Fazzalari N L, Parkinson I H
Division of Tissue Pathology, Institute of Medical and Veterinary Science, Adelaide, Australia.
J Bone Miner Res. 1997 Apr;12(4):632-40. doi: 10.1359/jbmr.1997.12.4.632.
Primary osteoarthritis of the hip results in changes to the architecture of subchondral cancellous bone. These changes in architecture occur through the action of osteoclasts and osteoblasts in selectively removing and adding bone. The quantitative description of the bone architecture helps in understanding the etiology of primary osteoarthritis. Fractal analysis is a method for describing complex shapes, which is expressed numerically as the fractal dimension. A box counting method was used, where the perimeter of binary profiles of cancellous bone samples was measured for different box sizes. The fractal dimension was the absolute value of the slope of the straight line segments from the plot of the log number of boxes versus the log box size. Cancellous bone samples from two subchondral regions, superior and inferomedial, to the fovea were analyzed from primary severe osteoarthritic specimens taken following total hip replacement surgery (n = 19, aged 51-80 years) and autopsy controls (n = 25, aged 18-90 years). There were three straight line segments identified on the log-log plot, for each subject, indicating a fractal dimension over three different ranges of scale. The results show that in the superior region there is a highly significant difference between the groups (p < 0.0001) for fractal 1 and pivot point 2. The histomorphometry shows significant differences for bone volume/total volume, bone surface/total volume, trabecular separation, and osteoid surface/total volume between groups. In the inferomedial region fractal 1 and fractal 2 are significantly different. For the histomorphometry, trabecular thickness and eroded surface/total volume are significantly different between the groups. The pivot points, i.e., the box size at which the fractal dimension changes, were of similar magnitude to the trabecular thickness and trabecular separation. These data suggest that the fractal geometry analysis of cancellous bone identifies architectural features not easily recognized by conventional bone histomorphometry. The fractal dimension is a descriptor of bone structure which simplifies the description of a complex structure and enables changes in cancellous bone architecture, due to disease, to be identified.
髋关节原发性骨关节炎会导致软骨下松质骨结构发生改变。这些结构变化是通过破骨细胞和成骨细胞选择性地去除和添加骨质的作用而发生的。对骨结构进行定量描述有助于理解原发性骨关节炎的病因。分形分析是一种描述复杂形状的方法，其以分形维数的形式用数值表示。采用了盒计数法，即针对不同的盒尺寸测量松质骨样本二元轮廓的周长。分形维数是盒数对数与盒尺寸对数的图中直线段斜率的绝对值。从全髋关节置换术后获取的原发性重度骨关节炎标本（n = 19，年龄51 - 80岁）和尸检对照（n = 25，年龄18 - 90岁）中，分析了距小凹上方和内下两个软骨下区域的松质骨样本。对于每个受试者，在对数 - 对数图上识别出三条直线段，表明在三个不同尺度范围内的分形维数。结果表明，在上部区域，分形1和枢轴点2在组间存在极显著差异（p < 0.0001）。组织形态计量学显示，组间在骨体积/总体积、骨表面积/总体积、小梁间距和类骨质表面积/总体积方面存在显著差异。在内下区域，分形1和分形2存在显著差异。对于组织形态计量学，组间小梁厚度和侵蚀表面积/总体积存在显著差异。枢轴点，即分形维数发生变化时的盒尺寸，其大小与小梁厚度和小梁间距相似。这些数据表明，松质骨的分形几何分析能够识别出传统骨组织形态计量学不易识别的结构特征。分形维数是骨结构的一种描述符，它简化了对复杂结构的描述，并能够识别因疾病导致的松质骨结构变化。
