| Ultra high molecular weight polyethylene (UHMWPE) is widely used in orthopedics as a load bearing component due to its excellent biocompatibility, high toughness, and high wear resistance. However, despite its excellent performance in vivo, wear is still a major concern since wear particulate debris induces osteolysis.; Cross-linking of UHMWPE by gamma radiation or electron beam has been accepted to improve the wear resistance. Although cross-linking enhances wear properties, other mechanical properties, such as ductility, modulus, impact strength, fatigue strength, and creep have been found to be deteriorated. Furthermore, gamma radiation generates significant amount of free radicals, which play a major role of such deterioration.; This study is aimed to improve wear resistance without sacrificing mechanical properties of UHMWPE. The proposed 3-layered acetabular cup is composed of a PMMA-precoated outermost layer for better fixation to bone cement, a highly cross-linked innermost layer for enhanced wear resistance against metal or ceramic femoral heads, and conventional UHMWPE in the middle to secure better mechanical properties.; Oxidation is another concern for irradiated UHMWPE. Anti-oxidation by mixing a chemical to UHMWPE resin powder prior to irradiation was investigated. Hydroquinone (HQ) was studied as an antioxidant for irradiated UHMWPE. By improving oxidation resistance of UHMWPE, wear property is expected to be sustained without deteriorating mechanical properties over a long period of time.; The oxidation of UHMWPE is a complex sequence which is yet fully understood. Especially it is more complex in in vivo implantation for a long term. Accelerated aging study of UHMWPE with HQ was conducted to simulate the long-term oxidation process.; This study showed that HQ is an effective chemical additive to reduce the oxidation without sacrificing mechanical strength. |
