Abdominal cyst after early failure of polyethylene liner in total hip arthroplasty

Abstract

We report a case in which the early failure of a polyethylene liner, coupled with a 32-mm CrCo ball head, caused pelvic cyst formation simulating an abdominal mass. The presence of the mass with inguinal swelling lead us to diagnosis liner failure, as shown by radiography. An extraperitoneal cyst surrounding the iliopsoas muscle from the lesser trochanter up to the lumbosacral junction was demonstrated with pre-operative computed tomography and sonography. The cyst contained fluid and many large particles of polyethylene debris. The liner and the head were substituted and the cyst was removed through a different abdominal approach. We hypothesize that debris falls out and concentrates along the iliopsoas muscle from the very beginning of wear, and then the muscle concentration forces pumped it along the muscle belly. From the histologic point of view, large polyethylene particles were observed in the removed tissue, and no major osteoclastic activation was found.