3 Questions about Patellar Dislocations Answered

Story submitted by Ian Rice MD, a sports medicine orthopedic surgeon with the TriHealth Orthopedic and Sports Institute.

Patellar Dislocations: Who’s At Risk?

A patellofemoral, or patellar (kneecap) dislocation involves the patella slides out of place (from the femoral trochlea, where it tracks under normal conditions). This typically results from a sudden change in direction, often during a sport activity. 

Patellar dislocations are more common in athletes and active people, but can happen to anyone during a traumatic incident. Athletes who have loose ligaments, a shallow groove for the patella to track, or rotational problems in their femur or tibia bones, however, are at a higher risk. 

However, most people don’t realize they have these risk factors until they are injured and see an orthopedic surgeon. 

The initial injury can have lasting consequences, as these dislocations can cause loose fragments of cartilage or bone in the knee joint, and patients with a prior history of patellar dislocation are more likely to have repeat dislocations in the future, either in the same or opposite knee. 

When multiple dislocations occur, we often refer to this as chronic patellar instability.

Can I Still Play Sports? When Can I Return?

After a patellar dislocation, athletes are usually cleared to play once they’ve regained full strength and function. Also, athletes should be able to perform well enough to be effective in their sport, and cut from side to side without a feeling of instability. They should also understand the risks of returning to play, including a repeat dislocation.

How Are Patellar Dislocations Treated?

A workup typically includes X-rays and may require additional testing such as an MRI or CT scan to fully define the injury, and determine why the patient had the injury, if risk factors are present.

Fortunately, many patellar dislocations may be treated without surgery. For first-time dislocators, standard treatment includes wearing a brace, applying ice to the area, and elevating the area to control swelling. They may also go into a rehab program to strengthen the quadriceps muscles that stabilize the patella.

Sometimes Surgery Is Needed

If an MRI is ordered for a severe case, sometimes surgery is needed to reconstruct the ligament, move the attachment of the patellar tendon, deepen the groove, or remove loose pieces.

For athletes who dislocate their patella on multiple occasions, their doctor may recommend a reconstructive procedure. During patellar dislocations, the medial patellofemoral ligament (MPFL) is usually torn. This rarely heals on its own, so the surgeon would make a new ligament from the patient’s own hamstring tendon or a donor tendon, and connect the new ligament to the inside of the patella and inside of the femur.

The procedure is called an MPFL reconstruction, and is performed using small incisions. In expert hands, this procedure has a 95+% success rate of preventing future dislocations. 

Tags: Orthopedics

Last Updated: November 5, 2015