Pelvic mass caused by polyethylene wear after uncemented total hip arthroplasty.

A 50-year-old man developed a pelvic mass following uncemented total hip arthroplasty. The mass communicated with the hip via an acetabular defect after loosening of the acetabular component. Operative and histologic findings revealed a foreign body reaction to polyethylene debris. Revision arthroplasty and excision of the pelvic mass were performed successfully through a single incision. A mass adjacent to a loose prosthesis may present as polyethylene failure following total hip arthroplasty. Revision arthroplasty and excision of the mass after an accurate diagnosis are recommended.