pain signals ascend from the spinal dorsal horn to the rostral ventral medulla (RVM) and periaqueductal grey matter (PAG). They are then transmitted to the thalamus, where they are sent to higher brain centers, such as the primary and secondary somatosensory cortices (S1/S2), prefrontal cortex (PFC), anterior cortex (ACC), amygdala (AMG), and nucleus accumbens (NAc). Descending pathway (red line), involves important areas of the brainstem such as the RVM, PAG, and locus coeruleus (LC) between the DMN and SN networks in patients with chronic pain, making difficult for individuals to “switch off” their pain [5]. In healthy subjects, there is a negative correlation between DMN and SN. That is, when the DMN is active the SN is inactive, and vice-versa. As the SN coordinates the activation of the DMN and the central executive network. However, in chronic pain patients, there is a reduce in this anticorrelation. The cause of the increase of correlation between the DMN and the SN can be due to an alteration of the normal functioning of the SN because a constant state of attention given by the continuous input of nociceptive stimuli, so that the introspection capacity of the DMN decreases as it needs the coordination of the SN for its correct functioning. So, we can see a loss of the SN's ability to inhibit the DMN, due to a continuous input of nociceptive information. 1.3 Clinical Decision Support System (CDSS) A CDSS has the aim to improve healthcare provision by refining medical decisions accuracy with specific clinical knowledge and imaging extracted information. To obtain a direct clinical decision gain, the characteristics of an individual patient must be compared against a computerized clinical knowledge database, and then specific assessments or recommendations are presented to the clinician to help taking decisions on that patient [12]. Validated CDSS have been shown
Brain Network Functional Connectivity Clinical Relevance … 735 to increase the capacity of healthcare professionals in a range of patient care decisions and tasks, and nowadays actively support the provision of quality care. In our scenario, the CDSS aims to predict whether a subject has chronic AKP or not. Machine learning is a field of artificial intelligence based on the paradigm that systems learn from data, identify patterns, and provide decisions with minimal human intervention. In our example, we will define a machine learning classification algorithm, which is a supervised learning technique. In this type of algorithm, the program learns from previously classified observations and with this information it classifies a new one [13]. Demographic recorded variables which can influence the brain functional network were recorded (age, dominant hand, scholarship, and pain duration), and participants completed a selfreporting questionnaires regarding neuropathic pain, anxiety, depression, kinesiophobia and catastrophizing. Clinical pain intensity was obtained by asking subjects to rate their pain on a Visual Analogue Scale (VAS) [14]. Anxiety and depression were evaluated using the Hospital Anxiety and Depression Subscale (HAD) [15]. Pain-related fear associated with avoidance of movement and physical activity was measured using the Tampa Scale for Kinesiophobia (TSK) [16], and catastrophizing was measured using the Pain Catastrophizing Scale (PCS) [17]. 2 2.2 Resting State MRI Data Acquisition Our Clinical Results 2.1 Participants and Clinical Assessments To prove the relationship between functional brain modifications associated to chronic knee pain, we will report here on a prospectively evaluated series of 40 subjects, all young women to avoid biases, equaly distributed (20 women with 6 months duration chronic AKP, 27.4 ± 9.0 years, mean ± SD, 18–44 range; and 20 healthy women without any knee or other types of pain, aged 28.85 ± 7.6 years, 20–43 range). Patients and controls were matched for age, both groups having a normal distribution. All subjects gave written consent for this study. The AKP group included patients with self-reported pain around or behind the patella aggravated by activities that load the joint, without identifiable pathological causes. Cases for the control group were excluded if they presented acute or chronic pain in the last 6 months and a history of psychologic or psychiatric disorders. The study was approved by the hospital Institutional Review Board (IRB) (CEIm:3/2018) and conducted according to the Declaration of Helsinki. MR images were acquired on a 3 T magnet (Achieva, Philips Healthcare Best, Netherlands) using an 8-channel head coil with parallel acquisition technology (SENSE). All participants were instructed at the beginning of the acquisitions to avoid movements, keep their eyes closed, stay awake and think of a blue sky. The acquisition protocol consisted of a high spatial resolution T1 weighted 3D gradient echo sequence with the following parameters: TE = 3 s, TR = 6.2 s, FA = 100, voxel size = 1 1 1 m m3, and 6 min of duration. This sequence provides a high contrast between white matter (WM), grey matter (GM) and cerebrospinal fluid (CSF) to segment and parcellate the different brain regions. The rs-fMRI T2* weighted 2D EPI BOLD sequence was acquired with the following parameters: TE = 35 ms, TR = 2000 ms, temporal dynamics = 265, voxel size = 1.8 1.8 5 mm3, and an overall duration of 9 min. This sequence allows to explore FC networks by sampling the brain hemodynamic response during neuronal activation at the resting state,
736 acquiring the whole brain volume with a temporal resolution of 2 s per partition. 2.3 Image Processing To increase reproducibility, all MR images were preprocessed using the CONN and SPM12 toolboxes. The rs-fMRI images were corrected (intra-patient registration) from slice time and patient movement, normalized to MNI space, registered with the structural images and smoothed. Artefact detection was used to depict intensity peaks and excessive patient movements by using ART-repair software and a componentbased noise correction method (CompCor). Acquisitions showing a mean image shift greater than 0.9 mm or global BOLD signal changes greater than 5 standard deviations were flagged as possible outliers. The intensity level of BOLD timeseries was normalized and images were spatially registered towards a standardized MNI space, with 2-mm isotropic voxels for the functional data and 1 mm for the structural. Segmentation GM, WM and CSF was applied before the Harvard–Oxford probabilistic atlas brain parcellation on 91 cortical and 15 subcortical regions of interest (ROI), plus 26 cerebellar regions defined by the Automated Anatomical Labelling (AAL) atlas. Commonly characterized networks were obtained by seed-areas on known networks (SN, DMN, Dorsal Attention Network-DAN, Sensorimotor Network-SMN, Visual Network-VN and Cerebellar Network-CN). Spatial smoothing was used to minimize sharp edges for multi-subject averaging, to increase the BOLD signal-to-noise ratio. The main confounder effects (24 parameters for head movement obtained from the ARTrepair programme and intensity effects that do not correspond to the grey matter) were included in a linear regression model, with a bandpass filtering (0.008–0.09 Hz) to obtain BOLD timeseries signal free of unwanted effects. M. Beser-Robles et al. 2.4 Image Analysis An atlas-based ROI-to-ROI analysis represented the level of partial correlation between all pairs of brain ROIs, using a general linear model (GLM) to estimate the strength of connectivity between brain areas by analyzing the correlation of the BOLD signal of each pair of brain ROIs. The effect sizes are represented by Pearson's correlation coefficients (r) with a Fisher's ztransformation. In the statistical analysis, significant clusters were determined by two thresholds, one at voxel level and one at cluster level (grouping of voxels). The significance level was defined by a voxel-level threshold of p < 0.001 uncorrected to control for cluster spread, and a cluster-level threshold of p < 0.05 corrected for false discovery rate (FDR), for multiple comparisons across the whole brain [18]. The first analysis consisted of a between-group comparison to study significant unbiased differences in functional connectivity of each pair of regions between patients and controls, adding laterality, scholarship, anxiety, and depression as covariates in a GLMbased regression statistical analysis. The second analysis was a study of significant differences in functional connectivity related to the level of catastrophizing in patients. For both analyses, a student’s t statistic was used, considering as significant only pair of regions presenting a pvalue that fulfills the above conditions. 2.5 Classification Model With the aim of identifying AKP patients using a clinical decision system, we trained and evaluated 6 supervised learning classifiers: Logistic Regression (LR), Linear Discriminant Analysis (LDA), K-neighbors (KNN), decision Trees (DT), Gaussian Naive Bayes (GNB) and Support Vector Machine (SVM). All were implemented with the Scikit-learn machine learning library. These algorithms use as inputs the significant
Brain Network Functional Connectivity Clinical Relevance … results of the correlation analysis between pairs of regions and their correspondence with patients or controls, learning to classify any new data as patient or control. As each classifier uses a different learning method, we evaluated the most optimal by analyzing the accuracy of the 6 models [19]. When dealing with supervised learning models, data must be separated into the training set and the test set. To avoid bias due to the splitting of the data set, a cross-validation approach was used to ensure that results are independent of the partition between training and test data. There are many methods of cross-validation, although the leave-one-out (LOO) maximizes the robustness of the classifier. This method consists of training the classifier with the n-1 observations and testing with the remaining one, doing this as many times as the number of observations in the study sample. To build our CDSS, we trained and evaluated the 6 models determining their accuracy and area under the curve (AUC), which measures the classifier's ability to distinguish between classes. 2.6 Results Regarding the clinical data collected from the pain patients, the mean VAS score obtained was 6.84 ± 1.7. In addition, a large proportion of patients presented results compatible with kinesiophobia (75%) and catastrophic thoughts (55%). Anxiety (30%) and depression (10%) Table 1 Demographic characteristics of AKP patients, expressed as percentage for categorical variables and mean for quantitative variables 737 were also observed in smaller amounts. Patients’ demographics and clinical evaluation are summarized in Table 1. Regarding the functional connectivity analysis, significant differences in regions and networks (p-FDR < 0.05) were found between AKP patients and matched healthy controls (Table 2). For most functional connectivity changes, a higher correlation in absolute terms was observed between patients’ ROIs compared to controls, except for the sensorimotor network and the temporal planum with their respective ROIs, where a lower correlation was observed in chronic pain conditions. We do highlight the fMRI changes produced in the mPFC, as a region of the DMN, and the superior regions of the SMN, because of their role in the processing of pain stimuli, which has been seen in different studies [20]. We also observed differences in the thalamus, which acts as a transmitter of the nociceptive stimulus to the rest of the higher structures. Also, the role of the cerebellum was highlighted as many regions showed FC alterations. A visual representation of these significant differences in FC is shown in Fig. 3. In the analysis performed to evaluate the effect of catastrophizing, statistically significant differences (p-FDR < 0.05) were observed in FC in different regions (Table 3). A lower correlation in absolute value was observed when patients present catastrophic ideas, except in the posterior cingulate gyrus (PC) with the Vermis area. We can also highlight the changes produced in the mPFC and some regions of the cerebellum, and Demographic variables Patient group Duration of symptoms (mean ± std) 9.32 ± 7.96 Laterality (right-handed %) 85% VAS (mean ± std) 6.84 ± 1.7 Anxiety (%) 30% Depression (%) 10% Kinesiophobia (%) 75% Catastrophization (%) 55% Education level (high level %) 80%
738 M. Beser-Robles et al. Table 2 FC AKP patients vs. Controls. ROI1 and ROI2 constitute the pair of evaluated regions on which the rs-fMRI connectivity showed significant differences between patients and controls. ß values for Patients and Controls represent the correlation between ROI1 and ROI2. Columns 2 and 4 indicate the spatial location of the regions in the Montreal Neurologic Institute (MNI) coordinates. The correlation strength represents the behavior of the correlation between the two ROIs, whether it increases or decreases in the case of patients ROI 1 MNI coordinates ROI 2 MNI coordinates ß Patients ß Controls Thalamus r (10, 2, 8) LG r (20, −44, −8) −0.06 −0.13 Cereb45 r (−8, −32, −12) pSTG l (−57, −47, 15) −0.16 mPFC (1, 55, −3) PO r (51, −30, 28) Cerebellar Network (posterior) (0, −79, −32) LG l SMN-Sup (9, −31, 67) PT l (−60, −30, 8) Fig. 3 Ring view of the significant differences in the correlation of ROIs pairs between patients and controls. The color bar represents the value of the T-statistic, reddish colors denote a positive association (greater correlation/FC in patients than in controls) and blue colors denote a negative association (lower correlation/FC in patients than in controls). ROIs shown in mid-axial slices T Student p-FDR Correlation strength 4.54 0.0118 " in patients −0.25 4.32 0.0219 " in patients −0.10 −0.17 4.31 0.0224 " in patients (−18, −42, −6) 0.03 −0.07 4.19 0.0322 " in patients lPFC l (−43, 33, 28) 0.03 0.08 −4.81 0.0053 # in patients Ver9 (1, −55, −35) 0.04 0.14 −4.35 0.0201 # in patients
Brain Network Functional Connectivity Clinical Relevance … 739 Table 3 FC AKP Catastrophizing subjects. ROI1 and ROI2 constitute the pair of evaluated regions on which the rsfMRI functional connectivity has shown significant differences between patients and controls. ß represents the catastrophizing patient’s correlation between ROI1 and ROI2. Columns 2 and 4 indicate the spatial location of the regions in the Montreal Neurologic Institute (MNI) coordinates. The correlation strength represents the behavior of the correlation between the two ROIs, whether it increases or decreases in the case of catastrophizing patients ROI 1 MNI coordinates ROI 2 MNI coordinates PC (1, −37, 30) Ver8 (1, −64, −34) PC (1, −37, 30) Cereb3 l rPFC (30, 48, 9) mPFC (1, 55, −3) ß T Student p-FDR Correlation strength 0.13 4.03 0.0211 " with catastrophization (−9, −37, −19) −0.13 −4.36 0.0159 # with catastrophization Cuneal l (−12, −90, 22) −0.08 −4.20 0.0256 # with catastrophization Cereb1 l (−36, −66, −30) −0.07 −4.12 0.0328 # with catastrophization Fig. 4 Ring view of the significant differences in the correlation between pairs of ROIs when studying the effect of catastrophizing thoughts. The color bar represents the value of the T-statistic, reddish colors denote a positive association (higher correlation/FC in catastrophizing patients) and blue colors denote a negative association (lower correlation/FC in catastrophizing patients). Position of ROIs shown in mid-axial slices in the PC as a region of the SMN. A visual representation of these significant differences in FC is shown in Fig. 4. Finally, the significant correlations results between regions and AKP patient networks were used as inputs to feed the classification models. After testing the 6 supervised learning classification models, the K-nearest neighbors (KNN) model was chosen as it gave the best results from the accuracy and the AUC curve (Table 4).
