Abstract Currently, preclinical wear tests for total hip replacements is carried out by using mechanical simulators under a simplified normal gait cycle as recommended by the international guidelines ISO-14242. Nevertheless, the wear tests have a long duration and are expensive so that the aim of this paper was to propose a novel in silico approach for wear calculation in lubricated total hip replacements. The proposed in silico simulation is based on the accurate modelling of the tribological phenomena acting in the joint during certain kinematical and dynamical conditions under non-Newtonian unsteady mixed elasto-hydrodynamic lubrication conditions (MEHL). The analyzed hip joint is modeled as soft polymeric acetabular cup, PE GUR1020 (EtO), against hard metallic CoCrMo femoral head. The calculation of the fluid film pressure field within the joint gap is achieved during the in silico simulations by imposing the ISO 14242-3 kinematics and dynamics, to evaluate the cumulated wear volume over a single gait cycle by using a modified Archard’s model. The main purpose of this study is to propose an in-silico wear calculation approach reproducing the classical in vitro wear testing of total hip replacements accounting for unsteady synovial lubrication effects between the femoral head and the acetabular cup. The predicted wear, extrapolated from a novel proposed approach based on the wear slopes, was compared with the value from in vitro simulations showing a satisfactory agreement, allowing the authors to conclude that the proposed model is suitable to be used as in silico hip joint wear simulator.

中文翻译：

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在 ISO 14242-3 框架内进行模拟全髋关节置换磨损测试，考虑到混合弹性流体动力润滑效应

摘要 目前，全髋关节置换的临床前磨损试验是通过使用机械模拟器在国际指南 ISO-14242 推荐的简化正常步态周期下进行的。然而，磨损测试持续时间长且成本高，因此本文的目的是提出一种新的计算机模拟方法，用于润滑全髋关节置换术的磨损计算。所提出的计算机模拟基于对在非牛顿不稳定混合弹性流体动力润滑条件 (MEHL) 下的某些运动学和动力学条件下作用于关节的摩擦学现象的精确建模。分析的髋关节建模为软聚合物髋臼杯 PE GUR1020 (EtO)，与硬金属 CoCrMo 股骨头相对。通过施加 ISO 14242-3 运动学和动力学，在计算机模拟过程中实现了关节间隙内流体膜压力场的计算，以使用修改后的 Archard 模型评估单个步态周期内的累积磨损量。本研究的主要目的是提出一种模拟磨损计算方法，重现全髋关节置换术的经典体外磨损测试，以解决股骨头和髋臼杯之间不稳定的滑液润滑效应。从基于磨损斜率的新方法推断得出的预测磨损与体外模拟的值进行了比较，结果显示出令人满意的一致性，使作者得出结论，所提出的模型适合用作硅胶髋关节磨损模拟器。