AO Research Institute Davos, Davos, Switzerland.
Department of Orthopaedic Surgery, University of Munich (LMU), Munich, Germany.
J Anat. 2021 Mar;238(3):669-678. doi: 10.1111/joa.13337. Epub 2020 Oct 20.
Cortical bone and its microstructure are crucial for bone strength, especially at the long bone diaphysis. However, it is still not well-defined how imaging procedures can be used as predictive tools for mechanical bone properties. This study evaluated the capability of several high-resolution imaging techniques to capture cortical bone morphology and assessed the correlation with the bone's mechanical properties. The microstructural properties (cortical thickness [Ct.Th], porosity [Ct.Po], area [Ct.Ar]) of 11 female tibial diaphysis (40-90 years) were evaluated by dual-energy X-ray absorptiometry (DXA), high-resolution peripheral-quantitative-computed-tomography (HR-pQCT), micro-CT (μCT) and histomorphometry. Stiffness and maximal torque to failure were determined by mechanical testing. T-Scores determined by DXA ranged from 0.6 to -5.6 and a lower T-Score was associated with a decrease in Ct.Th (p ≤ 0.001) while the Ct.Po (p ≤ 0.007) increased, and this relationship was independent of the imaging method. With decreasing T-Score, histology showed an increase in Ct.Po from the endosteal to the periosteal side (p = 0.001) and an exponential increase in the ratio of osteons at rest to those after remodelling. However, compared to histomorphometry, HR-pQCT and μCT underestimated Ct.Po and Ct.Th. A lower T-Score was also associated with significantly reduced stiffness (p = 0.031) and maximal torque (p = 0.006). Improving the accuracy of Ct.Po and Ct.Th did not improve prediction of the mechanical properties, which was most closely related to geometry (Ct.Ar). The ex-vivo evaluation of mechanical properties correlated with all imaging modalities, with Ct.Th and Ct.Po highly correlated with the T-Score of the tibial diaphysis. Cortical microstructural changes were underestimated with the lower resolution of HR-pQCT and μCT compared to the histological 'gold standard'. The increased accuracy did not result in an improved prediction for local bone strength in this study, which however might be related to the limited number of specimens and thus needs to be evaluated in a larger collective.
皮质骨及其微观结构对骨强度至关重要，尤其是在长骨骨干。然而，成像程序如何用作机械骨特性的预测工具仍未得到很好的定义。本研究评估了几种高分辨率成像技术捕捉皮质骨形态的能力，并评估了与骨机械性能的相关性。通过双能 X 射线吸收法 (DXA)、高分辨率外周定量计算机断层扫描 (HR-pQCT)、微计算机断层扫描 (μCT) 和组织形态计量学评估 11 名女性胫骨骨干 (40-90 岁) 的微观结构特性 (皮质厚度 [Ct.Th]、孔隙率 [Ct.Po]、面积 [Ct.Ar])。通过机械测试确定刚度和最大失效扭矩。DXA 确定的 T 评分范围为 0.6 至-5.6，T 评分较低与 Ct.Th 降低相关 (p ≤ 0.001)，而 Ct.Po 增加 (p ≤ 0.007)，这种关系独立于成像方法。随着 T 评分的降低，组织学显示从内骨到骨膜侧的 Ct.Po 增加 (p = 0.001)，以及休息时的骨单位与重塑后的骨单位之比呈指数增加。然而，与组织形态计量学相比，HR-pQCT 和 μCT 低估了 Ct.Po 和 Ct.Th。T 评分较低还与刚度显著降低相关 (p = 0.031) 和最大扭矩降低相关 (p = 0.006)。提高 Ct.Po 和 Ct.Th 的准确性并不能提高对机械性能的预测，机械性能与几何形状 (Ct.Ar) 最密切相关。机械性能的离体评估与所有成像方式相关，Ct.Th 和 Ct.Po 与胫骨骨干的 T 评分高度相关。与组织学的“金标准”相比，较低分辨率的 HR-pQCT 和 μCT 低估了皮质微观结构的变化。在本研究中，增加的准确性并没有导致局部骨强度的预测得到改善，这可能与标本数量有限有关，因此需要在更大的群体中进行评估。