740 M. Beser-Robles et al. Table 4 Classification System Results. Shows the accuracy and AUC classifier results for each supervised learning model. LR: Logistic Regression; LDA: Linear Discriminant Analysis; KNN: K-neighbors; DT: Decision Trees; GNB: Gaussian Naive Bayes; SVM: Support Vector Machine. The best result obtained in accuracy and AUC has been highlighted in green Supervised learning model tested Accuracy (%) AUC LR 57.5 0.55 LDA 65 0.67 KNN 67.5 0.70 DT 57.5 0.52 GNB 57.5 0.62 SVM 67.5 0.60 3 Discusion Patients with AKP have significant rsFC differences compared to matched healthy subjects. Comparing rsFC between patients and controls, there is an absolute increment in the correlation between regions appear for AKP patients, highlighting the connections of mPFC/POr, Thalamus r/LG r, Cereb45/pSTG and the posterior part of the cerebellar network with the LG l. Moreover, absolute decreases in the correlation between regions appear for AKP patients in the regions of PT/Ver9 and the superior part of the SMN with the lPFC. Catastrophizing has an effect on the rsFC of AKP patients, with an increase in the correlation between PC/Ver8 and a decrease in the correlation between the regions of PC/Cereb3, rPFC/cuneus and mPFC/Cereb1. In addition, the connectivity between regions was able to reach a 68% cross-validation accuracy to discriminate AKP patients from controls. Several other studies have found functional nodes involved in the development of chronic pain, mainly in the DMN, SMN and SN [21, 22]. The mPFC is one of the most important regions in the DMN, being related to pain modulation and emotional appraisal. mPFC presents a significant increase in correlation with the POr in patients against controls, increasing the existing anticorrelation between these regions. The POr is a region of the SII which has been involved in the discriminative sensory aspect of pain. These results are in line with those of Pujol and colleagues [23], where we can see that in chronic pain condition there is an increased connectivity between the SII and DMN. In addition, previous studies reported that cortical prefrontal areas are involved in cognitive functions, such as planning, decision making and detection of unfavorable outcomes, avoidance of risky choices based on emotions, and goal-oriented behaviors [24, 25]. The role of the thalamus in chronic pain is also relevant, showing a higher correlation with the right part of the lingual gyrus (LG r). The thalamus is one of the most important regions in the development of chronic pain, as it receives projections from multiple ascending pain pathways and modulates ascending nociceptive information [26], while the LG is involved in sensorimotor integration [27]. The increased anticorrelation between these regions has also been shown in previous studies [28, 29]. On the other hand, previous studies [30, 31] have shown that the role of the cerebellum seems very important in the development of chronic pain, since there are alterations in the correlation of the cerebellum with multiple regions. Here, we found an increased correlation of two cerebellar regions with different regions (pSTG and LG l) and a decreased correlation between area Vermis 9 (structure located between the cerebellar hemispheres) and PT l. Evidence suggests that specific nociceptive activation is processed in the deep cerebellar nuclei, the anterior vermis and bilaterally in lobules IV, V and VI of the cerebellar hemispheres [30]. This suggests that cognitive processing areas in the cerebellum may be related to pain encoding. In patients with AKP we have also observed an increased correlation between regions of the superior part of the somatosensory network (postcentral gyrus, precentral gyrus and supplementary cortex) with the dorsolateral prefrontal cortex (lPFC), a region that is part of the central executive network and is related to pain modulation and regulation [32]. These regions are correlated in healthy subjects, and a decrease in
Brain Network Functional Connectivity Clinical Relevance … the correlation between them could indicate lower suppression of nociceptive impulses, due to the chronic pain condition. Catastrophizing is the most important aspect among all the psychological factors affecting AKP patients, being significantly related to pain and disability (see Chap. 6). Pain catastrophizing is a psychological construct that includes cognitive, emotional, and behavioral processes (fearavoidance behaviors, altered mood and motivation) that amplify perceived painful sensations and predispose to the perpetuation of pain [33]. When studying this in AKP patients, significant differences were found in the FC of AKP patients showing catastrophizing. Patients with catastrophizing showed, in general, a decrease in correlation between regions, especially between regions of the cerebellum and the DMN. We highlight the effect of the posterior cingulate gyrus (PC) region with different areas of the cerebellum, showing a significant increase in the correlation with the Vermis 8 area, and a significant decrease in the correlation with the third lobe of the cerebellum. We can also observe a decrease in different regions of the prefrontal cortex. On the one hand between the mPFC and the first lobe of the cerebellum, which as we have seen is a key region in the development of chronic pain. On the other hand, between the rostral prefrontal cortex and the cuneus, which has the function of integrating and processing somatosensory information. These results are in line with previous studies showing changes in the connectivity patterns of different areas, including the PC, mPFC and cerebellum [30]. The deactivation of the mPFC and PC during nociceptive stimulation has been associated with the attentional capture of pain [32, 34, 35], which is enhanced by negative pain cognitions, such as catastrophizing. This suggests that patients with high catastrophizing scores may have increased attentional capture by pain and, thus, an inability to divert their attention away, resulting in a decreased ability to modulate their pain. Development of a predictive diagnostic model using a pattern of FC to differentiate subjects with chronic pain is relevant in clinical practice. Significant results obtained from the analysis of 741 fMRI images allowed the construction of a classifier with an accuracy of 67% for the identification of AKP patients. Although these promising results need external validation to assess reproducibility, they show that the information provided by rs-fMRI analysis can be use for pattern detection. This clinical decision support tool may be a step towards improving our understanding of pain mechanisms. Insurance companies and legislation have a great interest in objective measurements of pain-related disability, but we still have a long way to go before brain imaging can be used as a diagnostic tool after validation and regulatory acceptance. These issues are being addressed from different perspectives, including neuroethics. If valid objective processes can be established to detect/define pain, this would have huge implications for the insurance industry and the legal field, as a significant number of cases are related to pain, suffering and disability. In addition, it will provide patients with objective evidence of their condition and its evolution over time [36]. Regardless of the wide impact that patellofemoral pain has today, there are few studies that focus on this specific area to depict the implications that chronic pain has on brain connectivity. We have demonstrated that chronic patellofemoral pain altered the FC in regions of the DMN and the SMN. These areas can also be observed in other types of widely studied chronic pain, such as low back pain [37]. As a difference, regions such as the insula or the ACC are not so affected in the patellofemoral pain model. This study is in line with a previous one [27], showing that in AKP sensorimotor regions and thalamus acquire greater importance than SN regions. As a result, pain‐disrupted sensorimotor connectivity may influence patients with patellofemoral pain perception of function, pain, and fear of movement, and that it can be resultant to altered central neural processes. This could be due to the fact that in this type of pain the sensory and cognitive components acquire greater relevance. However, to determine the specific differences between the different mechanisms of chronic pain, future studies comparing these conditions are needed.
742 M. Beser-Robles et al. A major limitation is the transversal design as the study does not track individuals before the onset and through the development of pain. Therefore, the observed rs-fMRI changes cannot be specifically determined to be caused by the presence of chronic pain. In addition, the number of patients and control subjects in our study was relatively small. But based on a previous study about the minimum sample size [38], and estimating an effect size of 0.15 and a minimum AUC around 0.70 as an acceptability cut-off, we would need a sample size between 38 and 46 subjects, which is very close to our 40 subjects. We do believe that the magnitude of the effects balance the small sample size; moreover, larger samples are necessary given that the variability in symptomatology of these patients is large. Age, handedness and received education were included as covariates to endorse that the observed changes were mainly due to AKP. To control the error rate, a threshold of p-FDR 0.05 (uncorrected p values of 0.001) was established to improve the consistency and robustness of the results. Finally, alterations in FC could depend on the intensity and duration of pain, both of which were highly variable in our series, so future studies will be necessary to investigate the influence of these variables on chronic patellofemoral pain. 4 Future Oportunities The following aspects can he highlighted for future studies on relevant challenges and developments. New studies might be design to develop a predictive model that will allow to determine the probability that a knee pain is or is not of patellofemoral origin. Also, new studies are needed to evaluate resting state connectivity fMRI as a tool to monitor the follow-up of these patients after treatment. Finally, further studies should lay the groundwork for using repetitive transcranial magnetic stimulation treatments in this type of pathology. In summary, the following aspects can be highlighted from the use of re-fMRI in chronic pain studies: – Chronic pain has a disruptive effect on some functional brain networks. FC is altered in patients with AKP compared to matched control subjects, having a generalized impact on global brain function. – The level of catastrophization presented by the patients conditioned new alterations in functional connectivity. – Functional brain networks alterations allow the use of a clinical decision support system to help clinician to accurately identify patients suffering from chronic pain. This could be a first step towards the objectification and identification of pain. References 1. Valdes-Hernandez PA, Montesino-Goicolea S, Hoyos L, et al. Resting-state functional connectivity patterns are associated with worst pain duration in community-dwelling older adults. Pain Reports. 2021;6: e978. 2. Magnetic Resonance Imaging (MRI). https://www. nibib.nih.gov/science-education/science-topics/ magnetic-resonance-imaging-mri. 3. Lv H, Wang Z, Tong E, et al. Resting-state functional MRI: everything that nonexperts have always wanted to know. AJNR Am J Neuroradiol. 2018;39:1390. 4. Loggia ML, Jensen KB. Imaging pain in the human brain. In: Imaging of the Human Brain in Health and Disease (Elsevier, 2014), 427–451. 5. Kucyi A, Salomons T, Davis K. Mind wandering away from pain dynamically engages antinociceptive and default mode brain networks. Proc Natl Acad Sci USA. 2013;110:18692–7. 6. Moseley G. A pain neuromatrix approach to patients with chronic pain. Man Ther. 2003;8:130–40. 7. Fox MD, Snyder AZ, Vincent JL, et al. The human brain is intrinsically organized into dynamic, anticorrelated functional networks. Proc Natl Acad Sci. 2005;102:9673–8. 8. Tracey I, Mantyh P. The cerebral signature for pain perception and its modulation. Neuron. 2007;55:377–91. 9. Yang S, Chang MC. Chronic pain: structural and functional changes in brain structures and associated negative affective states. Int J Mol Sci. 2019;20:3130. 10. Baliki MN, Geha PY, Apkarian AV, et al. beyond feeling: chronic pain hurts the brain, disrupting the default-mode network dynamics. J. Neurosci. 2008;28.
