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, or imbalance in these factors may cause recurrent patellar dislocation or subluxation episodes. These persistent problems may result in kneecap pain, damage to the joint lining underneath the kneecap, loss of the ability to participate in sports activities, and even difficulty with activities such as squatting, kneeling, and go- ing up and down stairs. If not treated appropriately, these repeat injuries may result in eventual arthritic dam- age to the undersurface of the kneecap and the trochlear groove.
After treating patients for nearly 4 decades with patellar instability, we decided to write this eBook to help patients and parents understand this problem, the treatment options that are currently available, and what to expect as a result of these options. This eBook provides information on basic knee anatomy, how the knee and lower limb should work to keep the patella stable, the potential effects of patellar instability, treatment options for acute dislocations and recurrent subluxations, when surgery is necessary, different types of operations that are commonly done, and exercises to help improve muscle strength and flexibility.
This eBook should not be used for self-diagnosis and treatment of patellar instability. Only a qualified orthopedist or sports medicine-trained physician can make a definitive diagnosis of knee problems. For medical professionals, we recommend our textbook “Noyes’ Knee Disorders. Surgery, Rehabilitation, Clinical Outcomes” for more comprehensive information regarding the diagnosis and treatment of patellar pain and alignment issues, and other knee problems such as knee ligament tears, preventing knee ligament injuries in the female athlete, and lower limb realignment procedures. 7 Basic Knee Anatomy
The knee is a hinge joint. It is made up of 4 bones that are held together by ligaments, tendons, and muscles. The femur (or thigh bone) is the large bone in the thigh. The tibia (or shin bone) is the large bone in the lower leg and the fibula is the smaller bone in the lower leg that lies parallel to the tibia. There are 2 joints, or articula- tions, in the knee. The tibiofemoral joint is the area where the femur and tibia meet. The patellofemoral joint is the portion of the knee where the patella and femur (trochlear groove and femoral condyles) meet.
The patella (kneecap) is a small bone in the front of the knee. It is actually the largest sesamoid bone in the human body. A sesamoid bone is a small, independent bone that is located in a tendon. The shape of the patella is not consistent among people; 4 different patellar forms have been identified in the medical literature. The patella lies close to a groove known as the trochlear (or femoral) groove, located at the end of the femur (the femoral condyle). This grove provides stability to the patella as the knee bends.
As the knee bends and straightens, the patella glides up and down through the trochlear groove. The patella also moves side to side, and tilts and rotates with knee motion.
There are two large, strong tendons that connect the patella to the bones and muscles that surround the knee. The patellar tendon (also called the patellar ligament) connects the quadriceps muscles (the 4 large muscles in front of the thigh) and patella to the upper part of the tibia, called the tibial tuberosity. The quad- riceps muscles are the rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis. The quadri- ceps tendon connects the quadriceps muscles to the patella. 8
There are 2 types of cartilage in the knee joint: meniscus and articular cartilage. The meniscus is a C-shaped structure that is located between the weight bearing ends of the femur (femoral condyle) and tibia (tibial pla- teau). There are 2 menisci in each knee, the medial meniscus (inner side) and the lateral meniscus (outer side). The menisci are located on the top of the tibia. You may have heard someone say they “tore their cartilage”, which usually means they have torn their meniscus.
Articular cartilage is a smooth protective lining or layer of tissue that is located on the ends of bones where they meet in the knee. In the knee joint, articular cartilage is located on the end of the femur (femoral condyle), the top of the tibia (tibial plateau), on the undersurface of the patella, and on the trochlear groove. This type of cartilage allows the bones to glide smoothly and the knee to flex and bend easily. Arthritis refers to the break- down or damage to articular cartilage.
There are three bursae in the knee, which are fluid-filled sacs that help cushion the joint. These are the prepa- tellar burase, located in front of the patella; the anserine bursae, located on the inner (medial) side of the knee about 2 inches below the joint; and the infrapatellar bursae, located underneath the patella.
The fat pad lies behind and on either side of the patellar tendon.
The lateral retinaculum sits along the lateral (outside) border of the patella. The medial retinaculum is on the opposite, inside border of the patella.
Ligaments connect bones and help provide stability to joints. There are 4 main ligaments in the knee. The anterior cruciate ligament and the posterior cruciate ligament cross each other in the center of the knee. They each connect the femur to the tibia. The medial collateral ligament is located on the medial (or inner) side of the knee and it also connects the femur to the tibia. The lateral collateral ligament is located on the lateral (or outer) side of the knee and it connects the femur to the fibula.
Each ligament has a main job in helping to keep the knee stable when we walk, run, go up and down stairs, kneel, and do any weight bearing activity. In addition, the muscles and other soft tissues in the knee joint help provide stability. 9 There are smaller ligaments that also exist in the knee, such as the meniscotibial ligament that attaches the edg- es of the menisci to the top of the tibia.
On the medial (inside) area of the knee, the medial patellofemoral ligament (MPFL) is an important structure with respect to patellar stability. The MPFL attaches the inner edge of the patella to the medial portion of the femur. It may be torn during a patellar dislocation injury.
The transverse ligament connects the lateral meniscus to the medial meniscus. The popliteofibular ligament and fabellofibular ligament connect the femur to the top of the fibula.
The muscles that are involved with bending and straightening the knee and also in helping to provide stability to the knee are the quadriceps and hamstrings. The quadriceps help straighten the knee. The hamstrings are the muscles at the back of the upper leg (called the biceps femoris, semitendinosus, gracilis, semimembranosus) that flex or bend the knee. Other muscles are also important in providing stability during walking, running, and the like. These include the muscles in the hip (gluteus maximus, gluteus medius, piriformis, adductor mus- cles) and in the calf (gastrocnemius and soleus).
The iliotibial band is a large band of thick tissue located on the outside of the thigh. It extends from the hip to the knee. This structure also helps to stabilize the knee joint during activities such as running. Connected to the iliotibial band is the lateral retinaculum. The lateral retinaculum attaches to the patella and provides stabil- ity by limiting how much the kneecap moves medially, or toward the inside. If the retinaculum is too tight, the patella becomes tilted and an operation called a lateral release may be required. 10 Basic Knee Biomechanics: The Important Structures and How They Should Work to Keep Your Patella Stable and Pain-free
Biomechanics is the study of mechanics of living things. More specifically, it is the study of the action and con- sequences of external and internal forces on the body. The term biomechanics was developed during the early 1970’s when engineering mechanics and sciences were applied to medicine in order to develop a better under- standing of how the body works. Understanding the complex interactions between internal and external forces on the knee joint has greatly improved our ability to diagnose and treat many injuries and problems. In order to understand how and why the patella may become unstable, a general understanding of the basic anatomy and mechanics of the patellofemoral joint is required.
The Extensor Mechanism
The patellofemoral joint is the portion of the knee where the patella and femur meet. There are many struc- tures that affect the function of the patellofemoral joint in terms of how the patella tracks and absorbs the forces of weight bearing. These structures are collectively referred to as the “extensor mechanism”:
- Quadriceps muscles (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) - Quadriceps tendon - Patella - Patellar tendon - Medial retinaculum - Lateral retinaculum - Medial patellofemoral ligament (MPFL) - Tibial tubercle
These structures propel the legs forward when you walk, run, or jump. An injury, deficien- cy, or anatomic abnormality of any of these structures may result in patellar instability, as we will discuss in detail next.
Factors That Influence Patellar Stability
Patellar stability, defined as the condition in which the kneecap glides normally and stays within the trochlear groove as the knee flexes and extends, is influenced by several factors:
- The angle of knee flexion - The dynamic patella stabilizers (quadriceps tendon, patellar tendon, rectus femoris muscle, vastus medialis muscle, vastus lateralis muscle, iliotibial band) - The shape (geometry) of the trochlear groove and lateral femoral condyle 11
- The static patella stabilizers (trochlear groove, MPFL, patellomeniscal ligament, patellotibial ligament, medial retinaculum, lateral retinaculum)
Angle of Knee Flexion and Dynamic Stabilizers A quadriceps muscle contraction straightens the knee by pulling at the patella, which in turn pulls on the tibial tubercle, causing the knee to extend. As the knee flexes, the patella acts like a pulley, causing the kneecap to be pressed into the trochlear groove.
The patella is most unstable in the range of 0-30 degrees of knee flexion. The quadriceps muscles are relaxed at this angle and the patella is not seated in the trochlear groove. Thus, it can easily be moved either towards the right or left.
As the knee is flexed, patellar stability is normally increased due to the combined tensions of the quadriceps muscles and the patellar tendon that pull the patella into the trochlear groove. The vastus medialis oblique (VMO) muscle pulls the patella toward the inside (medial) of the knee joint. The MPFL acts as a check-rein to resist a patella dislocation toward the outside (lateral) portion of the knee joint. The vastus lateralis muscle tends to pull the patella toward the outside (lateral) aspect of the knee.
It is also important to understand the relationship between knee flexion and contact that occurs between the patella and trochlear groove. When the knee is full extended (0 degrees), there is very little contact between the undersurface of the patella and the trochlear groove. Then, from 0-90 degrees of knee flexion, increased contact occurs. At first, contact occurs between the inferior (distal) pole of the patella and the trochlea. Then, as flexion increases to about 45 degrees, the contact area moves toward the central portion of the patella. At 90 degrees of flexion, only the superior (top) region of the patella is in contact with the distal aspect of the trochlear groove. At approximately 120-135 degrees of flexion, only the most medial and lateral parts of the patella come into contact with the lateral and medial femoral condyles.
Forces on the patella rise to about 3 times body weight when climbing up stairs, 5 times body weight when descending stairs, 7 times body weight during running, and up to 20 times body weight during deep squatting. The quadriceps muscles absorb energy during walking and running.
An alteration caused by excessive weakness, tightness, or imbalances of the dynamic stabilizers may result in 12 patellar maltracking or instability problems, and increase the forces on the kneecap that lead to eventual deteri- oration of the joint lining.
The Shape of the Trochlear Groove and Lateral Femoral Condyle When looking at a leg from the front, the quadriceps muscles and tendon do not form a straight line. They point one way above the patella, and another way below the patella. The quadriceps angle (Q angle) is the angle formed by one line drawn from the pelvis anterior superior iliac spine to the middle of the patella, and a second line drawn from the middle of the patella to the tibial tubercle. The normal Q angle in men ranges from 8-14 degrees. In women, the normal Q angle ranges from 11-20 degrees.
Because of the Q angle, the patella has a tendency to be pulled toward the outside (lateral portion) of the knee when the quadriceps muscles contract (tighten). This is where the shape, height, and slope of the trochlear groove is important to help keep the patella in its proper position. Normally, the groove is higher on the out- side (lateral side), which keeps the patella from sliding out of position as the knee bends and straightens. 13
There are different shapes, or variations of the trochle- ar groove. There is what is considered a normal ap- pearance (just shown in the illustration above) and 4 variations called shallow, flat, convex, and cliff. These 4 variations are associated with what is termed troch- lear dysplasia, or an abnormal shape of this area of the knee. A shallow or dysplastic trochlear groove that develops in some people allows the patella to move too far side-to-side and may be a source of chronic patellar instability problems.
The Main Static Stabilizer: Medial Patellofemoral Ligament The MPFL is a very important static stabilizer that helps prevent the patella from moving too far laterally out of the trochlear groove. Our understanding of the vital role this ligament plays in patellar stability is fairly recent (within the last 15 years or so). In knees with a large Q angle, the MPFL provides a balancing force that resists the increased lateral pull on the patella. 14 The MPFL is always damaged in patellar dislocation injuries, although the extent of the damage varies and does not require surgery initially. Over time, the amount of damage to this ligament may become more of a problem if patellar subluxation or dislocation episodes continue. A second ligament located on the medial side of the knee (medial patellomeniscal ligament) is another important stabilizer. Some people have excessively tight static stabilizers, such as the medial or lateral retinaculum. Excessive loose- ness of these structures may also cause problems with patellar stability.
The Hip Muscles Researchers have recently emphasized the role of the hip muscles in patients with patellar pain and instability. Realize that the hip shares a common bone with the knee - the femur. At the hip joint, the femur connects with the acetabulum of the pelvis and acts as a “ball-and-socket” joint that moves in all directions. At the knee joint, the femur is tightly connected to the tibia through ligaments, tendons, and the joint capsule. Weakness of the hip muscles (hip abductors and external rotators) may directly impact the knee joint by causing the femur to internally rotate and the knee to go into a knock-knee (valgus) position and the foot to turn outward (pronate), as shown in the photograph below.
A few studies have shown that patients with patellar pain and instability have weak hip muscles, but it is un- clear if this problem was present before or as a result of the patellar pain. Even so, it makes sense to include hip strengthening exercises in a physical therapy program for kneecap pain, which we will discuss later in this eBook.
Extensor Mechanism Malalignment “Extensor mechanism malalignment” is a commonly used phrase by orthopaedic surgeons to describe patellar tracking or instability problems. The term indicates an abnormal relationship between the patella and trochlear groove, which may be due to problems with the static and/or dynamic stabilizers we just discussed.
Some problems associated with soft tissue and muscle weakness or tightness may be resolved with muscle strengthening and flexibility exercises, shoe inserts, anti-inflammatory medications, and restriction from high-impact activities that overload the knee joint. However, there are cases where some of the stabilizers are completely deficient and unable to function properly that require surgery. We will discuss these issues later in this eBook. 15
Summary
To summarize, the most common risk factors that may increase the risk of patellar instability are:
- Traumatic patellar dislocation injury - Age less than 20 - Excessive weakness, tightness or imbalance of the dynamic stabilizers - Abnormally shaped trochlear groove - Deficient MPFL from a prior injury or congenital laxity - Family history of patellar dislocation injuries - Patellar dislocation opposite knee
In addition, there are other more rare conditions that may influence patellar stability:
- A rotational malalignment of the femur and tibia (femoral anteversion and external tibial torsion, known as “miserable malalignment”) - A patella alta position (where an abnormally long patellar tendon affects the position of the patella) - Problems from previous surgery, such as an overly extensive lateral release
The term “miserable malalignment” was first introduced in the medical literature in 1979 by orthopaedic surgeon Dr. Stan James. This type of malalignment, which is inherited, is referred to as a rotational malalign- ment because the femur at the hip joint is rotating inward while the tibia is rotating outward. These problems become quite pronounced during weight bearing activities. There exist two abnormalities related to the bony alignment: femoral anteversion and external tibial torsion. Femoral anteversion produces an inward pointing, or “squinting”, patella, shown here:
Patients with this syndrome who have significant patellar pain and frequent dislocation or subluxation epi- sodes may require an extensive operation known as a rotational osteotomy of the femur and tibia. Because this represents a very complex condition, we will not discuss this problem in detail in this eBook. It is important to understand that the orthopaedic surgeon must determine if this rotational malalignment is present because if it is, surgery at the knee joint is contraindicated. Instead, the rotation is corrected at the femur and tibia. If a sur- geon suspects this problem may be present, a special diagnostic study (called a rotational magnetic resonance imaging [MRI]) at the hip, knee, and ankle is obtained so that precise measurements may be made. 16 The Effects of Patellar Instability
Patellar Dislocation Injuries
Patellar dislocations are categorized as either low-energy or high-energy injuries. In a low-energy injury, only a small amount of force is required to dislocate the patella, such as a sudden twisting injury in a knee with abnor- mally lax medial patellar ligaments and a dysplasic (flat) trochlea. Anatomic abnormalities that predispose a patient to a dislocation are a frequent finding in low-energy injuries. On the other hand, a high-energy injury involves much greater force (usually in a knee with normal anatomy), such as that incurred by a direct blow to the patella during a sports activity. It is important to distinguish between these types of injuries because the expected outcome, extent of damage sustained in the knee joint, and treatment recommendations differ as we will discuss later.
Nearly all patellar dislocations occur in the lateral direction, meaning the patella slides out of the groove to- ward the outside of the knee. The patella may return to the normal position on its own (called a spontaneous reduction), or the patient or a medical professional may have to relocate it back into place. This painful injury is often accompanied by swelling and loss of normal knee motion and requires a medical evaluation.
Studies have shown that 50-80% of patients who sustain a high-energy patellar dislocation also suffer an osteo- chondral fracture, whereby the articular cartilage lining and bone on the undersurface of the patella or femoral condyle are torn and fractured. Osteochondral fractures may require surgery to remove the damaged joint fragments. The MPFL is damaged in these injuries and nearly all patients sustain a bone bruise to the patella and lateral femoral condyle. These problems occur much less frequently in patients with low-energy injuries. Fortunately, most patients who suffer first-time dislocations do not require surgery. However, there are some instances where an operation is necessary soon after the injury and we will discuss this topic in detail later in this eBook. In all patients, appropriate orthopaedic management of the injury is required, including a com- prehensive examination, x-rays, and often MRI to determine the extent of the damage to the knee. A course of protection, partial weight bearing with crutches, bracing, and physical therapy is required to restore normal knee and lower extremity function, which we will discuss in detail later.
