Long-term results of knee synovectomy in pigmented villonodular synovitis.

1. Pigmented villonodular synovitis (PVS) commonly affects the knee as a monoarticular proliferative process. The etiology is not understood. 2. Partial synovectomy for localized PVS and wide synovectomy for diffuse PVS institute a favorable result, despite a rather high rate of recurrence at long-term follow-up. 3. Cases that involve bony erosion have a low incidence of recurrence but present an unsatisfactory prognosis even after curettage and wide synovectomy (postoperative progress of osteoarthritic changes).