Failure of a polyethylene total knee component presenting as a thigh mass. Report of a rare complication of total knee arthroplasty.

Early failure caused by wear of the polyethylene bearing surface of a metal-backed tibial platform or a metal-backed patellar component in a total knee prosthesis has been a recognized complication; patients with these problems initially have pain and instability. A patient who had a cystic mass in the distal thigh was evaluated, and osteolysis of the distal femur was detected. Polyethylene debris and reactive synovium were confirmed surgically and histologically, indicating a cause-effect relationship of polyethylene wear debris and failure of the total knee arthroplasty. Regular and long-term patient follow-up evaluation after total joint arthroplasty is essential for the detection of early evidence of occult polyethylene wear.