Pigmented villonodular synovitis after TKA associated with tibial component loosening

There is no known causal link between total knee arthroplasty (TKA) and pigmented villonodular synovitis (PVNS). There also is no known relationship between PVNS and implant loosening after TKA in the literature. This article presents a case of PVNS in a patient undergoing revision TKA for tibial component loosening. A 74-year-old woman who had undergone cemented bilateral TKA 5 years earlier presented with painful swelling in her right knee. At the time of the primary TKA, no abnormal signs were found in the synovial membrane. Routine follow-up radiographs did not indicate implant loosening. At the patient's final follow-up examination before revision surgery, a radiolucent lesion was found below the tibial component. During revision surgery, there was focal proliferation of the synovial tissue with heavy pigmentation around the anteromedial part of the tibial component. The abnormal tissue was removed, and the tibial component was exchanged. The articular surface of the polyethylene was not damaged, and backside wear was not found. For the revision surgery, 5-mm thick medial metal block and extension stem were used. Histological analysis of the resected tissue revealed the typical appearance of PVNS. We present a typical case of PVNS found during revision TKA 5 years after primary TKA. It is hoped this report will encourage surgeons to consider PVNS in the differential diagnosis of patients who present with painful swelling of the knee and to consider PVNS as one of the causes of implant loosening after TKA. Further research about causal factors between PVNS and implant loosening are needed.