The effects of immobilization on vascular canal orientation in rat cortical bone
The effects of immobilization on vascular canal orientation in rat cortical bone
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DOI：
10.1111/j.1469-7580.2011.01450.x
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发表时间：
2012-01-01
影响因子：
2.4
通讯作者：
Cooper, David M. L.
中科院分区：
文献类型：
--
作者：
Britz, Hayley M.;Jokihaara, Jarkko;Cooper, David M. L.
众所周知，骨骼能够适应负荷的变化。然而，关于负载如何具体影响皮质骨的内部 3D 微结构，人们知之甚少。本研究的目的是通过实验检验负载是大鼠胫骨骨干初级血管管 3D 方向的决定因素这一假设。通过显微 CT 扫描 10 只大鼠（30 周龄）固定（坐骨神经切除术）27 周的左胫骨、来自这些相同大鼠的右 SHAM 手术胫骨（内部对照）和来自 10 只正常年龄匹配大鼠（外部对照）的右胫骨。在 3D 中定量评估平均根管方向（针对整个骨段和按区域）、孔隙率百分比、根管直径和根管间距。与外部对照相比，固定胫骨的管方向显着 (P < 0.001) 更径向（9.9 度），但与内部对照没有差异 (P = 0.310)。比较外部和内部对照组，内部对照组的方向显着（P < 0.05）更径向（6.8 度）。孔隙率百分比和根管间距没有发现差异。与内部（P < 0.001）和外部对照（P < 0.001）胫骨相比，固定胫骨的管直径显着更大。相对于外部对照的方向差异表明大鼠皮质骨的组织受到负载的影响。尽管固定组和内部对照组之间没有检测到根管方向的预测差异，但得出平均值的各个根管方向的分布揭示了所有三组的独特模式。内部对照表现出固定和外部对照之间的中间位置，表明对侧麻痹导致相对于外部对照所代表的正常状态的负载改变。这在按象限进行的区域分析中也很明显。加载的骨骼具有相同的横截面形状；然而，它们的内部结构不同。这些结果为负载对初级皮质骨 3D 组织的影响提供了新的见解，并且对于理解皮质骨适应、疾病和机械性能之间的关系具有重要意义。
It is well established that bone is capable of adapting to changes in loading; however, little is known regarding how loading specifically affects the internal 3D microarchitecture of cortical bone. The aim of this study was to experimentally test the hypothesis that loading is a determinant of the 3D orientation of primary vascular canals in the rat tibial diaphysis. Left tibiae from 10 rats (30 weeks old) that had been immobilized (sciatic neurectomy) for 27 weeks, right SHAM-operated tibiae from these same rats (internal control) and right tibiae from 10 normal age-matched rats (external control) were scanned by micro-CT. Mean canal orientation (for the whole bone segment and by region), percent porosity, canal diameter and canal separation were quantitatively assessed in 3D. Canal orientation in the immobilized tibiae was significantly (P < 0.001) more radial (by 9.9 degrees) compared to the external controls but did not differ from the internal controls (P = 0.310). Comparing the external and internal controls, orientation was significantly (P < 0.05) more radial in the internal control group (by 6.8 degrees). No differences were found for percent porosity and canal separation. Canal diameter was significantly greater in the immobilized vs. internal (P < 0.001) and external control (P < 0.001) tibiae. The differences in orientation relative to the external controls indicated that the organization of cortical bone in the rat is affected by loading. Although the predicted difference in canal orientation was not detected between immobilized and internal control groups, the distributions of individual canal orientations, from which the mean values were derived, revealed distinctive patterns for all three groups. The internal controls exhibited an intermediate position between the immobilized and external controls, suggesting that paralysis on the contralateral side resulted in altered loading relative to the normal state represented by the external control. This was also evident in a regional analysis by quadrant. The loaded bones had the same cross-sectional shape; however, their internal structure differed. These results provide novel insights into the impact of loading on the 3D organization of primary cortical bone and have implications for understanding the relation between cortical bone adaptation, disease and mechanical properties.