Metal-on-metal hip resurfacing in patients with pigmented villonodular synovitis: a report of two cases.

Pigmented villonodular synovitis (PVNS) of the hip joint is a rare and benign tumor of the synovia. This local, aggressive, proliferative disorder of the joint synovial membrane can lead to secondary osteoarthritis and represents a small percentage of all patients undergoing total hip replacement (THR). Because of the usually young age of the patients undergoing THR for PVNS, a resurfacing arthroplasty of the hip appears as a beneficial treatment option due to its bone-conserving nature, good joint stability, and ability to easily convert to a THR if needed. This article describes 2 cases of metal-on-metal hip resurfacing in patients with pigmented villonodular synovitis. In patient 1, PVNS was suspected on radiographs but confirmed only after removal of a mass of thick, grey-brown spotted synovia. A complete synovectomy was performed prior to hip resurfacing. Seven years postoperatively, radiographs show secure fixation of the components with no radiolucencies. In patient 2, arthroscopy of the hip joint had been performed 3 months prior, but PVNS had not been diagnosed. Pigmented villonodular synovitis was confirmed during the operation when incising a yellowish nodular mass protruding from the capsule. Granuloma was also found in the inferior and anterior part of the acetabulum. Four years postoperatively, the patient exhibits excellent clinical and radiographic results. Complete surgical removal of all tissue affected with PVNS is the key to a successful resurfacing, which is otherwise technically similar to resurfacing in patients with other etiologies. The mid-term results of the 2 presented cases are satisfying and show the potential of the resurfacing technique for young patients with PVNS of the hip.