Wang Ji, Zhou Bin, Jenny Hu Yizhong, Zhang Zhendong, Eric Yu Y, Nawathe Shashank, Nishiyama Kyle K, Keaveny Tony M, Shane Elizabeth, Edward Guo X
Bone Bioengineering Laboratory,Department of Biomedical Engineering,Columbia University,New York, NY 10027.
Bone Bioengineering Laboratory,Department of Biomedical Engineering,Columbia University,New York, NY 10027;Department of Orthopedic Surgery,First Affiliated Hospital,School of Medicine,Shihezi University,Shihezi, Xinjiang, China.
J Biomech Eng. 2019 Apr 1;141(4):0410051-9. doi: 10.1115/1.4042680.
The high-resolution peripheral quantitative computed tomography (HR-pQCT) provides unprecedented visualization of bone microstructure and the basis for constructing patient-specific microfinite element (μFE) models. Based on HR-pQCT images, we have developed a plate-and-rod μFE (PR μFE) method for whole bone segments using individual trabecula segmentation (ITS) and an adaptive cortical meshing technique. In contrast to the conventional voxel approach, the complex microarchitecture of the trabecular compartment is simplified into shell and beam elements based on the trabecular plate-and-rod configuration. In comparison to voxel-based μFE models of μCT and measurements from mechanical testing, the computational and experimental gold standards, nonlinear analyses of stiffness and yield strength using the HR-pQCT-based PR μFE models demonstrated high correlation and accuracy. These results indicated that the combination of segmented trabecular plate-rod morphology and adjusted cortical mesh adequately captures mechanics of the whole bone segment. Meanwhile, the PR μFE modeling approach reduced model size by nearly 300-fold and shortened computation time for nonlinear analysis from days to within hours, permitting broader clinical application of HR-pQCT-based nonlinear μFE modeling. Furthermore, the presented approach was tested using a subset of radius and tibia HR-pQCT scans of patients with prior vertebral fracture in a previously published study. Results indicated that yield strength for radius and tibia whole bone segments predicted by the PR μFE model was effective in discriminating vertebral fracture subjects from nonfractured controls. In conclusion, the PR μFE model of HR-pQCT images accurately predicted mechanics for whole bone segments and can serve as a valuable clinical tool to evaluate musculoskeletal diseases.
高分辨率外周定量计算机断层扫描（HR-pQCT）为骨微结构提供了前所未有的可视化，也为构建患者特异性微有限元（μFE）模型奠定了基础。基于HR-pQCT图像，我们开发了一种板杆式μFE（PR μFE）方法，用于对全骨段进行分析，该方法采用了个体小梁分割（ITS）和自适应皮质网格化技术。与传统的体素方法不同，基于小梁板杆结构，将小梁部分复杂的微结构简化为壳单元和梁单元。与基于μCT体素的μFE模型以及力学测试测量结果（计算和实验的金标准）相比，使用基于HR-pQCT的PR μFE模型对刚度和屈服强度进行非线性分析显示出高度的相关性和准确性。这些结果表明，分割后的小梁板杆形态与调整后的皮质网格相结合，能够充分捕捉全骨段的力学特性。同时，PR μFE建模方法将模型大小缩小了近300倍，并将非线性分析的计算时间从数天缩短至数小时以内，使得基于HR-pQCT的非线性μFE建模在临床上有更广泛的应用。此外，在先前发表的一项研究中，我们使用了一组曾有椎体骨折患者的桡骨和胫骨HR-pQCT扫描数据对所提出的方法进行了测试。结果表明，PR μFE模型预测的桡骨和胫骨全骨段的屈服强度能够有效区分椎体骨折患者和未骨折的对照者。总之，基于HR-pQCT图像的PR μFE模型能够准确预测全骨段的力学特性，可作为评估肌肉骨骼疾病的有价值的临床工具。
