Abstract
Pigmented villonodular synovitis is a rare proliferative process, especially in children. Pigmented villonodular synovitis can affect the synovial joint, tendon sheaths, and bursa membranes. Within synovial joint involvement, it is commonly seen in the knee joint but hip, ankle, shoulder, wrist, and other joints can be involved. The appearance characteristic is found on a magnetic resonance imaging scan. Complete excision and synovectomy are the usual treatment. In this article, we report a case of pigmented villonodular synovitis of the knee in a 12- year-old girl who underwent total synovectomy after the diagnosis was confirmed by biopsy. Three years after surgery, neither recurrence nor joint degeneration was found. The osteochondral defect at the tibial plateau was filled with calcium phosphate bone paste.