Ding M, Hvid I
Department of Orthopaedic Surgery, Aarhus University Hospital, Denmark.
Bone. 2000 Mar;26(3):291-5. doi: 10.1016/s8756-3282(99)00281-1.
Structure model type and trabecular thickness are important characteristics in describing cancellous bone architecture. It has been qualitatively observed that a radical change of trabeculae from plate-like to rod-like occurs in aging, bone remodeling, and osteoporosis. Thickness of trabeculae has traditionally been measured using model-based histomorphometric methods on two-dimensional (2-D) sections. However, no quantitative study has been published based on three-dimensional (3-D) methods on the age-related changes in structure model type and trabecular thickness for human peripheral (tibial) cancellous bone. In this study, 160 human proximal tibial cancellous bone specimens from 40 normal donors, aged 16 to 85 years, were collected. These specimens were micro-computed tomography (micro-CT) scanned, then the micro-CT images were segmented using optimal thresholds. From accurate 3-D data sets, structure model type and trabecular thickness were quantified by means of novel 3-D methods. Structure model type was assessed by calculating the structure model index (SMI). The SMI was quantified based on a differential analysis of the triangulated bone surface of a structure. This technique allows quantification of structure model type, such as plate, rod objects, or mixture of plates or rods. Trabecular thickness is calculated directly from 3-D images, which is especially important for an a priori unknown or changing structure. Furthermore, 2-D trabecular thickness was also calculated based on the plate model. Our results showed that structure model type changed towards more rod-like in the elderly, and that trabecular thickness declined significantly with age. These changes become significant after 80 years of age for human tibial cancellous bone, whereas both properties seem to remain relatively unchanged between 20 and 80 years. Although a fairly close relationship was seen between 3-D trabecular thickness and 2-D trabecular thickness, real 3-D trabecular thickness was significantly underestimated using 2-D method.
结构模型类型和骨小梁厚度是描述松质骨结构的重要特征。已经定性观察到，在衰老、骨重塑和骨质疏松过程中，骨小梁会从板状急剧转变为杆状。传统上，骨小梁厚度是通过基于模型的组织形态计量学方法在二维（2-D）切片上进行测量的。然而，尚未有基于三维（3-D）方法对人类外周（胫骨）松质骨结构模型类型和骨小梁厚度的年龄相关变化进行定量研究的报道。在本研究中，收集了来自40名年龄在16至85岁的正常供体的160份人类胫骨近端松质骨标本。对这些标本进行了微计算机断层扫描（micro-CT），然后使用最佳阈值对微CT图像进行分割。从精确的三维数据集中，通过新颖的三维方法对结构模型类型和骨小梁厚度进行了量化。结构模型类型通过计算结构模型指数（SMI）来评估。SMI是基于对结构的三角化骨表面的差异分析进行量化的。该技术能够对结构模型类型进行量化，例如板、杆状物体或板与杆的混合物。骨小梁厚度直接从三维图像中计算得出，这对于先验未知或变化的结构尤为重要。此外，还基于板模型计算了二维骨小梁厚度。我们的结果表明，老年人的结构模型类型向更杆状转变，并且骨小梁厚度随年龄显著下降。对于人类胫骨松质骨，这些变化在80岁以后变得显著，而在20至80岁之间，这两个特性似乎保持相对不变。尽管三维骨小梁厚度和二维骨小梁厚度之间存在相当密切的关系，但使用二维方法时，实际的三维骨小梁厚度被显著低估。