In the first few months following a patellar dislocation injury, patients may experience pain, fear, and problems with kneeling, squatting and all sports activities. One study found that 58% of patients had significant problems with strenuous activities 6 months after their injury. While many patients will not experience further patellar instability problems following appropriate management, studies have reported that 14-57% of adult patients and 36-71% of children and teenagers will suffer recurrent dislocation injuries. These patients are at risk for incurring further damage to the stabilizing ligaments and soft tissue structures that surround the patella. Stud- ies have reported that > 90% of patients who suffer from recurrent patellar dislocations develop damage to the articular cartilage joint lining in the patellofemoral joint. Therefore, all efforts should be followed to prevent a recurrent dislocation and further damage to the knee joint. Surgery usually becomes necessary in these cases to restore normal patellar stability and knee function, which should be done before significant joint damage occurs.
Patellar Subluxation Episodes
Patellar subluxation, when the kneecap moves partially out of the trochlear groove during knee flexion and then goes back to its normal position, is less painful but may eventually cause problems if it occurs frequently and is not treated effectively. This problem may happen suddenly without warning during sports or regular daily activities. It may be thought of as a temporary, partial dislocation of the kneecap. Patellar subluxation 17 may happen due to malalignment (anatomical) problems we previously discussed, weak leg and hip muscles, or from damage to soft tissues from a previous patellar dislocation injury.
Recurrent patellar instability results in pain that may be felt under, around, or most commonly, in the front of the kneecap. Patients may experience knee giving-way or buckling (instability) during sports activities that involve twisting and turning, running on uneven surfaces, and even during daily activities such as squatting, kneeling, and going up and down stairs. These problems result in a decrease in physical activity due to lack of confidence in the knee joint.
Cases of patellar subluxation (without a history of a traumatic injury) need to be carefully evaluated to deter- mine the causes of the problem which, in many patients, may be greatly helped with conservative treatment methods. Surgery is delayed to allow for muscle strengthening, balance training, and often a patellar support brace is used during sports. In some patients, the type of sport and/or the level of participation needs to be changed. For instance, sports that involve jumping, twisting, or turning activities may repeatedly aggravate the problem. If conservative methods fail to prevent recurrent subluxation episodes, surgery may become neces- sary to correct all anatomic abnormalities that exist.
It is important to note that many terms abound in the medical literature and on the Internet to describe patellar pain and instability. These include:
- Patellofemoral pain syndrome - Painful patellar syndrome - Patellofemoral pain - Runner’s knee - Jumper’s knee - Housemaid’s knee - Anterior knee pain - Retropatellar pain - Chondromalacia patella - Patellofemoral chondromalacia - Extensor mechanism malalignment - Subluxation - Instability
There is considerable confusion about what all of these terms mean and if they represent an actual diagno- sis or just a general description of what is believed to be going on with the knee. For instance, we previously discussed the term “extensor mechanism malalignment”, which is a frequent diagnosis made by physicians. We noted that malalignment may be influenced by many different parts of the knee, lower limb, and even hip, and the determination of the exact source(s) is very important to achieve a precise diagnosis and treatment plan.
This is why, in cases of patellar subluxation or recurrent dislocation, it is important for the physician to de- termine to the best of their ability exactly what is causing the patellar instability in order to treat the problem efficiently and correctly. A diagnosis should indicate all of the problems present, which can only be made after a thorough examination of the knee and entire lower limb that includes x-rays and a MRI. There frequently exists more than one source or cause of patellar instability that requires treatment. 18 The Knee Examination
History
The physician will first take a thorough history to find out how your injury happened, or when your symptoms began if you did not have a specific injury. You will be asked about what problems you are having such as pain, swelling, and instability (giving-way). It is important to indicate if you have ever had injuries or similar prob- lems with the opposite knee. Any previous problems or injuries to your affected knee should be noted, even if you believe they may not be related to your current problems. If you did not have an injury, it is important to determine what activities cause your patellar instability problems to occur. Some patients also have pain and swelling with subluxation episodes and this should also be noted. It is helpful to write down all of these events and provide this description to your physician to make sure your history is complete and accurate.
If you are seen after a traumatic injury, all of the tests described below may not be able to be performed. In these cases, x-rays and MRI are required to determine the extent of the damage that exists in your knee.
Where Does It Hurt?
Your physician will try to determine the source of your patellar instability and also the areas in the knee that are painful. Several clinical examination tests and techniques should be done while you are standing, sitting, and lying down.
The physician will palpate, or feel, various areas on and around your entire knee joint. This will be done while you are sitting with your leg relaxed, and then with your knee bending and straightening. The physician is try- ing to determine exactly where your knee hurts. Sometimes, the pain is in a specific location and in other cases, it occurs in many different places or just “all over” (called diffuse pain).
To give you an idea of what the physician is feeling, some of the structures include the medial and lateral retinaculum, the fat pad, the iliotibial band, the medial patellofemoral ligament, the patellar tendon, the quad- riceps tendon, the insertions of these tendons, the insertions of the vastus medialis oblique and vastus lateralis oblique muscles, the tibial insertion of the patellar tendon, and the saphenous nerve. Your physician will check to see if you have any swelling in your soft tissues or a neuroma present. A neuroma is a small “knot” of nerve tissue that has been damaged that can be painful. 19 Your physician should measure the amount of motion in both of your knees, or how much they bend and flex. This is referred to as range of knee motion. When the knee is straight, that is referred to as 0 degrees. When the knee is fully flexed, it usually goes to about 135-140 degrees, although this varies between individuals.
Your physician will also see if you have what is called crepitus, or cracking, in your kneecap. Your physician will place their hand directly on your kneecap and ask you to bend and straighten your knee through its full range of motion several times over the exam table. Pressure will be applied to see if this causes pain. Crepitus usually indicates some damage to the joint lining on the undersurface of the kneecap, but may also be due to impinge- ment of the anterior fat pad, the synovial plica, or from an inflammed synovium.
Patellar Tracking
Your physician will determine how your kneecap moves, or tracks, within the trochlear groove as you bend and straighten your knee. Tests will be done to see if your patella moves too far to the right or left, or can be tilted abnormally.
Physician determining how much the kneecap can A kneecap that can be moved com- be moved toward the medial side. This is a normal pletely out of the trochlear groove. amount. This patient had suffered a knee dis- location and had several operations that failed to stabilize the patella. This photograph was taken with the patient asleep, just before we recon- structed the MPFL.
You will be asked to extend (straighten) your knee and then make a hard quadriceps muscle to determine how far your kneecap moves laterally (toward the outside of your leg). This is to determine what is called dynamic quadriceps muscle balance and is done in both legs at the same time.
The “J sign” refers to a condition in which the kneecap that moves too far laterally (toward the outside of the joint) when the knee is fully extended to 0 degrees. A positive J sign indicates there may exist an abnormally shaped, shallow or flat trochlea (as we just discussed under the Basic Knee Biomechanics section) that does not hold the patella in place. In addition, a patella alta (where an abnormally long patellar tendon affects the posi- tion of the patella) may exist that prevents early seating of the patella in the trochlear groove. 20
Lower Limb Alignment
The physician will determine the alignment of your leg by measuring different angles. One important angle we previously mentioned is the Q angle. This is the angle formed by drawing one line from the anterior superior iliac spine to the middle of the patella, and a second line from the middle of the patella to the tibial tubercle. The Q angle is measured with maximum external rotation of the leg.
Rotational alignment is measured if the physician suspects that abnormal hip femoral anteversion is present. The amount of internal and external hip rotation is determined by having the patient lie face-down on the ex- amination table. The legs are crossed with the knee s bent, as shown below. Then, the legs are stretched to rotate he hips out as far as possible.
Your physician will determine if your overall lower limb alignment is normal or in a valgus (knock-kneed) or varus (bow-legged) position. This will be done while you are standing and walking. The position of your knee- cap and your feet will also be assessed while you are standing and walking. A flat-footed position can be related to kneecap pain. Your physician will note if your legs move in the same manner when you walk, or if the knee that is hurting moves differently that the other or causes you to limp. 21 Ligaments and Menisci
Your physician should examine the meniscus (medial and lateral) and ligaments in your knee to make sure these structures are not injured. A ligament or meniscus tear may be a source of instability. The ligaments examined are the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral. There are specific tests for each ligament that the physician will do if a tear or problem is suspected because of a previous injury.
Single-leg Squat Test
If you are able, your physician may ask you to squat as low as you can on one leg at a time. This is called the single-leg squat test. It shows the amount of ankle dorsiflexion, ankle pronation, hip adduction, hip flexion, hip external rotation, and trunk lateral flexion. The test is used to detect poor hip strength and trunk control during a simple exercise. Poor hip strength may be a factor in patellar instability and pain.
Muscle Strength and Function
The function, strength, and flexibility of your leg and hip muscles will be determined. These muscles include the quadriceps, hamstrings, gastrocnemius, soleus, hip flexors and extensors, and hip abductor and adductors. This is especially important because, as we previously discussed, problems with muscle weakness, imbalance, or tightness are commonly associated with patellar instability and pain.
Imaging Studies
X-rays should be taken to determine if a fracture (break in the bone) has occurred or if a small piece of bone has flaked off or come loose from the patella, femoral condyle (end of the femur), or tibial tubercle. In addition, anatomic abnormalities that may predispose a patient to patellar instability are assessed with several different types of x-ray views, such as anteroposterior, lateral, and axial (Merchant). These images help determine the amount of joint space that exists between your kneecap and the end of the femur (femoral condyle), the length 22 of the patellar tendon, the depth and type of trochlear groove, and the lateral tilt of the patella.
In addition, various angles may be measured such as the sulcus angle, lateral patellofemoral angle, and congru- ence angle. Some of the x-rays will be taken while you are standing and others, while you are sitting or lying down.
X-ray showing a patella that is subluxed out of its normal position in the trochlear groove.
Your physician may also order a MRI. This is an important diagnostic test that shows all parts of the knee, in- cluding the ligaments, menisci, and other soft tissues that cannot be seen on an x-rays. This is especially indi- cated in knees with acute patellar dislocation injuries to detect damage to the MPFL, cartilage lining, and other stabilizing tissues. MRI is a noninvasive test that does not use any harmful rays and may be done in either a partially closed or open scanner. There are special MRI tests that will show the cartilage lining to detect injury.
Another test that may be ordered in special cases is a computed tomography (CT). Both MRI and CT scans are used to measure lower limb rotational alignment. This includes femoral anteversion, a condition in which the femoral neck leans forward with respect to the rest of the femur. This causes the knee to rotate internally (twist toward the midline of the body), which is referred to as a “squinting patella”. In addition, tibial torsion, or outward twisting of the tibia may be assessed. These extreme problems may result in what is termed misera- ble malalignment syndrome, a condition we will discuss later. These tests are critical to determine if surgery is necessary and if so, the proper procedure to perform.
Possible Diagnoses Related to Anatomical Problems
As we have discussed, it is important to have a precise diagnosis of exactly what is causing your patellar insta- bility. Of course, many patients who suffer a high-energy patellar dislocation injury do not have any anatomic abnormalities. However, a variety of anatomic abnormalities increase the risk of suffering a first-time low-ener- gy patellar dislocation, recurrent dislocations, or recurrent patellar subluxations. Knowing what may be wrong from an anatomical standpoint and/or understanding the source(s) of the instability are key elements in deter- mining the best course of treatment in these cases. Here are the possible diagnoses of anatomic abnormalities that may be made following the comprehensive examination we just discussed.
- Extensor mechanism malalignment: may or may not include excessive weakness, tightness or imbalance of the dynamic stabilizers; excessive Q angle; dysplasic trochlear groove; deficient or congenital laxity of the MPFL - Miserable malalignment syndrome (excessive femoral anteversion and external tibial torsion) - Patella alta (high riding patella, instability in knee extension) - Patella infera (low riding patella due to an abnormally short patellar tendon) - Bipartite patella (patella with two pieces, may be associated with tight lateral retinacular restraints) - Problems related to failed previous surgery, such as an excessive lateral retinacular release that causes medial 23 patellar subluxation - Genu valgum (knock-kneed) - Genu varum (bowed leg) - Genu recurvatum (hyperextended knee) - Increased swelling in the fat pad, causing impingement into the knee joint (Hoffa’s disease) - Articular cartilage damage in the patellofemoral joint
Treatment for Acute, First-Time Patellar Dislocations
General Comments
There are several factors that must be taken into consideration on deciding the appropriate treatment for a first-time patellar dislocation injury, including:
- Anatomic abnormalities that may have predisposed the patient to the injury - Amount of damage to the MPFL - Cartilage (osteochondral) fracture to the patella or femur - Patellar fracture or loose bone fragments in the knee joint - Amount of damage to the articular cartilage on the patella and femoral condyle - Damage to other knee structures, such as a meniscus tear
There are 3 basic treatment options for this injury, which apply to patients of all ages. The first and most com- mon is a conservative approach where a physical therapy program is prescribed for as long as necessary to return the knee to normal function. Many clinical research studies have failed to find a significant difference between immediate surgical treatment and conservative treatment, thereby making conservative treatment the usual recommended option.
In some patients, a staged conservative-operative approach is used in which a physical therapy program is rec- ommended for a period of time to allow recovery from the initial injury, followed by an operation if required. This approach is typically used in patients with anatomic abnormalities we have discussed such as marked laxity of the MPFL, excessive Q angle, or trochlear dysplasia. Surgery may be considered if the patient, upon completion of the rehabilitation program, continues to have symptoms and problems with a recurrent patellar dislocation or subluxation episodes. It is important to prevent recurrent dislocation episodes because these injuries usually cause further damage to the knee joint.
Some patients require an operation soon after the injury, although there are very few indications for immedi- ate surgical treatment of first-time patellar dislocations. Most surgeons agree that patients who sustain a large osteochondral fracture should be treated with surgery to fix the fracture. An osteochondral fracture represents an injury where the articular cartilage covering the end of a bone in the knee joint is fractured. This injury frequently also involves the bone that lies underneath the cartilage on the patella and lateral femoral condyle. When present, loose bodies (fragments of bone and/or cartilage floating in the knee) are also removed during arthroscopic surgery. At our center, MPFL reconstruction is not done immediately, but later after the patient has recovered from the fracture surgery, rehabilitation has been completed, and symptoms warrant the proce- dure.
Patients who sustain major damage to the MPFL and medial retinaculum frequently require surgery if they are involved with strenuous athletics. The injury is treated conservatively for a few months. Then, if marked residu- al patellar instability is detected on examination and symptoms exist, a MPFL reconstruction is warranted. We 24 prefer to delay surgery for 3-6 months to allow the patient to recover from the injury and participate in a pro- gram of careful physical therapy to avoid muscle atrophy, resolve pain and swelling, and regain normal range of knee motion.
A large meniscus tear may require early surgery, especially if the knee joint locks (where it cannot be flexed or extended) or is painful.
Conservative Treatment, Physical Therapy
Below we describe our program of physical therapy that is used following an acute, first-time knee dislocation. The time frames indicated are approximate because the recovery from this injury may differ between patients. This is due to many factors such as the amount of damage sustained to the structures of the knee joint, com- pliance with the rehabilitation program, the ability to mentally recover from the injury and regain confidence in the knee, and the final activity goals of each patient once their recovery is complete. Thus, guidelines are provided and as always, we highly recommend that the program be directed by a physical therapist experienced with knee injuries.
Weeks 1-3 post-injury Acute patellar dislocation injuries require a period of brace protection and crutch support to allow healing of the damaged ligaments and soft tissues that surround the patella. In our clinic, a brace is used at all times for the first 3 weeks after the injury. The knee brace allows 90 degrees of knee motion to be performed as will be discussed. Using crutches, the patient is allowed to place 50% of their body weight on the leg when walking.
The patient is instructed to maintain the leg in an elevated position with the limb supported in order to control lower extremity swelling, and to stay off the leg as much as possible for the first week. Ice is used for 15 min- utes, 4-6 times a day as needed for pain and swelling. Anti-inflammatory medications may be prescribed by the physician. In addition, the physical therapist may use an electrical muscle stimulation (EMS) machine or other modalities in the clinic to help resolve pain and swelling if required.
