Abstract
Particles generated at the non articulating surface (backside) of modular acetabular components have been implicated in the development of periprosthetic osteolysis after THA. Several design changes have been introduced in modern acetabular cups in an attempt to reduce backside wear, including the use of “non-modular cups”. We compared the backside wear of retrieved cementless non-modular cups, with modular cups of first and second generation designs. Nine retrieved non-modular cups (Implex) were match-paired for time-in-situ, patient age and weight, with 9 retrieved Trilogy cups, 9 Harris-Galante 1, and 9 Harris-Galante 2. The average time in situ was 2.5 years (1–7). The backside was divided in quadrants and each rated with a value from 0 (absence of wear) to 3 (severe backside wear) for a total ranging from 0 to 12. This new score was validated for intra and inter observer reproducibility. Among 36 quadrants in the HG1 group there were 3 rated 1, 23 rated 2, and 10 rated 3. In the HG2 group, 1 quadrant was rated 0, 16 rated 1, 14 rated 2, and 5 rated 3. In the Trilogy group, 6 quadrants were rated 0, 27 rated 1, and 3 rated 2. In the Implex group, 15 quadrants were rated 0, 21 rated 1. The average backside wear score and 95%CI were 8.4 (7.6–9.3); 7.3 (5.5–9.1); 3.7 (3.2–4.1); and 2.3 (1.3–3.4) respectively. The HG cups demonstrated more severe backside wear than the Trilogy and Implex (p< 0.02). There was a tendency towards less backside wear in the Implex cup when compared to the Trilogy (p=0.04). The difference between the HG1 and HG2 was not significant. We detected significant reduction in the backside wear of modern modular and non-modular acetabular cups when compared to first generation modular designs.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
