侧向冲击载荷作用下髋护具对股骨-骨盆复合体生物力学响应的影响

目的利用三维有限元法研究髋部护具对人体股骨-骨盆复合体在侧向冲击载荷作用下生物力学响应的影响。方法基于中国力学虚拟人模型库建立股骨-骨盆-软组织复合体的三维有限元模型,包括皮质骨、松质骨和软组织,并在此基础上建立髋部护具和股骨-骨盆-软组织复合体系统的三维有限元模型;同时,在两个模型中构建刚体平面仿真地面。约束地面刚体,对两个模型均施加侧向2 m/s的速度载荷,整个仿真分析时间设定为20 ms。通过三维有限元分析计算获得两模型受侧向冲击载荷过程中应力、应变变化特性,对比分析髋部护具对股骨-骨盆复合体生物力学响应的影响。结果髋部护具使股骨-骨盆复合体在侧向冲击载荷作用下的应力峰值出现时间提前4 ms以上,且应力应变水平出现大幅度降低;皮质骨上的应力峰值降低67.88%以上,松质骨上的峰值应力下降69.34%以上,松质骨上的压缩主应变峰值降低可达63%。结论在侧向冲击载荷作用下,髋部护具对股骨-骨盆复合体具有良好的保护作用,能够有效预防骨折的发生或降低骨折风险。

Effects of hip protector on biomechanical response of the pelvis-femur complex under lateral pelvic impacts during sideways falls

Objective To investigate the effect of hip protector on biomechanical response of the human pelvis-femur complex under lateral pelvic impacts during sideways falls using three dimensional(3D) finite element(FE) method.Methods Based on the model database of China Mechanical Virtual Human,a 3D FE model of the pelvis-femur-soft tissue complex including cortical bone,cancellous bone and soft tissue capsule and the pelvis-femur-soft tissue complex with a two-layer hip protector were created,respectively.The rigid plane model was also constructed in the two models for ground simulation and constrained in all freedoms.The average hip lateral impact velocity of 2 m/s was applied to the two models,and the time for simulation analysis was set at 20 ms.The stress and strain distribution on the two models under lateral impacts could be obtained by the 3D FE calculation.The comparative analysis was performed to study the effect of the hip protector on biomechanical response of the pelvis-femur complex.Results The hip protector made the peak Von Mises stress appeared 4 ms more earlier in the pelvis-femur complex with a significant decrease in the stress and strain level.The average Von Mises stress peak was decreased by 67.88% and 69.34% in the cortical bone and in the cancellous bone,respectively,and the compressive principal strain peak was decreased by 63%.Conclusions Under lateral pelvic impacts,the two-layer hip protector could act as safeguard for pelvis-femur complex,thus effectively prevent the occurrence or reduce the risk of bone fracture.