Metal-on-Polyethylene Total Hip Arthroplasty: Exploring wear and corrosion resistance through visual analysis techniques

金属-聚乙烯（MoP）是目前全髋关节置换术（THA）器械中使用最广泛的轴承组合，2017年在英国占骨水泥一期髋关节植入物的87.1%。MoP通常用于小直径设备，以限制聚乙烯（PE）磨损碎片的产生，聚乙烯磨损碎片会导致骨溶解，导致无菌松动和失效。这些小直径轴承广泛使用，但这些装置限制了患者的髋关节功能，并容易脱位；这是继磨损相关失败（如骨溶解）后进行翻修的第二大原因。对于植入前功能相对较低的老年患者，这些限制在很大程度上是可以接受的，但对于通常更活跃的年轻患者来说，这些限制是有问题的。较大直径的轴承克服了这些限制，但伴随的轴承表面积的增加导致磨损碎片的产生和可能的腐蚀。因此，如果可以证明，当使用现代材料和制造技术时，与现有设备相比，大直径MoP设备可以在可接受的磨损和腐蚀公差范围内运行，那么新的大轴承技术可以被广泛采用。这将带来大直径轴承的好处，如更大的运动范围和更低的脱位风险，并将增加骨科磨损和耐腐蚀性的知识，这可以应用于其他植入技术。目的研究并改进一种新型MoP THA装置的耐蚀性和耐磨性。这将包括测试样品植入物的耐磨性、耐腐蚀性和疲劳寿命的实验。项目的主要目标总结如下：第一年：文献综述，实验设计，夹具和髋关节部件的制造，初步试验和综述论文的撰写。第二年：磨损和腐蚀研究，学习和发展XPS样品分析知识，中期论文发表和会议报告。第三年：设计和实施髋关节模拟器的新升级，以提供增强的测试参数，验证论文发表，参加会议和论文发表。第四年：论文准备和完成实验，更新实验结果的论文发表，参加会议并准备ISO和ASTM测试机构的建议。本项目开展的研究应有助于更广泛地采用大直径MoP THA装置，将前面讨论的优势传递给患者。此外，从这个项目中获得的知识应该提高对磨损和腐蚀方法的理解，这将导致生产更耐磨损和腐蚀的髋关节植入物；这也可以应用于其他矫形装置。为了帮助实现这一结果，将产生新的测试方法，与骨科社区共享。其他成果包括评估现代PE材料用于大直径MoP tha的适用性，以及设计表面分析样品评估方案，以贡献给国家联合登记处。为什么选择纽卡斯尔大学？纽卡斯尔大学是英国生物工程领域的领先研究中心。该研究小组设在工程学院，但也受益于与该大学医学院、英国国家医疗服务体系（NHS）、医疗慈善机构和主要工业合作伙伴的紧密联系。该研究小组还受益于该领域多位领先学者的专业知识，并拥有一系列设备和设施，如NEXUS，这将有助于项目的进展。

Project IntroductionMetal-on-Polyethylene (MoP) is currently the most widely used bearing combination in total hip arthroplasty (THA) devices, accounting for 87.1% of cemented primary hip implants in the UK in 2017. MoP is typically used in small diameter devices in order to limit the production of Polyethylene (PE) wear debris, which causes osteolysis leading to aseptic loosening and failure. These small diameter bearings are widely used but these devices limit patient hip functionality and are susceptible to dislocation; this is the second leading cause of revisions following wear related failures such as osteolysis. These limitations are largely acceptable in older patients who tend to have relatively low functionality prior to implantation, but are problematic for younger patients who are usually more active. Larger diameter bearings combat these limitations, but the accompanying increase in surface area of the bearing results in increased wear debris production and possibly corrosion.Therefore if it can be shown that, when using modern materials and manufacturing techniques, a large diameter MoP device can perform within acceptable wear and corrosion tolerances compared to existing devices, then the new large-bearing technology could be widely adopted. This would deliver the benefits of large diameter bearings such as larger range of motion and reduced risk of dislocation, , and would increase knowledge of orthopaedic wear and corrosion resistance in general, which could be applied to other implant technologies. ObjectivesThe project will investigate and improve corrosion and wear resistance of a novel MoP THA device. This will involve experiments testing the wear resistance, corrosion resistance and fatigue life of sample implants. The main objectives of the project are summarized below:Year 1: Literature review, design of experiments, manufacture of fixture and hip components, preliminary tests and review paper writing.Year 2: Wear and corrosion studies, learning and developing XPS sample analysis knowledge, interim paper publication and conference presentation.Year 3: Design and implement novel upgrades to hip simulator to provide enhanced testing parameters, validation paper publication, conference attendance and thesis commencement. Year 4: Thesis preparation and finishing experiments, paper publication on updated experimental results, conference attendance and preparation of ISO and ASTM testing body recommendations. The research undertaken in this project should aid wider adoption of large diameter MoP THA devices, delivering the advantages discussed previously to patients. Additionally, the knowledge gained from this project should improve understanding of wear and corrosion methods, which would lead to the production of hip implants that are more resistant to these; this could also be applied to other orthopaedic devices. To aid in this outcome new testing methodologies will be produced, to be shared with the orthopaedic community. Other outcomes include an assessment of the suitability of modern PE materials for use in large diameter MoP THAs, and the design of a surface analysis sample assessment protocol, for contribution to the National Joint Registry.Why Newcastle University?Newcastle University is a Leading UK research centre in the field of bioengineering. The research group is housed in the school of engineering, but also benefits from strong ties with the university's medical school, as well as the NHS, medical charities and leading industrial partners. The research group also benefits from the expertise of multiple leading academics in the field, as well as having an array of equipment and facilities such as NEXUS that will aid the progress of the project.