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Robotic-Assisted Patellofemoral Arthroplasty Joseph C. Brinkman, Christian Rosenow, Matthew Anastasi, Don Dulle, and Anikar Chhabra 1 Introduction Isolated patellofemoral osteoarthritis (PFOA) involves defects in the articular cartilage lining the patellar facets or femoral trochlea. It is a relatively common condition that affects approximately 10% over 40 years of age and 20% over 55 years of age [1, 2]. The prevalence and debilitating nature of the condition has prompted interest in optimizing treatments for it. Traditionally, conservative treatment of isolated PFOA is similar to that of multicompartment osteoarthritis (OA) and includes short-term bracing, taping, physical therapy, and corticosteroid injections [3]. Joint preservation interventions such as chondroplasty, microfracture, and extensor mechanism realignment operations also exist, but do not completely address the joint surfaces. While total knee arthroplasty (TKA) has long been the standard for knee OA, its efficacy in patients with PFOA is somewhat limited. TKA restricts activity tolerance and disrupts normal J. C. Brinkman C. Rosenow M. Anastasi D. Dulle A. Chhabra (&) Department of Orthopaedic Surgery, Mayo Clinic, 5777 E. Mayo Blvd, Phoenix, AZ 85054, USA e-mail: Chhabra.Anikar@mayo.edu Department of Sports Medicine, Mayo Clinic, 5777 E. Mayo Blvd, Tempe, Phoenix, AZ 85054, USA Alix School of Medicine, Mayo Clinic, 5777 E. Mayo Blvd, Phoenix, AZ 85054, USA extensor mechanism function while removing functional native connective tissues, such as the menisci and cruciate ligaments [4]. Additionally, in patients with isolated patellofemoral arthritis, TKA involves unnecessarily replacing the intact medial and lateral compartments. Patellofemoral arthroplasty (PFA) was subsequently developed to address only the affected compartment, leaving the remaining compartments and associated soft tissues in their native state. Patellofemoral arthroplasty (PFA) was first described by McKeever in 1955 utilizing a Vitallium alloy patellar shell [5]. This was later advanced when Lubinus described a dedicated resurfacing implant in 1979 [6]. Initial success was limited by issues regarding patellar maltracking, alignment, and patellar catching [7–10]. Second-generation components developed in the 1990’s utilized anterior femoral resection and valgus tracking angles with wide trochlear surfaces designed to promote improved tracking [4]. Overall, modern PFA techniques more reliably restore patellofemoral anatomy and function. These implants have demonstrated favorable survivorship with 10 and 20 year survival rates of 83.3% and 66.6%, respectively [11]. However, interest in optimizing technique and implants has continued. The advent of robotic surgical systems has driven development of numerous robotic techniques in orthopaedics. Robotics has been particularly prominent in hip and knee arthroplasty, where it has been reported to improve the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_58 745
746 accuracy and precision relative to manual techniques [12]. Success in total, as well as unicompartmental, knee arthroplasty has prompted recent interest in applying robotic technology to patellofemoral arthroplasty. This technology allows for preoperative and virtual PFA templating utilizing the patient’s computed tomography (CT) as a reference. Intraoperatively, a robotic arm assists with bone cuts and correct positioning of the components. The goal with these measures is to optimize the sizing, alignment, and positioning of the components relative to the patient’s patellofemoral anatomy. As poor results of manual PFA are typically due to excessive internal rotation of the trochlear component, these features of RA-PFA are believed to contribute to improved reproducibility and success of the procedure [13, 14]. Investigations of RA-PFA are few, but outcomes have demonstrated accurate alignment and functional benefit in short-term follow-up studies [15]. Additionally, minimally invasive RA-PFA is associated with smaller incision size, faster recovery, and reduced soft-tissue disruption [16–18]. The procedure also has downsides that should be considered. First, PFA, either robotic or manual, is often considered a temporizing repair reserved for young, active patients in whom TKA would significantly limit functional capacity. It is believed that many of these patients will eventually require TKA as a result of tibiofemoral arthritis advancement. In these cases, performing PFA with a fair likelihood of eventual TKA increases the patient’s exposure to a second procedure, operative risk, anesthetic, and carries a significantly greater use of resources [19, 20]. Widespread adoption of RA-PFA is also limited by capital and infrastructure factors as it carries increased costs associated with robotic arm installment, maintenance, and operation. Many centers may be unwilling to invest in these systems given the above factors without studies evaluating long-term outcomes, survivability, and cost–benefit analyses. Further, the presence and availability of CT scanners for preoperative planning is a requisite for adoption of roboticassisted techniques. Lastly, apprehension regarding the learning curve for robotic J. C. Brinkman et al. techniques may exist; however, multiple studies have demonstrated that surgeon comfort with robotic systems develops quickly without a learning curve impact on component alignment [21–23]. 2 Indications and Contraindications Success with PFA is known to depend on proper patient selection [19]. Generally, PFA is reserved for young, active patients with severely limiting pain and evidence of isolated PFOA. These patients typically report anterior knee pain with activities that load the knee such as descending stairs, squatting, or sitting for a prolonged period [24]. Classically, pain is less severe with ambulation on even surfaces or when the knee is in the fully extended position. Surgical management is considered in patients who have failed extensive attempts at nonoperative management including activity modification, non-steroidal medication, physical therapy, and bracing. Extensive chondrosis, malalignment of the PFJ, and dysplasiainduced OA are also relative indications for PFA [25]. It is believed that the procedure is most appropriate for patients between the ages of 40 and 60 [19, 26]. Several contraindications also exist. Primarily, the surgery relies on native knee kinematics created by a stable joint, functional ligaments, and intact soft tissue structures including the menisci. These are considered a fundamental requirement for successful PFA. Tibiofemoral arthritis is reported as a common cause of PFA failure and the most common contraindication [25]. As PFA does not address the soft tissues affecting the joint, a significantly increased Qangle is a contraindication as this would indicate patellofemoral malalignment that cannot be corrected with PFA. However, retinacular releases and patellar osteoplasty can be performed to address milder patellar subluxation or tilt forces [24]. Contraindications also include inflammatory arthritis, active infection, or complex regional pain syndrome. Mechanical limb axis malalignment of >8 degrees valgus or >5 degrees of valgus requires alternate intervention, as does
Robotic-Assisted Patellofemoral Arthroplasty patella baja [27]. Obesity, although not an absolute contraindication, does portend poorer results and is, at times, utilized as a relative contraindication [28]. Utilizing robotics is up to the discretion of the surgeon. Generally, indications and contraindications do not vary significantly from manual techniques, though consideration of longer operative time should be included in decision-making. 3 Preoperative Planning A standard series of X-rays should first be obtained. These include standing AP, flexion PA (Rosenberg), lateral, and sunrise views of the knee in addition to full-length standing radiographs (Fig. 1). The sunrise view may be taken at various degrees of flexion in order to evaluate for patellar subluxation tilt, or femoral trochlear dysplasia. Typically, 30 degrees of flexion is sufficient [29]. The lateral view affords investigation for patellofemoral joint space, alignment, and patellar size. The full-length standing radiographs allow for evaluation of complete lower limb alignment. If desired, this can be further investigated with CT scan or Magnetic Resonance Imaging for formal measurement of the tibial tubercle-trochlear groove (TT-TG) distance may assist in operative decision-making as it relates to the need for tubercle osteotomy. In order to create a preoperative template for use in the robotic system, a CT scan must be obtained in order to identify bony landmarks that can be later referenced to ensure reproducible intraoperative findings. 4 Surgical Technique 4.1 Patient Positioning The patient should be placed supine on the operative table. A post of the surgeon’s preference is placed on the operative side to assist in maintaining leg positioning while allowing for 747 full knee range of motion. The authors prefer to utilize a nonsterile tourniquet and the limb is prepped and draped in standard sterile fashion. For robot positioning, the robotic arm is typically positioned on the operative side to allow for optimized and independent use by the surgeon. The computer referencing monitor and stand is placed on the opposing side. The monitor is ideally placed at a comfortable and easily visible location for the surgeon. It is imperative that the nonoperative side of the patient is free of any obstructions as a clear line of sight is required for robotic tracking. The camera is angled toward the operative knee, using laser alignment if available. Lastly, the guidance module should be placed where a robotic representative can easily maintain visibility of the surgeon. 4.2 Operative Technique After induction of anesthesia, an examination under anesthesia is performed to assess for range of motion, patellar tracking, crepitation, and knee stability. Prior to incision for arthroplasty, a diagnostic arthroscopy (DA) should be performed. Standard anteromedial and anterolateral portals are utilized to arthroscopically assess each of the three knee compartments with a special focus on evaluating the cartilage integrity. This scrutinization ensures that cartilage integrity reflects that of preoperative imaging and ensures that cartilage to the tibiofemoral articulation is preserved, thus not contraindicating PFA. Additionally, diagnostic arthroscopy allows for assessment of the soft tissues of the knee, including the cruciate and collateral ligaments. Again, confirmation of isolated PFOA is required prior to proceeding with PFA. Upon completion of the diagnostic arthroscopy, a medial parapatellar approach to the joint is initiated. This is started approximately 3 cm above the superior pole of the patella and extends distally to the tibial tubercle. In the MAKO (Stryker, Kalamazoo, MI) system, two reference pins are then inserted into the anterior femur
748 J. C. Brinkman et al. A B C Fig. 1 Isolated patellofemoral osteoarthritis plain radiographs as demonstrated on sunrise (A), lateral (B), and anteroposterior (C) radiographs
Robotic-Assisted Patellofemoral Arthroplasty 749 Fig. 2 Mako guide pins attached through right femur with receiver in place proximal to the incision percutaneously (Fig. 2). Registering the femur may then be performed utilizing the reference pins, allowing the robotic system to overlay the intraoperative data with the preoperative CT. Arthrotomy then allows further visualization of the articular surface. Care is taken to avoid disrupting the menisci, intermeniscal ligaments, and articular cartilage. The infrapatellar and suprapatellar fat pads can be partially removed to allow for lateral patellar subluxation. Care should be taken to avoid removing soft tissue medial to the patella in anticipation of eventual soft tissue balancing. Next, a rongeur can be utilized to remove any visible osteophytes, soft tissue adhesions, or chondral defects. Mapping is started at the trochlea. Mapping is achieved using both a blunt- and a sharp-tipped probe and Knee End Effector Array (Fig. 3). Calibration of these systems to ensure accurate triangulation of the position of the probe is vital for adequate intraoperative mapping of the joint. Articular surfaces are mapped by marking points with the sharp-tipped probe. Two points are marked on the superior edge of the trochlea, one medial and one lateral. Five points are marked along the trochlear groove. Finally, three points are marked on each side of the medial and lateral transition zones. These points are matched with preoperative CT. The sharp probe can be used to push through the cartilage for accurate mapping, as cartilage is not detected on the preoperative CT scan. Preoperative templating may then be adjusted according to the intraoperative mapping that has been performed. The robotic arm may then be advanced into position over the operative field, with centering of the robotic base at the patient’s hip, located one to two meters away from the operative table. The cutting handle is also brought in and placed approximately 10 cm directly above the knee joint. Once in position, beginning with the burring arm, bone over the trochlear surface is removed in accordance with
750 J. C. Brinkman et al. A B Fig. 3 Intraoperative mapping of the patellofemoral joint. Mako Registration to sync to preoperative computed tomography as seen from the navigation console the future trochlear implant (Fig. 4). Of note, the robotic burr does not allow removal of bone outside of the templated plan. Implant lug holes are created using the burr with special attention to only plunge once to create lug holes in order to avoid creating excessively large lug holes. The trochlear implant may then be trialed to ensure adequate sizing and smooth patellar tracking.
