A 63-year-old woman with osteoarthritis had undergone right total knee arthroplasty. Nineteen months later, the patient presented with a recurrent hemoarthrosis. Open arthrotomy revealed hypertrophic synovium with small clots in the suprapatellar pouch, but entrapment of synovial tissues could not be observed. Histological examination of the extirpated specimen showed fibrous hypertrophy of synovium. The patient has no symptoms 51 months after surgery.