Low wear rate at 6

Free radicals formed in the cross-linking process may over time alter the mechanical properties of highly cross-linked polyethylene. Vitamin E-infused highly cross-linked polyethylene was therefore developed to achieve low wear-rate and good mechanical properties in the long term. To present 6-year results from the initial randomised controlled trial. We measured wear and periacetabular bone remodelling in cementless total hip arthroplasty; 32- or 36-mm Biolox Delta heads and vitamin E-infused highly cross-linked polyethylene (E-Poly) were used. Markerless radiosterometric analysis measured the in vivo wear and dual energy x-ray absorptiometry was used to analyse bone remodelling in 40 hips at 6-year follow-up. In the proximal direction the wear for 32- and 36-mm heads was 0.15？mm (95% confidence interval [CI], 0.08–0.21) and 0.06？mm (95% CI, -0.002–0.12), respectively (p = 0. 015). However, between 3？months and 6？years (excluding the period of “bedding in”), the proximal wear for 32- and 36-mm heads was 0.10？mm (95% CI, 0.05–0.15) and 0.05？mm (95% CI, -0.01–0.11), respectively (p = 0.12). The annual proximal wear rate for 32- and 36-mm heads from 3？months to 6？years was 0.02？mm and 0.01？mm, respectively. There was no difference in bone remodelling around the cup from baseline to 6？years for the total material and no differences between study groups. Wear of this vitamin E-infused highly cross-linked polyethylene is still low at 6-year follow-up, with no significant difference in wear from 3？months to 6？years between 32- and 36-mm heads