Disclaimer This movie is an educational resource only and should not be used to manage Patellofemoral Instability. All decisions about the management of Patellofemoral Instability must be made in conjunction with your Physician or a licensed healthcare provider.
MULTIMEDIA HEALTH EDUCATION MANUAL TABLE OF CONTENTS SECTION CONTENT 1. Normal Knee Anatomy a. What is Patellofemoral Instability? b. Normal Knee Anatomy 2. Patellofemoral Instability a. Signs and Symptoms b. Causes c. Diagnosis 3. Treatment Options a. Conservative Treatment b. Surgical Treatment Introduction c. Surgery d. Post Operative Care e. Risks and Complications
Unit 1: Normal Knee Anatomy What is Patellofemoral Instability? Patellofemoral Instability results from one or more dislocations or partial dislocations, also called subluxations. This malalignment can damage the underlying soft structures such as muscles and ligaments that hold the knee in place. Once damaged, these soft structures are unable to keep the patella (knee cap) in position. To learn more about patellofemoral instability, let us first learn about normal knee anatomy and function. (Refer fig.1) Normal Knee Anatomy The knee is essentially made up of four bones. The femur or thighbone is the bone connecting the hip to the knee. The tibia or shinbone connects the knee to the ankle. The patella (kneecap) is the small bone in front of the knee that rides on the knee joint as the knee bends. The fibula is a shorter and thinner bone running parallel to the tibia on its outside. The joint acts like a hinge but with some rotation. The knee is a synovial joint meaning it is lined by synovium. The synovium produces fluid lubricating and nourishing the inside of the joint. (Refer fig.2) (Fig.1) Normal Knee Anatomy (Fig.2)
Unit 1: Normal Knee Anatomy Articular cartilage is the smooth surfaces at the end of the femur and tibia. It is the damage to this surface that causes arthritis. Femur Condyle Tibia Fibula Patella Menisci Femur: The femur (thighbone) is the largest and the strongest bone in the body. It is the weight bearing bone of the thigh. It provides attachment to most of the muscles of the knee. Femur (Refer fig.3) (Fig.3) Condyle: The two femoral condyles make up the rounded end of the femur. Its smooth articular surface allows the femur to move easily over the tibial (shinbone) meniscus. Condyle (Refer fig.4) (Fig.4)
Unit 1: Normal Knee Anatomy Tibia: The tibia (shinbone), the second largest bone in the body, is the weight bearing bone of the leg. The menisci incompletely cover the superior surface of the tibia where it articulates with the femur. The menisci act as shock absorbers, protecting the articular surface of the tibia as well as assisting in rotation of the knee. (Refer fig.5) Tibia (Fig.5) Fibula: The fibula, although not a weight bearing bone, provides attachment sites for the Lateral collateral ligaments (LCL) and the biceps femoris tendon. The articulation of the tibia and fibula also allows a slight degree of movement, providing an element of flexibility in response to the actions of muscles attaching to the fibula. (Refer fig.6) Fibula (Fig.6) Patella: The patella (kneecap), attached to the quadriceps tendon above and the patellar ligament below, rests against the anterior articular surface of the lower end of the femur and protects the knee joint. The patella acts as a fulcrum for the quadriceps by holding the quadriceps tendon off the lower end of the femur. Patella (Refer fig.7) (Fig.7)
Unit 1: Normal Knee Anatomy Menisci: The medial and the lateral meniscus are thin C-shaped layers of fibrocartilage, incompletely covering the surface of the tibia where it articulates with the femur. The majority of the meniscus has no blood supply and for that reason, when damaged, the meniscus is unable to undergo the normal healing process that occurs in the rest of the body. (Refer fig.8) Menisci (Fig.8) In addition, a meniscus begins to deteriorate with age, often developing degenerative tears. Typically, when the meniscus is damaged, the torn pieces begin to move in an abnormal fashion inside the joint. The menisci act as shock absorbers protecting the articular surface of the tibia as well as assisting in rotation of the knee. As secondary stabilizers, the intact menisci interact with the stabilizing function of the ligaments and are most effective when the surrounding ligaments are intact.
