Dislocation of the mobile bearing component of a patellofemoral arthroplasty: a report of two cases.

Isolated degenerative osteoarthritis of the patellofemoral joint can be treated with a patellofemoral arthroplasty. Improvements in patellar resurfacing designs have resulted in diminished complication rates. We describe two cases of dislocation of the polyethylene bearing, which is an unusual complication of a mobile bearing metal-backed patellar component of a patellofemoral arthroplasty.