Mechanics and Performance of Traceable UHMWPE Implants

描述（由申请人提供）：全髋关节置换术（THR）是美国晚期退行性关节疾病的标准治疗。2002年，估计有243，000名美国人从这一程序中受益。然而，所有THR手术中有18%是翻修手术，与初次THR相比，翻修手术的结局更差，经济负担更大。在美国，由于骨质溶解和对聚乙烯磨屑的组织反应，髋关节植入物松动被认为是限制植入物寿命的主要问题。在过去的十年中，用于THR的聚乙烯材料在灭菌和配方方面发生了重大变化，因此，目前临床实践中使用的聚乙烯采用了一系列灭菌和辐射交联工艺。然而，目前尚不清楚这些过程在多大程度上影响了聚乙烯关节面部件在体内长期植入过程中氧化降解的趋势。还不清楚体内聚乙烯氧化对当代髋关节置换术临床性能的影响程度。在这项为期5年的竞争性延续研究中，我们建议将我们对可追溯伽马空气灭菌聚乙烯髋关节面组件的研究扩展到包括用于髋关节置换术的回收伽马惰性灭菌和高交联聚乙烯关节面。已知伽马空气灭菌聚乙烯髋关节关节假体在体内发生氧化降解，极限强度显著降低，提出以下三个新假设：（1）当代伽马惰性灭菌聚乙烯髋关节假体在体内使用期间将发生{区域特异性}机械性能降解;（2）退火的高交联聚乙烯髋关节轴承（含有残留自由基）将在体内发生{区域特异性}机械性能退化，并且重熔的高交联聚乙烯髋关节轴承，经处理以淬灭自由基，不会在体内显著降解;和（3）作为高度交联内衬翻修原因的磨损和松动的发生率低于伽马惰性灭菌内衬。

DESCRIPTION (provided by applicant): Total hip replacement (THR) surgery is the standard of care for advanced degenerative joint disease in the US. In 2002, an estimated 243,000 Americans benefited from this procedure. However, 18% of all THR surgeries are revisions, which have poorer outcomes and greater economic burden than primary THRs. Loosening of hip implants, due to osteolysis and tissue reactions to polyethylene wear debris, is considered to be the main problem limiting implant longevity in the US. Within the past decade, polyethylene materials used for THR have undergone major changes in sterilization and formulation, so that a range of sterilization and radiation crosslinking processes are now applied to polyethylene used in clinical practice. However, it remains unclear to what extent these processes affect the tendency of polyethylene bearing components to oxidatively degrade during long-term implantation in the body. It is further unknown to what extent oxidation of polyethylene in the body impacts the clinical performance of contemporary hip replacements. In this five-year competing continuation, we propose to extend our study of traceable gamma-air sterilized polyethylene hip bearing components to encompass retrieved gamma-inert sterilized and highly crosslinked polyethylene bearings for hip arthroplasty. Knowing that gamma air-sterilized polyethylene hip bearing components undergo in vivo oxidative degradation with significant reduction of ultimate strength, the following three new hypotheses are proposed: (1) contemporary gamma inert sterilized polyethylene hip bearings will undergo {region-specific} degradation of mechanical properties during in vivo use; (2) annealed highly crosslinked, polyethylene hip bearings that contain residual free radicals will undergo {region-specific} degradation of mechanical properties in vivo and remelted highly crosslinked polyethylene hip bearings, that are processed to quench free radicals, will not degrade significantly in vivo; and (3) wear and loosening as reasons for revision of highly crosslinked liners will be lower in prevalence than in gamma inert sterilized liners.