Serum metal ion levels after second-generation metal-on-metal total hip arthroplasty

Metal-on-metal bearings for total hip arthroplasty are increasing in popularity. However, metal ion toxicity, metal hypersensitivity, and metal carcinogenicity are the causes concern for patients with metal-on-metal hip replacement. We investigated serum levels of cobalt and chromium ions in patients with successfully implanted second-generation metal-on-metal total hip arthroplasty (THA) using PINNACLE-A (DePuy, Warsaw, IN, USA). Thirty-three patients underwent primary cementless THA with the use of a 36-mm femoral head PINNACLE-A with a metal-on-metal articulation. Blood samples were taken preoperatively, at 3 months, and at 1 year, and levels of cobalt and chromium were determined. At 3 months, levels of both cobalt and chromium had increased significantly compared with preoperative levels. There were no significant differences between levels of either metal at 3 months and 1 year. Patients with metal-on-metal THA had higher circulating levels of metal ions than before arthroplasty at 3 months, with no additional significant increases at 1 year in this study.