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 (55°–63°, mean 58°), intermediate inclination (44°–46°, mean 45°), and smallest inclination (23°–37°, mean 33°). 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 58°, 63°, and 61° 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 cup placement also for metal-on-metal articulations.