侧向冲击载荷作用下股骨-骨盆复合体的生物力学响应

Biomechanical response of the pelvis femur complex under lateral pelvic impacts during sideways falls

目的利用三维有限元分析方法研究股骨-骨盆复合体在人体侧向摔倒时冲击载荷作用下的生物力学行为特性。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;同时,构建一个刚体平面仿真地面。约束地面刚体,对整个股骨-骨盆-软组织复合体模型施加侧向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股骨-骨盆侧摔冲击过程中应力应变变化特性。结果在13 ms时,股骨大转子处软组织与地面的接触力达到最大值7 656 N,对应的骨盆软组织上的最大等效应力值为2.64 MPa。冲击过程中,耻骨联合处骨皮质上等效应力出现极大值,为142.64 MPa,接近其屈服强度;股骨颈和大转子处应力水平较高,股骨颈处皮质骨上的最大等效应力值为76.49 MPa;股骨颈处松质骨上的最大等效应力值为8.44 MPa,最大压缩应变值为0.94%;股骨大转子处松质骨上的最大等效应力值为8.50 MPa,最大压缩应变值为0.93%。结论人体股骨-骨盆复合体在侧摔减速冲击载荷作用下股骨颈、大转子及耻骨联合处易出现骨折。

Objective To investigate the biomechanical characteristics of the human pelvis-femur complex under lateral pelvic impacts during sideways falls using three dimensional （3 D） 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 was created, including cortical bone, cancellous bone and soft tissue capsule. A rigid plane model was also constructed for ground simulation and constrained in all freedoms. The average hip lateral impact veloci- ty of 2 m/s was applied to the model and the time for simulation analysis was set at 20 ms. The stress and strain distribution on the pelvis-femur complex were obtained by the 3D FE calculation and analysis. Results On the contact surface, the peak impact load reached to 7 656 N at 13 ms, while the maximum Von Mises stress on thesoft tissue was 2.64 MPa. Simultaneously, the peak Von Mises stress of 142.64 MPa on the cortical bone oc- curred in the region of pubic symphysis, which was approximate to the yield stress on the cancellous bone. The Von Mises stress level was higher in the region of the femur neck and greater trochanter. At 13 ms, the peak Von Mises stress on the cortical bone of the femur neck was 76.49 MPa and that on the cancellous bone was 8.44 MPa with the peak compressive principal strain being 0.94%. The peak Von Mises stress on the cancellous bone of greater trochanter was 8.50 MPa, while the peak compressive principal strain was 0.93%. Conclusions Bone fractures of the pelvis-femur complex tend to occur in the region of the femur neck, greater trochanter and pubic symphysis under deceleration impacts during sideways falls.