The physical therapist helps the patient perform passive and active range of knee motion exercises to prevent the development of scar tissue around the patella. The therapist makes sure active and passive 0-90 degrees of knee flexion is performed to prevent knee stiffness. In prior years, the recommendation for a patellar disloca- tion was a brace or cast and knee motion was not allowed. Today, modern programs stress early knee motion, return of normal gait, and use of crutches until muscle strength returns. The goal is to prevent a recurrent patellar dislocation as the patient resumes daily activities.
It is also important to begin an immediate muscle strengthening program in physical therapy to prevent or lessen muscle weakness from the injury. The therapist may use EMS and biofeedback in the clinic to help facil- itate strong muscle contractions of the quadriceps and hamstrings. A portable EMS machine may also be used at home to assist quadriceps contractions approximately 6 times per day for 15 minute sessions. Quadriceps strengthening exercises initially consist of isometrics and straight leg raises and may progressed to wall sits at 70 degrees of flexion. Theraband resistance exercises for plantar flexion are performed. Hamstring and gastroc- nemius flexibility exercises are also done.
Weeks 4-6 post-injury During this time period, the rehabilitation program is advanced and the patient is allowed to gradually resume full weight bearing when they demonstrate they can walk normally. The knee brace is replaced with a com- pression knee sleeve or other patellar support device. EMS and ice are used in physical therapy as required to 25 control pain and swelling. Range of motion exercises are continued until the patient has achieved full motion equal to the opposite knee.
Simple balancing exercises are initiated by the therapist to help restore patient confidence. Dills are begun to increase what is called proprioception and neuromuscular control. Proprioception is the awareness you have of movement or position of your body or a part of your body. This is what allows us to walk without looking constantly at our feet. It allows us to drive without watching our feet on the pedals and our hands on the steer- ing wheel. Neuromuscular control is the interaction between the brain and movement of any parts of the body. Elite athletes usually display phenomenal neuromuscular control as they perform difficult maneuvers in their sport during competition.
Exercises to improve proprioception and neuromuscular control initially include weight shifting side-to-side and diagonally, mini-squats on the floor and then on an unstable surface, wall sits, and balance exercises with a ball toss. The patient continues to perform quadriceps isometrics and straight leg raises. In addition, hip, core, and upper body strengthening exercises are incorporated for patients who wish to resume sports activities. Core strengthening focuses on stomach and back muscles and may be helpful in improving overall balance.
Static flexibility exercises are done by the patient at the end of each exercise session for the quadriceps, ham- strings, calf muscles (gastrocnemius/soleus), hip muscles, and iliotibial band. The therapist may also perform what is called proprioceptive neuromuscular facilitation, in which stretching may be accomplished by either passive or active assisted means. Passive means the therapist moves the limb to achieve the stretch as far as possible while the patient lies completely relaxed. Active assisted means the patient is also involved. For ex- ample, for the hamstrings, the patient lies on their back on a table and the therapist brings one leg up with the knee kept straight as far as possible until the hamstrings stretch is felt. Then, the patient is asked to tighten the quadriceps muscles and push against the therapist for a few seconds. Then, the patient completely relaxes and the therapist will stretch the leg further, which promotes even better hamstrings flexibility.
Weeks 7-9 post-injury At this time, the patient should be able to walk normally and have a full range of motion in the injured knee. Pain and swelling should be within normal limits. The emphasis during this phase of rehabilitation is on returning lower extremity strength to normal and to begin cross-training for cardiovascular endurance. More advanced balance and proprioception exercises are important components of this phase for the therapist to perform. If the patient is not an athlete, the overall goal at this point is to return to normal activities of daily living without any limitations. If the patient desires to return to sports activities, then additional exercises are added to the rehabilitation program as described below.
Strengthening of the leg and hip muscles is progressed when the patient is able to tolerate new and more diffi- cult exercises. Single-leg exercises such as step-ups, lateral step-downs, squats, and single-leg wall sits may be done. Straight leg raises are performed with ankle weights (up to 10 pounds) for hip strengthening and control. Toe raises are done off of the edge of a step or with weight added for resistance. Wall sits are continued, with a gradual increase in time the exercise is performed. The patient may also hold hand weights to add more resis- tance. Theraband resistance is used with mini-squats and terminal knee extension. Theraband or resistance bands may be used while the patient performs “monster walking” or “crab walking”, or may be attached to a heavy stable surface while the patient performs various hip kicking exercises.
The patient may begin strengthening on exercise equipment such as the leg press (in the range of 80°-10°), knee extension (90°-30°), seated hamstring curls (0°-90°), hip abduction/ adduction, and calf presses. It is important for the patient to be educated on exercises and machines that should be avoided because they place high forces 26 on the patella. These include bicycling with high resistance, stair climbing machines, knee extension machine in the end range of 30-0 degrees, deep squats, and deep lunges.
Endurance training is begun using either a stationary bicycle, elliptical cross-trainer, or swimming for 20-30 minutes at least 3 times per week. Balance training includes balancing on an unstable surface such as a rocker board, wobble board, or balance board in the physical therapy clinic. Balance activities are progressed from two-legged to single-leg standing.
Knee Braces/Sleeves
There are different options for braces or knee sleeves that the patient may use for support after the initial 3 weeks during which they are in a long-leg brace. Elastic knee sleeves that provide mild compression are useful if the patient has recurrent mild swelling. There are many different types of patellar support braces (with or without straps) that help keep the patella located and decrease the risk for recurrent subluxation or dislocation episodes. The physician or physical therapist can provide a recommendation for these types of braces. There are also patellar tendon straps that provide compression on the patellar tendon that may improve patellar stability and decrease pain. Patellar taping is also an option that the physical therapist may suggest to improve patellar stability.
Training for Return to Sports
General Comments The focus of this final phase is on return to full sports activities. By this time, the patient should have no pain, swelling, or limitations with the exercise program. A knee sleeve is used for activity if required. We recommend a gradual progression of specific exercises and drills for patients who wish to return to sports after their injury. The training required will depend on the sport and level of participation the patient wishes to return to that has been approved by the physician. The goal is to prevent a reinjury including not only another patellar dis- location, but other serious problems such as a giving-way episode resulting in a knee ligament tear. We believe training should slowly build the patient’s confidence and ability to perform all of the requirements of their sport. We rate sports according to the specific movements that are required of the knee and lower limb into 3 levels:
Level 1: jumping, hard pivoting, cutting (such as basketball, soccer, volleyball, American football, gymnastics) Level 2: running, twisting, turning (such as tennis, racquetball, handball, ice hockey, skiing) Level 3: low impact (such as bicycling, swimming, water aerobics)
Our sports training protocol consists of 3 programs and, as you will see, not all sports require completion of all of these programs. These include (in order of progression) the running and agility program, the basic plyomet- ric (jump) training program, and the advanced plyometric (jump) and neuromuscular training program.
Return to unrestricted sports in Level 1 is permitted after completion of the advanced plyometric (jump) and neuromuscular training program. Return to unrestricted sports in Level 2 is permitted after completion of the running and agility program; however, some patients may benefit from also completing the basic plyometric (jump) training program. Return to level 3 does not require completion of the running and agility program. However, if the patient wishes to return to level 3 activities, they must still receive clearance from their surgeon.
There are specific criteria or goals that must be meet in order to begin each portion of the training for sports segment of the rehabilitation program, which are detailed below. 27
There are important reasons why we recommend completion of advanced plyometric (jump) and neuromus- cular retraining before patients are allowed to return to sports such as soccer and basketball. These and other activities that require jumping, pivoting, and cutting place the knee at risk for sustaining another injury. Our patients are encouraged to complete our Sportsmetrics program, which offers this final progression of ad- vanced jumps and drills. This program was developed many years ago and is used today throughout the world to prevent noncontact ACL injuries in female athletes. It is also of tremendous value in the final preparation to resume the most strenuous, high-risk sports after any major knee injury or surgery. See http://www.sportsmet- rics.org for more information.
Running and Agility Program In our clinic, the following criteria must be met for patients to begin the running and agility program:
- < 30% deficit in quadriceps and hamstrings strength compared to the opposite side measured on an isokinetic or manual muscle test done by the physical therapist
- A normal patellofemoral examination as determined by the physician (no joint damage, no or only mild pa- tellar crepitus, normally patellar stability, no joint effusion, no tenderness)
- No pain, swelling, or instability with all other activities
- Approval by the physician to begin program
The running program is based on the patient’s athletic goals, particularly the position or physical requirements of the sport that will be resumed when released. For instance, if the patient wants to return back to short dura- tion, high intensity activities, they should focus on sprinting rather than long-distance endurance running.
The running and agility program is performed 3 times per week, on opposite days of the strength program. Since the running program may not provide an aerobic workout initially, the patient should do cross-training (use a stationary bicycle, for instance) to facilitate cardiovascular fitness. The cross-training exercise is done on the same day as the strength workout. There are 4 levels in the running program:
Level I: Straight-ahead run-walk combinations. Run distances: 20, 40, 60, 100 yds (18.29, 36.58, 54.86, 91.44 m) in forward and backward directions. Speed: ¼ to ½ of normal. Gradually progress to ¾ and then to full speed. Interval training-rest approach: rest 2-3 times the length of training.
Level II: Lateral running, crossover maneuvers over 20 yds (18.29 m). Side-to-side running over cups. Sports-specific equipment used to enhance skill development.
Level III: Figure-eight drills over 20 yds (18.29 m) and then decrease to 10 yds (9.14 m).
Level IV: Cutting patterns, directional changes at 45° and 90° angles, progress from subtle to sharp cuts.
Basic Plyometric (Jump) Training Program Plyometric training is begun upon successful completion of the running and agility program provided there is no pain, swelling, or instability with any activity. The jump training should be done on a firm, yet forgiving surface such as a wooden gym floor. Very hard surfaces like concrete should be avoided. A cross-training or running shoe should be worn to provide adequate shock absorption, as well as stability to the feet. During 28 the various jumps, the patient should keep their body weight on the balls of the feet and land softly with both knees bent. The knees should be kept shoulder-width apart on landing.
Plyometric training is performed 2-3 times weekly. Each jump is done for 15 seconds. Three sets of each jump are performed. At first, the patient should rest between each set for 30-45 seconds. The rest time is gradually reduced to 15-30 seconds. The patient should complete as many jumps or single-leg hops as possible and re- cord the number on a training log. The program is progressed as the number of hops completed in 15 seconds increases, along with confidence. There are 3 levels in the basic plyometric training program:
Level I: level surface box hopping, both legs: front-back, side-side, diagonal, pivot hops, 90° and 180° direc- tions. Level II: level surface box hopping, single leg: front-back, side-side, diagonal, pivot hops, 90° and 180° direc- tions. Level III: vertical box hops.
Advanced Plyometric (Jump) and Neuromuscular Training Advanced neuromuscular retraining (such as the Sportsmetrics program - see http://www.Sportsmetrics.org) should be done as end-stage rehabilitation for anyone who wants to return to Level I high risk sports activities (such as soccer or basketball) after a knee dislocation. Whenever possible, each training session should be done under the supervision of a certified instructor, athletic trainer, or physical therapist. In order to begin this final phase of rehabilitation, the following criteria must be met:
- Normal patellofemoral test - < 15% deficit in peak torque for the hamstrings and quadriceps on isokinetic testing (180°/sec and 300°/sec) 29
- < 15% deficit in the distance hopped between legs on single-leg hop for distance and single-leg triple hop for distance tests. In addition, the patient should demonstrate the ability to stick and hold landing with no “wig- gle-wobble” in their knees.
- Successful completion of the running and agility and basic plyometric programs with no pain, swelling, or giving-way - Successful completion of basic plyometric training program - Approval by the physician to begin program
During this final phase of rehabilitation, the patient continues with strengthening and other exercises as rec- ommended by the physical therapist. Plyometrics are done on alternating days (Monday, Wednesday, Friday), with strengthening and conditioning exercises done on the other days of the week (Tuesday, Thursday, Satur- day). It is helpful to keep track of progress using training logs during each session.
The patient must master the jumps in one phase before entering the next phase. This may take longer than the usual 2-week period per phase of the standard Sportsmetrics program. If the patient does not have access to a certified Sportsmetrics instructor, then the program may be accomplished at home with instructional video- tapes. The physical therapy team should be involved at the beginning of each of the 3 stages of Sportsmetrics training in order to provide instruction on correct technique for the jumps.
Release to Unrestricted Sports Activities The following criteria are used at our center to release patients to unrestricted athletic activities:
- Successful completion of phase 3 of the Sportsmetrics training program for patients who wish to return to Level I high-risk sports such as soccer and basketball. - Successful completion of the running and agility program for patients who wish to return to Level II sports that do not involve cutting, pivoting, jumping, and many quick starts and stops. - Normal patellofemoral examination. - No pain, swelling, or instability with any activity. - < 10% deficit in peak torque of the hamstrings and quadriceps on isokinetic testing (180°/sec and 300°/sec). - < 15% deficit in the distance hopped on single-leg timed and triple crossover hop tests. - > 60% normalized knee separation distance on video drop-jump test. - No valgus motion of knee or medial-lateral movement of knee on a single-leg squat test. 30 - Approval by the physician to return to unrestricted activities.
The patient should perform additional cardiovascular endurance and sports-specific agility and skill drills as required for their sport. They should notify their therapist or surgeon if knee pain, swelling, overuse symptoms, or patellar instability episodes occur. The single-leg hop tests and video drop-jump tests are described in detail in references #5 and #37.
Results of Conservative Treatment for First-Time Patellar Dislocation Injuries
Several studies have been published on the outcome of conservative management of acute patellar dislocation injuries. In addition, there have been many systematic reviews that assessed the difference in outcome between conservative and early surgical treatment. The recommendations we provide in this eBook are based on both our experience and the findings of the majority of studies published to date.
In very general terms, approximately 70% of adult patients do well following a program of physical therapy in terms of no future problematic patellar instability or knee symptoms. A recent systematic review of the out- come of conservative management in 1,210 patients found “a large proportion of patients reported acceptable outcomes following physiotherapy” (Smith, 2010). The studies in this review all had different rehabilitation programs, although most used an initial period of immobilization or brace protection to allow joint tissues to heal and emphasized quadriceps strengthening.
It is important when assessing the published results of conservative treatment to separate out patients with high-velocity injuries who do not have any pre-disposing anatomic abnormalities we previously discussed from those who sustain low-velocity injuries who frequently have more than one problematic anatomic factor lead- ing to a high risk for a recurrent dislocation. In addition, the results of initial conservative treatment need to be assessed in terms of the restoration of normal patellofemoral factors such as patellar glide (movement) in order to determine if the injured MPFL and other medial soft tissues have healed.
For instance, one recent study (Sillanpaa ‘09) comprised of patients in military service (mostly young men) followed an average of 7 years after their injury reported that nearly 50% had recurrent patellar instability. All of these patients had a complete MPFL rupture that was not surgically restored. In comparison, a group of pa- tients who underwent early surgical repair of ruptured MPFL and retinacular structures had no further patellar dislocation or subluxation episodes. We recommend that patients who sustain a complete MPFL rupture un- dergo a rehabilitation program first. Then, if the patellar examination still demonstrates an abnormal amount of patellar glide from a lack of sufficient healing, and if the patient demonstrates patellar instability symptoms, an MPFL reconstruction should be considered.
Another recent study (Camanho ‘09) compared conservative to immediate surgical repair of the ruptured MPFL in a group of 33 patients (20 women and 13 men). At 2 years post-injury, none of the patients in the sur- gical repair group had experienced another patellar dislocation episode. Thirteen patients in the conservative group (81%) had patellar instability problems. The problem was that 12 of these 13 patients had predisposing anatomic abnormalities (dysplastic trochlea, valgus malalignment, patella alta) that were not surgically ad- dressed.
One recent systematic review (Hing 2011) of 5 randomized studies found no difference between surgical and non-surgical management of patellar dislocation injuries in regard to the risk of recurrent dislocation, subjec- tive outcome scores, or the need for late surgery. However, another review (Smith 2011) of 11 randomized and nonrandomized studies did find a higher rate of subsequent patellar instability in patients treated conserva- 31 tively versus those treated operatively. In both of these studies, the authors were unable to account for pre-dis- posing anatomic abnormalities and thus, their findings must be taken with caution. This problem had been previously noted by investigators from the Cleveland Clinic (Stefancin 2007) who, in an analysis of 70 studies, recommend conservative management in the majority of patients who sustain first-time patellar dislocation. The exceptions were those we have noted previously in this eBook; the presence of an osteochondral fracture, major damage to the MPFL that does not adequately heal, and recurrent instability problems even after a pro- gram of rehabilitation has been completed.
