Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Gusshausstrasse 27-29, 1040 Vienna, Austria.
INSIGNEO Institute for in silico Medicine, Department of Mechanical Engineering, University of Sheffield, Edgar Allen House, 241 Glossop Road, Sheffield S10 2GW, UK.
J Mech Behav Biomed Mater. 2014 Apr;32:287-299. doi: 10.1016/j.jmbbm.2014.01.006. Epub 2014 Jan 24.
Quantitative computed tomography (QCT) based nonlinear homogenized finite element (hFE) models of the human femur do not take bone׳s microstructure into account due to the low resolution of the QCT images. Models based on high-resolution peripheral quantitative computed tomography (HR-pQCT) are able to include trabecular orientation and allow the modeling of a cortical shell. Such a model showed improvements compared to QCT-based models when studying human vertebral bodies. The goal of this study was to compare the femoral strength prediction ability of subject specific nonlinear homogenized FE (hFE) models based on HR-pQCT and QCT images. Thirty-six pairs of femurs were scanned with QCT as well as HR-pQCT, and tested in one-legged stance (STANCE) and side-ways fall (SIDE) configurations up to failure. Non-linear hFE models were generated from HR-pQCT images (smooth meshes) and compared to recently published QCT based models (voxel meshes) as well as experiments with respect to ultimate force. HR-pQCT-based hFE models improved ultimate force (R(2)=0.87 vs 0.80, p=0.02) predictions only in STANCE configuration but not in SIDE (R(2)=0.86 vs 0.84, p=0.6). Damage locations were similar for both types of models. In conclusion, it was shown for the first time on a large femur dataset that a more accurate representation of trabecular orientation and cortex only improve FE predictions in STANCE configuration, where the main trabecular orientation is aligned with the load direction. In the clinically more relevant SIDE configuration, the improvements were not significant.
基于定量计算机断层扫描(QCT)的非线性均匀有限元(hFE)模型并未考虑骨骼的微观结构,因为 QCT 图像的分辨率较低。基于高分辨率外周定量计算机断层扫描(HR-pQCT)的模型能够包括小梁的方向,并允许对皮质壳进行建模。与基于 QCT 的模型相比,这种模型在研究人类椎体时显示出了改进。本研究的目的是比较基于 HR-pQCT 和 QCT 图像的个体非线性均匀 FE(hFE)模型对股骨强度的预测能力。对 36 对股骨进行了 QCT 和 HR-pQCT 扫描,并在单腿站立(STANCE)和侧向跌倒(SIDE)配置下进行测试,直至失效。从 HR-pQCT 图像生成非线性 hFE 模型(平滑网格),并与最近发表的基于 QCT 的模型(体素网格)以及实验结果进行比较,以评估极限力。基于 HR-pQCT 的 hFE 模型仅在 STANCE 配置下提高了极限力的预测(R(2)=0.87 对 0.80,p=0.02),而在 SIDE 配置下没有提高(R(2)=0.86 对 0.84,p=0.6)。两种类型的模型的损伤位置相似。总之,这是首次在大型股骨数据集上表明,对小梁方向和皮质的更准确表示仅在 STANCE 配置下提高了 FE 预测,因为主要的小梁方向与载荷方向一致。在临床更相关的 SIDE 配置中,改进并不显著。
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