Increased Blood Cobalt and Chromium After Total Hip Replacement

Abstract

OBJECTIVE: To determine metal concentrations in blood and urine of patients who received cobalt-chromium-alloy metal on metal hip implants. METHODS: Cobalt and chromium were determined in blood and urine of 76 patients and 26 controls by electrothermal atomic absorption spectroscopy. RESULTS: A significant postoperative elevation of the metal concentrations was observed for total hip replacement patients in contrast to the control group. Twenty-nine patients exceeded the EKA (Expositionäquivalente für Krebserzeugende Arbeitsstoffe) threshold limits for cobalt in blood and for cobalt and chromium in urine. We obtained a significant correlation between cobalt in blood and cobalt in urine (r = 0.79; p < 0.005), chromium in blood and chromium in urine (r = 0.79; p < 0.005), cobalt in blood and chromium in blood (r = 0.69; p = 0.008), and cobalt in urine and chromium in urine (r = 0.95; p = 0.004). CONCLUSION: Our findings suggest that in total hip replacements using metal-metal pairings, metal ions of the alloys are released. This release may lead to significantly elevated metal concentrations in biological fluids. Long-term studies are needed to determine the risk of metal-metal implants as a potential cause of cobalt and chromium toxicity.