Mechanical Evaluation of Fracture in the Proximar Femur during Falls and Development of Hip Protector

在本研究中，为了探讨跌倒导致髋部骨折的原因，我们进行了以下研究：1)用身体股骨模拟跌倒的实验；2)用身体股骨的X射线CT图像建立有限元模型进行有限元分析；3)建立了针对单个股骨的有限元模型系统。研究结果如下：1.对89~95岁女性身体股骨施加静载荷，探讨了载荷方向与骨折危险性的关系。结果：1.应力集中在头下上部和颈椎后基底部。对10具(77~94岁)身体股骨进行冲击试验，发现股骨颈骨折主要由压应力引起，骨折类型受股骨形状和骨密度的影响。在对65岁男性左侧身体股骨模型进行有限元分析的结果中，颈后基底区的骨折风险随着干轴旋转角度的增加而增加。认为不同标本形状的差异对股骨颈骨折有一定影响。因此，我们开发了一种利用最小数量的股骨形态参数来构建股骨近端个体有限元模型的方法。该方法不仅可以在较短的时间内建立有限元模型，而且可以方便地根据不同的股骨形状进行有限元分析。

In the present study, in order to examine the cause of hip fracture by falls, we performed the following studies : 1) experiments to simulate falls by use of cadaveric femora, 2) finite element analyses to use finite element models created from X ray computed tomographic images of cadaveric femora, 3) construction of the system creating finite element models for individual femora. The results obtained are summarized as follows :1. Static loads were applied to cadaveric female femora (aged 89-95), and the relation between the fracture risk and the load direction was discussed. The results showed that the stress concentration is observed in the superior subcapital and posterior basicervical regions.2. From the impact tests for 10 cadaveric femora (aged 77-94), it was found that femoral neck fractures are mainly caused by compressive stresses, and that the femoral shapes and bone density influence the type of fracture.3. In the results of the finite element analyses with the model from the left cadaveric femur 65 ages male, the fracture risk on the posterior basicervical region increased with the rotation angle around the diaphyseal axis.4. It was thought that the differences of shapes among specimens had some influences on femoral neck fracture. Hence we developed a method that constructs individual finite element models of proximal femur by using the minimum amount of morphological parameters of femur.5. By this method, we can construct the models in shorter time than before, and moreover it became much easier to perform the finite element analyses taking account of individual femoral shapes.