2.1 Biocompatibility of Alumina-Ceramic in Total Hip Replacement. Macroscopic- and Microscopic Findings on Capsular Tissues after Long-term Implantation

Clinically the low wear of self-pairing aluminaceramic type BIOLOX (Feldmühle/CERASIV) in the self-locking AUTOPHOR and cemented XENOPHOR prosthesis (Osteo AG) was confirmed radiographically after 10 years (29) and recently after 20 years (33) of clinical experience. In laboratory measurements of retrieved prostheses (chiefly after infection or aseptic loosening) the low wear rate of ceramic self-pairing components was also confirmed by Mittelmeier et al. (28, 30), being at the socket 5,4 μm and on the head 2,6 μm/year in average. This results were in the range reported by Boutin and Blanquaert (3) with a wear of 9 μm/year on the head and 6 μm/ year on the socket in average. Dorlot (12), found a wear rate of 0,025 μm/year as the normal wear behaviour of firm well positioned alumina ceramic components in self-pairing design, pointing out, that higher wear-rates are caused either by false positioning of the components (primary or secondary due to loosening) or insufficient material properties of the alumina-ceramics. Dorlot’s (12) results could be confirmed by Walter’s (41) investigations, reporting wear rates in a range between 0,025 μm/year and 5 μ/year in well positioned cases.