Goff M G, Chang K L, Litts E N, Hernandez C J
Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA; Department of Biomedical Engineering, Cornell University, Ithaca, NY, USA.
Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA.
J Biomech. 2014 Sep 22;47(12):3156-61. doi: 10.1016/j.jbiomech.2014.06.016. Epub 2014 Jun 21.
Theories of mechanical adaptation of bone suggest that mechanical loading causes bone formation at discrete locations within bone microstructure experiencing the greatest mechanical stress/strain. Experimental testing of such theories requires in vivo loading experiments and high-resolution finite element models to determine the distribution of mechanical stresses. Finite element models of in vivo loading experiments typically assume idealized boundary conditions with applied load perfectly oriented on the bone, however small misalignments in load orientation during an in vivo experiment are unavoidable, and potentially confound the ability of finite element models to predict locations of bone formation at the scale of micrometers. Here we demonstrate two different three-dimensional spatial correlation methods to determine the effects of misalignment in load orientation on the locations of high mechanical stress/strain in the rodent tail loading model. We find that, in cancellous bone, the locations of tissue with high stress are maintained under reasonable misalignments in load orientation (p<0.01). In cortical bone, however, angular misalignments in the dorsal direction can alter the locations of high mechanical stress, but the locations of tissue with high stress are maintained under other misalignments (p<0.01). We conclude that, when using finite element models of the rodent tail loading model, small misalignments in loading orientation do not affect the predicted locations of high mechanical stress within cancellous bone.
骨的机械适应性理论表明，机械负荷会导致骨微结构内承受最大机械应力/应变的离散位置处形成骨。对这些理论进行实验验证需要进行体内负荷实验和高分辨率有限元模型，以确定机械应力的分布。体内负荷实验的有限元模型通常假设理想的边界条件，即施加的负荷完全作用于骨上，然而在体内实验中负荷方向存在小的偏差是不可避免的，这可能会混淆有限元模型在微米尺度上预测骨形成位置的能力。在此，我们展示了两种不同的三维空间相关方法，以确定负荷方向偏差对啮齿动物尾巴负荷模型中高机械应力/应变位置的影响。我们发现，在松质骨中，负荷方向存在合理偏差时，高应力组织的位置保持不变（p<0.01）。然而，在皮质骨中，背侧方向的角度偏差会改变高机械应力的位置，但在其他偏差情况下，高应力组织的位置保持不变（p<0.01）。我们得出结论，在使用啮齿动物尾巴负荷模型的有限元模型时，负荷方向的小偏差不会影响松质骨内高机械应力的预测位置。
