TRIBOLOGICAL PROPERTIES OF CARBON-FIBER-R EINFORCED PLASTIC (CFRP) - EXPERIMENTAL AND CLINICAL-RESULTS

Wear of the articulating components (especially PE-UHMW) of total hip endoprostheses is the most important technical factor limiting the fun ctional lifetime. To minimize wear debris, ceramic heads, according to ISO 6474 (Al2O3), have been used, from 1969 paired with Al2O3 and sin ce 1975 paired with PE-UHMW. Al2O3 balls articulating with cups made f rom CFRP have been in clinical use since 1988. Laboratory experiments and in-vivo testing showed minimized wear debris and mild biological r esponse to wear products using CFRP (carbon fiber reinforced plastic) instead of PE-UHMW as the cup material. The articulating surfaces of r etrieved ceramic heads (Al2O3 - Biolox(R)) and cementless CFRP cups (c arbon fiber reinforced plastic, Caproman(R)) were compared using spher icity measurement techniques, scanning electron microscopy (SEM) and r oughness measurements (including advanced roughness parameters R(vk) o r R(pk) according to ISO 4287). Altogether, the first results of the c linical study showed that the combination Al2O3-ball/CFRP-cup came up to the expected lower wear rates compared with the conventional combin ations. The wear rates are comparable with the combination Al2O3/Al2O3 without the material-related problems of ceramic components in all ce ramic combinations.