Abstract
Purpose: The purpose of this study was to monitor serum cobalt (Co) and chromium (Cr) levels in patients after metal-on-metal resurfacing hip arthroplasty with the Cormet 2000® prosthesis, and to evaluate the effect of patient characteristics, prosthesis characteristics, clinical and radiographic measures on metal levels.
Methods: Serum Co and Cr levels were determined in 32 patients with Cormet resurfacing prostheses at 0.5, 1 and 2 years postoperatively using ICP-MS and are reported as & #61549;g/L. Control levels were measured in 20 patients without implants.
Results: Medium Co and Cr were 0.21 and 0.16 in controls without implants. Medium Co at 6 months (2.65), 1 year (3.62) and 2 years (2.80), and Cr at 6 months (3.74), 1 year (4.73) and 2 years (4.68) were signifi-cantly increased in the Cormet group when compared to control levels (p < .0001). Metal levels did not correlate with cup inclination, component position, head size, age, weight, sex or Harris Hip scores. Markedly elevated Co (35, 63) and Cr (13, 70) levels were found in two patients with excessive cup abduction. In addition, one patient with a loose implant that required revision had markedly elevated Co (19) and Cr (44) levels.
Conclusions: Significantly increased levels of cobalt and chromium were released from Cormet 2000 articulations at all time points. Excessive cup abduction was associated with markedly elevated ion levels indicating that accurate cup placement is an important consideration in resurfacing arthroplasty. The significantly increased trace metal levels following resurfacing with the Cormet prosthesis is a concern and warrants further monitoring.
Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