Robotic-Assisted Patellofemoral Arthroplasty A Fig. 4 The robotic arm guides preparation of the joint. A Robotic arm in position for trochlear resection view from professional representative’s monitor; B Trochlea status Once the trochlear implant is appropriately in place, attention is turned to the undersurface of the patella. The everted patella should be measured for maximal thickness utilizing a caliper at the lateral and medial aspects. For patellar sizing, size is estimated by measuring the proximal– distal height of the patellar articular surface. The ideal patellar size is one that does not exceed the inferior or superior margins. Patellar resurfacing is then performed using a reamer or saw, depending on surgeon preference. A patellar reaming guide can be clamped in order to ensure the spikes are fully seated and that the guide sits flush. For optimized patellar tracking, the drill guide should be placed medially on the patella. In doing so, this will lateralize the remaining patellar surface to avoid over-tightening of the vastus lateralis and thereby decrease the risk of a lateral subluxation force. Once in an acceptable position, the peg holes are then drilled followed by placement of the trial patellar component (Fig. 5). Remeasurement of the patellar thickness is performed to ensure appropriate remaining thickness. Additionally, the knee can be taken through range of motion with special attention to 751 B postresection with retractors in soft tissue to allow for visualization. Three peg hole burr cuts visible Fig. 5 Final components in position
752 J. C. Brinkman et al. patellar tracking and transitioning through flexion and extension. Once the trials are deemed acceptable, they are removed to allow for irrigation of the bony surfaces. Cement can then be mixed and applied to the trochlear implant and resected trochlear notch. The trochlear implant is then placed and impacted, followed by removal of excess cement. The implant is manually held in place until the cement is fully cured, as can be deemed by manufacturing time or the hardening time of an additional sample of cement. Cementation is then performed of the resurfaced patella, peg holes, and patellar implant. The patellar component is then positioned and held in place by clamping to allow for an adequate compression force of the patellar implant. Again, excess cement is resected followed by clamp removal once fully cured. The joint is then irrigated and taken through another manual range of motion check. There should be no patellar tilt or subluxation as the knee is put through flexion and extension. Arthrotomy closure is made using ethibond figure-of-eight sutures followed by an additional A layer of #0 vicryl suture in a running locking fashion. Again, soft tissue balancing and patellar tracking is confirmed with range of motion. Layered closure is then performed, with the authors’ preference for #0 vicryl followed by #2– 0 vicryl sutures. Skin closure is typically performed with staples. A soft dressing is placed in accordance with the surgeon’s preference. 5 Postoperative Course Rehabilitation following robotic-assisted PFA should follow the same protocol as manual PFA. Weight-bearing as tolerated with an emphasis on range of motion exercises may be initiated in the immediate postoperative period, with gradual increase in activity. Physical therapy may be initiated based on surgeon preference within the first 1–2 weeks. Patients are generally permitted to stationary bike at 4 weeks, with gradual return to full activity within 6–8 weeks. During follow up, postoperative radiographs should include standard anteroposterior, lateral, and merchant B Fig. 6 Postoperative A lateral and B anteroposterior plain radiographs
Robotic-Assisted Patellofemoral Arthroplasty view imaging (Fig. 6). Alignment can be assessed with patellar symmetry, patellar tilt, and subluxation distance [16]. 6 Discussion Robotic-assisted patellofemoral arthroplasty is a viable approach to operative management of isolated patellofemoral osteoarthritis. It offers several unique advantages when compared to manual PFS (Table 1). Pre-operative planning using 3-dimensional reconstructed images allows for more accurate appreciation of joint condition, alignment, and eventual implant sizing. Intraoperative cartilage mapping then affords reproducible joint alignment and positioning. These advantages may avoid sources of inconsistency or error that could cause ongoing symptoms in patients that undergo PFA. Owing to the recency of the robotic application to PFA, outcome studies are few. Turktas et al. examined 30 RA-PFA knees with a follow up of 15.9 months. In this series, there were no patients with patellar mal-tracking or misalignment. Additionally, there was a significant increase in post-operative Oxford Knee Score when compared preoperatively. Similar increases in outcome scores were also demonstrated in a study by Ackroyd et al. These studies suggest that RA-PFA offers a reliable procedure that affords patients predictable benefit in functional outcomes. However, its associated limitations should also be acknowledged. Longer term follow up studies are still needed in order to fully 753 assess the outcomes, survivability, and issues not appreciable in shorter term follow up. Additionally, RA-PFA requires a significant financial investment into the robot itself as well as preoperative CT scanning. This financial cost is further increased at institutions that prefer to always undergo arthroscopic evaluation of the knee prior to PFA. Together, these capital costs may limit its availability to all institutions. 7 Conclusion Robotic-assisted patellofemoral arthroplasty is an emerging treatment for isolated patellofemoral arthritis. It has the potential to allow for more accurate and anatomic implant sizing and positioning. Although further studies are required to determine its long-term outcomes, it appears to have favorable short-term survivability, outcomes, and joint alignment. Comparable studies to non-robotic PFA will afford data that can be utilized in cost–benefit analyses and to better inform its future role. 8 Take Home Messages • Patellofemoral arthritis is common and can be a debilitating condition for which treatment options typically include total or isolated patellofemoral knee arthroplasty. • Standard patellofemoral arthroplasty is associated with several issues including patellar mal-tracking and inconsistent alignment. Table 1 Advantages and Disadvantages of Robotic-Assisted Patellofemoral Arthroplasty Advantages Implant design and fixation more anatomical than previous systems Reduced malalignment and mal-tracking Short-term follow-up positive Disadvantages Long-term follow-up not yet available Capital investment and operating costs for robot are significant Preoperative CT scan required Note CT: Computed tomography
754 J. C. Brinkman et al. • Robotic-assisted patellofemoral arthroplasty was recently developed in order to address issues with standard arthroplasty and allows for patient-specific templating for implant size, alignment, and positioning. • Outcomes of robotic patellofemoral arthroplasty are promising and demonstrate low rates of malalignment and mal-tracking in addition to encouraging outcome scores • Several operative pearls including avoiding oblique reference pins, achieving appropriate soft tissue balancing, and checking for lateral facet deficiency are key to reliable outcomes. • Further longer-term studies will assist in full analysis of the outcomes, results, and cost– benefit nature of robotic patellofemoral arthroplasty. 9 Key Message • Robotic patellofemoral arthroplasty appears to be a reproducible, beneficial, and feasible treatment for isolated patellofemoral arthritis. Acknowledgements Figures adapted from Elsevier Inc. https://doi.org/10.1016/j.eats.2019.11.013. References 1. Davies AP, Vince AS, Shepstone L, Donell ST, Glasgow MM. The radiologic prevalence of patellofemoral osteoarthritis. Clin Orthop Relat Res. 2002;402:206–12. 2. Grelsamer RP, Stein DA. Patellofemoral arthritis. J Bone Joint Surg Am. 2006;88(8):1849–60. 3. Sisk D, Fredericson M. Taping, bracing, and injection treatment for patellofemoral pain and patellar tendinopathy. Curr Rev Musculoskelet Med. 2020;13 (4):537–44. 4. Strickland SM, Bird ML, Christ AB. Advances in patellofemoral arthroplasty. Curr Rev Musculoskelet Med. 2018;11(2):221–30. 5. Mckeever DC. Patellar prosthesis. J Bone Joint Surg Am. 1955 (5):1074–84. 6. Lubinus HH. Patella glide bearing total replacement. Orthopedics. 1979;2(2):119–27. 7. Blazina ME, Fox JM, Del Pizzo W, Broukhim B, Ivey FM. Patellofemoral replacement. Clin Orthop Relat Res. 1979;144:98–102. 8. Tauro B, Ackroyd CE, Newman JH, Shah NA. The Lubinus patellofemoral arthroplasty. A five- to tenyear prospective study. J Bone Joint Surg Br. 2001;83(5):696–701. 9. Kooijman HJ, Driessen APPM, van Horn JR. Longterm results of patellofemoral arthroplasty. A report of 56 arthroplasties with 17 years of follow-up. J Bone Joint Surg Br. 2003;85(6):836–40. 10. Krajca-Radcliffe JB, Coker TP. Patellofemoral arthroplasty. A 2- to 18-year followup study. Clin Orthop Relat Res. 1996 Sep;(330):143–51. 11. van der List JP, Chawla H, Zuiderbaan HA, Pearle AD. Survivorship and functional outcomes of patellofemoral arthroplasty: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2017;25 (8):2622–31. 12. Deckey DG, Rosenow CS, Verhey JT, Brinkman JC, Mayfield CK, Clarke HD, et al. Robotic-assisted total knee arthroplasty improves accuracy and precision compared to conventional techniques. Bone Joint J. 2021;103-B(6 Supple A):74–80. 13. Cobb J, Henckel J, Gomes P, Harris S, Jakopec M, Rodriguez F, et al. Hands-on robotic unicompartmental knee replacement: a prospective, randomised controlled study of the acrobot system. J Bone Joint Surg Br. 2006;88(2):188–97. 14. Law J, Hofmann A, Stevens B, Myers A. Patellofemoral arthroplasty technique: Mako. In: Lonner JH, editor. Robotics in Knee and Hip Arthroplasty: Current Concepts, Techniques and Emerging Uses [Internet]. Cham: Springer International Publishing; 2019 [cited 2021 Nov 13]. p. 115–22. Available from: https://doi.org/10.1007/978-3-030-16593-2_12 . 15. Turktas U, Piskin A, Poehling GG. Short-term outcomes of robotically assisted patello-femoral arthroplasty. Int Orthopaedics (SICOT). 2016;40 (5):919–24. 16. Dahm DL, Al-Rayashi W, Dajani K, Shah JP, Levy BA, Stuart MJ. Patellofemoral arthroplasty versus total knee arthroplasty in patients with isolated patellofemoral osteoarthritis. Am J Orthop (Belle Mead NJ). 2010;39(10):487–91. 17. Laskin RS, van Steijn M. Total knee replacement for patients with patellofemoral arthritis. Clin Orthop Relat Res. 1999;367:89–95. 18. Odumenya M, McGuinness K, Achten J, Parsons N, Spalding T, Costa M. The Warwick patellofemoral arthroplasty trial: a randomised clinical trial of total knee arthroplasty versus patellofemoral arthroplasty in patients with severe arthritis of the patellofemoral joint. BMC Musculoskelet Disord. 2011;12(1):265. 19. Leadbetter WB, Ragland PS, Mont MA. The appropriate use of patellofemoral arthroplasty: an analysis of reported indications, contraindications, and failures. Clin Orthop Relat Res. 2005;436:91–9.
Robotic-Assisted Patellofemoral Arthroplasty 20. Woon CYL, Christ AB, Goto R, Shanaghan K, Shubin Stein BE, Gonzalez Della Valle A. Return to the operating room after patellofemoral arthroplasty versus total knee arthroplasty for isolated patellofemoral arthritis-a systematic review. Int Orthop. 2019;43(7):1611–20. 21. Begum FA, Kayani B, Morgan SDJ, Ahmed SS, Singh S, Haddad FS. Robotic technology: current concepts, operative techniques and emerging uses in unicompartmental knee arthroplasty. EFORT Open Rev. 2020;5(5):312–8. 22. Kayani B, Konan S, Huq SS, Tahmassebi J, Haddad FS. Robotic-arm assisted total knee arthroplasty has a learning curve of seven cases for integration into the surgical workflow but no learning curve effect for accuracy of implant positioning. Knee Surg Sports Traumatol Arthrosc. 2019;27(4):1132–41. 23. Mahure SA, Teo GM, Kissin YD, Stulberg BN, Kreuzer S, Long WJ. Learning curve for active robotic total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2021. 24. Walker T, Perkinson B, Mihalko WM. Patellofemoral arthroplasty: the other unicompartmental knee replacement. J Bone Joint Surg Am. 2012;94 (18):1712–20. 755 25. Lonner JH. Patellofemoral arthroplasty. J Am Acad Orthop Surg. 2007;15(8):495–506. 26. Delanois RE, McGrath MS, Ulrich SD, Marker DR, Seyler TM, Bonutti PM, et al. Results of total knee replacement for isolated patellofemoral arthritis: when not to perform a patellofemoral arthroplasty. Orthop Clin North Am. 2008;39(3):381–8, vii. 27. Leadbetter WB, Seyler TM, Ragland PS, Mont MA. Indications, Contraindications, and Pitfalls of Patellofemoral Arthroplasty. JBJS. 2006;88(suppl_4): 122–37. 28. Sabatini L, Schirò M, Atzori F, Ferrero G, Massè A. Patellofemoral joint arthroplasty: our experience in isolated patellofemoral and bicompartmental arthritic knees. Clin Med Insights Arthritis Musculoskelet Disord. 2016;9:189–93. 29. Iwano T, Kurosawa H, Tokuyama H, Hoshikawa Y. Roentgenographic and clinical findings of patellofemoral osteoarthrosis. With special reference to its relationship to femorotibial osteoarthrosis and etiologic factors. Clin Orthop Relat Res. 1990; (252):190–7.
Modern Patellofemoral Inlay Arthroplasty—A Silver Lining in the Treatment of Isolated Patellofemoral Arthritis Marco-Christopher Rupp, Jonas Pogorzelski, and Andreas B. Imhoff 1 Key Notes • Contemporary patellofemoral inlay arthroplasty demonstrates high patient satisfaction with significant improvements in knee function and pain relief while avoiding progression of tibiofemoral arthritis at mid-term follow-up. • Patient selection is the key to success. • In patients with significant trochlea dysplasia or with (minor) rotational malalignment, an onlay prosthesis might be beneficial as its design addresses those factors better than an inlay design. 2 Introduction Isolated patellofemoral osteoarthritis (PFOA) is a complex and multifactorial pathology. Primary OA of the patellofemoral joint is a relatively rare entity and is defined as isolated OA to the patellofemoral joint without concomitant or underlying pathologies in the sense of tibiofemoral malalignment or patellofemoral instability. Secondary OA however is much more common M.-C. Rupp J. Pogorzelski A. B. Imhoff (&) Department of Orthopaedic Sports Medicine, Hospital Rechts der Isar, Technical University of Munich, Munich, Germany e-mail: imhoff@tum.de and is the result of non-physiologic patellofemoral biomechanics, e.g. due to trochlear dysplasia or axial/torsional malalignment of the femur and tibia with subsequent maltracking of the patella or patellofemoral instability. With multiple etiological factors exhibiting a combined effect on the biomechanical and clinical outcome following PFIA, the surgical management for PFOA is part of a nuanced therapeutical concept and should be viewed in the context of concomitant pathologies. Patellofemoral inlay arthroplasty (PFIA) as a design variant of patellofemoral arthoplasty was first described in the literature in 1979 [1]. In principle, the idea behind the PFIA design was to retain the anatomy of the trochlea and replace only the degenerated part of the cartilage without having to perform a more invasive resection of the subchondral bone. The trochlear component was inserted flush with the surrounding cartilage of the trochlea (“inlay”). However, the first results of these arthroplasty models led to high failure rates due to the suboptimal geometry of these models [2, 3] A trochlear groove that was, by design, non-physiologically deep and an insufficient mediolateral coverage of the trochlea in the first arthroplasty models often resulted in patellofemoral maltracking with persistent pain and additional patellofemoral instability [2, 3]. Based on these experiences, novel surgical techniques and a new generation of inlay arthroplasty models have been developed in recent years (Fig. 1). © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_59 757
