Patellofemoral Instability Causes, Symptoms & Treatment

Your kneecap, or patella, connects muscles in your thigh (femur) to your shinbone (tibia). When your knee bends, it slides along a groove (femoral groove) at the end of your thigh bone. Patellofemoral Instability is a condition that occurs when the kneecap comes out of this groove. When this happens, it can result in pain, difficulty walking, and other problems. When the kneecap comes out of the groove a little, but not completely, it is called subluxated. When it moves completely out of the groove, it is dislocated.

There are several reasons an unstable kneecap can develop. Some people are simply more prone to problems with their kneecap due to heredity. They may be born with ligaments that are looser or a groove that is uneven or too shallow, causing the kneecap to dislocate easily.

For many, a sudden twisting motion or change in direction when your foot is planted and your knee turns inside can cause the kneecap to pop out of its groove. This motion is common when playing sports, such as football or basketball. Patellofemoral Instability is common in these sports:

• Football
• Gymnastics
• Wrestling
• Basketball
• Ice Hockey
• Soccer
• Volleyball

When your kneecap is not lined up correctly, it may feel loose or like it’s out of place. You may feel slipping, grinding, catching, or popping in your knee. This means your kneecap is not tracking correctly in its groove. If your kneecap completely dislocates, you can experience extreme pain and swelling. Visibly, it may look like a bone is out of place, and you may not be able to bend or straighten your knee. Your kneecap may stay dislocated, or it may go back into place on its own. Some common symptoms of a kneecap that is not tracking correctly include:

• Knee buckles and can no longer support your weight
• Kneecap slips off to the side
• Knee catches during movement
• Pain in the front of the knee that increases with activity
• Pain when sitting,going up or down stairs
• Stiffness
• Creaking or cracking sounds during movement
• Swelling

If you have symptoms of patellofemoral instability, nonsurgical treatments should always be tried first. These may include ice, rest, and exercises to strengthen the muscles in your thigh. Sometimes, your doctor may recommend a stabilizing brace to keep your knee aligned.

You can also try these exercises at home:

Often, the kneecap goes back into place on its own. However, if you have an initial patella dislocation episode and your kneecap is out of place, you should be seen in the emergency room where the doctor will gently push the kneecap back into place. If you have an episode where your kneecap dislocates completely, after initial treatment you should schedule an appointment to be seen by your doctor.

You may also want to see your orthopedic specialist if conservative treatment does not relieve your feelings that your kneecap is out of place or if you have persistent pain in your knee after a subluxation or dislocation episode.

Your doctor may ask you questions about your activity, perform a thorough physical examination, and conduct an apprehension test, which involves carefully moving the area around your patella as you extend your knee. If your kneecap is partially out of place, you are likely to experience a feeling that your kneecap is about to dislocate while the doctor performs this test. This helps to confirm the diagnosis of patella instability.

To make a diagnosis, your doctor may prescribe X-rays to see how your kneecap fits in its groove. Often, a CT scan is needed to assess the kneecap tracking. Your doctor may also recommend a magnetic resonance imaging (MRI) test to view the knee and surrounding tissues. This test will help determine if there are other reasons for your pain, such as a tear in the cartilage or ligaments of the knee.

Try these exercises to help address your condition:

Below is a PDF of the Exercise Program

Patellofemoral Instability

If an unstable kneecap persists, surgery may be recommended to correct a knee after multiple dislocations. Surgery can also be an effective means of addressing damage to the underside of the kneecap and the end of the thigh bone caused by dislocation of the patella. The exact surgical procedure varies greatly for this condition based on the degree of kneecap damage and the degree of improper tracking of the kneecap.

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Experiencing a partially or fully dislocated kneecap can be a painful experience that limits your mobility and prevents you from being active. Getting treatment and following your doctor’s guidance can help ensure that you achieve full strength and range of movement in your knee, allowing you to return to play. Recovery varies depending on the degree of instability and whether surgical or non-operative treatments are needed.