Nickel-, chrom- and cobalt-concentrations in human tissue and body fluids of hip prosthesis patients

The world-wide experience with millions of metallic implantations suggests the biocompatibility of modern alloys, commonly made of cobalt, chromium and nickel. There is, however, little information available on the internal metal exposure resulting from implants. In this study we assessed the metal concentrations in body fluids and tissue samples (muscle, bone) of patients who had undergone total hip replacement. Our patients were divided up into two groups. One group had firmly fixed implants two years after surgery. The other group had loose implants of the same Co-Cr-Mo alloy. Urine analyses revealed an increased renal elimination of nickel, chromium and cobalt. Cobalt and nickel exceeded the upper normal value. In serum the concentrations of nickel and chromium were normal or slightly elevated, the cobalt concentrations were significantly elevated. In some cases tissues adjacent to the implant showed extremely high concentrations of chromium and cobalt. This finding was also obtained in tissues that had no direct contact with the arthroplasty. The findings suggest that alloys of prostheses can undergo corrosion and release metal ions.