758 M.-C. Rupp et al. Fig. 1 Modern patellofemoral inlay prosthesis (Kahuna Prosthesis, Arthrosurface, Franklin, MA, USA) However, as PFOA is a multifactorial pathology, concomitant soft-tissue and bone-based reconstructive procedures have to be considered during conception of the surgical plan. In the case of accompanying malalignment of the femur, surgical procedures such as alignment corrective osteotomies to optimize mechnical leg alignment and patellofemoral tracking [4] may be indicated, since performing an isolated PFIA may not be fully able to restore physiological alignment. Compared to total knee arthroplasty (TKA) in the treatment of isolated PFOA, the procedure is relatively minimal invasive and the tibiofemoral joint compartments can be preserved during the PFIA procedure [5–7]. Lower intraoperative morbidity, shorter intraoperative tourniquet times and a shorter rehabilitation time in young patients postoperatively [8–10] typically result in improved mobility and extension strength of the knee joint with a comparable postoperative satisfaction compared with TKA [7, 8, 11, 12]. Since the PFIA can also be converted to a TKA in cases where the tibiofemoral OA progresses [9], the implantation of a modern PFIA is a viable therapeutic alternative to TKA, especially in younger patients. This chapter aims to provide an overview of the indications and contraindications for PFIA and recommendations for clinical practice. 3 Indication PFIA is indicated in patients suffering from isolated disabling PFOA with minimum grade III– IV (Kellgren-Lawrence classification) or chondral defects grade III–IV (Outerbridge classification) that refractory to conservative treatment and/or failed prior surgery. Performing an isolated PFIA is generally reserved for patients without patellofemoral instability. High-grade patellofemoral or tibiofemoral malalignment as defined by a mechanical valgus or varus of more than 5°; a femoral anteversion of more than 30°; a tibial torsion of more than 40°; a tibial tuberosity trochlear groove distance of more than 20 mm or less than 8 mm; a Caton-Deschamps Index of more than 1.2 or less than 0.8; or a lateral patellar tilt of more than 5° should be managed according to a previously published algorithm [4] additionally to the implantation of a PFIA. 4 Contraindication Contraindications for PFIA implantation are symptomatic tibiofemoral OAwith pain at the joint line during activities of daily living, chronic
Modern Patellofemoral Inlay Arthroplasty … 759 regional pain syndrome, active infection, inflammatory arthropathy, chondrocalcinosis, and a fixed loss of knee range of motion. 5 Surgical Technique Contemporary inlay arthoplasty models typically consist of a cobalt chrome trochlear component that is connected to a titanium taper post via a taper interlock and an (optional) additional allpolyethylene patella component. Most systems are distributed with multiple implant sizes with varying offsets to facilitate a patient-specific geometry match. All inlay prostheses are designed to be implanted flush with the surrounding cartilage into a bone bed within the native trochlea sparing the femoral bone stock (Fig. 2). Typically, inlay arthroplasty models include a trochlear groove that narrows distally to allow for sufficient patella tracking without causing lateral hypercompression of the patella. Compared to an onlay design, the more anatomic principle of the inlay design closely reproduces the complex patellofemoral kinematics. By desing, this avoids soft tissue irritation due to patellofemoral overstuffing, which is an accepted risk factor for the development and progression of tibiofemoral OA due to secretion of proinflammatory cytokines [13]. The arthroplasty procedure is performed according to the specific manufacturers instructions. Typically, the PFIA procedure is performed via a minimally invasive lateral parapatellar approach to spare the medial patellastabilizing soft tissue structures. A further advantage of the lateral approach is that overhanging patellar osteophytes, that are typically located laterally, can be resected without compromising the approach to the trochlea for the implantation of the PFIA. An offset drill guide is used to correctly localize the center for the reamer with the knee in full extension. In principle, the correct placement for the drill guide is located at the center of the trochlear articular surface to confirm trochlear defect coverage (Fig. 3). A guide pin is advanced into the bone, Fig. 2 Second-Generation patellofemoral inlay arthroplasty model (WAVE Prosthesis, Arthrosurface, Franklin, MA, USA) implanted flush with the surrounding cartilage after creation of a bone bed within the native trochlea Fig. 3 An offset drill guide is used to establish a working axis prependicular to the central trochlear articular surface and to confirm trochlear defect coverage once the superior and inferior drill guide feet are optimally aligned with the trochlear orientation. In order determine the adequate implant size, the
760 M.-C. Rupp et al. fixation stud. Finally, the trochlear component is positioned using an impactor. Subsequently, debridement of patellar osteophytes, circumpatellar denervation and resurfacing of the patella are performed. To replace the patellar surface, a drill guide is inserted emplyoing an alignment guide. The medial/lateral and superior/inferior offsets are measured and an implant bed is reamed. The patellar component is then mounted onto the implant holder and cemented into the bone bed. Postoperative radiographs in three planes are obtained routinely to confirm optimal implant positioning. (Fig. 6). 6 Fig. 4 The implant bed is reamed employing a guide block medial/lateral as well as superior/inferior offsets are measured using specific measurement instrumentation. Next, the implant bed is reamed three-dimensionally using a guide block (Figs. 4 and 5). Subsequently, the screw fixation stud is advanced into the bone. The trochlear component is then aligned with the appropriate offsets of the implant holder and placed onto the taper of the Rehabilitation All patients are discharged once they are able to flex the knee joint to a minimum of 90° and can climb stairs on crutches safely. All patients are limited to partial weight bearing with 20 kg for two weeks until the healing process of the soft tissue is consolidated. Early rehabilitation includes lymphatic drainage and continuous passive motion for the first two weeks as tolerated. Patients are then allowed to increase weight bearing in a step-wise fashion until full weight Fig. 5 The correct positioning of the implant is confirmed by positioning of a trial implant that will be used for positioning the tape post
Modern Patellofemoral Inlay Arthroplasty … 761 Fig. 6 Postoperative radiographs of the inlay implant in three planes routinely obtained to confirm implant positioning bearing is achieved approximately six weeks after surgery. Full active range of motion is typically allowed two weeks after surgery. 7 Clinical Outcome The results after PFIA are mainly influenced by the patient selection, the surgical technique and the arthroplasty design. Early complications are common and mainly caused by implant misplacement and/or postoperative patella maltracking or patellofemoral instability, while longterm failures are mainly the result of progression of tibiofemoral osteoarthritis. An adequate patient selection may be the key factor in achieving favorable outcomes following PFIA. As such—according to the current state of knowledge—risk factors for inferior clinical outcome include an increased body mass index (BMI) prior surgery, an etiology of primary PFOA as compared to secondary PFOA, presence of degenerative changes in the tibiofemoral joint compartments, lack of retropatellar resurfacing during the PFIA procedure as well persistent patellofemoral instability and malalignment following the PFIA procedure [14–17]. As of biomechanical studies, peak pressure following patellofemoral arthroplasty significantly increases compared to the native joint [5, 18]. As such, if patellar resurfacing is not performed at index surgery, non-physiological pressure conditions may predispose for an abrasion of the native patellar cartilage in contact with the inlay arthroplasty [5]. This may consequently lead to a progression of retropatellar cartilage degeneration resulting in pain as wells as poor postoperative results and may require revision surgery. This finding was confirmed by a multi-center case series, in which the lack of patellofemoral resurfacing at the index surgery was significantly correlated with failure [16]. Interestingly, the presence of primary OA of the patellofemoral joint also seems to be a risk factor for inferior outcome after implantation of a PFIA as compared to patients with secondary PFOA. In this regard, a prospective case series reported that there is a significant progression of tibiofemoral OA in patients with primary PFOA while the tibiofemoral compartments remains
762 relatively unchanged in patients undergoing PFIA for secondary PFOA [15]. Patients with secondary PFOA due to patellofemoral instability, in which the anatomical risk factors predisposing for patellofemoral instability were addressed during PFIA implantation, were shown to benefit significantly more from undergoing PFIA than patients with primary PFOA [15]. Potentially patients with primary OA are more prone to degenerative changes in the tibiofemoral joint compartments as part of the inflammatory reactions that occurs within the joint during primary OA [13]. This is in accordance with subsequent outcome studies that reported significantly better results following PFIA in the presence of secondary OA due to trochlear dysplasia with concomitant patellofemoral instability [19–21]. An increased BMI was identified as a further independent factor in PFIA predictive of unfavorable clinical outcome postoperatively [16, 22]. As such, obesity may lead to rapid progression of tibifemoral OA and predispose for an early conversion to TKA. According to the current literature, this is still the main reason for the failure of PFIA [14, 17, 23]. When respecting these risk factors during patient selection, the PFIA procedure is a viable, minimally invasive alternative to the traditional TKA procedure for isolated PFOA. In a study regarding the midterm outcome following PFIA [24], the patient reported outcome scores improved significantly both at short- and midterm follow up with no significant difference between the two time points. In this case series, 17.1% of the patients failed leaving a survival rate of 83% after five years, reflecting the early experiences with modern generation PFIA. In patients who did not fail, no changes in the vertical patellar alignment or significant progression of tibiofemoral OA were observed until final follow up. The main mode of failure reported in this case series was persistent knee pain. An independent case series on the early experiences of modern generation PFIA, who evaluated the outcome after a mean follow-up of 35 months following PFIA, confirmed the promising clinical outcome. Significant M.-C. Rupp et al. improvements were observed across all patient reported outcome measures and similarly, no radiological progression of tibiofemoral OA was noted. Around 10% of the patients were converted to TKA, again with persistent pain being the main reason for failure. In the largest series to date, including a total of 263 patients (49 ± 12 years) at mid-term follow-up, 93% of the patients included in the final analysis were satisfied with the procedure with a mean transformed WOMAC Score of 84.5 ± 14.5 points, a mean KOOS Score of 73.3 ± 17.1 points, a mean Tegner Score of 3.4 ± 1.4 points and a mean VAS pain of 2.4 ± 2.0 points. With an overall failure rate was 11% (28 patients), the authors concluded that PFIA shows high patient satisfaction with good functional outcomes at short- to mid-term followup. However, the outcomes reported following isolated PFIA are heterogenous throughout the literature. In a prospective case series of 18 patients [25], a significant progression of OA in the medial tibiofemoral compartment caused a total of 5 implants (28%) to fail within six years. However, even when acknowledging for this high failure rate, clinically significant improvements were observed for clinical and functional outcomes; with an improvement in the the American Knee Society Subjective Score (AKSS) of more than 20 points in 91% of the patients. The relatively high revision rate reported in this case series [25] highlights the necessity for careful preoperative patient selection. A recent review article analyzing the clinical outcome following patellofemoral arthroplasty depending on the size of the respective center proposed found that the outcome in specialized centers with substantial cumulative experience with the procedure may be superior, highlighting the multifactorial complexity of the management of PFOA [26]. This notion is highlighted retrospective cohort of 20 patients who underwent PFIA. 55% of the patients with an increased patellofemoral congruence angle and an elevated Insall–Salvati index and showed an initial satisfactory result, but failed due to pain during follow-up after a
Modern Patellofemoral Inlay Arthroplasty … median time of 25 months. Beckmann et al. concluded that patients with craniolateral types of PFOA as well as a patella alta should be treated with an patellofemoral onlay arthroplasty, as this type of implant is superior in covering the proximal part of the patellar track as compared to the PFIA design [27]. Accordingly, Feucht et al. [28] found that preoperative patellofemoral anatomy is significantly associated with clinical improvement and failure rate after isolated inlay PFA. It was demonstrated that less clinical improvement and a higher failure rate must be expected in patients with patella alta (ISI > 1.2 and PTI < 0.28), absence of trochlear dysplasia, and a lateralized position of the tibial tuberosity (TT-PCL distance > 21 mm), further highlighting the necessity for an adequate patient selection for the PFIA procedure [28]. Overall, when respecting risk factors associated with inferior outcomes during a concise diagnostic work-up and careful patient selection process, PFIA implantation has been shown to be a viable, minimally invasive alternative to TKA in the treatment of PFOA. Yet, future studies reporting on the the long-term outcome following PFIA are required and further research is necessary to define risk factors for failure or insufficient clinical improvement following PFIA. References 1. Blazina ME, et al. Patellofemoral replacement. Clin Orthop Relat Res. 1979;144:98–102. 2. Borus T, et al. Patellofemoral joint replacement, an evolving concept. Knee. 2014;21(Suppl 1):S47-50. 3. Cartier P, Sanouiller JL, Khefacha A. Long-term results with the first patellofemoral prosthesis. Clin Orthop Relat Res. 2005;436:47–54. 4. Imhoff AB, et al. Prospective evaluation of anatomic patellofemoral inlay resurfacing: clinical, radiographic, and sports-related results after 24 months. Knee Surg Sports Traumatol Arthrosc. 2015;23 (5):1299–307. 5. Vandenneucker H, et al. Isolated patellofemoral arthroplasty reproduces natural patellofemoral joint kinematics when the patella is resurfaced. Knee Surg Sports Traumatol Arthrosc. 2016;24(11):3668–77. 763 6. Tanikawa H, et al. Influence of total knee arthroplasty on patellar kinematics and patellofemoral pressure. J Arthroplasty. 2017;32(1):280–5. 7. Odgaard A, et al. The mark coventry award: patellofemoral arthroplasty results in better range of movement and early patient-reported outcomes than TKA. Clin Orthop Relat Res. 2018;476(1):87–100. 8. Dahm DL, et al. Patellofemoral arthroplasty versus total knee arthroplasty in patients with isolated patellofemoral osteoarthritis. Am J Orthop (Belle Mead NJ). 2010;39(10):487–91. 9. van Jonbergen HP, Werkman DM, van Kampen A. Conversion of patellofemoral arthroplasty to total knee arthroplasty: a matched case-control study of 13 patients. Acta Orthop. 2009;80(1):62–6. 10. Kamikovski I, Dobransky J, Dervin GF. The clinical outcome of patellofemoral arthroplasty vs total knee arthroplasty in patients younger than 55 years. J Arthroplasty. 2019;34(12):2914–7. 11. Walker T, Perkinson B, Mihalko WM. Patellofemoral arthroplasty: the other unicompartmental knee replacement. J Bone Joint Surg Am. 2012;94 (18):1712–20. 12. Dy CJ, et al. Complications after patello-femoral versus total knee replacement in the treatment of isolated patello-femoral osteoarthritis. A metaanalysis. Knee Surg Sports Traumatol Arthrosc, 2012;20(11):2174–90. 13. Kapoor M, et al. Role of proinflammatory cytokines in the pathophysiology of osteoarthritis. Nat Rev Rheumatol. 2011;7(1):33–42. 14. van der List JP, et al. Survivorship and functional outcomes of patellofemoral arthroplasty: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2017;25(8):2622–31. 15. Beitzel K, et al. Prospective clinical and radiological two-year results after patellofemoral arthroplasty using an implant with an asymmetric trochlea design. Knee Surg Sports Traumatol Arthrosc. 2013;21 (2):332–9. 16. Imhoff AB, et al. The lack of retropatellar resurfacing at index surgery is significantly associated with failure in patients following patellofemoral inlay arthroplasty: a multi-center study of more than 260 patients. Knee Surg Sports Traumatol Arthrosc, 2021. 17. Bendixen NB, Eskelund PW, Odgaard A, Failure modes of patellofemoral arthroplasty-registries vs. clinical studies: a systematic review. Acta Orthop, 2019;90(5):473–478. 18. Calliess T, et al. Patella tracking and patella contact pressure in modular patellofemoral arthroplasty: a biomechanical in vitro analysis. Arch Orthop Trauma Surg. 2016;136(6):849–55. 19. Dahm DL, et al. Patellofemoral arthroplasty: outcomes and factors associated with early progression of tibiofemoral arthritis. Knee Surg Sports Traumatol Arthrosc. 2014;22(10):2554–9. 20. Nicol SG, et al. Arthritis progression after patellofemoral joint replacement. Knee. 2006;13(4):290–5.