Unit 2: Patellofemoral Instability Signs and Symptoms Signs and symptoms of Patellofemoral Instability can include the following: Causes Pain, especially when standing up from a sitting position. Feeling of unsteadiness or tendency of the knee to give way or buckle. Recurrent Subluxation: When the kneecap slips partially out of place repeatedly. Recurrent Dislocation: When the kneecap slips all the way out of position repeatedly. Severe pain, swelling and bruising of the knee immediately following subluxation or dislocation. Visible deformity and loss of function of the knee often occurs after subluxation or dislocation. Sensation changes such as numbness or even partial paralysis can occur below the dislocation as a result of pressure on nerves and blood vessels. Patellofemoral Instability can be caused by a number of factors that affect the way the patella moves along the groove of the femur (trochlear groove) when the leg is bent or straightened. The patella normally moves up and down with a slight tilt without touching the other knee bones. In Patellofemoral Instability the patella does not maintain its normal path of movement and can slip out of the trochlear groove either partially (subluxation) or completely (dislocation). A combination of factors can cause this abnormal tracking and include the following: Anatomical Defect Abnormal Q Angle Patellofemoral Arthritis Improper Muscle Balance Anatomical Defect: Flat feet or fallen arches and congenital abnormalities in the shape of the patella bone can cause misalignment of the knee joint.
Unit 2: Patellofemoral Instability Abnormal Q Angle: The Q angle is a medical term used to describe the angle between the hips and knees. The higher the Q angle, such as in patients with Knock Knees, the more the quadriceps pull on the patella causing malalignment. Patellofemoral Arthritis: Patellar malalignment causes uneven wear and tear and can eventually lead to arthritic changes to the joint. Improper Muscle Balance: Quadriceps, the anterior thigh muscles, function to help hold the kneecap in place during movement. Weak thigh muscles can lead to abnormal tracking of the patella, causing it subluxate or dislocate. Diagnosis Evaluating the source of Patellofemoral Instability is critical in determining your treatment options for relief of the instability. Patellofemoral Instability should be evaluated by an Orthopaedic specialist for proper diagnosis and treatment. Treatment options will be dependent on the severity of the instability, the cause of the instability, and the athletic activity level expectations of the patient after surgery. Your physician will perform the following: Medical History Physical Examination Depending on what the history and exam reveal, your doctor may order medical tests to determine the cause of your knee pain and to rule out other conditions. Diagnostic Studies may include: X-rays CT Scan MRI
Unit 2: Patellofemoral Instability X-rays: A form of electromagnetic radiation that is used to take pictures of bones. (Refer fig.9) X-Rays (Fig.9) CT Scan: This test creates 3D images from multiple x-rays and shows your physician structures not seen on regular x-ray. (Refer fig.10) CT Scan (Fig.10) MRI: Magnetic and radio waves are used to create a computer image of soft tissue such as nerves and ligaments. (Refer fig.11) MRI (Fig.11)
Unit 3: Treatment Options Conservative Treatment The goal of conservative treatment for Patellofemoral Instability is to restore full range of motion by restoring the normal tracking pathway of the patella during flexion and extension of the knee. Treatment options include the following: Closed Reduction Pain Meds Rest Ice Physical Therapy Orthotics Bracing Closed Reduction: Following a dislocation, your Orthopaedist can often manipulate the knee joint realigning it into proper position. Surgery may still be necessary to restore normal function depending on your situation. (Refer fig.12) Pain Meds: Over the counter pain meds such as aspirin and NSAID s (non-steroidal antiinflammatory drugs) such as ibuprofen can help with the pain and swelling. (Refer fig.13) Closed Reduction (Fig.12) Pain Meds (Fig.13)
Unit 3: Treatment Options Rest: Stay off the injured knee as much as possible and avoid activities that require excessive pivoting such as basketball and soccer. (Refer fig.14) Ice: Ice packs applied to the injury will help diminish swelling and pain. Ice should be applied over a towel to the affected area for 20 minutes every hour. Never place ice directly over the skin. (Refer fig.15) Rest (Fig.14) Ice (Fig.15) Physical Therapy: Your physician may refer you to a therapist for instruction in strengthening and stretching exercises of the quadriceps and hamstrings, the leg muscles that help stabilize the patella. Your therapist will likely recommend non-weight bearing exercise such as swimming and water aerobics to limit stress on the knee during exercise. (Refer fig.16) Physical Therapy (Fig.16) Orthotics: Shoe inserts to support the arches of the feet may be ordered when Patellofemoral Instability is caused by foot abnormalities, such as flat feet. (Refer fig.17) Orthotics (Fig.17)
Unit 3: Treatment Options Bracing: Soft braces with cut outs over the patella may be suggested for support and alignment of the injured or rehabilitating knee. (Refer fig.18) Bracing (Fig.18) Surgery Introduction Surgical treatment of Patellofemoral Instability is sometimes necessary to help return the patella to a normal tracking path when conservative treatment options are unsuccessful. The goal of surgery is to re-align the patella and decrease the Q-angle. Surgical treatments can be categorized into two types: Proximal re-alignment procedures Distal re-alignment procedures Proximal re-alignment procedures: Proximal re-alignment involves lengthening structures on the outside of the patella that are restraining movement and/or shortening ligaments on the inside of the patella. Usually done in young patients still growing, it is often done in combination with distal re-alignment. Distal re-alignment procedures: Distal re-alignment decreases the Q-angle by dividing the tibial tubercle so that the bone and patellar tendon can be moved toward the inside of the knee. Screws are used to reattach the bone to the tibia. Your surgeon will decide which options are best for you depending on your specific circumstances.
