Influence of the wear-couple and patient activity on linear wear in total hip replacement

Abstract

In total hip replacement different factors have a major impact on wear behaviour and long-term durability. Beside the wear-couple the influence of patient activity is relatively undefined. Aim of this studies was to examine the wear behaviour of alumina heads in combination with conventional polyethylene (PE) (n=99) vs. CoCr heads (n=109), the wear behaviour of alumina heads in combination with highly-crosslinked PE (n=70), and the influence of patient activity in the groups with alumina heads. Linear wear was analyzed using Martell's method and activity was assessed using electronic step-watch monitors. Compared to CoCr heads the use of alumina significantly reduced linear wear. A further reduction was observed with the combination of alumina and highly-crosslinked PE after a certain period of higher wear during bedding-in. In spite of being nearly 20 years younger the activity in the patients with the highly-crosslinked PE differed only about 20% compared to the patients with conventional PE. In conclusion the selection of the wear-couple has a significant influence on linear wear while patient activity in our study groups was in the same magnitude.