股骨及髋臼纵向撞击伤的计算机模拟生物力学研究

Biomechaulcal study of computer-simulated longitudinal impact injuries to femur and acetabulum

目的建立具有生物力学特性的股骨及大部分骨盆三维有限元模型，探讨股骨远端发生撞击时响应过程及股骨各部和髋臼损伤的生物力学基础。方法采用GE多层螺旋CT对1例健康志愿者进行从骨盆上缘到胫骨平台部的CT扫描，三维影像重建，数据转换，运用自编程序与vtk软件相结合的方法，模仿刚体撞击股骨远端。分析在撞击时股骨干、股骨转子部、股骨颈和髋臼等部位的应力改变。结果当着力点位于股骨远端时，应力沿股骨干、股骨转子部、股骨颈向髋臼传导，并产生不同强度。前三部位应力达到峰值时间接近，髋臼应力发生延迟。结论股骨及髋臼纵向撞击伤的三维有限元模型可研究现实中难以反复再现的撞击状态；撞击中骨横截面积的变化和应力传导方向的改变会产生应力集中和梯度差，这可能是撞击伤的生物力学机制之一。

Objective To probe into the biomechanics of impact which results in injury to different parts of femur and acetabulum in a biomechanical three-dimensional finite element model of femur and most part of acetabulum, Methods Multi-layer spiral CT scanning was performed on a healthy volunteer from the upper border of pelvis to tibial plateau. The images were reconstructed in a three-dimensional manner. The data were transformed by VTK and serf-programmed soft ware to establish a biomechanical three-dimensional finite element model of femur and most part of acetabulum on which impact by a hard object onto the distal of femur was simulated, The stress changes at the femoral shaft, trochanter, neck, and acetabulum were analyzed after the impact injury had occurred. Results When the impact occurred at the distal femur, the stresses were conducted along the shaft, trochanter, and neck onto the acetabulum in different intensities. The stresses at the shaft, trochanter and neck reached the peak at approximately the same time, but the stress peak at the acetabulum was delayed, Conclusions This three-dimensional finite element model can repeatedly simulate the impact condition of femur and acetabulum, which is impossible in real life, After impact, the different cross areas of bone and changed conductive direction may lead to concentration and gradient discrepancy of stresses which may be one of the biomechanical mechanisms for impact injury in theory.