人工膝関節用超高分子量ポリエチレン脛骨インサートにおける塑性流動現象の考察(機械要素,潤滑,工作,生産管理など)

概要

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The wear phenomenon of ultra-high molecular weight polyethylene(UHMWPE) in knee and hip prostheses is one of the major restriction factors on the longevity of these implants. In retrieved knee prostheses with screw holes in the tibial tray, cold flow into the screw holes is frequently observed on the undersurface of the UHMWPE tibial inserts. In most retrieved cases, the protruded areas of cold flow on the undersurface were located on the reverse side of the severely worn and deformed surface of the UHMWPE tibial insert. It appears that the cold flow into screw holes contributes to the increase of wear of the UHMWPE tibial insert. In this study, knee joint simulator tests and finite element analyses of the simplified knee prostheses were performed, in order to investigate the influence of the cold flow into screw holes on the wear of the UHMWPE tibial insert. The results of this study suggest that the cold flow into screw holes is associated with delamination and increase of wear in the contact area on the articulating UHMWPE surface.
2005-06-25