764 21. Feucht MJ, et al. Preoperative patellofemoral anatomy affects failure rate after isolated patellofemoral inlay arthroplasty. Arch Orthop Trauma Surg, 2020. 22. Liow MH, et al. Obesity and the absence of trochlear dysplasia increase the risk of revision in patellofemoral arthroplasty. Knee. 2016;23(2):331–7. 23. van Jonbergen HP, et al. Long-term outcomes of patellofemoral arthroplasty. J Arthroplasty. 2010;25 (7):1066–71. 24. Imhoff AB, et al. High patient satisfaction with significant improvement in knee function and pain relief after mid-term follow-up in patients with isolated patellofemoral inlay arthroplasty. Knee Surg Sports Traumatol Arthrosc, 2018. 25. Laursen JO. High mid-term revision rate after treatment of large, full-thickness cartilage lesions M.-C. Rupp et al. and OA in the patellofemoral joint using a large inlay resurfacing prosthesis: HemiCAP-Wave(R). Knee Surg Sports Traumatol Arthrosc. 2017;25 (12):3856–61. 26. Benignus C, et al. When nothing else works: patellofemoral joint arthroplasty. Sportverletz Sportschaden. 2021;35(4):227–33. 27. Beckmann J, et al. Patella alta and patellar subluxation might lead to early failure with inlay patellofemoral joint arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2019;27(3):685–91. 28. Feucht MJ, et al. Preoperative patellofemoral anatomy affects failure rate after isolated patellofemoral inlay arthroplasty. Arch Orthop Trauma Surg. 2020;140(12):2029–39.
Virtual Orthopaedic Examination in Patellofemoral Disorders Casey L. Wright and Miho J. Tanaka 1 Introduction Telehealth (also referred to as telemedicine or virtual care) is a rapidly emerging field encompassing a wide range of care paradigms utilizing electronic platforms to provide healthcare services. Telehealth models include triage, radiographic assessment, remote monitoring devices, “store-and-forward” telehealth, asynchronous care, an “at-home” model, and a “regional-hub” model [1]. Virtual musculoskeletal care has primarily been provided through the latter two models. In the “at-home” model, physicians connect directly with patients via a virtual platform to provide healthcare services. Studies comparing at-home telehealth and in-person care demonstrate the success of telehealth in diagnosing and treating a variety of musculoskeletal problems. A study of face-to-face and telehealth visits conducted on the same day for 42 patients with chronic shoulder, knee, or lumbar spine issues demonstrated 83.3% diagnostic and management agreement with an 89% patient satisfaction rating [2]. Despite such encouraging results, prior to the COVID-19 pandemic, telehealth historically C. L. Wright M. J. Tanaka (&) Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA e-mail: mtanaka5@mgh.harvard.edu played only a small role in orthopaedic practices. The unanticipated global spread of severe acute respiratory syndrome coronavirus 2 (SARSCoV2), however, accelerated reliance on telehealth within orthopaedic surgery to enable surgeons to continue providing routine musculoskeletal care during a period in which inperson evaluation was limited to urgent or emergent issues [3]. King and colleagues, who detailed their department’s telehealth implementation process during the pandemic-enforced restrictions, expanded the use of telehealth from 0.4 to 76% of their daily encounters [4]. Early studies evaluating the ability of virtual visits to develop appropriate surgical plans validate the quality of telehealth care. Within sports medicine surgeries, only 4% of surgical plans formulated during telemedicine visits subsequently changed during in-person re-evaluation [5]. In the evaluation of patellofemoral disorders, the diagnoses rely heavily on history and physical examination. When converting the patellofemoral evaluation to a virtual encounter over telemedicine, adaptations to known examination techniques can be considered. Several orthopaedic departments who have published their experience with the rapid implementation of telehealth have advocated for a consistent, structured approach to promote the efficiency and success of the virtual encounter, with instructions for patients to review prior to the visit [1, 4, 6]. Virtual assessments can be augmented with the use of digital measurements or goniometers © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6_60 765
766 C. L. Wright and M. J. Tanaka and can be performed either within a telemedicine platform or through a screen capture process. Virtual goniometers are an effective tool to standardize measurements across patients and are available in a variety of formats. They are available as browser extensions (Protractor, ben. builingham), smartphone applications (DrGoniometer, CDM s.r.l., Milano, Italy [7]), and through the use of a standard goniometer during a virtual visit, including to assess a screen-captured image [8]. Virtual goniometers demonstrate compatibility with multiple telehealth platforms utilized as a browser extension [6]. Several studies have demonstrated high reliability in range of motion measurements obtained virtually [7–10]. Dent and colleagues reported success with the use of a standard clinical goniometer to assess individuals during virtual encounters, which is applicable regardless of telemedicine platform [8]. They noted high agreement between elbow flexion and extension measurements taken during an in-person encounter and when using the same goniometer during a teleconference (Pearson coefficient in flexion: 0.93, in extension: 0.86). Some studies suggest digital knee range of motion assessments using still images have equivalent accuracy and increased precision compared to both visual assessment and standard goniometry [11, 12]. The goals of this chapter are to highlight the considerations when performing evaluation of the patellofemoral joint through a telemedicine visit. We discuss the examination workflow, modifications of standard examination maneuvers, benefits and limitations of the virtual visit, as well as guidelines for optimizing the efficiency and efficacy of the virtual examination. 2 Preparation for the Telemedicine Visit Preparation for the telemedicine visit by both the patient and physician are integral to ensuring a successful and efficient visit. Protocols for the virtual visit, including payment policies, consent, technology requirements, and instructions for the visit, should be discussed at the time of scheduling. X-rays performed in advance of the visit should be made available for review prior to or at the time of the visit. If images are performed at a facility outside of one’s institution, those images should be submitted in advance so they may be uploaded for review prior to the start of the encounter. Adequate audiovisual capabilities on the part of the patient can significantly improve the quality and flow of the examination. Patients can be instructed to visit a remote verification site to confirm they have the appropriate software and audiovisual capabilities to participate in the appointment. Educational materials sent to the patient in anticipation of the virtual visit should set appropriate expectations and include written, photographic, or video instructions of the physical examination maneuvers to be performed (Tables 1 and 2) Instructions provided in advance of the visit allows patients to familiarize themselves with the upcoming examination, advises of the expectations of the patient during the visit, and allows the patient to prepare for the visit. A standardized protocol for both the preparation for and performance of the virtual visit can improve the diagnostic accuracy and efficiency of the evaluation. 3 Inspection Similar to in an in-person evaluation, the virtual examination begins with inspection, which can be easily performed with the patient standing and facing the camera. Thorough inspection should note skin changes, erythema, incisions, scars, and the presence of an effusion. Asymmetries in patellar position, or muscle bulk and tone may be noted. As with other musculoskeletal assessments, it is helpful to utilize the contralateral leg as a control throughout the examination. However, physicians should be mindful that many patients with patellofemoral disorders may have bilateral involvement, which may influence examination findings [13, 14]. In a recent randomized control trial of 112 patients with patellofemoral pain syndrome, Hott and colleagues
Virtual Orthopaedic Examination in Patellofemoral Disorders 767 Table 1 Example of patient instructions to prepare for a virtual visit (Adapted from Tanaka et al. JBJS 2020 [6]) How to prepare for a virtual visit After speaking with a physician or provider regarding your symptoms, he or she will guide you through a physical examination. To improve the success of the visit, please ensure you conduct the virtual appointment in a space that allows for the following: Privacy: Please conduct the visit in a quiet space with minimal background noise in which you are able to speak privately with your physician regarding your health concerns Space: The visit should be conducted in a space that allows for the camera to be positioned 6 feet (1.8 m) in front of you on a low surface (2–3 feet off the ground), such as a chair or low table. This allows for appropriate visualization of your knees during the examination. Sufficient floor space for 6–8 strides should be available for assessment of your gait Camera: The camera should be positioned on a table top or chair such that it does not need to be held during the encounter, yet can be repositioned as needed throughout the examination Lighting: Adequate lighting is crucial to ensure your provider is able to visualize the necessary details of the physical examination. Please minimize backlighting by facing the camera away from windows and light sources Seating: It is best to utilize a swivel chair or easily moveable chair during the examination that will allow you to transition from facing the camera to having your side facing the camera. The physician will also need to evaluate you while you are lying down, so it is necessary to either have a couch or adequate floor space available for you to lie down Clothing: For appropriate visualization, please wear shorts that end 3″ above your knees and remove your shoes and socks Table 2 Summary and workflow for the virtual patellofemoral examination The virtual examination Seated in chair Inspection (frontal view) • Skin changes, erythema, incisions, scars, effusion • Asymmetries in patellar position, muscle bulk, tone Palpation (frontal view) • Tibial tubercle, patellar tendon, quadriceps tendon insertion, medial and lateral patellar facets, medial and lateral joint lines, medial and lateral femoral condyles, medial and lateral collateral ligaments • Adductor tubercle (“Bassett’s sign”) Patellar Instability (frontal view) • J sign • Patellar apprehension • Patellar glide Range of Motion • Hip internal and external rotation (frontal view) • Hip flexion with upper extremity assistance (lateral view) • Knee flexion and extension (lateral view) Muscle Strength (lateral view) • Knee extension • Extensor lag • Hip extension – rise from seated without upper extremity support Foot Pronation (lateral view) Standing Gait Hypermobility (Beighton scale) (frontal view) Lower Extremity Alignment (frontal view) • Leg lengths, muscular atrophy • Q angle • Genu valgum, tibial tubercle lateralization, tibial torsion, femoral anteversion (continued)
768 C. L. Wright and M. J. Tanaka Table 2 (continued) The virtual examination Range of Motion • Hip abduction and adduction (frontal view) • Hip flexion and extension (lateral view) • Knee flexion and extension (lateral view) Muscle Strength (frontal and lateral view) • Single-leg knee bend Seated or laying on ground Range of Motion (lateral view) • Hip flexion and extension (side-lying or supine) • Hip abduction and adduction (side-lying) Muscle Strength (lateral view) • Hip abduction (side-lying) • Hip flexion (straight leg raise) (supine) • Knee flexion (prone) found 72% of included patients had bilateral symptoms [13]. Muscular atrophy is an important finding to identify in patellofemoral disorders. This can be assessed virtually by assessing for side-to-side differences between the symptomatic and contralateral leg. Atrophy can be assessed in the seated, standing, or supine position. The use of digital pixel measurements, aided by a browser extension such as Page Ruler Redux (rocha.codes) can be incorporated to detect subtle differences as a percentage relative to the contralateral side (Fig. 1). Vastus medialis oblique (VMO) atrophy has been associated with a variety of patellofemoral disorders [15, 16], and discordant atrophy between the VMO and vastus lateralis has been shown contribute to lateral patellar instability [17]. In patients with patellar maltracking, patellar tilt has been correlated with the differential activation of the vastus lateralis and medialis [18]. VMO inhibition has been noted to occur at smaller volumes than for other quadriceps muscles, resulting in a dynamic quadriceps imbalance [19]. Identification of muscular atrophy can serve as the basis for a targeted rehabilitation protocol. Assessment for hypermobility should be performed using the Beighton scale [20]. During scoring, one point per side is assigned for the ability to extend each fifth metacarpophalangeal joint beyond 90°, to touch each thumb to the forearm with the wrist flexed, to hyperextend each elbow beyond −10°, and to hyperextend each knee beyond −10°, as well as one point for the ability to place both palms flat on the floor while standing with the knees extended. A score of four or greater indicates hypermobility, which may contribute to instability. A recent study comparing 82 individuals with recurrent patellar dislocation to age- and sex-matched controls found those with a history of patellar dislocations were more likely to have generalized joint laxity (24% vs 10% of controls, P = 0.013) [21]. Among 174 patients who underwent isolated MPFL reconstruction, 55.1% had a positive Beighton score, although this was not found to influence post-operative outcomes [22]. 4 Lower Extremity Alignment Assessment of lower extremity alignment is an integral aspect of the patellofemoral exam, as the presence of malalignment can contribute to instability and pain [23]. For assessment of limb alignment and symmetry, the patient should assume a bipedal stance facing the camera with equal distribution of weight between each foot and toes pointing forward (Fig. 2). The presence of “squinting patellae”, where the patellae appear to be internally rotated, can indicate the presence of excessive femoral anteversion or tibial torsion [24]. The Q angle is the angle formed by the intersection of two lines drawn from the anterior
