Case report: femoral neuropathy secondary to total hip arthroplasty wear debris.

Femoral nerve palsy after THA is well known, but delayed palsy is rare. We describe a 58-year-old man who had progressive thigh pain, weakness, and numbness develop 13 years after cementless arthroplasty of his left hip. Plain radiographs showed substantial liner wear. MRI of the lumbar spine was unrevealing and EMG showed a peripheral neurogenic process involving the left femoral nerve. The large intrapelvic cystic mass was confirmed by an abdominopelvic CT scan. Percutaneous aspiration of the cyst was performed. Cultures of the fluid were negative and cytopathologic examination showed necrotic debris without malignant cells. Biopsy revealed necrosis and abundant foreign body granulation tissue with polarizable debris. During surgical removal of the cyst, a defect of the inner acetabular wall was noted. After subsequent revision arthroplasty with allograft bone, the patient's clinical symptoms improved and his EMG returned to normal.