Mechanics and Performance of Traceable UHMWPE Implants

描述（由申请人提供）：全髋关节置换术（THR）是晚期退行性关节疾病的标准治疗。然而，所有THR手术中有13-18%是再次手术，与初次THR相比，再次手术的结局更差，经济负担更大。在过去的十年中，随着第一代高交联超高分子量聚乙烯材料（重熔和退火）的引入以及最近第二代材料的引入，关节面技术在配方和组件设计方面发生了重大变化，第二代材料通过连续退火或维生素E扩散进行稳定。随着这些更耐磨材料的出现，股骨头尺寸增加，以减少不稳定的发生率。十年前，我们开始了多机构可追溯的检索收集，以确定聚乙烯部件的体内变化，并分析假体周围组织对聚乙烯磨损碎屑的反应。我们已经制定了方案，通过分析假体周围组织样本来测量回收植入物的机械性能、氧化和体积磨损，以及聚乙烯磨屑的大小和形状和相关的免疫反应。我们现在有证据表明，伽马惰性灭菌、退火和重熔聚乙烯在短期至中期植入时间（<10年）内会在体内发生降解。仍然需要了解高交联聚乙烯体内降解的长期影响，并评价新材料和设计修改的性能。通过取出研究，我们将评价：植入超过5年的取出退火和重熔关节面的性能;第二代高交联内衬的临床性能;以及股骨头尺寸、磨损和边缘损坏之间的关系。我们假设：植入5年后，退火和重熔高交联内衬翻修的体内氧化、磨损和松动原因将无差异;第二代聚乙烯配方将保持与重熔高交联内衬相当的氧化稳定性和机械性能;股骨头尺寸大于28 mm不会增加第一代和第二代交联内衬的关节面磨损和边缘损坏。通过更好地了解关节面技术因素和聚乙烯部件的生存率，实现拟定目标将改善THR的临床性能。

DESCRIPTION (provided by applicant): Total hip replacement (THR) surgery is the standard of care for advanced degenerative joint disease. However, 13-18% of all THR surgeries are reoperations, which have poorer outcomes and greater economic burden than primary THRs. Bearing technologies have undergone major changes with respect to formulation and component design over the past decade with the introduction of first-generation highly crosslinked ultra-high molecular weight polyethylene materials (remelted and annealed) and the recent introduction of second-generation materials, stabilized with sequential annealing or vitamin-E diffusion. With the advent of these more wear resistant materials, head sizes have increased to reduce the incidence of instability. Ten years ago, we began a multi-institution traceable retrieval collection to determine in vivo changes to polyethylene components and to analyze periprosthetic tissue responses to polyethylene wear debris. We have developed protocols to measure the mechanical properties, oxidation, and volumetric wear of retrieved implants, as well as the size and shape of polyethylene wear debris and the associated immunologic response through analysis of periprosthetic tissue samples. We now have evidence to show that degradation of gamma inert-sterilized, annealed, and remelted polyethylene occurs in the body for short- to intermediate-term implantation times (<10 years). There is a continued need to understand the long-term effects of in vivo degradation of highly crosslinked polyethylenes and to evaluate the performance of new material and design modifications. Through explant studies we will evaluate: the performance of retrieved annealed and remelted bearings implanted greater than 5 years; the clinical performance of second-generation highly crosslinked liners; and relationships between head size, wear, and rim damage. We hypothesize that: beyond five years of implantation, in vivo oxidation, wear and loosening as reasons for revision of annealed and remelted highly crosslinked liners will not differ; 2nd-generation polyethylene formulations will preserve oxidative stability and mechanical properties comparable to remelted highly crosslinked liners; and femoral head sizes greater than 28 mm will not increase bearing surface wear and rim damage in first and second generation crosslinked liners. Achieving the proposed aims will lead to improved clinical performance of THRs through a better understanding of bearing technology factors and survivorship of polyethylene components.