Table of Contents About the Authors 4 Introduction 6 Basic Knee Anatomy 7 Basic Knee Biomechanics: The Important Structures and How They Should Work to Keep Your Patella Stable and Pain-free 10 The Extensor Mechanism 10 Factors That Influence Patellar Stability 10 Summary 15 The Effects of Patellar Instability 16 Patellar Dislocation Injuries 16 Patellar Subluxation Episodes 16 The Knee Examination 18 History 18 Where Does It Hurt? 18 Patellar Tracking 19 Lower Limb Alignment 20 Ligaments and Menisci 21 Single-leg Squat Test 21 Muscle Strength and Function 21 Imaging Studies 21 Possible Diagnoses Related to Anatomical Problems 22 Treatment for Acute, First-Time Patellar Dislocations 23 General Comments 23 Conservative Treatment, Physical Therapy 24 Knee Braces/Sleeves 26 Training for Return to Sports 26 Results of Conservative Treatment for First-Time Patellar Dislocation Injuries 30 Treatment for Chronic Recurrent Patellar Instability 31 General Comments 31 Conservative Treatment, Physical Therapy 31 What to do When Conservative Management Fails 33 Choosing an Orthopaedic Surgeon in the U.S. 33 Operations to Correct Patella Instability 34 Examination Under Anesthesia 35 Lateral Release 35 Proximal-Distal Realignment Procedures 35 Proximal Realignment (Tightening Existing Tissues) 37 MPFL Reconstruction Plus Proximal Realignment 37 Trochleoplasty 37 Operations for Damage to the Joint Lining (Articular Cartilage) 37 Arthroscopic Debridement 37 Microfracture, Abrasion Arthroplasty 38 Osteochondral Autograft Transfer 39 Autologous Chondrocyte Implantation 39 Preparing for Surgery 40 Getting Your House Ready 40 Food and Medications 41 Practice the Exercises You Will Do After Surgery 43 Mental Preparation 43 The Night Before Surgery 43 The Day of Surgery 44 Recovering From Surgery 46 Prevention of Blood Clots in Your Leg (Deep Venous Thrombosis) 46 Home Exercises to Improve Strength and Flexibility 47 Quadriceps Isometrics: Full Extension 47 Quadriceps Isometrics: Multi-angle 47 Straight Leg Raise: Hip Flexion 48 Straight Leg Raise: Hip Extension 49 Straight Leg Raise: Hip Abduction 49 Straight Leg Raise: Hip Adduction 49 Straight Leg Raises With Resistance Band 50 Mini-squats 51 Hamstring Curls, Ankle Weight 51 Knee Extension, Active-Assisted 51 Wall Sits 52 Toe Raises 52 Heel Raises 52 Lateral Step-ups 52 Step-downs, Stable and Unstable Surface 53 Lunge, Straight 53 Lunge, Lateral 53 Lunge, Diagonal 53 Hamstring Stretch 54 Calf Stretch 54 Iliotibial Band Stretch 54 Quadriceps Stretch 55 Health, Fitness Club Exercise Machines 55 Leg Press 55 Hip Abduction/Adduction 56 Multi-Hip 56 Knee Extension 56 Hamstring Curls 57 Upper Body Weight Training 57 Core Training 57 Stationary Bicycle 57 Cross-Country Ski 58 Elliptical 58 Pool Training 58 Water Walking and Other Basic Aquatic Exercises 58 Swimming (Straight Ahead Kicking) 58 Weight Loss Tips 59 Acronyms and References 59 Appendix 1. Surgical Details: Proximal Realignment 63 Appendix 2. Surgical Details: Proximal Realignment With MPFL Reconstruction 64 Appendix 3. Surgical Details: Distal Realignment 66 Appendix 4. Surgical Details: Correction of Patella Alta 68 4 About the Authors Dr. Frank Noyes is an internationally recognized orthopaedic surgeon and researcher who has specialized in the treatment of knee injuries and disorders for nearly 4 decades. He is the founder and chairman of the Cin- cinnati SportsMedicine and Orthopaedic Center and its nonprofit research foundation. Dr. Noyes completed his orthopaedic training at the University of Michigan Medical Center. He then received a 4-year clinical and research appointment as an orthopaedic surgeon in the United States Air Force, was commissioned as a Lieu- tenant Colonel, and began his landmark research into knee ligament injuries, the effects of immobilization, bio- mechanics of ligaments, prevention of ACL injuries in the female athlete, the diagnosis of many knee injuries and problems, and the results of treatment for a variety of knee disorders. Along with Dr. Edward Grood, Dr. Noyes established one of the first biomechanics laboratories in the United States at the University of Cincinnati College of Engineering. The laboratory was subsequently named in his honor as the Noyes Tissue Engineering and Biomechanics Laboratory. Dr. Noyes has won every conceivable award for his clinical and laboratory research from societies such as the American Academy of Orthopaedic Surgeons, the American Orthopaedic Society of Sports Medicine, the Orthopaedic Research and Education Foundation, as well as the University of Cincinnati. He was inducted into the American Orthopaedic Society for Sports Medicine’s Hall of Fame in 2008. Dr. Noyes has been selected by his peers as one of the Best Doctors in America every year since 