Specimen diameter and "side artifacts" in cancellous bone evaluated using end-constrained elastic tension.
Specimen diameter and "side artifacts" in cancellous bone evaluated using end-constrained elastic tension.
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DOI：
10.1016/j.bone.2010.03.024
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发表时间：
2010-08
期刊：
影响因子：
4.1
通讯作者：
W. Lievers;A. C. Petryshyn;A. Poljšak;S. Waldman;A. K. Pilkey
中科院分区：
文献类型：
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作者：
W. Lievers;A. C. Petryshyn;A. Poljšak;S. Waldman;A. K. Pilkey
在取芯样品的松质骨测试中，侧伪影是由于样品制备过程中松质骨小梁网络的断裂而低估了真实(即原位)力学性能。尽管其他研究人员提出了来自有限元模型的修正系数，但也有人建议通过增加试件直径来最小化副作用。6个不同直径(3.1~10.6 mm)的标本，来自两个不同的解剖部位(牛股骨髁和牛腰椎)，使用环氧端帽方案进行弹性拉伸力学测试，以消除末端伪影。弹性模数在两个部位都受到直径的显著影响。例如，5.1 mm的试件平均低估了10.6 mm试件的弹性模数约20%。然而，8.3 mm和10.6 mm标本在两个解剖部位之间没有统计学差异，这表明8.3 mm直径的标本足够大，可以避免侧面伪影。由Micro-CT图像建立的有限元模型表明，随着直径的增加，弹性模量接近一个渐近值，并且随着直径的减小，弹性模量随结构的变化而下降。这些结果从实验和数值上证实，在适当大的试件直径下，副作用可以忽略不计，而这个最小直径将取决于松质骨的结构。后一种结果的一个重要含义是，在比较具有不同结构(例如正常和骨质疏松)的测试组时，必须适当选择样本直径，以确保侧向伪影的大小不会混淆组之间的真正差异。
In cancellous bone testing of cored samples, side artifacts are the underestimation of the true (i.e. in situ) mechanical properties due to the severing of the trabecular network during specimen preparation. Although other researchers have suggested correction factors derived from finite element method (FEM) models, it is proposed that side effects can be minimized by increasing the specimen diameter. Six different diameter specimens (3.1–10.6mm), from two different anatomic sites (bovine femoral condyle and bovine lumbar vertebrae), were mechanically tested in elastic tension using an epoxy endcap protocol to eliminate end artifacts. Elastic modulus was found to be significantly affected by diameter in both sites. For example, the 5.1mm samples underestimated the elastic modulus of the 10.6mm samples by an average of roughly 20%. Yet no statistical difference was detected between the 8.3 and 10.6mm samples in either anatomic site, suggesting that 8.3mm diameter specimens were sufficiently large to avoid side artifacts. FEM models created from micro-CT images reveal that modulus approaches an asymptotic value with increasing diameter, and demonstrate an architecture-dependent drop in modulus at decreasing diameters. These results confirm, both experimentally and numerically, that side effects can be ignored given a suitably large specimen diameter and that this minimum diameter will be dependent on the cancellous architecture. An important implication of the latter result is that specimen diameters must be chosen appropriately when comparing test groups with different architectures (e.g. normal versus osteoporotic) to ensure that the magnitude of side artifacts does not confound the true differences between the groups.