Dong X Neil, Guo X Edward
Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
J Biomech. 2004 Aug;37(8):1281-7. doi: 10.1016/j.jbiomech.2003.12.011.
The objective of this study was to examine the dependence of the elastic properties of cortical bone as a transversely isotropic material on its porosity. The longitudinal Young's modulus, transverse Young's modulus, longitudinal shear modulus, transverse shear modulus, and longitudinal Poisson's ratio of cortical bone were determined from eighteen groups of longitudinal and transverse specimens using tensile and torsional tests on a servo-hydraulic material testing system. These cylindrical waisted specimens of cortical bone were harvested from the middle diaphysis of three pairs of human femora. The porosity of these specimens was assessed by means of histology. Our study demonstrated that the longitudinal Young's and shear moduli of human femoral cortical bone were significantly (p<0.01) negatively correlated with the porosity of cortical bone. Conversely, the elastic properties in the transverse direction did not have statistically significant correlations with the porosity of cortical bone. As a result, the transverse elastic properties of cortical bone were less sensitive to changes in porosity than those in the longitudinal direction. Additionally, the anisotropic ratios of cortical bone elasticity were found to be significantly (p<0.01) negatively correlated with its porosity, indicating that cortical bone tended to become more isotropic when its porosity increased. These results may help a number of researchers develop more accurate micromechanics models of cortical bone.
本研究的目的是考察作为横观各向同性材料的皮质骨弹性特性对其孔隙率的依赖性。利用伺服液压材料测试系统进行拉伸和扭转试验，从18组纵向和横向标本中测定了皮质骨的纵向杨氏模量、横向杨氏模量、纵向剪切模量、横向剪切模量和纵向泊松比。这些皮质骨圆柱形腰部标本取自三对人股骨的中骨干。通过组织学方法评估这些标本的孔隙率。我们的研究表明，人股骨皮质骨的纵向杨氏模量和剪切模量与皮质骨孔隙率呈显著负相关（p<0.01）。相反，横向弹性特性与皮质骨孔隙率无统计学显著相关性。因此，皮质骨的横向弹性特性对孔隙率变化的敏感性低于纵向。此外，发现皮质骨弹性的各向异性比与其孔隙率呈显著负相关（p<0.01），这表明当皮质骨孔隙率增加时，其趋于变得更各向同性。这些结果可能有助于许多研究人员开发更精确的皮质骨微观力学模型。