Virtual Orthopaedic Examination in Patellofemoral Disorders A Fig. 1 Pixel measurements can aid in side-to-side comparison of muscle bulk and can be described as a percentage. In this image, the patient’s right thigh A 769 B measures 73 pixels (A) and the left thigh measures 69 pixels, indicating 95% symmetry (B) B Fig. 2 Standing alignment is assessed from both the frontal (A) and lateral (B) views
770 superior iliac spine (ASIS) to the center of the patella and from the center of the patella to the tibial tubercle. Genu valgum, lateralization of the tibial tubercle, increased external tibial torsion, and increased femoral anteversion can increase the Q angle. The relationship between the Q angle and patellofemoral disorders remains controversial [25–31] as it may be influenced by the lack of standardization in how the Q angle is measured. Consequently, Merchant and colleagues proposed a validated protocol for the assessment of a “Standard Q Angle” to improve inter- and intra-observer reliability [32]. During the virtual examination, adaptation of this technique consists of measuring the Q angle using a web-based goniometer with the patient in the standing position facing the camera and the patellae pointing forward. (Fig. 3). The patient Fig. 3 The Q angle can be measured on the frontal standing view as the angle between a line connecting the anterior superior iliac spine (ASIS) to the midpoint of the patella and another connecting the midpoint of the patella to the tibial tubercle. Asking the patient to place their thumb or index finger on the ASIS enables its identification C. L. Wright and M. J. Tanaka can be asked to place their thumb or index finger on their anterior superior iliac spine to aid in obtaining this measurement. The patient should be instructed to relax their quadriceps muscles prior to measurements being taken. It should be noted that lateral subluxation of the patella may falsely decrease the Q angle measurement. Assessment of hip range of motion can be helpful in detecting rotational abnormalities. Hip internal and external rotation can be measured with the patient seated in a chair facing the camera and the knees flexed to 90° (Fig. 4). The addition of digital lines overlying the image may assist in comparison of leg lengths, while muscular atrophy may again be assessed using comparison of pixel measurements. Careful attention should be paid to noting modifiable asymmetries, which may be addressed through treatment options such as orthotics or tailored rehabilitation programs [6]. An assessment of patellar height, while commonly performed on radiographs, has also been described clinically by noting whether the patella faces superiorly (alta) or inferiorly (baja) while viewing the knees of a seated patient from the front with the knees in 90° of flexion [33] (Fig. 5). Patella alta is an important risk factor for instability as it hinders engagement of the patella in the trochlear groove during early flexion (0–30°), predisposing to lateral subluxation and tilt in extension [34]. While the severity of patella alta is confirmed using radiographic measurements, the presence of patella alta on examination can help identify patients in whom lower extremity malalignment may be contributing to their symptoms [35, 36]. Foot pronation, resulting in internal tibial rotation, can affect dynamic patellofemoral alignment [37] and has been shown to correlate with patellofemoral pain [16, 38, 39]. Barton and colleagues found individuals with PFPS demonstrated significantly greater foot pronation as detected by longitudinal arch angle (effect size, 0.90) and foot posture index (effect size, 0.71) [38]. Foot pronation may be assessed using standing heel position or navicular drop, which are adaptable to the virtual visit. Foot pronation may be quickly assessed using hindfoot valgus
Virtual Orthopaedic Examination in Patellofemoral Disorders A 771 B Fig. 4 During seated range of motion testing, hip internal and external rotation can be measured with the knee at 90° of flexion with the patient facing away from the camera in the bipedal standing position. To assess navicular drop, the patient can mark the proximal aspect of the navicular tuberosity on the symptomatic leg (Fig. 6). The distance from the mark to the floor should then be measured while the patient is seated in a relaxed position with the foot resting on the floor [39]. For adequate visualization, the chair should be oriented 90° from the camera with the medial aspect of the examined foot facing the camera. The measurement is then repeated in a weightbearing single leg stance, using a chair or wall for balance only. While a ruler or calibrated sheet of paper may serve as a reference to enable more accurate measurements, the proportion of navicular drop may provide an estimate of foot pronation. Assessment of foot pronation utilizing the navicular drop test has been shown to have good inter- and intraobserver reliabilities (ICCs 0.73–0.91 [40]; ICCs > 0.86 [39]) and can identify a modifiable risk factor that can be addressed through the use of an orthotic support. 5 Gait Assessment of gait from the front and back allows for evaluation of antalgia, asymmetry, stride length, patellar orientation, alignment, and pelvic tilt. Assessing 6–8 stride lengths is generally sufficient and can be performed during the virtual encounter, provided the encounter is conducted in an area with adequate floor space [6]. A shortened stance is suggestive of ipsilateral leg pain. Circumduction, which can be assessed on either the frontal or posterior view, may indicate difficulty with knee flexion. Pelvic tilt, on the other hand, suggests contralateral hip abductor weakness, which often results in
772 C. L. Wright and M. J. Tanaka condyles, quadriceps tendon insertion, medial and lateral patellar facets, and the medial and lateral collateral ligaments. Tenderness over the adductor tubercle (“Bassett’s sign”) is suggestive of MPFL disruption at its femoral attachment [43], which can be associated with patellar instability. In their prospective observational study of 23 patients with acute patellar dislocations, Sallay and colleagues noted a sensitivity of 70% for Bassett’s sign [44]. Tenderness may guide providers in prognostication, as well. In their randomized control trial of 112 patients with PFPS, Hott and colleagues found an increased number of pain locations correlated with inferior 1-year outcomes [13]. 7 Fig. 5 Digital markers placed at the proximal and distal aspects of the patella, as well as at the proximal aspect of the tibial tubercle, can aid in approximation of patellar height increased IT band tension [16]. In-toeing is suggestive of femoral anteversion, which can contribute to a lateralizing force on the patella due to an external rotation moment at the knee [41]. 6 Palpation Physician-guided palpation can be a useful aspect of the virtual examination. Palpation is ideally performed with the patient seated facing the camera with their feet hanging freely [42]. As in the in-person examination, physicians should begin by asking patients to point to the area of their pain with one finger before guiding them through a series of palpation points. Instructions mailed to the patient prior to the visit can provide a helpful visual reference of where to identify such points. Areas to be palpated include the tibial tubercle and patellar tendon, medial and lateral joint lines, medial and lateral femoral Range of Motion Virtual range of motion assessments can be performed in either the standing, seated, or supine position. With the patient in the standing position facing the camera, the physician can note hip range of motion in abduction and adduction. From the lateral view, with the patient facing 90° from the camera, the physician can assess the flexion/extension arc of the hip and knee. Knee hyperextension may be assessed by asking the patient to push their knees posteriorly while maintaining a bipedal stance. Patients who have difficulty maintaining their balance may hold on to a chair for stability. Alternatively, the assessment may be performed in both the seated and supine positions. The seated position allows assessment of hip internal and external rotation, hip flexion with upper extremity assistance, knee flexion and extension and evaluation of the presence of an extensor lag. While oriented 90° from the camera, the lateral view may be utilized to visualize knee extension, antigravity strength, and the presence or absence of an extensor lag. Asking the patient to bring the heel in toward the buttock allows for flexion assessment. The lateral supine position allows near full assessment of hip range of motion as the patient ranges the superior hip from maximal flexion sequentially to abduction, extension, and adduction [16].
Virtual Orthopaedic Examination in Patellofemoral Disorders B A Fig. 6 Navicular drop, a measure of foot pronation, can be assessed by measuring the height of the navicular tuberosity in the unloaded and loaded positions. In these 8 773 Muscle Strength and Functional Testing Assessment of strength remains a vital aspect of the patellofemoral exam, as quadriceps weakness [15, 45] and hip abduction, external rotation, and extension weakness [46–49] have been demonstrated to be prevalent in patellofemoral disorders. While the virtual exam may be limited in the ability to detect subtle weakness or side-toside differences in strength, particularly in patients whose habitus or range of motion limitations limit participation, antigravity strength remains an important aspect of the physical exam. While knee extension is readily assessed in the seated position, knee flexion (prone), hip flexion (supine straight leg raise), and hip abduction (lateral supine) are best assessed with the patient lying on a couch or bed. Hip images, navicular height measures 30 pixels in the unloaded position and 23 pixels in the loaded position, indicating a 23% change extension strength may be assessed by asking the patient to stand from the seated position without utilizing upper extremity support [6] (Fig. 7). Functional assessments of strength, which may lend themselves to the virtual examination, may be more predictive of patellofemoral disorders than manual strength testing [50]. When assessing functional strength, Nunes and colleagues found patients with PFPS climbed stairs more slowly and performed fewer consecutive chair stands (by 12%), which can be assessed during the virtual encounter. Stair climbing may be simulated with step-up-step-down testing. The utility of functional strength assessments is further supported by their high intra-rater reliability and association with variations in pain scales [51]. Numerous specialized tests for the evaluation of functional strength, dynamic alignment/ tracking, and severity of symptoms are easily
774 C. L. Wright and M. J. Tanaka latency in gluteus medius activation, decreased hip abduction torque, and decreased lateral flexion force [52], which may contribute to symptomatology among patients with patellofemoral symptoms [53]. 9 Fig. 7 Hip extension strength can be tested by having the patient transition from seated to standing without using his or her upper extremities adaptable to the virtual examination. A simple squat and single-leg knee bend viewed from anteriorly and laterally provide an assessment of functional strength, lower extremity support (core, hip, and quad strength and foot pronation), dynamic patellar tracking, pain, and subjective crepitus. Dynamic valgus alignment of the knee and pelvic tilt can be identified during during this maneuver (Fig. 8). The step-down test, which simulates a single-leg squat similarly allows assessment of balance, eccentric quadriceps strength, dynamic alignment, and support. To perform, the patient can be observed stepping down off a small step first with one leg and then the other. Crossley and colleagues demonstrated good inter- and intra-rater reliability (k = 0.800– 0.600 and k = 0.800–0.613, respectively) when utilizing the step-down test to evaluate hip muscle dysfunction [52]. Providers assessed overall functional movement with respect to Patellar Tracking Assessment of patellar tracking is an integral component of any patellofemoral assessment. The J sign represents lateralization of the patella in knee extension, which reduces into the trochlear groove during early knee flexion (Fig. 9). Tanaka and colleagues evaluated the correlation between patellar maltracking identified on dynamic kinematic computed tomography (DKCT) with symptoms of patellar instability among 76 knees [14]. They identified a J sign pattern, with increased lateral translation of the patella in knee extension, among 82% of individuals with patellar instability symptoms, with a sensitivity of 93% among individuals who demonstrated greater than three quadrants of lateral patellar motion in extension. Several studies have evaluated the ability to use video assessment of knee flexion and extension to assess patellar tracking with variable results. Fujita and colleagues utilized video analysis to quantify patellar tracking among 23 knees with prior patellar dislocation, 23 asymptomatic contralateral knees, and 23 healthy controls [54]. Video-based measurements were able to successfully quantify patellar tracking, which was noted to be similar between affected and unaffected knees, as well as significantly different than healthy controls at low flexion angles. Best and colleagues, on the other hand, found orthopaedic surgeons correctly identified patellar maltracking in web-based video assessment of the J sign in only 68% of cases (k = 0.45) when compared with 4DCT [55]. Future advances to improve the precision of J sign assessment may help better identify risk factors and prognoses in the evaluation and treatment of patellar instability [35, 56–58].
