The purpose of the present study was to determine cobalt and chromium ion levels in the blood and urine of patients in whom a modern-generation metal-on-metal hip resurfacing device had been implanted.Methods:
A total of ninety-seven patients with a Conserve Plus metal-on-metal hip resurfacing implant were followed prospectively for two years. Cobalt and chromium levels in erythrocytes, serum, and urine were measured preoperatively as well as three, six, twelve, and twenty-four months postoperatively.Results:
The median serum cobalt and chromium ion levels were 1.04 µg/L (range, 0.31 to 7.42 µg/L) and 2.00 µg/L (range, 0.28 to 10.49 µg/L), respectively, at one year after surgery and 1.08 µg/L (range, 0.44 to 7.13 µg/L) and 1.64 µg/L (range, 0.47 to 10.95 µg/L), respectively, at two years after surgery. The corresponding mean levels (and standard deviations) of serum cobalt and chromium were 1.68 ± 1.66 µg/L and 2.70 ± 2.22 µg/L, respectively, at one year after surgery and 1.79 ± 1.66 µg/L and 2.70 ± 2.37 µg/L, respectively, at two years after surgery.Conclusions:
These levels compare favorably with other published ion results for metal-on-metal hip resurfacing and replacement implants. No pseudotumors or other adverse soft-tissue reactions were encountered in our study population. Further research is needed to determine the clinical importance of increased cobalt and chromium ion levels in serum and urine following metal-on-metal hip resurfacing.Level of Evidence:
Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.