Clarificaiton of Cuase of Occurrence and Biomechanism of Pressure Ulcer by Image-based Finite Element Method

明确压疮发生的根本原因，加强护理，预防压疮。根据压疮的起因是人体臀部骨骼-肌肉交界处的纤维组织受损这一假设，采用基于图像的有限元方法对界面应变进行了分析，并对其生物力学机制进行了探讨。在考虑7个参数的不确定性的情况下，提出了一种在蒙特卡罗模拟中寻找导致高应变值的参数对的计算方法。它们是脂肪和肌肉的力学性质、脂肪的体积分数、损伤的位置和大小以及定位。数值结果表明，对于脂肪体积分数较高的仰卧位躺在床上的脂肪和肌肉的杨氏模数较低的患者，由于剪切应变引起的纤维组织损伤的风险增加。

It is important to clarify the fundamental cause of occurence of pressur ulcer to improve the nursing care for its prevention. Based on the hypothesis that the initial cause of pressur ulcer lies in the damage of fibril tissue at the interface between bone and muscle in the human buttock, in this study, interfacial strain analysis was carried out by image-based finite element method and the biomechanism was discussed. An original computational method has been developed to find the pair of parameters that lead to high strain value in the Monte Carlo simulation considering the uncertainties in 7 parameters. They are the mechanical properties of fat and muscle, volume fraction of fat, location and size of damage and positioning. The numerical results implied that the risk of fibril tissue damage due to shear strain increased if the Young's moduli of fat and muscle are low for such patient that has high volume fraction of fat, lying on bed in supine position.