In terms of treatment of first-time patellar dislocations in children and teenagers, randomized studies and recent review articles recommend conservative management unless there is an osteochondral fracture or other injury such as a meniscus tear. The management consists of a period of protection and crutches, followed by comprehensive physical therapy already outlined in this eBook. Activity modification is required initially and patient compliance must be carefully monitored by both the medical team and the patient’s parents or guard- ians.
Treatment for Chronic Recurrent Patella Instability
General Comments
We believe it is important to emphasize that recurring patellar dislocations or subluxation episodes are a seri- ous problem because they often produce permanent arthritic damage to the knee joint. Patients who present to our clinic with these problems are first counseled to stop or avoid the sport or activity that produces the dislocation or subluxation episodes. They are entered into a comprehensive rehabilitation program that we will describe next, which includes all conservative measures available to correct the muscle and/or anatomic abnor- malities that exist.
It is not unusual that many months of careful exercises and avoidance of high impact loading activities are re- quired to produce relief from symptoms because many patients have very weak leg and hip muscles. They may walk abnormally and have lost the normal amount of motion in their knee. In some patients, just the program of physical therapy greatly improves symptoms and surgery can be avoided, at least in the short-term.
Conservative Treatment, Physical Therapy
First, the patient is advised to stop all sports or other aggravating activities. Swelling and pain need to be re- solved as soon as possible because these problems will hinder and prolong the physical therapy program. Ice is used for 15 minutes 4-6 times a day as needed for these symptoms. Anti-inflammatory medications may be prescribed by the physician. The physical therapist may use EMS or other machines to help resolve pain and swelling if required. An over-the-counter compression knee sleeve or wrap, or patellar taping, may be recom- mended. Options for bracing were previously discussed in the Knee Braces/Sleeves section.
The basic goals of the rehabilitation program are to correct any muscle problems such as weakness, imbalance, or excessive tightness. Muscles targeted include all of those in the lower extremity and hip. Exercises are se- lected that place only a small amount of load on the patella. Initially, the therapist may use EMS and biofeed- back to help “turn on” the quadricep muscles if the patient has a difficult time with muscle control. EMS may be used when the patient is performing exercises such as quadriceps isometrics, straight leg raises, and knee extensions. The therapist may assist the patient with flexibility exercises and perform soft tissue massage if very tight retinacular tissues exist around the kneecap. 32
The therapist assesses the position of the patient’s feet when standing and walking and may recommend arch supports, orthotics, and appropriate athletic shoes. If the patient does not have a normal walking pattern (referred to as gait), then the therapist may add drills and exercises to help resolve this problem. Women are advised to avoid high-heeled shoes.
If the patient is overweight, weight loss and nutritional counseling are provided. This is extremely important because every pound of body weight is multiplied 3-4 times during daily activities and up to 6-8 times with stairs and squatting activities. The patient may not improve and be resistant to the rehabilitation program until a normal body weight is achieved. If the patient is of normal weight, they are advised to be careful to maintain their current weight and reduce their fat and caloric intake due to the reduction in their activity level.
Strengthening of the leg and hip muscles is progressed when the patient is able to tolerate new and more dif- ficult exercises. Single-leg exercises such as step-ups, lateral step-downs, and single-leg wall sits may be done. Machines may be incorporated into the program such as the leg press, hamstring curl, and hip abductor-ad- ductor or multi-hip. Theraband or resistance bands may be used while the patient performs “monster walking” or “crab walking”, or may be attached to a heavy stable surface while the patient performs various hip kicking exercises.
In addition, drills are used to increase what is called proprioception and neuromuscular control. Propriocep- tion is the awareness you have of movement or position of your body or a part of your body. This is what allows us to walk without looking constantly at our feet. It allows us to drive without watching our feet on the pedals and our hands on the steering wheel. Neuromuscular control is the interaction between the brain and move- ment of any parts of the body. Elite athletes usually display phenomenal neuromuscular control as they per- form difficult maneuvers in their sport during competition.
Exercises to improve proprioception and neuromuscular control initially include weight shifting side-to-side and diagonally, mini-squats on the floor and then on an unstable surface, wall sits, and balance exercises with a ball toss. The exercises are progressed in difficulty and complexity based on the patient’s response to the pro- gram and future activity goals.
It is very important for the patient to be educated on exercises and machines that should be avoided because they place high forces on the patella. These include bicycling with high resistance, stair climbing machines, knee extension machine in the end range of 30-0 degrees, deep squats, deep lunges, and plyometrics.
It is also important to maintain or increase the strength of the core and upper extremity (arms, shoulders, back) muscles during the rehabilitation time period. Core strengthening focuses on stomach and back muscles and may be helpful in improving overall balance. Cardiovascular endurance training is done with “knee friend- ly” low impact devices such as an elliptical or ski machine and/or swimming when a pool is available. Wa- ter-based exercises are especially encouraged in patients who are overweight. These involve not just swimming, but a variety of strengthening and balance drills that help build overall body strength.
Static flexibility exercises are done by the patient at the end of each exercise session for the quadriceps, ham- strings, calf muscles (gastrocnemius/soleus), hip muscles, and iliotibial band. The therapist may also perform what is called proprioceptive neuromuscular facilitation, in which stretching may be accomplished by either passive or active assisted means. Passive means the therapist moves the limb to achieve the stretch as far as possible while the patient lies completely relaxed. Active assisted means the patient is also involved. For ex- ample, for the hamstrings, the patient lies on their back on a table and the therapist brings one leg up with the knee kept straight as far as possible until the hamstrings stretch is felt. Then, the patient is asked to tighten the 33 quadriceps muscles and push against the therapist for a few seconds. Then, the patient completely relaxes and the therapist will stretch the leg further, which promotes even better hamstrings flexibility.
For patients who desire to return to sports activities and who have received approval from their surgeon and therapist to begin more strenuous training, a gradual approach is advocated as discussed in detail in the pre- vious section in this eBook, Training for Return to Sports. It is imperative that the patient still be under the supervision of their physical therapist and that any activity that brings about pain, swelling, or instability be stopped immediately. In our clinic, patients who have arthritic damage in their knee are encouraged to return to low-impact aerobic and strength training activities only.
What to do When Conservative Management Fails
After the patient has rehabilitated to the best of the medical team’s ability, an evaluation is made of the condi- tion of the knee joint. If problems persist, surgery may be required to correct the distinct anatomic problems that are believed by the surgeon to be causing the recurrent patellar instability. The goals of surgery are to correct any malalignment issues, balance soft tissues, and reconstruct torn or deficient ligaments (especially the MPFL).
Many different types of operations have been described in the medical literature for extensor mechanism malalignment. The decision of which procedure to perform is based on the number and extent of anatomic problems that exist. This is where the physical examination and either CT or MRI determine important factors such as the Q angle, patellar translation (glide or movement) and tilt, lower limb rotational alignment (femoral anteversion and external tibial torsion), shape of the trochlear groove, the tibial tubercle-trochlear groove (TT- TG) distance, and patellar height (to diagnose a high riding patella [patella alta]; positive J sign).
In addition, several types of operations may be done for patients who have significant damage to the knee joint lining (articular cartilage). These range from removal of loose bodies and fragments of articular cartilage to cartilage restoration procedures discussed later in this section. The goals of treatment are to restore function and allow the patient to resume normal activities, depending on the damage that is present. Another goal is to prevent further damage because this may lead to the necessity of a joint replacement years later.
When the damage to the articular cartilage becomes severe and, over time, the normal amount of joint space is lost, a partial or total knee replacement may be required. Replacing just the patellofemoral joint is a valid treat- ment option, especially in patients 40-50 years of age (and sometimes younger) if other operations have failed to alleviate their kneecap pain and the medial and lateral compartments of the knee are not damaged. We have written a separate eBook, “Partial Knee Replacement: Everything You Need to Know to Make the Right Treat- ment Decision” which discusses the issues of replacing just a portion of the knee joint.
Choosing an Orthopaedic Surgeon in the U.S.
We recommend that you see a board-certified and fellowship-trained orthopedist for any serious knee prob- lems or operations. The training of an orthopaedic surgeon takes many years of undergraduate college, medical school, and residency education. Most surgeons finish residency training around the age of 30. Then, some choose 1-2 years of additional education known as a sports medicine or joint replacement fellowship in order to receive still more training in order to diagnose complex injuries and perform modern operations. 34
Orthopaedic surgeons may elect to become “board certified”. This means they must pass rigorous examinations above and beyond those required in medical school and residency. This certification is optional in the United States. Board certified surgeons actively participate in education and stay up to date with the latest advances in medicine and patient care.
Seeing a board certified and fellowship-trained orthopedist is especially important if you decide to have ma- jor surgery to correct patellar instability. The diagnosis and operations are quite sophisticated and should be performed by a physician who has had specialized, advanced training. We believe the success of knee surgery is based on 2 things: the ability of the surgeon to do the operation correctly and the ability of the physical therapy program to restore the best knee function possible. It really is a 50-50 process, with both of these issues sharing an equal role in the overall success or failure of the operation to get you back to activities.
The American Orthopaedic Society for Sports Medicine has a list of orthopaedic surgeons at http://www. sportsmed.org. As you can see from this society’s website, “Members must demonstrate continuing active research and educational activities in the field of sports medicine. Such activities may include service as a team physician at any level of competition, educating persons involved with the health of athletes, service to local, regional, national and international competitions, and the presentation of scientific research papers at sports medicine meetings.”
If you live in a large city with a major university or sports medicine center, that is one place to search for a board certified, fellowship trained orthopaedic surgeon. As well, you may know someone who underwent ma- jor knee surgery and had a successful result and seeing his or her surgeon is certainly a good place to start. It might help to consider “interviewing” a potential surgeon before you decide on who will perform your par- tial knee replacement operation. Some questions to ask are:
Do you treat patients with patellar instability on a routine basis?
Do you believe I should try physical therapy first, before surgery is considered?
If surgery is required, what are your preferred procedures? About how many of these do you do each year?
Where will my physical therapy be done? Who will my therapist be, and how long have you worked with the therapist? (Most surgeons have a few physical therapists they know and trust to work with patients who under- go major knee surgery. What you do not want is for the surgeon to leave finding a therapist in your hands!)
If I have surgery, do you or my therapist have a list of exercises that I will need to do postoperatively? Will I see my therapist before the operation to learn about the exercises? Will I be doing exercises at home? How often?
Can I talk to someone in your insurance department about my coverage, both for the operation and physical therapy visits?
How soon will I see you and my therapist after surgery? (We recommend 24-48 hours to make sure your mus- cles are working properly, the incision looks good with no signs of infection, and you understand the exercises you should be doing. We believe waiting 1 week or so after surgery is too long and that early therapy prevents many problems.) 35
Operations to Correct Patellar Instability
Many different operations have been described in the medical literature to treat patellar instability problems. The decision on the appropriate procedure or procedures to perform is based on the anatomic abnormalities that exist. Therefore, the operation should be individualized for each patient based on the extensive examina- tion we previously discussed. A MRI and lateral x-rays allow the surgeon to measure all of the indices required, including the patellar height. It is particularly important to determine if a high-riding patella (patella alta) is present. This requires a distal advancement of the tibial tubercle to regain patellar stability, as we will discuss later. For the majority of patients, a program of physical therapy should be completed first to correct muscle weakness or imbalances before any operation is performed.
Examination Under Anesthesia
For all operations, the patient is first placed asleep under anesthesia. The surgeon performs the same tests done in the clinic to assess crepitus in the patellofemoral joint, patellar tilt, passive medial-lateral patellar glide, and the Q angle. A diagnostic arthroscopy is performed and any intra-articular pathology is evaluated and treated. Particular attention is paid to patellar position, mobility, tracking, and the condition of the articular cartilage surfaces. The patella and femoral groove are inspected for damage or dysplasia. The medial and lateral move- ment of the patella is observed with the arthroscope at two different knee flexion angles (0 and 30 degrees).
Lateral Release
A lateral retinacular release is only performed if there are contracted and tight lateral tissues that prevent a normal medial patellar glide. In these cases, the patella cannot be moved more than 5 mm in the medial direc- tion under relaxed conditions. A lateral release is not performed alone for patellar instability problems, but is combined with other operative procedures such as a MPFL reconstruction. A lateral release is performed with the use of an arthroscope and a commercial radiofrequency wand which is guided through one of the small portals, or puncture wounds created in the knee. The wand is used to cut and divide the lateral retinacular tissues, which is done in a slow and careful manner to avoid cutting the insertion of the vastus lateralis muscle and the lateral soft tissue restraints. The arthroscope allows the surgeon to see and guide the resection. After the retinaculum has been incised, the surgeon checks to see how far the patella can move. When it can move in a normal manner, the procedure is concluded.
In severe cases of contracture of all of the lateral tissues (that also involves the vastus lateralis muscle and ten- don), an open procedure with an incision is required. The lateral tissues and tendons are lengthened in what is called a “z plasty” release. This procedure preserves the function of the vastus lateralis tendon and prevents excessive medial patellar glide which would occur if all of the lateral restraints were released.
Proximal-Distal Realignment Procedures
In patients with extensor mechanism malalignment, the operations performed are generally referred to as a proximal realignment, distal realignment, or a proximal-distal realignment. Basically, proximal realignment procedures change (tighten or loosen) the movement of the patella in the medial-lateral (side-to-side) direc- tions. These procedures include lateral retinacular release, medial retinacular capsular and MPFL plication, VMO advancement, and MPFL repair or reconstruction.
Distal realignment procedures correct an abnormal Q angle, which is based on the excessive lateral (outside) position of the attachment of the patellar tendon at the area of the tibia referred to as the tibial tubercle. The 36 most common procedure (called an osteotomy), which may be done through a small incision, involves cutting bone directly at the tibial tubercle attachment. The bone is moved in a medial direction in order to restore a normal Q angle. Small screws are used to stabilize the new position of the tibial tubercle. In technical terms, this procedure restores a normal tibial tubercle-trochlear groove (TT-TG) relationship. It is only performed when there is an obvious abnormal Q angle, and there is some controversy among surgeons regarding when it should or should not be done. An example of an indication is a markedly abnormal lateral position of the tibial tubercle, determined by an abnormal TT-TG ratio as measured on MRI (greater than 20 mm). This operation is advantageous because it decreases forces on the lateral patellar undersurface. The arthroscopic evaluation performed just before the procedure is valuable because it determines the location and amount of cartilage damage that is already present and helps to determine the possible expected benefits of the realignment.
A difficult condition to treat is a combination of patellar instability and a knock-knee (valgus) alignment. This is always associated with an abnormal lateral position of the tibial tubercle and abnormal Q angle. In these cases, a distal realignment is required; otherwise, the proximal MPFL procedure will fail to provide stability. In some knees, the proximal realignment is not required because the distal realignment alone may correct an ex- cessively abnormal Q angle. In some cases, it is necessary to correct the valgus alignment with a bone operation called an osteotomy which is done at the femur and tibia.
The above descriptions of the common operative procedures indicate the importance in diagnosing all of the anatomic abnormalities that exist in order to determine the appropriate combination of procedures to perform. You should feel comfortable discussing the reasons why one or more procedures are selected by your surgeon and the rationale for each.
Overall, in our clinic, the most common procedure performed is a proximal realignment. The distal realign- ment is only done in patients who have abnormal findings just described that require complete correction. The problem is that a distal realignment adds to the postoperative pain level and delays rehabilitation, altering the quadriceps strengthening program for 4 weeks to allow for healing of the bone cut. Accordingly, the rehabilita- tion program is 1-2 times more intensive than that required after a proximal realignment.
There are a few special problems that require further discussion. First, in patients who have patellar instability who are young and still growing, a proximal realignment may be performed, but a distal realignment is avoided because the growth plates are still open and could be damaged.
