Seven years of chronological changes of serum chromium levels after Metasul metal-on-metal total hip arthroplasty.

Although many authors have reported the serum concentrations of metal ions in patients who had metal-on-metal coupling prostheses, most of the studies were not longitudinal, and the follow-up periods were short. We evaluated the longitudinal changes of serum chromium levels in 44 patients who had undergone unilateral metal-on-metal total hip arthroplasty for a minimum of 7 years postoperatively. Although there was a consistent increase in the mean serum chromium level until 3 years after implantation, there was little difference in the levels from years 3 to 7 postoperatively. Although the serum chromium concentration was low throughout postoperative follow-up for 7 years in about 25% of patients, the serum chromium level stayed high or showed gradual elevation in 16.3% of our patients.