Your kneecap, or patella, usually rests in a groove at the end of the thighbone (femur). When your knee bends and straightens, the patella moves easily straight up and down within the groove. If you experience a hard blow or fall, the patella can completely or partially dislocate – sliding, instead, to one side or the other.
When the patella slips out of place, it typically causes pain and loss of function. Sometimes a piece of bone or cartilage can also dislodge or loosen when the patella dislocates. Even if the patella slips back into place by itself or continues to be unstable despite immobilization and physical therapy, surgery may be necessary.
An arthroscopic surgical technique may be used, which involves inserting small instruments near the knee to view the damage to the patella without making a large incision. Repair can then be made to help you return strong from a patella dislocation.