Second, as we mentioned previously, it is critical for the surgeon to determine if a patella alta position exists, in which the patella position is higher than normal due to an elongated patellar tendon. In these cases, the patella moves too far laterally with knee extension. You can tell if this is present by sitting in a chair with your feet flat on the floor (knee joint at 90 degrees of flexion). If the patella is pointing upward towards the ceiling rather than straight ahead and parallel to the floor, than you have a high riding patella. The surgeon will make specific measurements of the patellar position and length of the patellar tendon. The patella must just start to engage the trochlea in full knee extension. The purpose of the distal realignment is to move the tendon attach- ment at the tibial tubercle in a distal direction in order to accomplish this engagement. In addition, an MPFL reconstruction is usually required in these knees. The measurement procedures performed by surgeons are discussed in detail in other publications (Noyes FR, Barber-Westin SD. Operative options for extensor mecha- nism malalignment and patellar dislocation. In: Noyes FR, ed. Noyes’ Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes. Philadelphia: Saunders; 2009:995-1025 and Parikh S, Noyes FR. Patellofemoral Disorders: Role of Computed Tomography and Magnetic Resonance Imaging in Defining Abnormal Rotational Lower Limb Alignment. Sports Health: A Multidisciplinary Approach. 2011;3(2):158-169). 37 Details of the surgical procedures for proximal realignment, distal realignment, and correction of patella alta are provided in the Appendices
Proximal Realignment (Tightening Existing Tissues)
At the time of surgery, through a small incision located next to the patella, the surgeon inspects and examines the medial ligaments including the MPFL. When these ligaments are judged to not have healed and are of insufficient thickness and integrity, an advancement or tightening procedure (plication) is performed. Com- monly in men, the medial ligaments are intact but loose and the plication procedure is successful. However, in many patients (especially women) the medial ligaments are thin and insufficient from previous injuries. In these cases, an MPFL reconstruction is necessary along with the proximal realignment procedure.
MPFL Reconstruction Plus Proximal Realignment
If the patella can be moved laterally greater than 75% of its width and a deficient MPFL and medial retinacu- lum are detected, then a reconstruction is necessary. Many different types of MPFL reconstruction have been described in the literature; most use grafts to replace the deficient ligament. Grafts commonly selected include the quadriceps tendon, the semitendinosus tendon, and the gracilis tendon (all taken from the patient’s own leg). Allografts (tissue taken from cadavers) may occasionally be used. However, we believe using the patient’s own tissue is a safer option. Details of our preferred surgical procedure for a MPFL reconstruction are provided in Appendix 2.
Trochleoplasty
In some knees with trochlear dysplasia, the trochlea is both flat and has an abnormal bump on the lateral por- tion, referred to as a “trochlear bump”. This can block normal patellar alignment and prevent the movement of the patella into the center of the trochlea. There is an operation known as a trochleoplasty in which the bump is removed and a new central trochlear groove of added depth (about 6 mm) is created. This is considered a salvage, end-stage procedure for recurrent patellar instability in patients that have undergone other operations that failed. It is performed only for recurrent instability and not for patellar pain. Patients are advised that the abnormal dysplasia will most likely result in arthritis, even after the operation.
Operations for Damage to the Joint Lining (Articular Cartilage)
There are different operations that may be performed for damage to the joint lining in the patellofemoral joint. The decision of which to perform depends on the extent of the damage that the surgeon sees during the ar- throscopic examination. Some patients require both a procedure to correct malalignment and a second proce- dure for the joint lining damage, which may be done at the same time.
Arthroscopic Debridement
An arthroscopic debridement (sometimes referred to as a “clean out”) is used for patients who have cartilage fragmentation of joint surfaces, recurrent swelling not controlled by medications, and cartilage fragments float- ing inside the knee joint. This procedure is done for mild to moderate cases of joint damage, where knee pain, catching, or locking occur that are not resolved with the conservative treatment protocol we described earlier in this eBook. The tissues that may cause these symptoms are loose pieces of articular cartilage (called “loose bodies”) and small tears in a meniscus. Another frequent problem is articular cartilage that is fragmenting or 38 flaking off of the patellar or trochlear surface.
An arthroscope, a small fiber-optic TV camera, is inserted into the knee through a very small puncture wound (called a portal). The arthroscope sends images (which are greatly magnified) to a television monitor for the surgeon to see. The surgeon inserts small instruments into a second portal in the knee and removes or shaves any loose pieces of cartilage if they are still intact, removes any floating pieces of cartilage, and removes any chronically inflammed tissue. Fluid is also washed through the joint to remove debris.
This operation may provide short-term relief of symptoms and improvement in knee function; however, the amount of time that the benefits last is questionable and will vary from patient to patient. The operation does not stop or delay the arthritis process from continuing and it is expected that, in time, knee pain and problems will return. The recommendation for joint debridement is when the indications already described limit the normal function of the knee. This is the easiest operation of all described in this eBook to recover from and the potential benefit is that there may be a short-term relief of pain, patellar grinding, and knee limitations that can improve the patient’s quality of life, help with weight loss if required, and help promote a more active lifestyle.
Microfracture, Abrasion Arthroplasty
There are surgical procedures such as microfracture, abrasion arthroplasty, and drilling (also referred to as marrow stimulation) that are designed to produce tissue to replace small areas where articular cartilage has worn away. The tissue created by these operations is called fibrocartilage (or scar cartilage). The operations cre- ate bleeding from the marrow of the cancellous bone that lies underneath the articular cartilage. Stromal stem cells (also referred to as mesenchymal stem cells) from the bleeding bone marrow form clots that gradually change into fibrocartilage.
Fibrocartilage is not the same as normal hyaline articular cartilage because it has inferior strength and resil- iency. Therefore, the areas of fibrocartilage may deteriorate over time. Marrow stimulation procedures are used by some surgeons as a “first-line” operation in young active patients who have small areas of cartilage damage, typically 2-3 cm2. They are not appropriate for inactive patients or those who have widespread arthritic dam- age.
Marrow stimulation operations are done with the use of an arthroscope. Any loose or fragmented pieces of articular cartilage are removed from the joint. In the microfracture procedure, a small “pick” or “awl” (similar to an ice pick) is used to create small holes that go through the surface bone into the underlying marrow. The holes are spaced about 3-4 mm apart. As many holes are created as required to fill the area of articular cartilage defect.
Microfracture appears to have limited success in terms of reducing knee-related symptoms and allowing an increased level of activity, and the results tend to deteriorate with time. Overall, studies typically report poor- er results in patients older than 40 years of age, those who are overweight (body mass index greater than 25), patients with articular cartilage defects in multiple locations, and those with defects greater than 2 cm2 in size. Many surgeons have noted that microfracture is not successful for patella or trochlear lesions. There have been preliminary data recently published that found that a prior microfracture decreased the success of a future autologous chondrocyte implantation procedure in some patients.
There has recently been interest in “enhancing” microfracture by incorporating a collagen scaffold in an at- tempt to shield the stem cells and prevent them from migrating into other parts of the knee joint. The scaffold is placed directly over the microfractured area and held in place with fibrin glue. The belief is that the greater 39 number of stem cells kept in the lesion will produce a larger number of chondrocytes, resulting in the produc- tion of hyaline cartilage instead of fibrocartilage. To date, only two small case series from Germany and Italy have been published and conclusions cannot be reached on these operations from the limited data available.
Osteochondral Autograft Transfer
This operation, referred to as mosaicplasty, OATS, osteoarticular transfer system, or osteochondral autograft transfer, is indicated for cartilage defects that are relatively small (2-3 cm2) and surrounded by normal appear- ing cartilage. Larger, deeper defects do not do as well with this operation because of the technical limitations of the procedure. The operation is indicated for younger, active patients under the age of 50 who have a normal or nearly normal amount of joint space on x-rays. The repair tissue typically consists of approximately 80% hya- line (articular) cartilage and 20% fibrocartilage. The durability of the repair tissue and long-term benefits have not been established. Studies have shown that approximately 50% of carefully selected patients with cartilage defects on the undersurface of the patella treated with this procedure have good results, at least in the short- term. When this procedure fails or knee pain and limitations return, a second operation or other cartilage procedure is required.
This operation is done initially with the use of an arthroscope for one to two cylinder plugs or with a small incision for larger areas of damage that require three or more plugs. Any loose or fragmented pieces of cartilage are removed from the knee. The area of cartilage damage is measured to make sure the osteochondral autograft transfer procedure is indicated. Then, small cylinder plugs of healthy bone and articular cartilage are harvested from the same knee, usually from low pressure edges of the femoral condyles. The plugs that are taken vary in size and number according to the size of the defect to be filled. They are usually 6-8 mm in diameter. If the patellar undersurface is treated, an incision is required to directly view the patellar cartilage and perform the operation. Drill sockets are created within the defect and the plugs are inserted. The goal is to fill as much of the defect as possible (usually, 80-100%) to create a congruent surface. After surgery, the goal is to decrease pain, although limitations in physical activities usually remain with sports and patellar cracking may still occur.
Autologous Chondrocyte Implantation
For large areas of joint lining damage, a procedure called autologous chondrocyte implantation (ACI), or Car- ticel, may be considered. The first generation of this surgical procedure was developed in the late 1980’s-early 1990’s. It actually involves 2 operations. In the first, the surgeon takes a biopsy of healthy articular cartilage from your knee. Then, the cartilage is sent to a laboratory where it undergoes a 4-6 week process where mil- lions of cells known as chondrocytes are grown. Then, the surgeon implants these cells into the damaged area of the knee under a graft made of periosteum (tissue from the lower leg), where they grow to form new artic- ular cartilage. This operation has a 50/50 percent chance of decreasing pain with daily activities. However, it does not allow the resumption of strenuous athletic activities.
Now, “second” and “third” generation variations of ACI have been developed. These include the use of scaffolds and growth factors in an attempt to improve the results of this procedure. It is important to know that there are still many surgeons performing first generation ACI, especially in the U.S. where the second and third genera- tion ACI products have not been approved by the Food and Drug Administration (FDA).
In the U.S., only one company (Genzyme) has approval from the FDA to provide the laboratory services of cul- turing and growing chondrocytes. The cell therapy product is called Carticel and has been available since 1997. Patient candidates are under the age of 50 (must be skeletally mature) with complete loss of articular cartilage to bone. There must be a normal or nearly normal amount of joint space in the knee between the femur and 40 patella. The cartilage lesion must be surrounded by normal or nearly normal articular cartilage. It is possi- ble to treat more than one lesion in the knee at the same time. The patient must have normal lower extremity alignment, normal patellar tracking, functional menisci, functioning knee ligaments, and a normal body mass index. If there are any problems with these factors, they may be surgically addressed at the time of the ACI. For instance, if a patient has extensor mechanism malalignment, a proximal-distal realignment may be done at the same time as the second ACI operation when the cells are implanted into the knee. ACI is not indicated for patients with widespread osteoarthritis.
Clinical studies have reported that first-generation ACI appears to improve pain and knee limitations in ap- proximately 50% of patients with patellar lesions. This operation has helped many patients return to activities of daily living and, in some, light recreational activities. The goal is to decrease pain, although limitations usu- ally remain with demanding sports and patellar cracking may still occur.
The downside is that the healing fibrocartilage that fills the defect is not normal cartilage. It is difficult to reli- ably know which patients will benefit from the operation and which patients will continue to have symptoms. Few studies have been published to date on the results of second and third-generation ACI for patellar lesions. The majority of investigations represent case series and have potential conflicts of interest because the compa- nies that produce and sell the product contributed financial assistance to the investigation. Patients have typi- cally only been followed for a few years after surgery, which is too preliminary to assess the durability of these operations. It remains questionable if ACI will produce long-term desirable results for patellar lesions.
Preparing for Surgery
We realize that differences may exist between what your surgeon might recommend and what we tell our pa- tients in terms of getting ready for surgery. However, we believe that the information we will share with you is valuable and will make your life easier, especially in the first week or two after surgery.
Getting Your House Ready
There are important steps to take to prepare for your surgery. Preparation of your home, purchase of appropri- ate medications and food, and arranging for assistance for the first week after surgery should all be done well before you go to the hospital. We recommend to our patients that they take the first week off from school or work to stay home and rest. Make the necessary arrangements with teachers, school administrators, or your employer as required.
We ask our patients to have someone in their home assisting them at all times for at least the first week after surgery. We cannot stress how important this is, as for the first few days you will be on strong pain medication and will not be up to doing basic things such as cooking or cleaning. Your doctor and hospital staff will ask you to avoid making any major decisions for the first few days due to the effects of the anesthesia and pain medica- tion.
During the first week after surgery, you should be lying down on a bed or couch with your leg elevated above your heart as often as possible to help control swelling. The only exceptions are when you are doing your exer- cises or attending to personal bathroom needs. This is a critical time period to control pain and swelling, and the constant elevation of your leg is quite helpful.
Try to arrange your sleeping room on the first floor of your house. If you live in an apartment or residence on 41 another floor, we recommend you plan on staying put in your home for the majority of time the first week after surgery. You will most likely be on crutches, with the amount of time is up to your surgeon’s protocol, but we recommend avoiding stairs as much as possible the first week after surgery. A slip or fall could be disastrous for your knee or other parts of your body!
Set up a bed or a foldout couch in either a bedroom or other room on the first floor if possible, and put a good sized table next to it so you can keep medication, ice bags, water bottles, food, etc. right next to you. Place a towel over the table so you won’t have to worry about spilling water or food. Also, if there is a couch or recliner with a leg rest on the first floor, make sure there is a table next to it also for your supplies and cover it with a towel.
Have a good stock of books, magazines, movies, etc. on hand that can keep you occupied while you are resting on the bed or couch. Put fresh batteries in the remote control for your television! Charge up any item you plan on using, such as your music listening device, cell phone, and laptop computer.
If there will be someone living or staying with you the first week, they can get fresh clothes when you need them. If you may have time periods where you will have to be alone, have clean clothes ready close to where you will be spending most of your time. It will be somewhat difficult to put shoes on initially until you regain flexion in your knee. So have slippers, flip-flops, or shoes that you can slip on and off easily readily available.
Hopefully, you have a bathroom on the first floor or close to where you will be sleeping that you can use for at least the first week after surgery. Move all of your supplies into this bathroom, including toothbrush, tooth- paste, comb, brush, shaver, shaving cream, soaps, make-up, etc. Make sure you have an ample supply of toilet paper and tissue paper!
You will not be able to drive for a while after surgery. Your surgeon will tell you when you are allowed to drive or operate machinery. The rules we follow are the patient must be off of all prescription pain medications, be able to adequately bend their knee to sit comfortably in the driver’s seat, be 50% weight bearing, and be able to produce a good quadriceps contraction. Therefore, arrange for someone to drive you to your postopera- tive appointments to see your surgeon and physical therapist, and any other places you will need to go, for at least a few weeks after surgery. If you have to take a taxi, know the amount of money you will need and obtain the cash before surgery. Try to avoid public transportation. Even if you are on crutches, the chances of being pushed, shoved, or falling are not worth it, as damage can occur to your knee.
Your surgeon and the office staff will advise you on the preoperative hospital or laboratory tests that will be required, which usually are done within a week before surgery at the facility where your operation will take place. You will also undergo a physical examination. This will involve a thorough history of any medical con- ditions you have had, any other operations you have undergone, and current medications you are taking. It is quite helpful to bring along a list of all of your medications (include the name of the drug and dose you take) or the actual bottles of drugs. If you have had any operations in the past, write these down along with the dates to make this process easier. The examination will most likely involve a chest x-ray, blood pressure and tempera- ture readings, urinalysis, and blood tests. Other tests may be necessary as required by your physician.
Food and Medications
After surgery, we prescribe 1 aspirin a day for 5 days, a non-steroidal inflammatory drug (NSAID) for at least 5 days (unless contraindicated for stomach or heart disease issues), and pain medication for the first 2-3 weeks. Before the operation, any other medications you routinely take (such as blood pressure or allergy) are dis- 42 cussed to determine when they may be resumed postoperatively.
If, for instance, you normally take aspirin, NSAID, or Advil, you should stop 10 days before surgery. This is to reduce a complication of excessive bleeding during surgery. Also, medications for diabetes (insulin pills) should not be taken the day of surgery.
Well before surgery, make sure you have refilled your routine medications that have been approved by your doctor to be resumed immediately after the operation. You should also purchase whatever medications your surgeon will ask you to take after surgery, including aspirin, anti-inflammatory, and prescription and non-pre- scription pain drugs. Ask your surgeon what non-prescription pain medication you should take once you are weaned off of the stronger prescription drug. Many patients do not like the “feeling” of prescription pain drugs and try to stop taking them as soon as possible after surgery. You will need to switch to a non-prescription pain medication, such as Tylenol (acetaminophen), Motrin (ibuprofen), or Aleve (naproxen) as determined by your surgeon because the control of pain is of tremendous importance. If your pain is not adequately controlled, you will not be able to do your knee exercises and may have an increased risk of a complication such as muscle atrophy or loss of normal knee motion.
One other item to have on hand from the pharmacy is a laxative. Unfortunately, one side effect of surgery and pain medication is constipation. If you have never taken a laxative before, ask your surgeon for advice. If you already suffer problems with constipation, eat lightly and decrease meats and bulky food 2 days before surgery.
We recommend that you eat a yogurt product the week before surgery to lessen the risk of operative antibiotics disturbing normal intestinal flora, causing diarrhea.
