Mechanical loading causes detectable changes in morphometric measures of trabecular structure in human cancellous bone.
Mechanical loading causes detectable changes in morphometric measures of trabecular structure in human cancellous bone.
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机械载荷导致人类松质骨小梁结构的形态测量发生可检测的变化。
DOI：
10.1115/1.4024136
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Oravec,Daniel
中科院分区：
文献类型：
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作者：
Yeni,YenerN;Wu,Brenda;Huang,Lily;Oravec,Daniel
机械载荷和骨微观结构之间的关系对于那些寻求从微观结构预测骨力学性能或预测骨微观结构的组织如何由机械载荷驱动的人来说是感兴趣的。虽然材料中的应变和位移本质上是机械引起的微观结构外观变化的原因，但通常可用于评估骨质量的是微观结构组织的形态测量。因此，了解应变的历史是如何反映在骨微观结构的形态测量具有实际意义，因为它可以提供临床上可测量的指标，在骨的力学史，并提高解释骨的力学性能从微观结构的信息。本研究的目的是检查松质骨微观结构的形态测量指标对不同水平的连续水平应变的反应变化。实验方法包括对安装在μCT扫描仪上的定制加载装置中按顺序增加应变水平获得的人松质骨样本的微计算机断层扫描（μCT）图像进行体视学分析。我们发现，各向异性程度（DA）从基线到失败，从失败到postfailure下降。卸载后，DA部分从失败后水平恢复;然而，最终DA低于失败时和基线时。我们还发现，平均骨小梁厚度（Tb.Th.Av）增加与位移postfailure和卸载时没有恢复。当标本卸载时，平均骨小梁数量减少。此外，在postfailure位移Tb.Th的异质性作为衡量的标本内标准差（Tb.Th.SD）增加和小梁数量（Tb.N.SD）减少。此外，骨小梁数量的内部变异系数在破坏后位移时下降，但在卸载后没有恢复。最后，松质骨分离的变异系数在卸载时小于基线时。这些措施可以发展成基于图像的指数，以估计应变历史，损伤和残余机械性能，其中直接分析应力和应变，如通过有限元建模，可能是不可行的。在重塑成为对小梁结构的压倒性影响之前，可以使用多宽的时间间隔来估计应变历史仍有待确定。
The relationships between mechanical loads and bone microstructure are of interest to those who seek to predict bone mechanical properties from microstructure or to predict how organization of bone microstructure is driven by mechanical loads. While strains and displacements in the material are inherently responsible for mechanically caused changes in the appearance of the microstructure, it is the morphometric measures of microstructural organization that are often available for assessment of bone quality. Therefore, an understanding of how strain history is reflected in morphometric measures of bone microstructure has practical implications in that it may provide clinically measurable indices of mechanical history in bone and improve interpretation of bone mechanical properties from microstructural information. The objective of the current study was to examine changes in morphometric measures of cancellous bone microstructure in response to varying levels of continuum level strains. The experimental approach included stereologic analysis of microcomputed tomography (μCT) images of human cancellous bone samples obtained at sequentially increasing levels of strain in a custom-made loading apparatus mounted in a μCT scanner. We found that the degree of anisotropy (DA) decreased from baseline to failure and from failure to postfailure. DA partially recovered from postfailure levels upon unloading; however, the final DA was less than at failure and less than at baseline. We also found that average trabecular thickness (Tb.Th.Av) increased with displacements at postfailure and did not recover when unloaded. Average trabecular number decreased when the specimens were unloaded. In addition, the heterogeneity of Tb.Th as measured by intra-specimen standard deviation (Tb.Th.SD) increased and that of trabecular number (Tb.N.SD) decreased with displacements at postfailure. Furthermore, the intraspecimen coefficient of variation of trabecular number decreased at postfailure displacements but did not recover upon unloading. Finally, the coefficient of variation of trabecular separation at unload was less than that at baseline. These measures can be developed into image-based indices to estimate strain history, damage, and residual mechanical properties where direct analysis of stresses and strains, such as through finite element modeling, may not be feasible. It remains to be determined how wide a time interval can be used to estimate strain history before remodeling becomes an overriding effect on the trabecular architecture.