Subluxation means that a bone partially slides out of the joint. Subluxation in the knee joint usually happens at the patello-femoral joint. The patella sits in a groove at the lower end of the femur called the trochlea. It is held in the centre by the presence of ligamentous attachments.

Causes
Women are more susceptible to subluxation. Any accident or injury in sports, dancing.

Problems
Once the kneecap subluxates then the ligamentous attachments on the inside do not heal properly. There will be a tendency to repeated subluxation. During these outward movements of the patella, the cartilage can get flaked off and this leads to degenerative changes in the knee.

Treatment
Strengthening the quadriceps can prevent repeated subluxation. A brace can offer some protection. Surgery may be required for complete dislocation. I perform tibial tubercle transfer for this condition.