In terms of what you will eat and drink after surgery, you will be thirsty the first few days (another side effect of the surgery and pain medication). Plan on having either bottled water or someone who can get you glasses of water as you require. We recommend staying away from carbonated beverages after surgery. Food should be light and easy to digest - avoid heavy sauces, creams, and spices. Try not to consume a lot of sugar and sodium (salt). Reducing your sodium intake may help with the swelling you will have in your knee, or that may develop in your foot/ankle. Make a trip to the grocery store the day before surgery and carefully select items that will be easy on your stomach. You should have someone prepare your meals the first week after surgery. If necessary, you can prepare “comfort food” and freeze it so it can be eaten as you wish. You won’t need (or want) to eat large meals, but you will need to eat some food each time before you take pain medication.
Make sure you have a good supply of gallon-sized plastic bags on hand, or other bags that can be used to hold ice. You will be applying bags of ice to your knee quite frequently. If you do not have a reliable icemaker in your home, purchase a few bags of ice to have on hand for at least the first week after surgery. A bag of frozen vege- tables (for example, peas) may substitute for ice bags. A portable ice wrap machine costs approximately $150- 200 and is highly beneficial. The ice wrap dressing is worn continuously and the temperature is controlled.
You will need to take your temperature twice a day for about the first week after surgery, so make sure you have a working thermometer.
If you have pets, make sure you have a good supply of food and any other material (such as cat litter) they may require. If you have a dog that needs to be walked daily, find someone to handle this for you until you are off of crutches and can walk comfortably. If you can, pay any bills that are due or will be due the week after surgery. Have some cash on hand. 43 Practice the Exercises You Will Do After Surgery
If you have not already worked with a physical therapist before your operation, you will need to find one and have a consultation before surgery. Your surgeon should be able to recommend a physical therapist that he or she is familiar with and trusts to handle your important postoperative exercise program. We believe it is vital to have a good and trusting relationship with your therapist and the support staff (physical therapy assistants, athletic trainers, personal trainers), because you will be spending more time with these individuals than with your surgeon after the operation.
All of our patients see a physical therapist and learn the exercises they will perform at home a few days before their surgery. They are provided with a list of the exercises and how many or how long each one should be done every day. It is extremely important that you begin gentle range of knee motion, ankle pumps, and quadriceps isometrics the day after surgery. Find a place (preferable on the first floor) in your residence where you can do the exercises comfortably and safely.
You will most likely need to use crutches or a cane after your surgery. Your physical therapist should instruct you on the correct way to use them and make sure they fit you properly. Practice using your crutches (includ- ing going up and down stairs) so you are comfortable and confident with them before surgery. Take up any small throw rugs in your house, as these can be hazardous when using crutches. Consider purchasing a back- pack to use to carry items if you will be on crutches for a few weeks or longer.
Mental Preparation
An important aspect in getting ready for surgery is the development of a positive attitude and willingness to work hard every day for as long as is required to regain normal function in your knee. Getting the most infor- mation you can (such as reading this eBook) about surgery and rehabilitation is quite helpful for this process. This is why we make sure our patients meet with their physical therapist before surgery and have a comfort lev- el with the postoperative process. Don’t hesitate to ask any question, regardless of how you think it may sound, to your medical team. Fears of the operation and lengthy rehabilitation are to be expected. It is helpful to talk through these feelings with your friends, family members, and medical support staff. A complete understand- ing of what you are about to go through is extremely useful in developing a positive attitude.
Your medical team should provide you with realistic expectations and goals of the surgery. It is important to also realize that the recovery from surgery may take many months.
There are online message and support boards that can be helpful as you deal with your surgery and recovery, such as KneeGuru.com. Don’t hesitate to use these measures for support; however, be cautious and understand that patients recover in different time frames. Always use your own surgeon and physical therapist for deci- sion-making and determination of your progress. Do not become frustrated or lose your motivation because some patients seem to be making better progress than you both before and after surgery.
The Night Before Surgery
Your surgeon will ask you not to eat or drink anything after midnight (or at least 8 hours before surgery). This is called NPO, or nothing by mouth. It includes everything, even water. If you have medication you must and are allowed to take the morning of your operation, it should be done with a very small sip of water. The pur- pose for NPO is to reduce the risk of vomiting during the operation. 44 If you have a cough, fever, or open skin sore, call your surgeon’s office as this may prevent you from having surgery.
Try to get a good night’s sleep! Don’t consume excessive food or beverages (especially alcohol). You want to wake up feeling fresh and ready for the day ahead. If you are very anxious about surgery, your doctor can pre- scribe a mild evening sedative to help you sleep.
It is important to wash your body and the leg to be operated on with antibacterial soap 3-4 days before surgery, the night before, and the morning of surgery. We recommend Hibiclens (chlorhexidine) bottled soap that you may purchase at a pharmacy. This markedly reduces skin bacteria. If you have had a MRSA (methicillin-resoap thataphylococcus aureus) or other skin infection, be sure to tell your physician. MRSA is a very potent bacteria and may reside or colonize in the interior of your nose, which is detected by a preoperative nose culture swab.
The Day of Surgery
Take a shower the morning of surgery before coming to the hospital. As we just discussed, wash the leg to be operated on with Hibiclens. We ask our patients not to shave the leg that will be operated on. The staff at the hospital will take care of shaving the desired area of your knee and leg so you don’t accidentally cut yourself, which might prevent the operation from occurring that day. Let your doctor know if you have a tape or Iodine allergy or any antibiotic or medicine allergy.
Leave all of your jewelry at home, as none can be worn to the operating room and the hospital staff cannot be held responsible for any lost items. Bring a pair of loose fitting shorts and a shirt that is easy to pull on. Wear tennis shoes and bring socks. If you were given elastic TED hose stockings, a brace, or crutches, bring these items as well.
If your surgeon has approved any medication to be taken, do so at this time. Use as little water as possible to swallow the medications.
We ask our patients to arrive at the hospital 90 minutes ahead of the estimated starting time of the operation. You should bring something to read or listen to while you wait. Unless you have the very first starting time of the day, be prepared to wait even longer than your designated starting time. Some operations take longer than anticipated, and it is difficult to know in advance exactly when your surgery will begin.
You will eventually be called back to the “preop” area, which is usually located very close to the operating rooms. Here you will be assigned a nurse who will verify your medical history and current medications. The nurse will ask you if you are allergic to any medications.... and this will happen several times with other hos- pital staff, so don’t be surprised. Your nurse will immediately check your blood pressure, temperature, and oxygen saturation of hemoglobin in the blood (with a small pulse oximeter that is attached to your finger). Do not worry if your blood pressure is higher than normal because this is expected if you are nervous about the operation. Your nurse will begin your intravenous line (and attach monitors to allow your vitals to be watched during the operation. These include electrocardiography pads placed on your chest to monitor your heart rhythm, the pulse oximeter, and a blood pressure cuff.
You should have already discussed anesthesia with your surgeon. In addition, the anesthesiologist who will be involved with your operation will meet with you while you are being prepped. The anesthesiologist’s goal is to take you smoothly from your normal, awake, relaxed condition - to sleep in the operating room - to an awak- 45 ened state in the recovery room.
Your anesthesiologist will talk to you about any health problems you may have and their impact on your anesthetic. Feel free to ask any questions at this time. Conditions to be brought to his or her attention include diabetes, heart disease, lung disease, high blood pressure, previous anesthetic complications, or family history of problems with anesthesia. If you are taking any diet medications, please let the anesthesiologist know. A light general anesthesia is commonly used, but there are cases where spinal is recommended. Try not to be afraid of anesthesia, as the hospital staff will follow a specific routine to make this procedure safe and lessen any risks.
In accordance with the Joint Commission on the Accreditation of Healthcare Organizations, we follow the Universal Protocol in order to avoid operating on the wrong knee. In fact, since 2004 in the U.S., preoperative surgical site marking has been mandatory in hospitals and surgical centers. Our patients designate the knee to be operated on by writing their initials on the thigh (just above the knee) with a marker. The surgeon con- firms the correct knee joint and marks his or her initials on the same thigh area. Finally, before the operation begins, a “time-out” is taken at which point all of the surgical personnel repeat the identification of the patient, the correct leg to be operated on, the procedure that will be done, and verify any allergies that exist or special precautions that apply to the patient. Within two hours, you will receive a dose of antibiotics through the IV as a precaution for postoperative infection. This may be repeated at the end of the operation.
Once you are taken into the operating room, you will move from the transfer bed to the operating room table. Some operating rooms are cold, so be prepared and don’t hesitate to ask for a blanket! Soon, medication will be placed into your IV to put you to sleep. A tube may be placed in your throat while you are asleep as part of the anesthesia process.
When the operation is finished, the medicines that kept you asleep are discontinued and you will wake up in the recovery room. Do not be surprised if your vision is blurry or if your throat is a little sore. A nurse will be with you as you wake up and will ask if you have any pain or nausea. Anesthesia has come a long way and very few patients experience nausea or vomiting after their surgery. Surgeons administer pain medication at the end of the operation, which is called preemptive pain management. The nurse will ask you several times over the next hour or so if you are in any discomfort. On occasion, a femoral nerve block into the groin is performed if pain becomes a problem.
You will have elastic stocking on your non-operated leg. A large bulky compression dressing will be on your operated leg. Depending on your surgeon’s protocol, you may also have a knee immobilizer or brace over the dressing. In some instances, you will be able to go home the same day. In some cases where pain or nausea is a problem, the surgeon may decide you should stay overnight at the hospital.
Remember, it is normal to be scared or apprehensive about the surgery and hospital experience. Keep in mind that the hospital staff - nurses, anesthesiologist, and operative team - are all very experienced and will try to keep you as comfortable as possible during the entire process. It is exceedingly rare for a problem to occur, but if something does happen, you should be reassured that the medical professionals will be able to address the issue. 46
Recovering From Surgery
Prevention of Blood Clots in the Legs (Deep Venous Thrombosis)
The risk of blood clots in the legs (called deep venous thrombosis), or embolism in the lungs from a clot, is usually low after surgery. If you are overweight, have heart disease, diabetes, or history of blood clots or phle- bitis, your risk for this complication is increased. In these cases, you will be placed on a blood thinner medica- tion. Talk to your doctor if you or a member of your family has ever had phlebitis or a blood clot problem.
To lessen the risk of blood clots after surgery, we recommend that you walk around the house (using crutches or a cane) 6-8 times a day, for about 10 minutes at a time, starting the day of surgery. Take 1-2 aspirin a day (depending on body mass) for 5 days unless you are allergic to aspirin or you have a stomach ulcer or stomach bleeding condition. Use the TED hose stockings to maintain good blood flow. Do ankle pumps for 5 minutes every hour you are awake to increase circulation. Leave the compression dressing on until your postoperative appointment.
Importantly, call your surgeon’s office if you develop any calf or leg pain or swelling.
If you have experienced phlebitis or a blood clot previously, medication will be prescribed to thin your blood after the operation. In addition, if any members of your family have had blood clots, you will likely undergo screening tests to make sure you do not have an inherited gene disorder that may cause an increase in blood clotting.
For women taking oral contraceptives, be sure and talk with your surgeon to determine if you should stop the medication before surgery. Oral contraceptives may increase the risk of blood clots.
If you are prescribed Coumadin (Warfarin), remember not to eat spinach or green leafy vegetables that act to increase the effect of the medication. 47 Home Exercises to Improve Strength and Flexibility
Listed below are some simple exercises you may do at home to help strengthen and improve the flexibility of your leg and hip muscles. We strongly believe that you should be under the care of a physical therapist that can guide your rehabilitation program. There are other exercises that may be done in the physical therapy clinic under direct supervision. In addition, your therapist will help guide and progress your exercise program and make sure that the strength training does not cause further knee pain. Always do the stretches last in your exer- cise sessions. If any of these exercises cause pain in your kneecap, stop immediately.
Quadriceps Isometrics: Full Extension
Sit up in bed, on a couch, or on a table with your back well supported. Keeping your knee as straight as possi- ble, contract or squeeze your thigh muscle and raise your leg off of the bed or couch a few inches. Do not allow your knee to go into hyperextension. Hold for 10 seconds, then lower the leg back down and relax. Repeat 10 times. As you become stronger, see how long you can keep your leg off of the bed or couch. Challenge yourself to hold your leg for 30, 45, 60 seconds and so on. Perform on both legs.
Quadriceps Isometrics: Multi-Angle
Sit up in bed, on a couch, or on a table with your back well supported. Use pillows placed under your knee to change the angle of the knee joint. The goal is to put the knee at approximately 90, 60, and 30 degrees as shown below. For each joint angle, contract or squeeze your thigh muscle for 10 seconds, then lower the leg back down and relax. Repeat 10 times for each angle. Rest for 1 minute between sets. Perform on both legs.
Demonstration of knee flexion position at 90 degrees 48
60 degrees
30 degrees
Straight Leg Raise: Hip Flexion
Lie on your back. Tighten your thigh muscle, keep your knee as straight as possible, and lift your leg straight up off of the bed or floor. Hold for 3 seconds, then lower the leg back to the starting position. Perform 1 set of 10 repetitions, rest for 30 seconds, and repeat the exercise 2 more times for a total of 30 repetitions. Add weight around your ankle as the exercise becomes easy to complete. Perform on both legs. 49 Straight Leg Raise: Hip Extension
Lie on your stomach. Keeping your knee straight, lift your leg toward the ceiling. Hold for 3 seconds, then lower the leg back to the starting position. Perform 1 set of 10 repetitions, rest for 30 seconds, and repeat the exercise 2 more times for a total of 30 repetitions. Add weight around your ankle as the exercise becomes easy to complete. Perform on both legs.
Straight Leg Raise: Hip Abduction
Lie on your side, the opposite of the leg that is painful. Keeping your knee straight, lift the leg up sideways toward the ceiling. Hold for 3 seconds, then lower the leg back to the starting position. Perform 1 set of 10 repetitions, rest for 30 seconds, and repeat the exercise 2 more times for a total of 30 repetitions. Add weight around your ankle as the exercise becomes easy to complete. Perform on both legs.
Straight Leg Raise: Hip Adduction
Lie on your side, the one that is painful. Bend the opposite leg and place the foot on the ground in front of the other knee as shown below. Lift your leg toward the ceiling, keeping the knee straight and the toes pointed straight ahead. Hold for 3 seconds, then lower the leg back to the starting position. Add weight around your ankle as the exercise becomes easy to complete. Perform on both legs. 50 Straight Leg Raises With Resistance Band
In these exercises, you will perform the same motion that is done during straight leg raises, except you are standing with a resistance band or rubber tubing tied around your ankle/lower leg. Secure the other end of the band or tubing around a heavy object. You will change the position of your feet in order to work the hip ad- ductors, abductors, flexors, and extensors as shown in the photographs below. To help maintain balance, hold onto an object and slightly bend the leg that is not being exercised. Move the foot with the band in the desired direction out as far as possible to ensure the band is tight. Perform 3-5 sets of 30 repetitions, moving the band as fast as possible. Rest for 1 minute between sets. Perform on both legs.
Hip adduction, starting position (A) Hip abduction, starting position (A) and ending position (B) and ending position (B)
Hip flexion, starting position (A) Hip extension, starting position (A) and ending position (B) and ending position (B) 51 Mini-squats
From a standing position, squat down to a 45-degree angle. Hold for a few seconds and then slowly rise back up. Perform 3 sets of 20 repetitions each. This exercise may also be done on an unstable surface, such as foam, cush- ion, or rocker board.
Hamstring Curls, Ankle Weight
This exercise may be performed either from a standing position or lying on your stomach. Attach a small ankle weight (with the amount of weight determined by your physical therapist) and bend your knee from 0-90 degrees behind you as shown below. Perform 3 sets of 10 repeti- tions. Rest for 1 minute between sets. Perform on both legs.
Knee Extension, Active-Assisted
Sit up with your back well supported. Begin with your knee flexed to 90 degrees. Place the foot of the opposite leg underneath the other heel and use it to lift the leg so your knee comes up to 30 degrees. Then, tighten the thigh muscles of your leg as hard as possible, completely remove the opposite foot, and lower your leg slowly back to the 90-degree starting position. Perform 3 sets of 10 repetitions. Rest for 30 seconds between sets. Per- form on both legs. Add ankle weight when able, begin with 5-10 pounds and perform 3 to 5 sets of 10 repeti- tions. 52 Wall Sits
Wear gym shoes for this exercise. Stand in front of a wall and place your feet about 2 feet away from the wall. Then, sit against the wall until your knees are flexed to 60- 70 degrees. Feel the quadriceps muscles in both legs with your hands, which should feel equal. Wait until you feel a burn in your quadriceps and then hold this position as long as possible to achieve fatigue. Then, carefully stand up, rest for 2-5 minutes, then repeat the exercise. Perform 4 times a day. As you progress, you may place a ball between your knees and squeeze it as hard as possible for the entire exercise. You may also sit a little lower, to 90 degrees if possible, provided no pain is felt in your kneecap or patellar tendon.
