In vitro wear testing of Metal on Polymer artificial hip components under intermittent motion conditions.

背景全髋关节置换术（THR）在2007年被The Lancet杂志描述为“世纪手术”，是目前世界范围内最常用的关节置换术[1，2]。尽管该手术具有良好的成功率，但可能会出现并发症，导致一系列需要翻修手术的临床问题[1]。最常见的失效原因是关节面释放的磨损碎屑的不良影响。这在金属对金属植入物设计中尤其成问题，其磨损超过预期并释放破坏性金属碎片，对患者造成有害副作用[3，4]。随后，金属对聚合物（MoP）接头设计是目前最常用的[1]。临床前部件磨损测试对于避免此类问题至关重要。同样重要的是，这些测试准确模拟组件植入后可能遇到的条件。目前，人工髋关节组件的模拟器测试大多采用连续步行循环，速度为每秒一个循环（频率为1Hz），根据国际标准ISO 14242 [5]。这个标准也意味着一个人走了50万步才停下来，这对人们的生活方式是不准确的。人们倾向于短时间步行，然后站立，患者倾向于步行比建议慢得多[6，7]。因此，在间歇运动或“行走-站立-行走”载荷和运动方案下进行模拟器测试更具临床意义。有证据表明，在这些条件下，组件将经历更多的磨损，然而，有关MoP部件的研究很少[8-11]。目的研究在临床相关间歇运动和负载条件下金属对聚合物髋关节置换部件的磨损特性。目的 * 制定临床相关测试方案 * 更新模拟器编程以应用间歇运动条件 * 比较ISO标准和间歇运动条件下获得的组件磨损结果。方法纽卡斯尔大学新开发的髋关节模拟器（图2）将用于在ISO标准条件和间歇行走条件下以不同频率对最常见类型的THR植入物进行磨损测试。然后将对取得的结果进行比较分析。测试将按如下方式进行：* ISO 14242条件为1Hz* Walk-stand-walk条件为1Hz* ISO 14242条件为0.5Hz* Walk-stand-walk条件为0.5Hz所有测试将运行500万次循环，每500，000次循环暂停一次以进行磨损测量。将进行重量测量以及表面粗糙度分析，以评估部件磨损。还将对磨损碎屑进行分析。未进行评估的测试条件将按照ISO标准指南进行维护，以确保正确建立变量效应。影响仅在英国，2018年就进行了近10万例全髋关节置换术[1]。在植入前对人工关节进行更好的测试将确保患者能够尽可能多地活动，从而使他们能够过上更快乐，更富有成效的生活。据设想，本研究的结果可能有助于改变人工髋关节临床前磨损测试的现行标准，以纳入更多临床相关的测试条件。参考文献[1] W.英格兰、北方爱尔兰和马恩岛国家关节登记系统，“第16期年度报告”，2019年，第2054- 183 X期。[联机]。可查阅：www.njrcentre.org.uk[2] D.里尔蒙斯角Young和C. Rorabeck，“世纪的手术：全髋关节置换术”，《柳叶刀》，第370卷，第9597期，第100页。1508-1519，2007，doi：10.1016/S0140-6736（07）60457-7。[3]“REF影响案例研究支持国家和国际政策制定，

BackgroundTotal hip replacement (THR) was described as 'the operation of the century' in The Lancet in 2007, and is currently the most commonly implemented joint replacement procedure world-wide [1, 2]. Although this procedure has reputable success rates, complications can arise leading to a range of clinical issues which require revision surgery [1]. The most prevalent causes for failure are the adverse effects of wear debris released from articulating surfaces. This was particularly problematic in metal-on-metal implant designs, which wore more than expected and released damaging metal debris, causing detrimental side effects in patients [3, 4]. Subsequently, metal on polymer (MoP) joint designs are currently the most commonly implemented [1]. Pre-clinical wear testing of components is essential in avoiding such issues. It is also of high importance that these tests accurately simulate the conditions components are likely to encounter once they are implanted. Currently, simulator testing of artificial hip components mostly apply a continuous walking cycle, at a speed of one cycle per second (frequency of 1Hz), as per the international standard ISO14242 [5]. This standard also implies that a person walks for 500,000 steps before stopping, which is inaccurate to how people live. People tend to walk for short periods and then stand, with patients tending to walk much slower than is suggested [6, 7]. Thus, simulator testing under an intermittent motion or "walk-stand-walk" loading and motion protocol makes more clinical sense. Evidence suggests that, under these conditions, components will experience more wear, however research is minimal where MoP components are concerned [8-11].AimTo investigate wear characteristics of metal on polymer hip replacement components under clinically relevant intermittent motion and load conditions.Objectives* Develop clinically relevant testing protocol * Update simulator programming to apply intermittent motion conditions* Compare wear results from components obtained under ISO standard and intermittent motion conditions.MethodologyA newly developed hip simulator (figure 2), at Newcastle University, will be utilised to conduct wear tests on the most common type of THR implant under ISO standard conditions and intermittent walking conditions at varied frequencies. A comparative analysis will then be conducted of results obtained. Tests will take place as follows:* ISO 14242 condition at 1Hz* Walk-stand-walk condition at 1Hz* ISO 14242 condition at 0.5Hz* Walk-stand-walk condition at 0.5HzAll tests will run for 5 million cycles, pausing every 500,000 cycles to take wear measurements. Gravimetric measurements will be taken as well as analysis of surface roughness, to assess component wear. Wear debris will also be analysed.Test conditions which aren't being assessed will be maintained to ISO standard guidelines to ensure proper establishment of variable effects. ImpactAlmost 100,000 total hip replacements were conducted in 2018 in the UK alone [1]. Better testing of artificial joints prior to implantation will ensure that patients are able to live pain-free with as much mobility as possible, enabling them to live happier and more productive lives. It is envisaged that the results of this research could contribute to changes to the current standards for pre-clinical wear testing artificial hip joints to include more clinically relevant test conditions. References[1] W. National Joint Registry for England, Northern Ireland and the Isle of Man, "16th Annual Report," 2019, issue 2054-183X. [Online]. Available: www.njrcentre.org.uk[2] I. D. Learmonth, C. Young, and C. Rorabeck, "The operation of the century: total hip replacement," The Lancet, vol. 370, no. 9597, pp. 1508-1519, 2007, doi: 10.1016/S0140-6736(07)60457-7.[3] "REF Impact Case Study Supporting national and international policy development on the