Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, USA.
DePuy Synthes, West Chester, PA, USA.
J Biomech. 2021 May 7;120:110363. doi: 10.1016/j.jbiomech.2021.110363. Epub 2021 Mar 5.
Femoral strain is indicative of the potential for bone remodeling (strain energy density, SED) and periprosthetic femoral fracture (magnitude of principal strains) after total hip arthroplasty (THA). Previous modeling studies have evaluated femoral strains in THA-implanted femurs under gait loads including both physiological hip contact force and femoral muscle forces. However, experimental replication of the complex muscle forces during activities of daily living (ADLs) is difficult for in vitro assessment of femoral implant or fixation hardware. Alternatively, cadaveric tests using simplified loading configurations have been developed to assess post-THA bone mechanics, although no current studies have demonstrated simplified loading configurations used in mechanical tests may simulate the physiological femoral strains under ADL loads. Using an optimization approach integrated with finite element analysis, this study developed axial compression and combined axial compression and torque testing configurations for three common ADLs (gait, stair-descent and sit-to-stand) via matching the SED profile of the femur in THA-implanted models of three specimens. The optimized simplified-loading models showed good agreement in predicting bone remodeling stimuli (post-THA change in SED per unit mass) and fatigue regions as compared with the ADL-loading models, as well as other modeling and clinical studies. The optimized simplified test configurations can provide a physiological-loading based pre-clinical platform for the evaluation of implant/fixation devices of the femur.
股骨干应变表明全髋关节置换术后（THA）存在骨重建（应变能密度，SED）和假体周围股骨骨折（主应变幅度）的潜力。先前的建模研究已经评估了包括生理髋关节接触力和股骨肌肉力在内的步态载荷下 THA 植入股骨中的股骨应变。然而，对于体外评估股骨植入物或固定硬件，很难复制日常生活活动（ADL）期间复杂的肌肉力。相反，已经开发了使用简化加载配置的尸体测试来评估 THA 后的骨力学，尽管目前没有研究表明机械测试中使用的简化加载配置可以模拟 ADL 载荷下的生理股骨应变。本研究使用优化方法与有限元分析相结合，针对三种常见的 ADL（步态、下楼梯和从座位到站立）为三个标本的 THA 植入模型开发了轴向压缩和轴向压缩与扭矩组合测试配置，通过匹配股骨的 SED 分布。与 ADL 加载模型以及其他建模和临床研究相比，优化后的简化加载模型在预测骨重建刺激（SED 每单位质量的术后变化）和疲劳区域方面具有很好的一致性。优化后的简化测试配置可以为评估股骨植入物/固定装置提供基于生理加载的临床前平台。
