M22: Disorders of patella

M22.1: Recurrent subluxation of patella

The knee joint connects the thigh to the lower leg. The knee joint is made up of 3 bones. These bones are the thighbone (femur), the shinbone (tibia) and the kneecap. The kneecap sits in a groove at the front of the thighbone.

Your kneecap has slipped too far to one side in its groove in your femur. This can happen as a result of very normal movements not involving any excessive force. In certain circumstances this happens regularly. For example, when the muscles around the knee are too weak or when the kneecap is an unusual shape. If the kneecap has slipped too far to one side in the past it will get dislocated again more easily.