Locked knee from superior dislocation of the patella-diagnosis and management of a rare injury.

Knee locking is often caused by a torn meniscus or loose body. A rare cause of knee locking is a superior dislocation of the patella following trauma with less than 20 reported cases in the English literature. An unusual case of a locked knee secondary to interlocking osteophytes between the medial femoral condyle and the inferior pole of the patella without any history of trauma is presented.