The purpose of this study was to determine the material stresses experienced in the femoral neck during the stepping phase of recovery from a forward loss of balance achieved both using release from a static forward lean and rapid treadmill accelerations in 8 older adults. A scalable musculoskeletal model with 23 degrees of freedom and 92 force actuators was used to calculate joint reaction forces. A finite element model of the femur used joint reaction forces calculated by the musculoskeletal model to calculate the material stresses during stepping. Balance recovery from a static forward lean angle had a greater joint contact force and greater maximum tensile stress than a recovery from treadmill induced perturbations both before and after a training session. Hip joint contact loads were found to be large in magnitude, however, all stresses experienced by the bone are less than critical yield stresses for trabecular bone. We suggest that stepping balance recovery is safe for older adults with no obvious loss of bone density or strength and that analyses such as finite element analysis are necessary to understand stresses in the material at the joint level.

中文翻译：

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反应平衡训练期间股骨应力的联合肌肉骨骼有限元建模

本研究的目的是确定 8 名老年人在向前失去平衡恢复的迈步阶段，股骨颈所经历的物质应力，这两种方法都是通过静态前倾释放和跑步机快速加速实现的。使用具有 23 个自由度和 92 个力执行器的可扩展肌肉骨骼模型来计算关节反作用力。股骨的有限元模型使用肌肉骨骼模型计算的关节反作用力来计算迈步过程中的材料应力。在训练前后，与从跑步机引起的扰动恢复相比，从静态前倾角度恢复平衡具有更大的关节接触力和更大的最大拉伸应力。研究发现髋关节接触载荷很大，但骨骼承受的所有应力均小于骨小梁的临界屈服应力。我们建议，步进平衡恢复对于老年人来说是安全的，骨密度或强度没有明显损失，并且需要进行有限元分析等分析来了解关节水平材料中的应力。