Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Germany.
Department of Forensic Medicine, University Medical Center Hamburg-Eppendorf, Germany.
Bone. 2019 May;122:156-165. doi: 10.1016/j.bone.2019.02.014. Epub 2019 Feb 15.
Currently, bone densitometry fails to identify nearly half of those elderly patients at immediate fracture risk. To improve clinical assessment of vertebral fracture risk, we aimed to determine how the DXA-based 2D parameter Trabecular Bone Score (TBS) relates to subregional variability in 3D trabecular microstructure in young and elderly women compared to aBMD.
T12 vertebrae from 29 women (11 young: 32 ± 6 years, 18 aged: 71 ± 5 years) were DXA-scanned ex vivo in anterior-posterior (AP) and lateral projection providing vertebral aBMD and TBS. Additionally, aBMD and TBS were measured for three horizontal (superior, mid-horizontal, inferior) and three vertical subregions (anterior, mid-vertical, posterior) and related to 3D microstructure indices, i.e. bone volume per tissue volume (BV/TV), trabecular number and thickness (Tb.N, Tb.Th), based on HRpQCT.
Subregional high-resolution tomography showed significant differences in trabecular parameters for both age groups: In horizontal subregions, BV/TV was lowest superiorly, Tb.Th was highest mid-horizontally, and Tb.N was lowest mid-horizontally and highest inferiorly. Correspondingly, aBMD varied between horizontal subregions, with differences depending on projection direction. TBS varied only in lateral projections of the aged group, with lower values for the mid-horizontal subregion. In vertical subregions, BV/TV, Tb.N, and aBMD were highest posteriorly for both groups. TBS did not differ between vertical subregions. Regression analysis showed aBMD as a predictor explained more of the variance in subregional 3D microstructure compared to TBS. Stepwise multi-regression analysis revealed only three combinations of subregion, projection, and group where aBMD and TBS were both significant predictors.
Subregional aBMD reflects variations in trabecular bone microstructure better than subregional TBS for trisected regions. Specifically, lateral aBMD identifies microstructural heterogeneities independent of age and may improve prediction of vertebral strength and susceptibility to specific fracture types.
目前，骨密度测定法未能识别近一半处于骨折高风险的老年患者。为了改善对椎体骨折风险的临床评估，我们旨在确定 DXA 基础二维参数——骨小梁评分（TBS）与年轻和老年女性 3D 小梁微观结构的亚区域变异性的关系，与 aBMD 相比。
29 名女性（11 名年轻：32±6 岁，18 名年老：71±5 岁）的 T12 椎体在前后位（AP）和侧位进行体外 DXA 扫描，提供椎体 aBMD 和 TBS。此外，还测量了三个水平（上、中、下）和三个垂直亚区（前、中、后）的 aBMD 和 TBS，并与基于 HRpQCT 的 3D 微观结构指数相关，即骨体积/组织体积（BV/TV）、骨小梁数量和厚度（Tb.N、Tb.Th）。
亚区高分辨率断层扫描显示了两个年龄组的小梁参数存在显著差异：在水平亚区中，BV/TV 在上部最低，Tb.Th 在中部最高，Tb.N 在中部最低，下部最高。相应地，aBMD 在水平亚区之间存在差异，差异取决于投影方向。TBS 仅在年老组的侧位投影中发生变化，中水平亚区的 TBS 值较低。在垂直亚区中，BV/TV、Tb.N 和 aBMD 在后部对两个组均为最高。TBS 在垂直亚区之间没有差异。回归分析表明，aBMD 作为预测因子比 TBS 更能解释亚区 3D 微观结构的变异性。逐步多元回归分析显示，只有在三个亚区、投影和组的组合中，aBMD 和 TBS 都是显著的预测因子。
与 TBS 相比，亚区 aBMD 更能反映三分区域的小梁骨微观结构的变化。具体来说，侧位 aBMD 可以识别与年龄无关的微观结构异质性，并且可能改善对椎体强度和特定骨折类型易感性的预测。
