Quantitative computed tomography (QCT)-based finite element (FE) models of the vertebra are widely used in studying spine biomechanics and mechanobiology, but their accuracy has not been fully established. Although the models typically assign material properties based only on local bone mineral density (BMD), the mechanical behavior of trabecular bone also depends on fabric. The goal of this study was to determine the effect of incorporating measurements of fabric on the accuracy of FE predictions of vertebral deformation. Accuracy was assessed by using displacement fields measured via digital volume correlation—applied to time-lapse microcomputed tomography (μCT)—as the gold standard. Two QCT-based FE models were generated from human L1 vertebrae (n = 11): the entire vertebral body and a cuboid-shaped portion of the trabecular centrum [dimensions: (20–30) × (15–20) × (15–20) mm³]. For axial compression boundary conditions, there was no difference (p = 0.40) in the accuracy of the FE-computed displacements for models using material properties based on local values of BMD versus those using material properties based on local values of fabric and volume fraction. However, when using BMD-based material properties, errors were higher for the vertebral-body models (8.4–50.1%) than cuboid models (1.5–19.6%), suggesting that these properties are inaccurate in the peripheral regions of the centrum. Errors also increased when assuming that the cuboid region experienced uniaxial loading during axial compression of the vertebra. These findings indicate that a BMD-based constitutive model is not sufficient for the peripheral region of the vertebral body when seeking accurate QCT-based FE modeling of the vertebra.

中文翻译：

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织物对基于计算机断层扫描的椎骨有限元分析精度的影响。

基于定量计算机断层扫描 (QCT) 的椎骨有限元 (FE) 模型广泛用于研究脊柱生物力学和力学生物学，但其准确性尚未完全确定。尽管模型通常仅根据局部骨矿物质密度 (BMD) 来分配材料属性，但小梁骨的机械行为也取决于织物。本研究的目的是确定结合织物测量对椎体变形有限元预测准确性的影响。通过使用数字体积相关测量的位移场（应用于延时微计算机断层扫描（μCT））作为黄金标准来评估准确性。两个基于 QCT 的有限元模型是从人类 L1 椎骨 ( n  = 11) 生成的：整个椎体和小梁中心的长方体部分 [尺寸：(20–30) × (15–20) × (15– 20）毫米³ ]。 对于轴向压缩边界条件，使用基于 BMD 局部值的材料属性的模型与使用基于织物和体积分数局部值的材料属性的模型相比，有限元计算的位移精度没有差异 (p = 0.40 ) 。然而，当使用基于 BMD 的材料属性时，椎体模型的误差 (8.4-50.1%) 高于长方体模型 (1.5-19.6%)，这表明这些属性在椎体周围区域不准确。当假设长方体区域在椎骨轴向压缩期间经历单轴载荷时，误差也会增加。这些发现表明，在寻求基于 QCT 的椎体精确有限元建模时，基于 BMD 的本构模型不足以满足椎体的周边区域。