Abstract
In 2020 almost 90% of femoral heads for total hip implants in Germany were made of ceramic. Nevertheless, the cellular interactions and abrasion mechanisms in vivo have not been fully understood until now. Metal transfer from the head-neck taper connection, occurring as smear or large-area deposit, negatively influences the surface quality of the articulating bearing. In order to prevent metal transfer, damage patterns of 40 Biolox delta ceramic retrievals with CoC and CoPE bearings were analysed.
A classification of damage type and severity for each component (n=40) was done according to an established scoring system. To investigate the physical properties, the surface quality was measured using confocal microscopy, quantitative analysis of phase composition were performed by Raman spectroscopy and qualitative analysis of metal traces was done by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). The periprosthetic tissue was analysed for abrasion particles with SEM and EDX.
Both bearing types show different damage patterns. Dotted/ drizzled metal smears were identified in 82 % of CoC (n=16) and 96 % of CoPE (n=24) bearings. Most traces on the ceramic heads were identified in the proximal area while they were observed predominantly in the distal area for the ceramic inlays. The identified marks are similar to those of metallic bearings. Metallic smears lead to an increase of up to 30 % in the monoclinic crystalline phase of the ceramic. The roughness increases by up to six times to Ra=48 nm. Ceramic and metallic wear particles from the articulating surfaces or head neck taper junctions were found in the periprosthetic tissue.
Damage patterns on CoC hip implants seem to be similar to those of metallic implants. More detailed analysis of CoC implants are needed to understand the described damage patterns and provide advice for prevention.
