Ceramic composites have been developed to further improve the mechanical properties, reduce risk of fracture, and increase the survivorship of ceramic-on-ceramic bearings in total hip replacement1. The aim of this study was to evaluate the wear of two novel ceramic composite materials under edge loading conditions due to translational mal-positioning when used in both like-on-like and mixed pairing configurations; and to compare their performance to earlier generation ceramic-on-ceramic bearings. The head-on-cup configurations of three ceramic materials (see Figure 1), were ATZ-on-ATZ, ZTA-on-ZTA, Al2O3-on-Al2O3, ATZ-on-ZTA, ZTA-on-ATZ, Al2O3-on-ATZ, ATZ-on-Al2O3and Al2O3-on-ZTA. All combinations were size 28mm and were supplied by Mathys Orthopädie GmbH (Morsdorf, Germany). They were tested for four million cycles on the Leeds II hip simulator under microseparation2,3,4 conditions representing translational mal-positioning. The gait cycle comprised extension/flexion (−15º/+30º), internal external rotation (+/−10º) and a twin peak load with a maximum of 3kN. Microseparation was achieved by applying a 0.5mm dynamic medial/lateral displacement using a spring load resulting in edge loading at heel strike. New-born calf serum (25%) was used as a lubricant. Wear was assessed gravimetrically every million cycles. Statistical analysis was performed using one-way ANOVA (significance taken at p<0.05).Introduction
Materials and Methods
