O1222 ANALYSIS OF EARLY RETRIEVED ACETABULAR CUPS OF HIGHLY CROSSLINKED UHMWPE

Abstract

Aims: To solve the major problems of osteolysis due to particle debris in total hip arthroplasty, highly cross-linked UHMWPE were developed. Investigations on early retrieved components of Durasul™ (Centerpulse Orthopedics Ltd.) provide the opportunity to evaluate the highly crosslinked components for wear damage or other effects on the material. Methods: 12 Durasul™ alpha cups were surgically retrieved and analyzed. The range of in-vivo duration of the cups was between 3 and 15 months. The reasons for revision were not related to material failure. The investigations were made by microscopy and CMM measurement. To differentiate between creep and wear, the memory effect was used. Results: In the articulation, machining marks look partly flattened, or show a highly scratched surface. The loaded area shows some microscopic changes of the morphology like ripples and folds, which are shear-induced ripple formations and material overlappings. In some cases the retrieved cups show a yellow discoloration, indicating the in-vivo absorption of synovial liquid proteins. Conclusion: The findings from the retrievals showed that there is no adverse wear at 3–15 months and there were no material failures due to wear, delamination or cracks. All the effects are accumulating on the articulating surface and lead to the dull scratched morphology. Mechanisms like material overlapping and yellowing are reported also from conventional UHMWPE and do not show adverse effects on the long-term behaviour of the material.