1992. Dr. Noyes has published over 260 research studies and textbook chapters on many different types of knee injuries and disorders. He edited a textbook entitled, “Noyes’ Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes” which was written for orthopaedic surgeons, physical therapists, and other sports medicine health care professionals. Dr. Noyes is also a co-editor of “ACL Injuries in the Female Athlete. Causes, Impacts, and Conditioning Programs”, a textbook written for sports medicine health care professionals, coaches, and trainers involved with female athletes. Sue Barber-Westin has directed clinical research studies for Dr. Noyes’ research Foundation for nearly 3 de- cades. In the mid 1980’s, she authored one of the first studies that measured problems during single-leg hop- ping tests in patients with ACL injuries, “Quantitative Assessment of Functional Limitations in Normal and Anterior Cruciate Ligament-Deficient Knees.” She has co-authored 140 articles in medical journals and text- books, focusing on the clinical outcome of various knee operative procedures, the methods used to determine the results of clinical investigations, differences in neuromuscular indices between male and female athletes, ef- fects of neuromuscular training in female athletes, and prevention of ACL injuries in female athletes. Sue is the associate editor of “Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes” and is the co-editor for “ACL Injuries in the Female Athlete. Causes, Impacts, and Conditioning Programs”. Sue has personally undergone 4 knee operations and played competitive junior and collegiate tennis. In 2004, Sue and Dr. Noyes were members of the research team that won the Clinical Research Award from the Orthopaedic Research and Education Foundation. They are frequently invited to speak at national and interna- tional conferences and review articles for orthopaedic and sports medicine journals. Noyes and Barber-Westin have written several other eBooks for patients: 1. ACL Injury: Everything You Need to Know to Make the Right Treatment Decision 2. ACL Injury Rehabilitation: Everything You Need to Know to Restore Knee Function and Return to Activity 3. Knee Meniscus (Cartilage) Tears: Everything You Need to Know to Make the Right Treatment Decision 5 4. Patellar (Kneecap) Pain and Problems: Everything You Need to Know to Make the Right Treatment Deci- sion 5. Operations for Knee Arthritis: What To Do When All Else Has Failed To Stop Your Knee Pain 6. Knee Arthrofibrosis: Everything You Need to Know to Recognize, Treat, and Prevent Loss of Knee Motion After Injury or Surgery 7. Partial Knee Replacement: Everything You Need to Know to Make the Right Treatment Decision 8. PCL and Posterolateral Knee Ligament Injuries: Everything You Need to Know to Make the Right Treatment Decision 6 Introduction Instability of the patella (kneecap) is one of the most common reasons patients seek medical treatment at orthopaedic and sports medicine clinics. Normally, the patella glides smoothly and stays within what is termed the trochlear groove as the knee flexes (bends) and extends (straightens). An unstable kneecap comes either completely or partially out of the groove as the knee bends. The term “patellar instability’ may indicate either a dislocation, where the kneecap comes completely out of its normal position, or a subluxation, where the kneecap only partially moves out and then goes back into its normal position. There are many potential caus- es of patellar instability, ranging from a traumatic injury to inherent problems with the patient’s anatomy that predisposes them to this problem. Acute patellar dislocation is a common traumatic knee injury in children and teenagers. At least one-half of patellar dislocations occur during sports activities such as basketball, football, and soccer. One study report- ed that approximately 43 per 100,000 children aged 16 years or younger sustained this injury. Several studies found the risk of patellar dislocation was highest in individuals 10-19 years of age. While some investigations reported that females had a higher risk compared to males, others have questioned this finding. Once this inju- ry occurs, the chance of sustaining future dislocation injuries ranges from 14-57% in adult patients and 36-71% in children and teenagers. Chronic, or recurrent, patellar instability may occur for many reasons and may or may not happen as a result of a previous dislocation injury. There are many factors which affect patellar stability such as the angle of knee flexion, the shape (geometry) of the bones in the knee joint (trochlear groove and lateral femoral condyle), tissues referred to as static patella stabilizers, and tissues called dynamic patella stabilizers. An abnormality, weakness,