Liu Li, Morgan Elise F
Boston University, 110 Cummington Street, Boston, MA 02215, USA.
J Biomech. 2007;40(15):3516-20. doi: 10.1016/j.jbiomech.2007.04.019. Epub 2007 Jun 13.
Strain measurement is an essential tool in the study of trabecular bone structure-function relationships. Digital volume correlation (DVC) is a measurement technique that quantifies strains throughout the interior of a specimen, rather than simply those on the surface. DVC relies on tracking the movement of microstructural features, and as such, the accuracy and precision of this technique may depend on trabecular structure. This study quantified displacement and strain measurement errors in six types of trabecular bone that spanned a wide range of volume fraction and trabecular architecture. Accuracy and precision were compared across bone type and also across three DVC methods. Both simulated and real displacement fields were analyzed using micro-computed tomography images of specimens from the bovine distal femur, bovine proximal tibia, rabbit distal femur, rabbit proximal tibia, rabbit vertebra, and human vertebra. Differences as large as three-fold in accuracy and precision of the displacements and strains were found among DVC methods and among bone types. The displacement precision and the strain accuracy and precision were correlated with measures of trabecular structure such as structural model index. These results demonstrate that the performance of the DVC technique can depend on trabecular structure. Across all bone types, the displacement and strain errors ranged 1.86-3.39 microm and 345-794 microepsilon, respectively. For specimens from the human vertebra and bovine distal femur, the measurement errors were approximately 20 times smaller than the yield strain. In these cases, DVC is a viable technique for measuring pre- and post-yield strains throughout trabecular bone specimens and the trabecular compartment of whole bones.
应变测量是研究小梁骨结构-功能关系的一项重要工具。数字体积相关技术（DVC）是一种测量技术，它能够量化整个标本内部的应变，而不仅仅是表面的应变。DVC依靠追踪微观结构特征的移动，因此，该技术的准确性和精确性可能取决于小梁结构。本研究量化了六种类型小梁骨的位移和应变测量误差，这些小梁骨的体积分数和小梁结构范围广泛。比较了不同骨类型以及三种DVC方法的准确性和精确性。使用来自牛远端股骨、牛近端胫骨、兔远端股骨、兔近端胫骨、兔椎骨和人椎骨标本的微观计算机断层扫描图像分析了模拟和实际位移场。在DVC方法和骨类型之间发现位移和应变的准确性和精确性差异高达三倍。位移精确性以及应变准确性和精确性与小梁结构的测量指标（如结构模型指数）相关。这些结果表明，DVC技术的性能可能取决于小梁结构。在所有骨类型中，位移和应变误差分别在1.86 - 3.39微米和345 - 794微应变范围内。对于来自人椎骨和牛远端股骨的标本，测量误差比屈服应变小约20倍。在这些情况下，DVC是一种可行的技术，可以测量整个小梁骨标本和全骨小梁部分的屈服前和屈服后应变。
