Polyethylene-induced pes anserinus bursitis mimicking an infected total knee arthroplasty: a case report and review of the literature.

Polyethylene-induced pes anserinus bursitis after total knee arthroplasty (TKA) with the clinical manifestations mimicking an infected TKA is a very rare occurrence. We report such a case in a 74-year-old woman. She developed recurrent draining papules on the anterolateral aspect of the knee because of polyethylene-induced chronic pes anserinus bursitis 8 years after TKA. The diagnosis was established with a sinography study and confirmed by histopathologic examination of the surgical specimen. The symptoms were resolved after surgical excision of the lesion. Pes anserinus bursitis should be included in the differential diagnosis in knees with a draining sinus after TKA, and sinogram is considered the best method to establish the diagnosis.