Dislocation of the Kneecap

Patella (or kneecap) instability occurs when the kneecap moves out of position or dislocates – usually to the outside of the knee.

If left untreated, the likelihood of permanent damage and even more pain may increase.

The kneecap is held in position by the bones, ligaments and muscles around the knee. A groove called the trochlea is where the kneecap sits while the knee is bent.

The medial patellofemoral 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 also help hold the kneecap in position and help with kneecap tracking.

Symptoms of Patellar Instability/Dislocation

Patellar instability symptoms vary because it solely depends on how much the patella has moved out of place and the extent of the damage done to the knee.

Common symptoms include:

• Pain and swelling in the knee
• Pain when sitting
• Feeling a shift of the kneecap
• Creaking sounds upon movement of the knee
• Stiffness in the knee

Treatment Options

Typically, your treatment will begin with strengthening and bracing.

When patellar dislocations recur, they cause functional limitations and can even cause cartilage damage. If there is cartilage damage associated with a patella dislocation and/or there are additional dislocations, surgery is usually recommended to prevent further damage.

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, and reconstructing the MPFL can stabilize the kneecap.

During this surgery, the knee is inspected, and then a tendon graft is placed between 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 activities in 4 to 6 months.