Patella (kneecap) instability
Often this starts as a teenager; the kneecap dislocates usually during sports and the leg gives way. The episode is usually painful and the knee may become swollen. Often the kneecap spontaneously slips back into place, but sometimes realignment is required under sedation. The first line of treatment is almost always physiotherapy in order to strengthen the muscles are the knee (in particular the VMO muscles) to protect the kneecap.
If instability episodes recur, surgery can be considered to tighten soft tissues around the knee, alter the line of pull of muscles or alter the shape of the bones; all aim to improve stability. Following surgery, a brace is worn on the knee for six weeks and several months of physiotherapy are required before returning to all activity.