Cup inclination and serum concentration of cobalt and chromium after metal-on-metal total hip arthroplasty

We investigated whether cup inclination influences serum levels of cobalt and chromium after metal-on-metal total hip arthroplasty. Out of a consecutive series, 3 groups of 20 patients each were established according to their cup inclination: greatest inclination (55degrees-63degrees, mean 58degrees), intermediate inclination (44degrees-46degrees, mean 45degrees), and smallest inclination (23degrees-37degrees, mean 33degrees). We did not detect any statistically significant difference of serum cobalt (P =.23) or serum chromium (P =.13) levels between the 3 groups applying the Kruskal Wallis test. However , 3 patients with cup inclinations of 58degrees, 63degrees, and 61degrees exhibited 9.8-53.6-fold elevated cobalt and 9.5-30.5-fold elevated chromium levels when compared with the median concentrations of this trial. We therefore recommend accurate CLIP placement also for metal-on-metal articulations. Key words: total hip arthroplasty, metal-on-metal, serum cobalt, serum chromium, cup inclination. (C) 2004 Elsevier Inc. All rights reserved.