Miura Michiaki, Nakamura Junichi, Matsuura Yusuke, Wako Yasushi, Suzuki Takane, Hagiwara Shigeo, Orita Sumihisa, Inage Kazuhide, Kawarai Yuya, Sugano Masahiko, Nawata Kento, Ohtori Seiji
Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba city, Chiba, 260-8677, Japan.
BMC Musculoskelet Disord. 2017 Dec 16;18(1):536. doi: 10.1186/s12891-017-1898-1.
Finite element analysis (FEA) of the proximal femur has been previously validated with large mesh size, but these were insufficient to simulate the model with small implants in recent studies. This study aimed to validate the proximal femoral computed tomography (CT)-based specimen-specific FEA model with smaller mesh size using fresh frozen cadavers.
Twenty proximal femora from 10 cadavers (mean age, 87.1 years) were examined. CT was performed on all specimens with a calibration phantom. Nonlinear FEA prediction with stance configuration was performed using Mechanical Finder (mesh,1.5 mm tetrahedral elements; shell thickness, 0.2 mm; Poisson's coefficient, 0.3), in comparison with mechanical testing. Force was applied at a fixed vertical displacement rate, and the magnitude of the applied load and displacement were continuously recorded. The fracture load and stiffness were calculated from force-displacement curve, and the correlation between mechanical testing and FEA prediction was examined.
A pilot study with one femur revealed that the equations proposed by Keller for vertebra were the most reproducible for calculating Young's modulus and the yield stress of elements of the proximal femur. There was a good linear correlation between fracture loads of mechanical testing and FEA prediction (R = 0.6187) and between the stiffness of mechanical testing and FEA prediction (R = 0.5499). There was a good linear correlation between fracture load and stiffness (R = 0.6345) in mechanical testing and an excellent correlation between these (R = 0.9240) in FEA prediction.
CT-based specimen-specific FEA model of the proximal femur with small element size was validated using fresh frozen cadavers. The equations proposed by Keller for vertebra were found to be the most reproducible for the proximal femur in elderly people.
先前对股骨近端的有限元分析（FEA）已通过大网格尺寸进行验证，但在最近的研究中，这些网格尺寸不足以模拟带有小植入物的模型。本研究旨在使用新鲜冷冻尸体，以较小的网格尺寸验证基于近端股骨计算机断层扫描（CT）的特定标本FEA模型。
检查了来自10具尸体（平均年龄87.1岁）的20个近端股骨。对所有标本使用校准体模进行CT扫描。使用Mechanical Finder（网格，1.5毫米四面体单元；壳厚度，0.2毫米；泊松系数，0.3）对站立姿势配置进行非线性FEA预测，并与力学测试进行比较。以固定的垂直位移速率施加力，并连续记录施加的载荷和位移的大小。从力-位移曲线计算骨折载荷和刚度，并检查力学测试与FEA预测之间的相关性。
对一根股骨的初步研究表明，Keller提出的用于椎骨的方程在计算近端股骨元件的杨氏模量和屈服应力方面最具可重复性。力学测试的骨折载荷与FEA预测之间（R = 0.6187）以及力学测试的刚度与FEA预测之间（R = 0.5499）存在良好的线性相关性。力学测试中骨折载荷与刚度之间（R = 0.6345）存在良好的线性相关性，而在FEA预测中它们之间存在极好的相关性（R = 0.9240）。
使用新鲜冷冻尸体验证了基于CT的近端股骨特定标本FEA模型，其单元尺寸较小。发现Keller提出的用于椎骨的方程在老年人近端股骨中最具可重复性。
