iMBE, University of Leeds, UK.
iMBE, University of Leeds, UK.
J Mech Behav Biomed Mater. 2018 Feb;78:282-291. doi: 10.1016/j.jmbbm.2017.11.022. Epub 2017 Nov 17.
A more robust pre-clinical wear simulation framework is required in order to simulate wider and higher ranges of activities, observed in different patient populations such as younger more active patients. Such a framework will help to understand and address the reported higher failure rates for younger and more active patients (National_Joint_Registry, 2016). The current study has developed and validated a comprehensive combined experimental and computational framework for pre-clinical wear simulation of total knee replacements (TKR). The input mechanical (elastic modulus and Poisson's ratio) and wear parameters of the moderately cross-linked ultra-high molecular weight polyethylene (UHMWPE) bearing material were independently measured from experimental studies under realistic test conditions, similar to the loading conditions found in the total knee replacements. The wear predictions from the computational wear simulation were validated against the direct experimental wear measurements for size 3 Sigma curved total knee replacements (DePuy, UK) in an independent experimental wear simulation study under three different daily activities; walking, deep squat, and stairs ascending kinematic conditions. The measured compressive mechanical properties of the moderately cross-linked UHMWPE material were more than 20% lower than that reported in the literature under tensile test conditions. The pin-on-plate wear coefficient of moderately cross-linked UHMWPE was significantly dependant of the contact stress and the degree of cross-shear at the articulating surfaces. The computational wear predictions for the TKR from the current framework were consistent and in a good agreement with the independent full TKR experimental wear simulation measurements, with 0.94 coefficient of determination of the framework. In addition, the comprehensive combined experimental and computational framework was able to explain the complex experimental wear trends from the three different daily activities investigated. Therefore, such a framework can be adopted as a pre-clinical simulation approach to optimise different designs, materials, as well as patient's specific total knee replacements for a range of activities.
为了模拟更广泛和更高范围的活动，需要更强大的临床前磨损模拟框架，这些活动在不同的患者群体中都有观察到，例如更年轻、更活跃的患者。这样的框架将有助于理解和解决报告中年轻和更活跃患者更高失败率的问题（国家联合登记处，2016 年）。本研究开发并验证了一种全面的综合实验和计算框架，用于全膝关节置换的临床前磨损模拟。中等交联超高分子量聚乙烯（UHMWPE）轴承材料的输入机械（弹性模量和泊松比）和磨损参数是根据相似于全膝关节置换中发现的加载条件的实际测试条件下的实验研究独立测量的。在独立的实验磨损模拟研究中，对尺寸为 3 Sigma 弯曲的全膝关节置换（DePuy，英国）进行了三种不同日常活动（行走、深蹲和楼梯上升运动条件）下的计算磨损模拟预测与直接实验磨损测量进行了验证。中等交联 UHMWPE 材料的实测压缩力学性能比文献中报道的拉伸试验条件下低 20%以上。中等交联 UHMWPE 的销盘磨损系数与接触应力和关节表面的交叉剪切程度显著相关。当前框架的 TKR 计算磨损预测与独立的全 TKR 实验磨损模拟测量结果一致，框架的决定系数为 0.94。此外，综合的实验和计算框架能够解释从三种不同日常活动中研究得出的复杂实验磨损趋势。因此，这样的框架可以作为一种临床前模拟方法，优化不同设计、材料以及各种活动的患者特定的全膝关节置换。
