Occasionally patients dislocate their patella laterally out of its groove on the femur. Usually it happens the first time when the patient is a teenager.
The typical position when the knee dislocates is flexion & internal rotation, such as when dancing. The first dislocation is usually the most painful, and usually causes the most scratching or damage to the back of the kneecap. Sometimes the pieces of cartilage are large and need to be removed surgically.
Once the patella us reduced, the initial management of an acute patella dislocation is usually rest, ice & elevation. Physiotherapy is commenced about a weeks later. Most pain & swelling settles by 4-6 weeks.
Surgery is required if the patella keeps dislocating or the patients has chronic feeling of patella instability.