Wear of composite ceramics in mixed-material combinations in total hip replacement under adverse edge loading conditions

Ceramic composites have performed very well under adverse edge loading conditions when used in like-on-like configurations, where the femoral head and acetabular cup are of the same material. The aim of this study was to determine the wear of pure alumina (Al O ), alumina toughened zirconia (ATZ) and zirconia toughened alumina (ZTA) when used in mixed bearing combinations, under edge loading conditions due to translational mal-positioning. The head-on-cup configurations of three ceramic materials were ATZ-on-ZTA, ZTA-on-ATZ, Al O -on-ATZ, ATZ-on-Al O , Al O -on-ZTA, and ZTA-on-Al O . They were tested on the Leeds II hip simulator under microseparation conditions. The bedding in and steady state wear rates of ATZ-on-ZTA were 1.16mm /million cycles and 0.18mm /million, respectively, and for ATZ-on-Al O were 0.66 mm /million cycles and 0.20 mm /million, respectively. The wear rates of the other bearing combinations under these adverse microseparation conditions, Al O -on-ATZ, Al O -on-ZTA, ZTA-on-ATZ and ZTA-on-Al O were very low with no clear bedding in and steady state phases, and with steady state wear rates lower than 0.11 mm /million. The mixed material combinations tested in this study have shown slightly higher wear rates when compared to ATZ in like-on-like configuration reported previously, but superior wear resistance when compared to alumina-on-alumina bearings tested previously under the same adverse microseparation conditions. © 2016 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1361-1368, 2017.