Also known as a dislocated kneecap, patellar dislocation occurs when the bone in the front of the knee (called the kneecap or patella) slides too far to one side or the other. It is usually caused by an injury to the knee, like a hard blow or fall. When an injury to the patella happens, it can completely or partially dislocate. Common symptoms of a dislocated patella or kneecap include:
Feeling like the knee buckled or gave out
Sudden, severe pain and swelling
A noticeable bump on the outside of the knee, which may mean a kneecap that is out of place
The knee is held in a bent position
Bruising around the knee
A person with a dislocated kneecap needs immediate medical care. However, there are cases when a dislocated kneecap may move back into place on its own when the leg is straightened before getting to the hospital but will still require treatment to relieve painful symptoms. Multiple or repeated dislocations and kneecap instability–despite conservative treatments, such as physical therapy and bracing–surgery may be the best option to correct the problem. Arthroscopy is a surgical procedure that uses a tiny camera and miniature surgical instruments inserted through small incisions to reconstruct the patella's ligaments in place.