大腿骨頸部骨折防止用個体別ヒッププロテクターに関する生体力学的研究

本研究的目的是预防髋部骨折，这是经常观察到的老年人跌倒事故，并正在增加的案件数量。本研究针对预防髋部骨折的有效方法之一--髋部护具的生物力学设计要求进行了探讨，并建立了一个适用于髋部骨折预防性诊断和个人髋部护垫设计的股骨个体化有限元建模系统。我们使用该模拟系统评估了载荷方向、股骨形态和骨质疏松对髋部骨折的影响，并阐明了骨折风险与个体解剖特征和跌倒边界条件之间的关系。讨论了缓冲垫的材料和结构对缓冲性能的影响。接下来，我们开发了一个基于图像建模技术的个性化股骨有限元建模系统，使用CT图像。该建模系统采用映射网格法，可以方便地建立单个股骨的有限元模型。为了将该系统应用于多种类型的股骨，我们构建了一个数据库，该数据库由具有不同颈部角度和颈部长度的股骨块模型组成。通过从数据库中选择合适的块模型，我们可以快速地重建出精确的形态。通过与股骨试件断裂实验结果的比较，验证了系统所建立的部分模型的有效性。应力集中部位与断裂部位一致，主应变方向和大小的模拟结果与实验结果一致。从而验证了仿真系统的准确性。

The objective of this study is to prevent hip fracture which is frequently observed in a fall accident of elderly people and is increasing the number of cases. On this research project, we have discussed the biomechanical requirements for design of hip protector, which is one of the effective methods for hip fracture prevention, and constructed a new individual finite element modeling system for femur which is applicable to a preventive diagnosis for hip fracture and designing hip pads for individual persons.Firstly, we developed a fall simulation system to discuss the mechanism of hip fracture. We evaluated effects of load direction, morphology of femur and osteoporosis on hip fracture using this simulation system and clarified the relationship between the risk of fracture and individual anatomical characteristics, and boundary conditions of fall. We also discussed the effects of the material and structure of hip pad on the impact attenuation properties. Next we developed an individual finite element modeling system for femur based on image-based modeling technology using CT images. This modeling system is adopted the mapped-mesh method to construct a finite element model for individual femur easily. To apply the system to many types of femur, we constructed a database which consists of block models for femora with various neck angle and neck length. By choosing an adequate block model from the database, we can reconstruct an accurate morphology quickly. Some models constructed by the system was validated with comparing simulation results with those of fracture experiments using femur specimens. The site of stress concentration agreed with the fracture site and the simulation results of directions and values of principal strains were similar with experimental results. Thus we confirmed the accuracy of the simulation system.