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Patellofemoral instability occurs when the kneecap moves out of position – usually to the outside of the knee. This can occur from an injury, or in some cases, people who are predisposed can get this injury almost a-traumatically./p>
The kneecap is normally held in position by the bones, ligaments, and muscles around the knee. There is a groove, called the trochlea, in which the kneecap sits while the knee is bent. If this groove is shallow, the patella can be predisposed to instability. A ligament, called the medial patellofrmoral ligament (MPFL), attaches the kneecap to the inside of the femur and is critical for holding the kneecap in position. The muscles around the knee, especially the inside of the quadriceps or VMO, also help hold the kneecap in position and help with kneecap tracking.
Initially, treatment for a patellar or kneecap dislocation usually involves bracing and physical therapy to work on strengthening the quadriceps and VMO. When patellar dislocations become recurrent they cause functional limitations; they can even cause cartilage damage. This damage may even require surgical treatment via MPFL reconstruction.
The medial patellofemoral ligament or MPFL is the main soft tissue restraint to patella dislocation. When a patella dislocation has occurred this ligament is usually torn or stretched out. Even if a patient has a shallow trochlea (the groove the knee cap sits in) or other anatomic predisposition to kneecap instability, reconstructing the MPFL can stabilize the kneecap.
Surgical treatment of patella dislocations involves reconstruction of the medial patellofemoral ligament (MPFL). During this surgery the knee is inspected arthroscopically. Following this a tendon graft (usually one of the hamstring tendons) is placed between the medial epicondyle on the femur and kneecap. This procedure has been proven to be very successful in treating recurrent patellar instability. Patients are usually braced for 6 weeks after surgery and are able to return to sports in 4 to 6 months.