Engineering and Design of Upper Limb Joint Arthroplasties with Special Interest in Tribology, Load Transfer, and Contact Mechanics

关节成形术用关节植入物替换受损的软骨，以减轻疼痛和恢复运动。然而，这些装置在体内的失败导致需要昂贵而痛苦的翻修手术来更换植入物。为了降低这种风险，目前的研究提案旨在调查和解决几种最常见的上肢关节置换植入物失败模式，目的是改进植入物设计，并以提高加拿大人的生活质量和降低医疗保健系统的成本为长期目标。此外，本文开发的研究方法也可以扩展到骨科的其他新兴领域。*反向全肩关节置换术(RTSA)的使用越来越多，但关节磨损和肩胛骨缺口仍是一个令人担忧的问题。虽然交联聚乙烯(XLPE)的使用减少了髋关节置换术中的磨损，但在不同载荷下，XLPE和非XLPE在RTSA中的摩擦学性能还没有得到充分的探索。为了解决这一问题，将使用肩部磨损模拟器对XLPE和非XLPE肩周杯在正常和不利载荷下进行磨损测试。肩胛骨切迹是由于肩周杯与肩胛骨接触而产生的，如果肱骨杯有一个内侧下方的切开，这是可以防止的。为了评估这一概念的可行性，将使用有限元模型来估计在不显著改变接触力学的情况下可以移除的切开程度，然后将产生的切开在肱骨杯上进行磨损测试，以评估它们对RTSA磨损的影响。新的RHH材料的使用可能有助于减少这种情况，但它们对软骨的摩擦学性能尚不完全清楚。为了解决这一问题，将使用正脚架磨损装置对生物酸盐(一种顺应性材料)和热解碳(PYC)进行磨损测试，热解碳是一种平滑的降低模数的材料。将评估Biata的长期疲劳性和PYC与软骨的摩擦学性能。肩关节置换后的肱骨应力屏蔽是常见的，是插入僵硬的金属肩关节柄后骨卸载的结果。虽然肱骨干的设计已经有所改进，但最佳的短柄几何形状尚未确定。为了解决这一问题，我们将采用一种新的建模技术，利用有限元方法优化肱骨假体的几何形状。*提出的创新研究计划结合了几种新的方法，以推进摩擦学和上肢关节置换术的设计，有助于在降低医疗成本的同时改善患者的预后和生活质量。**

Joint arthroplasty replaces damaged cartilage with articulating implants to alleviate pain and restore motion. However, failure of these devices in the body results in the need for costly and painful revision surgery to replace the implant. To reduce this risk, the current research proposal aims to investigate and address several of the most common upper limb arthroplasty implant failure modes with the aim of improving implant design and the long-term goal of improving the quality of life of Canadians and reducing cost to the healthcare system. Furthermore, moving forward the resulting research methodologies developed herein can also be extended to other emerging areas of orthopaedics.******Reverse total shoulder arthroplasty (RTSA) is growing in use, however articular wear and scapular notching remain a concern. While the use of cross-linked polyethylene (XLPE) has reduced wear in hip arthroplasty, the tribological performance of both XLPE and non-XLPE in RTSA has not been fully explored for varying loads. To address this, a shoulder wear simulator will be used to perform wear testing of XLPE and non-XLPE humeral cups subjected to normal and adverse loads. Scapular notching arises due to contact of the humeral cup with the scapula, which could be prevented if humeral cups had an inferomedial cut-out. To assess the feasibility of this concept, finite element modelling will be used to estimate the degree of cut-out that can be removed without significantly altering contact mechanics, and the resulting cut-outs will then be made on humeral cups and subjected to wear testing to assess their impact on RTSA wear.******Radial head hemiarthroplasty (RHH) replaces only one side of the joint, however the substitution of cartilage with a stiff metallic implant results in degeneration of the opposing cartilage. The use of new RHH materials may help to reduce this, however their tribological performance against cartilage is not fully understood. To address this, wear testing of Bionate, a compliant material, and pyrolytic carbon (PyC), a smooth reduced modulus material, will be performed using an OrthoPOD wear apparatus. The long-term fatigue of Bionate and the tribological performance of PyC against cartilage will be evaluated.******Humeral stress shielding following shoulder arthroplasty is common and is a result of the unloading of bone following insertion of a stiff metallic humeral stem. Although humeral stem design has been improved somewhat, the optimal short stem geometry has yet to be defined. To address this, humeral stem geometry will be optimized using finite element methods employing a novel modelling technique which permits the estimation of expected stress shielding following stem implantation.******The proposed innovative research program incorporates several novel approaches to advance the tribology and design of upper limb arthroplasty, contributing to the long-term vision of improving patient outcomes and quality of life while reducing healthcare costs.**