Toe Raises
From a standing position, come up onto the toes of your feet, raising your heels completely off of the ground. Hold for 1-2 seconds and then slowly return to the starting position. This may also be done using just one foot (single-leg). Hold onto a stable object for balance and control if necessary.
Heel Raises
From a standing position, raise the toes of your feet as high as possible while keeping the heels on the ground. Hold for 1-2 seconds and then slowly return to the starting position. Hold onto a stable object for balance and control if necessary.
Lateral Step-ups
Stand next to a step or low platform. Place one foot up on top of the platform. Then, bring your other foot up, lightly tap this foot on the platform and return it back to the starting position. Lower and raise the foot by bending and straightening your knee, maintaining good balance and posture. Repeat 10-15 times and then do the same for the opposite side. You may increase the difficulty of this exercise by holding free weights in your hands. The height of the step or platform should be no more than 12 inches and may be lower if any pain is felt in the kneecap during the exercise. 53
Step-downs, Stable and Unstable Surface
Begin by standing on a step or low platform. Step down slowly on one leg, then step up backwards leading with the opposite leg. Repeat 10-15 times and then do the same for the opposite side. You may increase the difficulty of this exercise by holding free weights in your hands. The height of the step or platform should be no more than 12 inches and may be lower if any pain is felt in the kneecap during the exercise. This exercise may also be done by stepping onto any unstable surface, including foam, a cushion, or rocker board.
Lunge, Straight
From a standing position, step straight ahead with one leg out as far as possible. Bend the knees and lower the back leg toward the ground. Only go down as far as you can without experiencing pain in your kneecap. Keep the front knee over the ankle and keep your back straight and head up, looking forward. Hold for 2 seconds, then return to the starting position. Repeat 10 times, rest for 1 minute, and perform 10 more times. Perform on both legs.
Lunge, Lateral
From a standing position, hop to the side with one leg as far as possible. Land on that leg, bend the knee as much as possible without experiencing any pain in your kneecap, and keep the other leg off of the ground. Bal- ance and hold for 2 seconds, then return to the starting position by hopping back to the starting position using the opposite leg. Repeat 10 times, rest for 1 minute, and perform 10 more times. Perform on both legs.
Lunge, Diagonal
It is helpful for this exercise to create a “Y” shape on the floor with masking tape. From a standing position, hop out with one leg as far as possible diagonally (at an angle) to the left side. Land on that leg, bend the knee as much as possible without experiencing any pain in your kneecap, keeping the other leg off of the ground. Return to the starting position by hopping back with the opposite leg. Repeat 10 times, rest for 1 minute, and perform 10 more times. Perform on both legs. 54 Hamstrings Stretch
Sit with your leg lying straight in front of you and bend the opposite knee so that the foot is resting against the inner portion of the other thigh as shown below. Keeping your back straight, slowly lean forward until you feel a stretch in your hamstrings. Hold each stretch for 30 seconds and repeat 5 times on each leg.
Calf Stretch
Sit on a bed or recliner with a foot rest with your back well supported. Take a large towel and roll it up so that is long and thin as shown below. Wrap the middle of the towel around the toes of your leg. While keeping your knee straight, use the towel to bend your toes back toward you until you feel a stretch in your calf muscles. Hold each stretch for 30 seconds and repeat 5 times on each leg.
Iliotibial Band Stretch
Sit on the floor, bend your right knee, and keep the left knee straight and flat on the floor. Cross the foot of the right side over the left knee as shown below. Place one hand on the floor behind the hips and use the other arm to press the chest toward the knee and foot. This stretch may be done lying on the back to support the spine and neck. Hold each stretch for 30 seconds and repeat 5 times on each leg. 55
Quadriceps Stretch
From a standing position, grab a foot or ankle and lift it up behind your body. Gently pull the lower leg and foot up, directly behind the upper leg. Do not twist inward or outward. Hold each stretch for 30 seconds and repeat 5 times on each leg.
Health, Fitness Club Exercise Machines
Listed below are some simple exercises you may do at a health club to help strengthen the muscles of your legs and hips and improve your cardiac fitness. We strongly believe that you should be under the care of a physical therapist that can guide and progress your exercise program and make sure that the strength training does not cause further knee pain. Always do the stretches shown in the Home Exercise section last in your exercise sessions. If any of these exercises cause pain in your kneecap, stop immediately.
The first time you exercise on the machines described below, have a physical therapist or trainer make sure the machine is adjusted correctly according to your body dimensions. The therapist or trainer should also help to determine the amount of weight to start with initially.
Leg Press
Beginning at 70 degrees, extend your knees slowly to 10 degrees, hold for 1-2 seconds, and slowly return to 70 degrees. Make sure you do this exercise only from 70-10 degrees! Do not press your knees out until they are fully extended, and do not allow your knees to bend all of the way back. Push up through your heels and not your toes. Complete 3 sets of 10 repetitions. Rest for 30 seconds between sets. Gradually increase the amount of weight as you are able. 56 Hip Abduction/Adduction
If your fitness facility only has a hip abduction/adduction machine (and not a multi-hip cable machine), then use this to work these muscles. However, if your facility has a multi-hip cable machine, use that instead. On the abduction/adduction machine, be sure to work your legs together, moving gradually and holding the abduction or adduction position for 1-2 seconds before returning to the starting position. Complete 3 sets of 10 repeti- tions. Rest for 30 seconds between sets. Gradually increase the amount of weight as you are able.
Multi-Hip
A multi-hip machine allows all of the hip muscles to be exercised, including the hip flexors, extensors, abduc- tors, and adductors. Use good posture (keep your back straight) throughout the exercises and hold onto the support bars to ensure you are working just your hip muscles. Complete 3 sets of 10 repetitions in all 4 direc- tions on both sides. Rest for 30 seconds between sets. Gradually increase the amount of weight as you are able.
Multi-hip machine showing Multi-hip machine showing hip hip flexion adduction
Knee Extension
Beginning at 90 degrees, extend slowly to 30 degrees, hold for 1-2 seconds, and slowly return to 90 degrees. Make sure you only do this exercise from 90-30 degrees! Do not extend your knees out past 30 degrees, as this will place excessive forces on your kneecap. Complete 3 sets of 10 repetitions. Rest for 30 seconds between sets. Gradually increase the amount of weight as you are able. You may either use both legs to move the bar up and down, use both legs to push the bar up and one leg to bring the bar back down, or use just one leg to move the bar up and down. Perform equal sets on both legs.
Knee extension machine starting position at 90 degrees (A) and ending position at 30 degrees (B) 57 Hamstring Curls
Beginning at 0 degrees, flex slowly to 90 degrees, hold for 1-2 seconds, and slowly return to 0 degrees. Make sure you do this exercise from 0-90 degrees! Complete 3 sets of 10 repetitions. Rest for 30 seconds between sets. Gradually increase the amount of weight as you are able. You may either use both legs to move the bar down and up, use both legs to push the bar down and one leg to bring the bar back up, or use just one leg to move the bar down and up. Perform equal sets on both legs.
Hamstring curl machine starting position at 0 degrees (left) and ending position at 90 degrees (right)
Upper Body Weight Training
It is important during your rehabilitation to include exercises to strengthen the muscles in your arms, shoul- ders, chest, and upper back. There are many options available that use either free weights or weight machines. The major upper body muscle groups that should be exercised include the deltoids, pectorals, triceps, biceps, trapezius, rhomboids, and latissimus dorsi. Work with your therapist or a trainer at your fitness facility to de- velop this aspect of your training program. Your program should be tailored to the sport or activity you wish to return to upon your medical release.
Core Training
The “core” is the area of your body that includes your pelvis, abdomen, and lower back. Core strength is crucial to maintain postural support and movement of the trunk. Core stability contributes to athletic performance. In fact, poor core strength may cause injury. The muscles in the abdomen and lower back may be strengthened in many different ways, using either weight machines or exercises such as sit-ups, crunches, bicycle kicks, supine bridges, planks, etc. Work with your therapist or a trainer at your fitness facility to develop this aspect of your training program. Your program should be tailored to the sport or activity you wish to return to upon your medical release.
Stationary Bicycle
A stationary bicycle offers a cardiovascular exercise option that we allow provided it does not cause kneecap pain. It is important to adjust the seat height correctly so that your knee is just slightly bent when the pedal is in the lowest position. We recommend using low resistance and a level setting. If you begin to experience knee- cap or patellar tendon pain during or after riding the bicycle, stop and talk to your therapist. 58
Cross-Country Ski
This is an excellent machine to use for cardiovascular fitness because it has very little impact on your knee and it also works muscles in your core and upper body. At first, make sure your stride is short, you use the level setting (no incline), and a low resistance. If you begin to experience kneecap pain during or after using this machine, stop and talk to your therapist.
Elliptical
This is an excellent machine to use for cardiovascular fitness and has the additional benefits of applying very little impact on your knees (and other joints as well) while working the muscles in your core and upper body. At first, make you use the level setting (no incline) and a low resistance. If you begin to experience kneecap or patellar tendon pain during or after using the elliptical, stop and talk to your therapist.
Pool Training
Water Walking and Other Basic Aquatic Exercises
Walk in a pool with the water at least waist-high, forwards and backwards. Gradually increase your speed, the length of your steps, and the distance covered. Make sure you walk with high knee steps, exaggerated from your normal walking appearance. You can also march across the pool. Partial squats and lunges can be done in shallow water in the same manner as they are done on land. There are a variety of exercises that may be done in the pool to increase strength and flexibility, many of which require buoyant or other aquatic equipment. A kick board may be used when walking to increase the amount of resistance. A noodle may be used to support the upper body while doing bicycle kicking. Knee flexion curls may be done with a buoyant circle. Knee extension resistance exercises may be done by placing a noodle under the bottom of a foot and pressing down. In addi- tion, the upper extremity and core muscles may be exercised in a variety of ways in the pool. These including performing arm circles under water, first with the palms up and then with the palms facing down. A buoyant device can be placed between your legs and freestyle swimming done using just your arms. If you have access to a pool and enjoy training in the water, work with your therapist to develop a comprehensive program to be used in conjunction with your other land-based exercises.
Swimming (Straight Ahead Kicking)
If you would like to swim, use only straight ahead kicking, as in freestyle and backstroke. Consider adding a mask and snorkel to make breathing easier. You may also use flippers and perform simple flutter kicking to further strengthen your legs. 59 Weight Loss Tips
Our recommendations for weight loss and control are:
- Decrease size of portions - Decrease fat intake. Substitute for red meat, avoid saturated fats, substitute oils for polyunsaturated types (olive, canola, peanut) - Increase vegetable and fruit intake - Learn to count calories - Avoid unhealthy snacks and sweets - Avoid fat diets - Use meal supplements (Slim Fast, Ensure) - Seek counseling if required - Try a low carbohydrate diet - Develop a water exercise program with your therapist - Understand that for every pound of weight loss, there is 4-6 pounds of reduced pressure on the knee
Acronyms and References
ACI, autologous chondrocyte implantation CT, computed tomography EMS, electrical muscle stimulation FDA, Food and Drug Administration MPFL, medial patellofemoral ligament MPML, medial patellomeniscal ligament MPTL, medial patellotibial ligament MRI, magnetic resonance imaging MRSA, methicillin-resoap thataphylococcus aureus NSAID, non-steroidal inflammatory drug NPO, nothing by mouth Q angle, quadriceps angle PPS, patellofemoral pain syndrome PFC, patellofemoral chondrosis TT-TG, tibial tubercle/trochlear groove VMO, vastus medialis oblique
1. Apostolovic M, Vukomanovic B, Slavkovic N, et al. Acute patellar dislocation in adolescents: operative ver- sus nonoperative treatment. Int Orthop. 2011;35(10):1483-1487. 2. 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):472-479. 3. Balcarek P, Jung K, Ammon J, et al. Anatomy of lateral patellar instability: trochlear dysplasia and tibial tubercle-trochlear groove distance is more pronounced in women who dislocate the patella. Am J Sports Med. 2010;38(11):2320-2327. 4. Balcarek P, Jung K, Frosch KH, Sturmer KM. Value of the tibial tuberosity-trochlear groove distance in pa- tellar instability in the young athlete. Am J Sports Med. 2011;39(8):1756-1761. 60 5. Barber-Westin SD, Noyes FR. Testing for neuromuscular problems and athletic performance. In: Noyes FR, Barber-Westin SD, eds. ACL Injuries in the Female Athlete: Causes, Impacts, and Conditioning Programs. Ber- lin Heidelberg: Springer-Verlag; 2012:235-272. 6. Bicos J, Fulkerson JP, Amis A. Current concepts review: the medial patellofemoral ligament. Am J Sports Med. 2007;35(3):484-492. 7. Bitar AC, Demange MK, D’Elia CO, Camanho GL. Traumatic patellar dislocation: nonoperative treatment compared with MPFL reconstruction using patellar tendon. Am J Sports Med. 2012;40(1):114-122. 8. Buchner M, Baudendistel B, Sabo D, Schmitt H. Acute traumatic primary patellar dislocation: long-term results comparing conservative and surgical treatment. Clin J Sport Med. 2005;15(2):62-66. 9. Buckens CF, Saris DB. Reconstruction of the medial patellofemoral ligament for treatment of patellofemoral instability: a systematic review. Am J Sports Med. 2010;38(1):181-188. 10. Camanho GL, Viegas Ade C, Bitar AC, Demange MK, Hernandez AJ. Conservative versus surgical treatment for repair of the medial patellofemoral ligament in acute dislocations of the patella. Arthroscopy. 2009;25(6):620-625. 11. Camp CL, Krych AJ, Dahm DL, Levy BA, Stuart MJ. Medial patellofemoral ligament repair for recurrent patellar dislocation. Am J Sports Med. 2010;38(11):2248-2254. 12. Christiansen SE, Jakobsen BW, Lund B, Lind M. Isolated repair of the medial patellofemoral ligament in primary dislocation of the patella: a prospective randomized study. Arthroscopy. 2008;24(8):881-887. 13. Colvin AC, West RV. Patellar instability. J Bone Joint Surg Am. 2008;90(12):2751-2762. 14. Farr J, Covell DJ, Lattermann C. Cartilage lesions in patellofemoral dislocations: incidents/locations/when to treat. Sports Med Arthrosc. 2012;20(3):181-186. 15. Felus J, Kowalczyk B. Age-related differences in medial patellofemoral ligament injury patterns in trau- matic patellar dislocation: case series of 50 surgically treated children and adolescents. Am J Sports Med. 2012;40(10):2357-2364. 16. Fithian DC, Paxton EW, Stone ML, et al. Epidemiology and natural history of acute patellar dislocation. Am J Sports Med. 2004;32(5):1114-1121. 17. Garth WP, Jr., DiChristina DG, Holt G. Delayed proximal repair and distal realignment after patellar dislo- cation. Clin Orthop Relat Res. 2000;377:132-144. 18. Garth WP, Pomphrey M, Jr., Merrill K. Functional treatment of patellar dislocation in an athletic popula- tion. American Journal of Sports Medicine. 1996;24(6):785-791. 19. Gillespie H. Update on the management of patellar instability. Curr Sports Med Rep. 2012;11(5):226-231. 20. Gomes JL. Medial patellofemoral ligament reconstruction for recurrent dislocation of the patella: a prelim- inary report. Arthroscopy. 1992;8(3):335-340. 21. Hennrikus W, Pylawka T. Patellofemoral instability in skeletally immature athletes. J Bone Joint Surg Am. 2013;95(2):176-183. 22. Hing CB, Smith TO, Donell S, Song F. Surgical versus non-surgical interventions for treating patellar dislo- cation. Cochrane Database Syst Rev. 2011(11):CD008106. 23. Hsiao M, Owens BD, Burks R, Sturdivant RX, Cameron KL. Incidence of acute traumatic patellar disloca- tion among active-duty United States military service members. Am J Sports Med. 2010;38(10):1997-2004. 24. Jain NP, Khan N, Fithian DC. A treatment algorithm for primary patellar dislocations. Sports Health. 