DEVELOPMENT OF METHODS FOR EVALUATING MECHANICAL PROPERTIES OF RETRIEVED ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE COMPONENTS OF ARTIFICIAL JOINTS

Since artificial joints are expected to operate for more than decades in human body, animal and clinical studies are not suitable for evaluation of their durability. Instead, in-vitro mechanical tests have been employed, but they cannot fully reproduce complex in-vivo mechanical and biochemical environment. For instance, lipids in synovial fluid have been known to be absorbed in ultra-high molecular weight polyethylene (UHMWPE) components of artificial joints in vivo, and recently it was found that absorbed lipids have potential to degrade UHMWPE. In order to assure clinical relevance of the in-vitro mechanical tests, understanding of the effect of the in-vivo environment on mechanical properties is indispensable. However, well-developed mechanical tests cannot be applied to retrieved components, because they require large specimens. In this study, we attempted to develop methods to evaluate mechanical properties of retrieved UHMWPE components.We prepared five kinds of UHMWPE. Those are molded UHMWPE made...