Unit 3: Treatment Options Surgery Surgical treatment for Patellofemoral instability is performed under sterile conditions in the operating room with the patient under general anesthesia. Your surgeon will perform arthroscopy to evaluate the knee joint and determine the surgical plan required to repair the Patellofemoral instability. Arthroscopy is a surgical procedure in which an arthroscope is inserted into a joint through tiny incisions called portals. The arthroscope is a small fiber-optic viewing instrument made up of a tiny lens, light source and video camera. (Fig.19) The video camera attached to the arthroscope displays the image of the joint on a television screen, allowing the surgeon to look throughout the knee at cartilage and ligaments and under the kneecap. The surgeon can then determine the type of repair necessary to fix the instability. (Refer fig.19) The surgeon makes two small incisions (about ¼ of an inch) around the joint area. Each incision is called a portal. In one portal the arthroscope is inserted to view the knee joint. Along with the arthroscope, a sterile solution is pumped into the joint that expands the knee joint giving the surgeon a clear view and room to work. (Fig.20) (Refer fig.20)
Unit 3: Treatment Options With the images from the arthroscope as a guide the surgeon can look for any pathology or anomaly and repair it through the other portal with various instruments. This may involve debridement of articular cartilage or the removal of loose bodies. (Refer fig.21) (Fig.21) Once the evaluation is complete and the surgical plan developed, your surgeon will make a longer incision to perform the necessary stabilization procedure, as this cannot be done through tiny incisions. (Refer fig.22) (Fig.22) Depending on your situation, a Lateral Retinacular Release may be performed. In this procedure, your surgeon releases, or cuts, the tight ligaments on the lateral side (outside) of the patella enabling the patella to slide more easily in the femoral groove. Your surgeon may also perform a procedure to realign the quadriceps mechanism by tightening the tendons on the inside, or medial side, of the knee. (Fig.23) (Refer fig.23)
Unit 3: Treatment Options If malalignment is severe, a procedure called a Tibial Tubercle Transfer (TTT) will be performed. This procedure involves the surgeon removing a section of bone where the patellar tendon attaches on the tibia. The bony section is then shifted and properly realigned with the patella and reattached to the tibia with two screws. (Fig.24) (Refer fig.24) Once the malalignment of the patella is repaired and confirmed with arthroscopic evaluation, your surgeon will close the incisions with sutures and cover the area with a dressing. (Refer fig.25) (Fig.25) Post Operative Guidelines : Postoperative guidelines will be given to you by your surgeon and will be dependent on the type of repair performed. Common guidelines include: You will be taken to the recovery room and monitored for any complications. You will be given pain medication to keep you comfortable. Ice, compression, and elevation of the knee will be used to minimize swelling and pain. An immobilizer brace will be applied to the knee and crutches will be used for the first few weeks to prevent weightbearing on the knee. You will be given specific instructions regarding activity and a rehabilitation program of exercise and strengthening. Eating a healthy diet and not smoking will promote healing.
Risks and complications Patellofemoral Instability As with any major surgery there are potential risks involved. The decision to proceed with the surgery is made because the advantages of surgery outweigh the potential disadvantages. It is important that you are informed of these risks before the surgery takes place. Complications can be medical (general) or specific to knee surgery. Unit 3: Treatment Options Medical complications include those of the anesthetic and your general well being. Almost any medical condition can occur so this list is not complete. Complications include Allergic reactions to medications Blood loss requiring transfusion with its low risk of disease transmission Heart attacks, strokes, kidney failure, pneumonia, bladder infections Complications from nerve blocks such as infection or nerve damage Serious medical problems can lead to ongoing health concerns, prolonged hospitalization, or rarely death. Specific complications of Patellofemoral Stabilization Surgery include: Loss of ability to extend knee is a common complication that can be greatly minimized with strict adherence to your physical therapy program prescribed by your surgeon. Recurrent dislocations and/or subluxations with activity can occur before healing has taken place. Arthrofibrosis, the development of thick, fibrous material around the joint, often occurs after joint injury or surgery and can lead to joint stiffness and decreased movement. Continued Pain
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