Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014, Bern, Switzerland.
Institute for Risks and Extremes, Bern University of Applied Sciences, Jlcoweg 1, 3400, Burgdorf, Switzerland.
J Bone Miner Res. 2015 Jun;30(6):1000-8. doi: 10.1002/jbmr.2437.
As our population ages, more individuals suffer from osteoporosis. This disease leads to impaired trabecular architecture and increased fracture risk. It is essential to understand how morphological and mechanical properties of the cancellous bone are related. Morphology-elasticity relationships based on bone volume fraction (BV/TV) and fabric anisotropy explain up to 98% of the variation in elastic properties. Yet, other morphological variables such as individual trabeculae segmentation (ITS) and trabecular bone score (TBS) could improve the stiffness predictions. A total of 743 micro-computed tomography (μCT) reconstructions of cubic trabecular bone samples extracted from femur, radius, vertebrae, and iliac crest were analyzed. Their morphology was assessed via 25 variables and their stiffness tensor (CFE) was computed from six independent load cases using micro finite element (μFE) analyses. Variance inflation factors were calculated to evaluate collinearity between morphological variables and decide upon their inclusion in morphology-elasticity relationships. The statistically admissible morphological variables were included in a multiple linear regression model of the dependent variable CFE. The contribution of each independent variable was evaluated (ANOVA). Our results show that BV/TV is the best determinant of CFE(r(2) adj = 0.889), especially in combination with fabric anisotropy (r(2) adj = 0.968). Including the other independent predictors hardly affected the amount of variance explained by the model (r(2) adj = 0.975). Across all anatomical sites, BV/TV explained 87% of the variance of the bone elastic properties. Fabric anisotropy further described 10% of the bone stiffness, but the improvement in variance explanation by adding other independent factors was marginal (<1%). These findings confirm that BV/TV and fabric anisotropy are the best determinants of trabecular bone stiffness and show, against common belief, that other morphological variables do not bring any further contribution. These overall conclusions remain to be confirmed for specific bone diseases and postelastic properties.
随着人口老龄化，越来越多的人患有骨质疏松症。这种疾病导致骨小梁结构受损，骨折风险增加。了解松质骨的形态和力学性能如何相关是至关重要的。基于骨体积分数 (BV/TV) 和各向异性的形态-弹性关系可以解释弹性性能变化的 98%。然而，其他形态学变量，如个别骨小梁分割 (ITS) 和骨小梁评分 (TBS)，可以提高刚度预测的准确性。总共分析了 743 个从股骨、桡骨、椎体和髂嵴提取的立方骨小梁样本的微计算机断层扫描 (μCT) 重建。通过 25 个变量评估它们的形态，并使用微有限元 (μFE) 分析从六个独立的载荷情况计算它们的刚度张量 (CFE)。计算方差膨胀因子以评估形态变量之间的共线性，并决定将其纳入形态-弹性关系。将统计上可接受的形态学变量纳入依赖变量 CFE 的多元线性回归模型中。评估每个独立变量的贡献 (ANOVA)。我们的结果表明，BV/TV 是 CFE 的最佳决定因素(r² 调整=0.889)，尤其是与各向异性相结合时(r² 调整=0.968)。包含其他独立预测因子几乎不会影响模型解释的方差量(r² 调整=0.975)。在所有解剖部位，BV/TV 解释了 87%的骨弹性特性的方差。各向异性进一步描述了 10%的骨刚度，但通过添加其他独立因素来提高方差解释的程度是微不足道的(<1%)。这些发现证实，BV/TV 和各向异性是小梁骨刚度的最佳决定因素，并与普遍的观点相反，表明其他形态学变量没有带来任何进一步的贡献。这些总体结论仍有待在特定的骨骼疾病和后弹性特性中得到证实。