2011;3(2):170-174. 25. Lim AK, Chang HC, Hui JH. Recurrent patellar dislocation: reappraising our approach to surgery. Ann Acad Med Singapore. 2008;37(4):320-323. 26. Maenpaa H, Huhtala H, Lehto MU. Recurrence after patellar dislocation. Redislocation in 37/75 patients followed for 6-24 years. Acta Orthop Scand. 1997;68(5):424-426. 27. Maenpaa H, Lehto MU. Patellar dislocation. The long-term results of nonoperative management in 100 patients. Am J Sports Med. 1997;25(2):213-217. 28. Mayer C, Magnussen RA, Servien E, et al. Patellar tendon tenodesis in association with tibial tubercle dis- 61 talization for the treatment of episodic patellar dislocation with patella alta. Am J Sports Med. 2012;40(2):346- 351. 29. Nietosvaara Y, Aalto K, Kallio PE. Acute patellar dislocation in children: incidence and associated osteo- chondral fractures. J Pediatr Orthop. 1994;14(4):513-515. 30. Nikku R, Nietosvaara Y, Aalto K, Kallio PE. Operative treatment of primary patellar dislocation does not improve medium-term outcome: A 7-year follow-up report and risk analysis of 127 randomized patients. Acta Orthop. 2005;76(5):699-704. 31. Nikku R, Nietosvaara Y, Kallio PE, Aalto K, Michelsson JE. Operative versus closed treatment of pri- mary dislocation of the patella. Similar 2-year results in 125 randomized patients. Acta Orthop Scand. 1997;68(5):419-423. 32. Nomura E, Inoue M. Cartilage lesions of the patella in recurrent patellar dislocation. Am J Sports Med. 2004;32(2):498-502. 33. Nomura E, Inoue M. Hybrid medial patellofemoral ligament reconstruction using the semitendinous ten- don for recurrent patellar dislocation: minimum 3 years’ follow-up. Arthroscopy. 2006;22(7):787-793. 34. Nomura E, Inoue M, Kobayashi S. Long-term follow-up and knee osteoarthritis change after medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med. 2007;35(11):1851- 1858. 35. Nomura E, Inoue M, Osada N. Augmented repair of avulsion-tear type medial patellofemoral ligament injury in acute patellar dislocation. Knee Surg Sports Traumatol Arthrosc. 2005;13(5):346-351. 36. Noyes FR, Barber-Westin SD. Operative options for extensor mechanism malalignment and patellar dis- location. In: Noyes FR, ed. Noyes’ Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes. Philadelphia: Saunders; 2009:995-1025. 37. Noyes FR, Barber-Westin SD, Fleckenstein C, Walsh C, West J. The drop-jump screening test: difference in lower limb control by gender and effect of neuromuscular training in female athletes. Am J Sports Med. 2005;33(2):197-207. 38. Palmu S, Kallio PE, Donell ST, Helenius I, Nietosvaara Y. Acute patellar dislocation in children and adoles- cents: a randomized clinical trial. J Bone Joint Surg Am. 2008;90(3):463-470. 39. Panni AS, Cerciello S, Maffulli N, Di Cesare M, Servien E, Neyret P. Patellar shape can be a predisposing factor in patellar instability. Knee Surg Sports Traumatol Arthrosc. 2011;19(4):663-670. 40. Parikh S, Noyes FR. Patellofemoral Disorders: Role of Computed Tomography and Magnetic Resonance Imaging in Defining Abnormal Rotational Lower Limb Alignment. Sports Health: A Multidisciplinary Ap- proach. 2011;3(2):158-169. 41. Redziniak DE, Diduch DR, Mihalko WM, et al. Patellar instability. J Bone Joint Surg Am. 2009;91(9):2264- 2275. 42. Rood A, Boons H, Ploegmakers J, van der Stappen W, Koeter S. Tape versus cast for non-opera- tive treatment of primary patellar dislocation: a randomized controlled trial. Arch Orthop Trauma Surg. 2012;132(8):1199-1203. 43. 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. 44. Servien E, Verdonk PC, Neyret P. Tibial tuberosity transfer for episodic patellar dislocation. Sports Med Arthrosc. 2007;15(2):61-67. 45. Shah JN, Howard JS, Flanigan DC, Brophy RH, Carey JL, Lattermann C. A systematic review of complica- tions and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar disloca- tion. Am J Sports Med. 2012;40(8):1916-1923. 46. Sillanpaa P, Mattila VM, Iivonen T, Visuri T, Pihlajamaki H. Incidence and risk factors of acute traumatic primary patellar dislocation. Med Sci Sports Exerc. 2008;40(4):606-611. 47. Sillanpaa PJ, Maenpaa HM, Mattila VM, Visuri T, Pihlajamaki H. Arthroscopic surgery for primary trau- matic patellar dislocation: a prospective, nonrandomized study comparing patients treated with and without 62 acute arthroscopic stabilization with a median 7-year follow-up. Am J Sports Med. 2008;36(12):2301-2309. 48. Sillanpaa PJ, Mattila VM, Maenpaa H, Kiuru M, Visuri T, Pihlajamaki H. Treatment with and without ini- tial stabilizing surgery for primary traumatic patellar dislocation. A prospective randomized study. J Bone Joint Surg Am. 2009;91(2):263-273. 49. Sillanpaa PJ, Peltola E, Mattila VM, Kiuru M, Visuri T, Pihlajamaki H. Femoral avulsion of the medial patellofemoral ligament after primary traumatic patellar dislocation predicts subsequent instability in men: a mean 7-year nonoperative follow-up study. Am J Sports Med. 2009;37(8):1513-1521. 50. Smith TO, Chester R, Clark A, Donell ST, Stephenson R. A national survey of the physiotherapy manage- ment of patients following first-time patellar dislocation. Physiotherapy. 2011;97(4):327-338. 51. Smith TO, Davies L, Chester R, Clark A, Donell ST. Clinical outcomes of rehabilitation for patients follow- ing lateral patellar dislocation: a systematic review. Physiotherapy. 2010;96(4):269-281. 52. Smith TO, Davies L, Toms AP, Hing CB, Donell ST. The reliability and validity of radiological assessment for patellar instability. A systematic review and meta-analysis. Skeletal Radiol. 2011;40(4):399-414. 53. Smith TO, Donell ST, Chester R, Clark A, Stephenson R. What activities do patients with patellar instabili- ty perceive makes their patella unstable? Knee. 2011;18(5):333-339. 54. Stefancin JJ, Parker RD. First-time traumatic patellar dislocation: a systematic review. Clin Orthop Relat Res. 2007;455:93-101. 55. Waterman BR, Belmont PJ, Jr., Owens BD. Patellar dislocation in the United States: role of sex, age, race, and athletic participation. J Knee Surg. 2012;25(1):51-57. 56. Weber-Spickschen TS, Spang J, Kohn L, Imhoff AB, Schottle PB. The relationship between trochlear dys- plasia and medial patellofemoral ligament rupture location after patellar dislocation: an MRI evaluation. Knee. 2011;18(3):185-188. 57. White BJ, Sherman OH. Patellofemoral instability. Bull NYU Hosp Jt Dis. 2009;67(1):22-29. 63 Appendix 1. Surgical Details: Proximal Realignment
This procedure requires a small, 2-3 inch skin incision which is made along the medial aspect of the patella. The superficial and deep retinaculum are incised, taking care to avoid cutting through the muscle or under- lying synovium. The incision extends in the quadriceps tendon, thus detaching 2-3 cm of the VMO insertion into the patella. A tissue sleeve consisting of the VMO, MPFL, and medial patellomeniscal ligament (MPML) and medial retinacular tissues is created which will later be mobilized for tensioning and advancement as re- quired.
The quality of the MPFL and medial retinaculum is inspected and a decision is made if a MPFL reconstruction is necessary. A thin, abnormal medial retinaculum and MPFL indicates that a MPFL graft is required to be described later.
The extensor mechanism is reconstructed with medial plication (removal of abnormal slack tissues) of the VMO and MPFL so that the VMO advancement is in line with its fibers and prior insertion. The VMO tissue sleeve is moved laterally and partially overlapped in what is termed a vest-over-pants fashion. Three nonab- sorbable sutures are used. Three Ellis clamps are placed at the VMO center, MPFL, and MPML medial ana- tomic sites to re-establish a normal tension. The first suture is placed at the 1 o’clock position (right knee) so that the distal part of the VMO is brought laterally in the line of its attachment to restore normal tension at 20 degrees of flexion. The second suture is placed at the 2 o’clock position through the MPFL and medial patellar insertion. The third suture is placed at the 4-5 o’clock position through the MPML and medial retinaculum to plicate these structures in line with their normal patellar attachment. See Appendix 3 for a figure of the place- ment of these sutures.
A final tensioning of the sutures is performed with the knee at 30 degrees flexion with the patella held cen- tered within the trochlea. This tightening procedure allows for a normal slackness of the medial tissues and the MPFL, and for a normal medial patellar glide of 10-12 mm. The lateral subluxation of the patella is also as- sessed at 0 degrees to ensure that a normal medial restraint exists. The knee is taken through a range of motion of 0-135 degrees in order to observe normal tracking of the patella. 64 Appendix 2. Surgical Details: Proximal Realignment With MPFL Reconstruction
A MPFL repair or reconstruction is the most common procedure done to tighten the medial ligaments and prevent the patella from dislocating in the lateral direction. When the medial ligaments are stretched and thin or completely deficient, a tendon graft is used. This is called a MPFL reconstruction and there are many dif- ferent ways to perform this operation. An MPFL reconstruction is almost always indicated in revision surgery when a prior proximal realignment procedure has failed and a residual lateral patellar subluxation exists. In addition to the MPFL graft reconstruction, a proximal realignment (plication) of the existing medial tissues is also performed.
We use a small strip of the patient’s quadriceps tendon to reconstruct the MPFL. The advantage of this proce- dure is that no bone tunnels are placed into the patella or medial femoral condyle, as described in other MPFL reconstructions. A small 2-inch incision is required and is made at the medial edge of the patella.
Planned surgical incision (thick black line) is The surgeon dissects down through tissues to where shown. the length of the MPFL can be measured.
The three tendon components of the quadriceps tendon (rectus, confluent vastus medialis-vastus lateralis, in- termedius) is incised to create a graft which is kept attached at the top of the patella. Two to 3 mm of remaining quadriceps tendon is left attached to the VMO for later closure. Dissection is continued down to the normal anatomic attachment site of the MPFL.
A medial quadriceps tendon graft is harvested with the patellar attachment intact. 65 The dissection is continued down to the MPFL, medial patellomeniscal ligament, and the medial patellotib- ial ligament. The graft is passed beneath the medial retinaculum and up through a hole where it lies over the adductor tubercle and tendon.
Puncture of the medial retinaculum, posterior to the medial femoral epicondyle at the adductor tendon, with passage of graft beneath the retinaculum.
A proximal and/or distal realignment tensioning procedure is then performed as required. The 1 o’clock, 2 o’clock, and 5 o’clock sutures are shown as previously described in Appendix 1.
Imbrication of the VMO, medial retinaculum, MPFL, and medial patellotibial ligament (MPTL).
The quadriceps graft is sutured to the normal femoral MPFL attachment. Care is taken not to overtension or overtighten the repair.
Quadriceps graft sutured to the femoral attachment between the MPFL and adductor tendon.
The surgeon makes sure that there is a normal lateral glide of 25% of the width of the patella to avoid limiting normal patellar mobility. The MPFL should primarily function from 0-30 degrees of knee flexion to resist a lat- eral patellar dislocation. After suturing is complete, the knee should be ranged from 0 to 135 degrees, restoring normal patellofemoral tracking. 66 Appendix 3. Surgical Details: Distal Realignment
This procedure requires a small, 2-inch skin incision that is done lateral to the tibial tubercle. The patellar tendon insertion is identified and a retractor placed behind it to identify its insertion site on the tibial tubercle. Subperiosteal dissection is carefully performed to expose the anterolateral aspect of the tibia, reflecting the periosteum and the muscular origin of the anterior compartment.
The planned tibial tubercle osteotomy is 12-15 mm wide, 8 mm thick, and 35 mm long. At the distal end of the osteotomy, a hole is drilled through the tibial cortex. The drill hole is placed beneath the anterior tibial peri- osteum which maintains the normal proximal-to-distal position of the tibial tubercle and prevents a fracture extending to the distal tibia. Similarly, 4-5 holes are drilled on the anterolateral tibial cortex, along the line of the planned osteotomy. An axial 90-degree cut is made just proximal to the patellar tendon insertion to mark the proximal extent of the osteotomy.
The drill holes along the anterolateral surface of the tibia are then connected using a one-half inch osteotome. The osteotome is carried through the medial cortex directly adjacent to the tibial tubercle, while the distal peri- osteal hinge remains intact. The bone fragment is carefully mobilized and moved medially, usually 8-10 mm. The tibial tubercle is secured with a 3.2 mm drill bit.
The ability to glide the patella medially and laterally by one quadrant, with the knee in 20 degrees of flexion, is verified. Patellar tracking is next assessed by taking the knee through a range of motion. The patella should remain centralized within the femoral sulcus, with no medial or lateral tilt or subluxation in flexion or exten- sion. The Q-angle is assessed using a goniometer, with the knee in 30 degrees of flexion in neutral, internal, and external rotation. This measurement is repeated at 90 degrees of flexion. Once the ideal position is determined, the final fixation of the tibial tubercle is done with three 4-mm cancellous screws. A compression technique with over-drilling the tibial tubercle is performed and the screw head is countersunk to prevent prominence under the skin.
The basic steps of a proximal-distal patellar realignment operation are shown below. This procedure is done in knees that do not require a MPFL reconstruction.
The medial retinaculum and VMO 2 cm above the patella are advanced in line of their insertions to restore patellar stability. 67
The millimeters of tibial tubercle medial displacement required are measured at surgery.
A dovetail tibial tubercle osteotomy has been performed.
Postoperative x-ray 68 Appendix 4. Surgical Details: Correction of Patella Alta
Patella alta represents a congenital abnormality of an increased vertical position (height) of the patella due to an elongated patellar tendon, resulting in the patella not engaging within the trochlea until a mid-flexion range of motion. Patients typically present with significant complaints related to lateral patellar subluxation or dislo- cation which can affect all activities of daily living. In most patients, the patella alta abnormality does not occur in isolation and other abnormalities of the extensor mechanism are usually present. Some patients with patella alta and anterior knee pain and joint swelling have signs of patellofemoral crepitus and arthritis, but do not experience subluxation symptoms.
The indications for correcting a patella alta are recurrent dislocations and symptomatic anterior knee pain (and an obvious patella alta) that has not responded to conservative treatment. Commonly, associated patellar crepi- tus and articular cartilage damage exists and the patient is advised that symptoms of anterior knee pain related to the arthritis will continue. It is thus preferable to correct a symptomatic patellar alta condition early prior to the development of cartilage deterioration.
In addition to correcting the patella alta, a functional MPFL is required, because there is a loss of the normal geometric restraint provided by the trochlear groove. There are no established clinically proven rules regard- ing when correction of an abnormal patella height is required, or the amount of correction to be obtained at surgery. The goal is to restore a normal patellar height index for the index chosen, and to confirm that patel- lotrochlear contact has engaged the trochlear at full extension.
There are two different ways of measuring patellar height, which are done on a lateral x-ray. Below is an artist’s rendition of these methods.
On the left, the patellar vertical height ratio equals either A/B or C/B. Patella alta is defined as a ratio of > 1.0-1.2, depending on the measurement method used. On the right, the patellotrochlear ratio is measured; > 50% indi- cates patella infera.
After the surgeon has measured the patellar height, the determination is made of any other anatomic abnor- malities that require surgical correction, such as a deficient MPFL. A small 1.5-inch incision is made lateral to the tibial tubercle. A dissection is made medial and lateral to the tibial tubercle. The tibial tubercle is cut (8 mm deep x 35 mm long x 15 mm wide). The anterior tibial cortex just distal to the tibial tubercle is removed to allow the distal tibial tubercle to be moved. The tibial tubercle is moved distally which corrects the abnormal lateral tibial tubercle offset when present.
An x-ray is taken in the operating room and the patellar height is again measured. The tibial tubercle position is adjusted as required to restore a normal height. The patella should engage the trochlea at 0 degrees of knee 69 flexion. Three cancellous screws or cortical screws are used to fix the tibial tubercle at the new position. The patellar glide tests are repeated at 0 and 30 degrees of knee flexion.
Preoperative (left) and postoperative (right) x-rays of a patient with patella alta who ex- perienced multiple patellar dislocations. The patient also required a MPFL reconstruc- tion. The preoperative patellar height ratio of 1.6 was corrected to 1.0. The difference in the patellar height is obvious when looking at the difference in the length of the solid white line between the left and right photographs.