Mechanically assisted crevice corrosion of the head-neck taper in a large head metal-on-metal total hip arthroplasty

Taper corrosion of the head-neck junction is a potentially significant and devastating problem facing orthopedic surgeons. We present a case of a 53 year old male who presented for routine follow up for a left, large head, metal on metal total hip arthroplasty five years out. The patient was asymptomatic at the visit. X-rays at the time demonstrated a large amount of medial calcar osteolysis. Serum ion levels revealed a mildly increased cobalt and normal chromium level and hip aspiration revealed brownish fluid. At the time of revision surgery, corrosion of the head-neck taper was found with a normal appearing bearing surface leading to the diagnosis of mechanically assisted crevice corrosion of the head-neck taper with medial calcar osteolysis.