Abstract
Introduction: Polyethylene wear is an important factor for the longevity of total knee arthroplasty (TKA). One would expect that TKA lasting till death shows no or minimal wear compared to TKA undergoing revision surgery.
Material and Method: The present study retrospectively looks at the amount of front side wear on tibial retrievals and correlates clinical and radiological data sampled from these patients’ medical records. All Prostheses are of the same type and company (Stryker Howmedica, Allendale) with the following distribution: PCA 16, PCA modular 19 and Duracon 5. All inserts were gamma sterilized on air. Mean implantation time and mean age at implantation was 100.1 ±55.8 month and 70.7 ±7.4 years respectively. A modified visual score first described by Hood et al. 1983 served as measure for total damage on the polyethylene surface. Statistical Analysis was done by univariate analysis of variance.
Results: A highly significant influence on wear was found for the following factors: time of implantation (p< 0.001), kind of TKA design (p< 0.001), TKA belonging to the group of revision (0.016) and age at implantation (p< 0.021). A marginal influence was found for the factors: daily activity (p< 0.076) und kind of patella replacement (p< 0.085). Bodymass index and femorotibial axis had no measurable influence on wear.
Discussion: TKA retrieved at autopsy had and astonishingly high amount of wear. As a matter of fact none of the investigated implants was free of delamination, which is the most severe damage mode. In the present sample TKA design and time of implantation had a more important influence on wear than any other factor.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
