Abstract:

Objective A detailed FE （finite element） model of human lower limb was developed to explore the mechanism of injury suffering from rolling and impact， and to reconstruct a real case with the developed model. Methods Human lower limb consists of long bones， patella， menisci， knee ligaments and soft tissues. They were reconstructed by Mimics software on the basis of CT scans of a victim. The model was divided by structural grid approach， and the material properties of different parts were defined according to the literature data. The developed FE model was validated by three points bending tests of long bones， thigh and leg. Three different loading conditions including rolling and impact at low， medium and high speed were applied to explore the possible injury mechanism of a real case. Results A FE model of lower limb was developed， and it is mainly composed of hexahedral elements. The peak forces， maximum bending moments and history curves of the model in tests were agreed with the data in literatures. Under the running over condition， the segmental fracture pattern could be formed. Femur fracture pattern and mechanism were similar to the actual case of being run over by a wheel. Conclusion The study shows the method can be applied to explore possible mechanisms of lower limb fractures in forensic cases. The model can also help to determine the possible loading conditions.

Key words: forensic pathology, lower limb traffic injury, finite element model, injury reconstruction

摘要：

目的 建立完整的下肢有限元模型，探讨碾压及撞击情况下下肢的损伤机制，并利用此模型对一例真实交通事故中损伤下肢进行有限元分析。方法 基于交通事故受害者下肢完整的CT扫描图片，利用Mimics重建下肢长骨、髌骨、半月板、膝关节韧带以及软组织几何模型，利用结构化网格生成方法划分模型，并根据文献材料属性确定各部分的材料参数。通过长骨、大腿及小腿的三点弯曲模拟试验与文献试验结果对比验证模型的有效性。用轮胎模型分别以低、中、高的速度碾压大腿中段，及撞击大腿下段和股骨上段。通过碾压与撞击的模拟对比，得出下肢不同损伤的损伤机制，通过与真实交通事故中损伤下肢进行对比，分析验证该案例的损伤过程。结果 建立了一例完整的下肢有限元模型，主要以六面体网格进行单元划分。验证实验中，模型的接触力峰值，最大弯矩值以及弯矩曲线与文献报道的试验数据吻合。在轮胎碾压情况下，长骨可形成节段性骨折，股骨的骨折形态与案例中的骨折形态一致。结论 有限元模型及分析方法能应用于法医学损伤机制的分析与研究。

关键词: 法医病理学, 下肢交通伤, 有限元模型, 损伤重建