Mechanics and Performance of Traceable UHMWPE Implants

描述（由申请人提供）：全髋关节置换术（THR）手术是晚期退行性关节疾病的标准治疗。然而，在所有THR手术中，有13-18%是再手术，与原发性THR相比，再手术的效果更差，经济负担更大。在过去的十年中，轴承技术在配方和组件设计方面发生了重大变化，引入了第一代高交联超高分子量聚乙烯材料（重熔和退火）和最近引入的第二代材料，通过顺序退火或维生素e扩散稳定。随着这些更耐磨的材料的出现，头部尺寸增加，以减少不稳定的发生率。十年前，我们开始了一个多机构可追溯的检索收集，以确定体内聚乙烯成分的变化，并分析假体周围组织对聚乙烯磨损碎片的反应。我们已经制定了方案，通过分析假体周围组织样本来测量机械性能、氧化和回收植入物的体积磨损，以及聚乙烯磨损碎片的大小和形状以及相关的免疫反应。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到中期植入时间（<10年）内发生降解。人们仍然需要了解高交联聚乙烯在体内降解的长期影响，并评估新材料的性能和设计修改。通过外植体研究，我们将评估：植入5年以上的回收退火和重熔轴承的性能；第二代高交联衬垫的临床性能以及头部大小，磨损和边缘损伤之间的关系。我们假设：超过5年的植入，体内氧化，磨损和松动作为翻修的原因退火和重熔高度交联衬垫不会有不同；第二代聚乙烯配方将保持氧化稳定性和机械性能，可与重熔高交联内衬相媲美；股骨头尺寸大于28毫米不会增加第一代和第二代交联衬垫的轴承表面磨损和边缘损伤。通过更好地了解承载技术因素和聚乙烯组件的存活率，实现所提出的目标将导致THRs的临床性能得到改善。

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.