Mueller Thomas L, Stauber Martin, Kohler Thomas, Eckstein Felix, Müller Ralph, van Lenthe G Harry
Institute for Biomechanics, ETH Zürich, Zürich, Switzerland.
Bone. 2009 Feb;44(2):364-71. doi: 10.1016/j.bone.2008.10.045. Epub 2008 Nov 3.
Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength. Bone strength depends, among others, on bone density, bone geometry and its internal architecture. With the recent introduction of a new generation high-resolution 3D peripheral quantitative computed tomography (HR-pQCT) system, direct quantification of structural bone parameters has become feasible. Furthermore, it has recently been demonstrated that bone mechanical competence can be derived from HR-pQCT based micro-finite element modeling (microFE). However, reproducibility data for HR-pQCT-derived mechanical indices is not well-known. Therefore, the aim of this study was to quantify reproducibility of HR-pQCT-derived indices. We measured 14 distal formalin-fixed cadaveric forearms three times and analyzed three different regions for each measurement. For each region cortical and trabecular parameters were determined. Reproducibility was assessed with respect to precision error (PE) and intraclass correlation coefficient (ICC). Reproducibility values were found to be best in all three regions for the full bone compartment with an average PE of 0.79%, followed by the cortical compartment (PE=1.19%) and the trabecular compartment with an average PE of 2.31%. The mechanical parameters showed similar reproducibility (PE=0.48%-2.93% for bone strength and stiffness, respectively). ICC showed a very high reproducibility of subject-specific measurements, ranging from 0.982 to 1.000, allowing secure identification of individual donors ranging from healthy to severely osteoporotic subjects. From these in vitro results we conclude that HR-pQCT derived morphometric and mechanical parameters are highly reproducible such that differences in bone structure and strength can be detected with a reproducibility error smaller than 3%; hence, the technique has a high potential to become a tool for detecting bone quality and bone competence of individual subjects.
骨质疏松症被定义为一种以骨强度受损为特征的骨骼疾病。骨强度尤其取决于骨密度、骨几何形状及其内部结构。随着新一代高分辨率三维外周定量计算机断层扫描（HR-pQCT）系统的近期引入，对骨结构参数进行直接量化已变得可行。此外，最近已证明骨力学性能可通过基于HR-pQCT的微观有限元建模（microFE）得出。然而，HR-pQCT衍生的力学指标的可重复性数据并不为人熟知。因此，本研究的目的是量化HR-pQCT衍生指标的可重复性。我们对14个经福尔马林固定的尸体远端前臂进行了三次测量，并对每次测量分析三个不同区域。对于每个区域，确定皮质骨和小梁骨参数。通过精度误差（PE）和组内相关系数（ICC）评估可重复性。发现全骨区域在所有三个区域的可重复性值最佳，平均PE为0.79%，其次是皮质骨区域（PE = 1.19%）和小梁骨区域，平均PE为2.31%。力学参数显示出相似的可重复性（骨强度和刚度的PE分别为0.48% - 2.93%）。ICC显示个体特异性测量具有非常高的可重复性，范围从0.982到1.000，能够可靠地识别从健康到严重骨质疏松的个体供体。从这些体外结果我们得出结论，HR-pQCT衍生的形态学和力学参数具有高度可重复性，以至于骨结构和强度的差异能够以小于3%的可重复性误差被检测到；因此，该技术极有可能成为检测个体受试者骨质量和骨力学性能的工具。
