As long as your kneecap (patella) stays in its groove in the knee, you can walk, run, sit, stand, and move easily. When the kneecap slips out of the groove, problems and pain often result. The thighbone (femur) has a V-shaped notch (femoral groove) at one end to accommodate the moving kneecap. In a normal knee, the kneecap fits nicely in the groove. But if the groove is uneven or too shallow, the kneecap could slide off, resulting in a partial or complete dislocation. A sharp blow to the kneecap, as in a fall, could also pop the kneecap out of place.
Symptoms of Patellar/Knee Cap Dislocation
- 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
- Creaking or cracking sounds during movement
If the kneecap has been completely dislocated out of its groove, the first step is to return the kneecap to its proper place. This process is called reduction. Sometimes, reduction happens spontaneously. Other times, your doctor will have to apply gentle force to push the kneecap back in place.
A dislocation often damages the underside of the kneecap and the end of the thighbone, which can lead to additional pain and arthritis. Arthroscopic surgery can correct this condition.
If the kneecap is only partially dislocated, your doctor may recommend nonsurgical treatments, such as exercises and braces. Exercises will help strengthen the muscles in your thigh so that the kneecap stays aligned.