Virtual Orthopaedic Examination in Patellofemoral Disorders 775 B A Fig. 8 Frontal and lateral views of the patient performing a single-leg squat can provide information regarding lower extremity strength by evaluating for changes in coronal and sagittal alignment A B Fig. 9 Patellar tracking can be assessed in the frontal plane by having the patient extend (A) and flex (B and C) the knee. The J sign is observed when the patellar C displaces laterally in extension and can be quantified by quadrants of patellar motion
776 10 C. L. Wright and M. J. Tanaka Patellar Apprehension The patellar apprehension test was first described by Fairbank in 1937, in which patients exhibited apprehension when a laterally-directed force was applied to the patella [59]. A positive result occurs when there is verbal or non-verbal (e.g. quadriceps contraction) expression of apprehension. Notably, expression of pain does not constitute a positive test. Although the test has been shown to have limited sensitivity (<37%) [60] and fair to moderate inter-rater reliability (j = 0.30–0.65) [61], it has moderate specificity (70–92%) [60]. Recently, Lamplot and colleagues described a modification of the apprehension test for the virtual examination [62] (Fig. 10). While seated facing the camera, patients should place the ankle of the extremity being examined over the contralateral ankle, maintaining the knee in 20–30° of flexion. They should then use their thumbs to apply a laterally- Fig. 10 Patellar apprehension can be evaluated in the seated position with the ankle of the examined leg resting on the contralateral ankle and the knee in 20–30° of directed force to the patella while the provider observes for any anxiety and evaluates nonverbal apprehension. Assessment of increased translation, referred to as patellar glide and measured in patellar quadrants, may be suggestive of injury to medial or lateral restraints. Decreased translation, conversely, may be suggestive of lateral retinacular tightness or arthrofibrosis. Despite limited sensitivity and inter-observer reliability, the apprehension test remains a mainstay for the evaluation of patellar instability, as well as an outcome measure following patellar stabilization surgery. 11 Limitations to the Virtual Examination Despite efforts to describe adaptations to perform a comprehensive patellofemoral examination during the virtual visit, several limitations exist flexion. The patient should then be assessed for verbal and non-verbal apprehension while applying a laterallydirected force to the patella
Virtual Orthopaedic Examination in Patellofemoral Disorders 777 and should be communicated to the patient. 13 Take Home Points Certain tests that require manipulation of the: extremity or provocative testing, remain limited. Additionally, the sensitivity, specificity, and Tips for a successful virtual examination reliability of many of the virtually performed Preparation The virtual visit format, including tests has not been established. Recent efforts to payment policies, consent, technology standardize the virtual examination can increase requirements, and structure, should be discussed at the time of scheduling to the utility and reproducibility of this modality. manage patient expectations Additionally, the presence of incidental or appropriately unexpected findings in other areas of the body A pre-visit instruction packet mailed may not be easily identified through a focused to the patient in anticipation of the virtual examination. Confirmation of the virtual visit, providing a detailed preparation checklist and written or video examination findings with an in-person clinical instructions for examination evaluation is recommended prior to proceeding maneuvers, allows patients to prepare with intervention. for the visit and facilitates efficiency Furthermore, while telehealth has the potential A remote verification website enables to improve access to care, it may also exacerbate patients to confirm their setup meets healthcare disparities for specific populations. the audiovisual requirements in advance of the visit, mitigating both Individuals who lack access to necessary audioanxiety and inefficiencies visual capabilities and reliable internet connecLoose fitting clothing exposing at tions may not be able to participate in the virtual Set-up least 3″ above the knee allows for evaluation [4]. Those at increased risk include appropriate visualization during the older adults, individuals in rural communities, exam individuals with low household incomes, those Adequate lighting with minimal with limited education, or individuals with disbacklighting improves the provider’s ability to detect subtle physical ability. As physicians expand the use of teleexamination findings medicine and further refine the virtual visit, A moveable camera, in conjunction specific attention to how to facilitate access to with a swivel office chair or easily care for all populations is necessary to avoid moveable chair, allows for evaluation compounding healthcare disparities. in the frontal and lateral views Examination 12 Conclusion Telemedicine is a rapidly evolving field that has expanded the reach of orthopaedic care. Many components of the patellofemoral examination can be adequately adapted to the virtual examination, and incorporation of technological advances continue to improve the capabilities of this modality. When performing a virtual examination, adequate preparation by both the patient and physician is critical for optimizing efficiency and efficacy of the telemedicine visit. A standardized sequence of examination maneuvers designed to limit transitions between the standing, seated and supine positions improves the efficiency of the virtual visit (Table 2) Physical examination findings should be performed in a consistent manner across patients to improve reliability Critical interpretation of the examination maneuvers should seek to identify instability, which may be a surgical indication. Examination maneuvers that aid in identifying instability include limb alignment, the Q angle, the J sign, patellar apprehension, and patellar glide test (continued)
778 C. L. Wright and M. J. Tanaka Tips for a successful virtual examination After visit Additional imaging studies are useful adjuncts to the history and clinical examination completed during the virtual encounter. Limitations of the virtual examination should be discussed with the patient and inperson visits planned accordingly 9. 10. 11. 14 Key Message When performing a virtual examination, adequate preparation by both the patient and physician is critical for optimizing efficiency and efficacy of the telemedicine visit. 12. 13. 14. References 1. Emara AK, Zhai KL, Rothfusz CA, Minkara AA, Genin J, Horton S, et al. Virtual orthopaedic examination of the lower extremity: the know-how of an emerging skill. JBJS Rev. 2021;9(9). 2. Cottrell MA, O’Leary SP, Swete-Kelly P, Elwell B, Hess S, Litchfield MA, et al. Agreement between telehealth and in-person assessment of patients with chronic musculoskeletal conditions presenting to an advanced-practice physiotherapy screening clinic. Musculoskelet Sci Pract. 2018;38:99–105. 3. Services USCfMM. CMS adult electivesurgery and procedures recommendations: limit all non-essential plannedsurgeries and procedures, including dental, until further notice. 4. King D, Emara AK, Ng MK, Evans PJ, Estes K, Spindler KP, et al. Transformation from a traditional model to a virtual model of care in orthopaedic surgery: COVID-19 experience and beyond. Bone Jt Open. 2020;1(6):272–80. 5. Crawford AM, Lightsey HM, Xiong GX, Striano BM, Schoenfeld AJ, Simpson AK. Telemedicine visits generate accurate surgical plans across orthopaedic subspecialties. Arch Orthop Trauma Surg. 2021. 6. Tanaka MJ, Oh LS, Martin SD, Berkson EM. Telemedicine in the era of COVID-19: the virtual orthopaedic examination. J Bone Joint Surg Am. 2020;102(12): e57. 7. Ferriero G, Vercelli S, Sartorio F, Muñoz Lasa S, Ilieva E, Brigatti E, et al. Reliability of a smartphonebased goniometer for knee joint goniometry. Int J Rehabil Res. 2013;36(2):146–51. 8. Dent PA, Wilke B, Terkonda S, Luther I, Shi GG. Validation of teleconference-based goniometry for 15. 16. 17. 18. 19. 20. 21. 22. 23. measuring elbow joint range of motion. Cureus. 2020;12(2): e6925. Mehta SP, Kendall KM, Reasor CM. Virtual assessments of knee and wrist joint range motion have comparable reliability with face-to-face assessments. Musculoskeletal Care. 2021;19(2):208–16. Russell TG, Jull GA, Wootton R. Can the internet be used as a medium to evaluate knee angle? Man Ther. 2003;8(4):242–6. Russo RR, Burn MB, Ismaily SK, Gerrie BJ, Han S, Alexander J, et al. Is digital photography an accurate and precise method for measuring range of motion of the hip and knee? J Exp Orthop. 2017;4(1):29. Russo RR, Burn MB, Ismaily SK, Gerrie BJ, Han S, Alexander J, et al. Is digital photography an accurate and precise method for measuring range of motion of the shoulder and elbow? J Orthop Sci. 2018;23 (2):310–5. Hott A, Brox JI, Pripp AH, Juel NG, Liavaag S. Predictors of pain, function, and change in patellofemoral pain. Am J Sports Med. 2020;48(2):351–8. Tanaka MJ, Elias JJ, Williams AA, Demehri S, Cosgarea AJ. Characterization of patellar maltracking using dynamic kinematic CT imaging in patients with patellar instability. Knee Surg Sports Traumatol Arthrosc. 2016;24(11):3634–41. Pattyn E, Verdonk P, Steyaert A, Vanden Bossche L, Van den Broecke W, Thijs Y, et al. Vastus medialis obliquus atrophy: does it exist in patellofemoral pain syndrome? Am J Sports Med. 2011;39(7):1450–5. Post WR. Clinical evaluation of patients with patellofemoral disorders. Arthroscopy. 1999;15 (8):841–51. Petrera M, Dwyer T, Gobbi A. Patellofemoral Instability. Berlin, Heidelberg: Springer Berlin Heidelberg;2014. p. 59–66. Pal S, Besier TF, Draper CE, Fredericson M, Gold GE, Beaupre GS, et al. Patellar tilt correlates with vastus lateralis: vastus medialis activation ratio in maltracking patellofemoral pain patients. J Orthop Res. 2012;30(6):927–33. Spencer JD, Hayes KC, Alexander IJ. Knee joint effusion and quadriceps reflex inhibition in man. Arch Phys Med Rehabil. 1984;65(4):171–7. Beighton P, Horan F. Orthopaedic aspects of the Ehlers-Danlos syndrome. J Bone Joint Surg Br. 1969;51(3):444–53. Nomura E, Inoue M, Kobayashi S. Generalized joint laxity and contralateral patellar hypermobility in unilateral recurrent patellar dislocators. Arthroscopy. 2006;22(8):861–5. Hiemstra LA, Kerslake S, Kupfer N, Lafave MR. Generalized joint hypermobility does not influence clinical outcomes following isolated MPFL reconstruction for patellofemoral instability. Knee Surg Sports Traumatol Arthrosc Off J ESSKA. 2019;27 (11):3660–7. Brattstroem H. Shape of the intercondylar groove normally and in recurrent dislocation of patella.
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Epilogue The pathology of the patellofemoral joint has been a major concern amongst the orthopaedic community, with a high prevalence in the athletic and general population. Anterior knee pain and patellar instability often creates diagnostic and treatment challenges to the orthopaedic surgeon, with recalcitrant and enigmatic cases that are difficult to resolve. The pathophysiology of these challenging cases is nowadays more comprehensively—but not fully—understood under multifactorial models (anatomical, biomechanical, neuromuscular, genetic, psycho-emotional, environmental and socioeconomic factors) of complex interplay of the diverse contributing modifiable and non-modifiable risk factors. Recent predictive diagnostic models into the brain network functional connectivity of patients with anterior knee pain is also shedding some light on the pathways and drivers of pain which can help explain why in a subgroup of patients with structural abnormalities, some have pain and others do not, as well as to potential links to other predisposing factors. A manyfold of new research developments have also contributed to significant and important advances in the diagnosis, management and treatment of patellofemoral pathological conditions. The available diagnostic options are today more advanced, reliable and precise. Not only we have a more complete understanding of the several contributing factors, but we are also better equipped to assess their prevalence and potential impact on the patellofemoral joint. Emerging techniques are now available that can help the orthopaedic surgeon in the diagnosis process, as well as in the decision-making of the best course of treatment and better plan surgical procedures. With recent events, the relevance and usefulness of virtual consultation and tele-rehabilitation has gain ground and have become increasingly popular. The recent developments on virtual orthopaedic examination will play an important role in the future, allowing clinicians to reach a wider range of patients that, for many different reasons, are not available to attend physical consultations. This will be one of the stepping-stones for higher equity in the access for high-quality medical orthopaedic services for the population. Dynamic CT enhances our diagnostic arsenal and helps us to better measure the individual contribution of anatomic and pathomechanic factors on the course of patellar tracking during the full knee range of motion. The dynamic 3D CT will improve our ability to identify which biomechanical deficiencies that need to be corrected and which are the most adequate surgical approaches to restore normal patellar tracking. This technique can also be used postoperatively to evaluate the results of the different patellofemoral corrective techniques. Instrumented evaluation of patellofemoral laxity is also an important step to dynamically assess patellofemoral instability. These devices have the potential to overcome the limitations of measuring laxity during physical examination (qualitative assessment under manual exam) and available imaging procedures (which are mostly static evaluations). The Porto Patellofemoral Testing Device (PPTD) has emerged as clinically relevant tool to standardly quantify patellar position and displacement under external stress to the patella. The compatibility of the PPTD with CT and MRI offers the clinician a device able to measure patellofemoral laxity with high reliability, accuracy and precision, and with low intra- and inter-individual variability. The PPTD has shown clinical application in identifying anatomic and pathomechanic factors in both anterior knee pain and patellar instability. It can also be a helpful tool in evaluating any residual laxity after corrective surgery and better understand the surgical outcomes of the available surgical techniques. The use of finite element modelling (FEM) allows to evaluate the kinematic behavior of patellofemoral joint and simulate morphological changes of different pathological conditions using patient-specific models. The FEM helps the clinician to better understand the contributing factors that causing the patellofemoral disorder, it has its most relevant potential to improve the surgical approaches. Using FEM, orthopaedic surgeons can © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 V. Sanchis-Alfonso (ed.), Anterior Knee Pain and Patellar Instability, https://doi.org/10.1007/978-3-031-09767-6 781
782 better prepare their surgical planning by simulating different techniques and fixation points under the patient-specific morphology, which will individualize the surgical procedure to the specific needs of each individual. Several clinically relevant advances have also been accomplished in surgical techniques for patellofemoral disorders. Although patellar cartilage injuries still pose a challenge to orthopaedic surgeons, we have today a larger range of available and advanced techniques to deal with chondral and osteochondral patellar lesions and thus to treat the patient’s symptoms and associated disability, while aiming to prevent further damage to the cartilage and delay the early onset of osteoarthritis. With enhanced understanding of the medial patellofemoral ligament complex of the previously neglected role of the medial quadriceps-tendon femoral ligament (MQTFL) and the individual contributions of other relevant ligamentous structures (medial patellotibial and medial patellomeniscal ligaments) has also nudged orthopaedic surgeons to innovate and improve their surgical techniques of Epilogue MPFL reconstruction. Robotic-assisted surgery is already a reality and something to eagerly look for in the future to improve the outcomes of patellofemoral replacement. The path to better manage patellofemoral disorders may still be tortuous and often enigmatic, but with recent developments in this field, the future that lies ahead it is also bright. The key for improved care will rely on better understanding of the several predisposing factors that interplay in the physiopathology of patellofemoral disorders and in the individualization of treatment to the patient-specific needs. We keenly look forward for what the future may hold… João Espregueira-Mendes, MD Ph.D., Porto, Portugal. Director of Clínicas Espregueira – FIFA Medical Centre of Excellence. Vice-President of ISAKOS. President of ESSKA 2012–2014.