School of Biomedical Engineering, The University of Western Ontario, London, ON, Canada.
Surgical Mechatronics Laboratory, Roth|McFarlane Hand and Upper Limb Centre, St. Josephs Health Care, 268 Grosvenor St., London, ON, Canada.
Ann Biomed Eng. 2019 Feb;47(2):615-623. doi: 10.1007/s10439-018-02152-6. Epub 2018 Oct 25.
Preclinical and clinical bone strength predictions can be elucidated by understanding bone mechanics at a variety of hierarchical levels. As such, down-sampled micro-CT images are often used to make comparisons across image resolutions or used to reduce computational resources in micro finite element models (µFEMs). Therefore, the objectives of this study were to compare trabecular apparent modulus among (i) hexahedral and tetrahedral µFEMs, (ii) µFEMs generated from 32, 64, and 64 µm down-sampled from 32 µm µCT scans, and (iii) µFEMs with homogeneous and heterogeneous tissue moduli. Trabecular µFEMs were generated from scans at the three spatial resolutions taken from the glenoid vault of 14 cadaveric specimens. Simulated unconstrained compression was performed and used to calculate and compare the apparent modulus of each µFEM. It was found that models derived from high-resolution images that account for material heterogeneity are nearly equivalent whether hexahedral or tetrahedral elements are used. However, translation of stiffness from down-sampled scans are not equivalent to scans performed at the down-sampled resolution, or that account for trabecular material heterogeneity. Material heterogeneity is most representative of in vivo trabecular bone and to accurately model trabecular mechanical properties, material heterogeneity should be considered in future µFEM development.
通过了解不同层次的骨骼力学，可以阐明临床前和临床骨骼强度预测。因此，通常会使用下采样的 micro-CT 图像来比较不同图像分辨率，或用于减少微有限元模型（µFEM）中的计算资源。因此，本研究的目的是比较（i）六面体和四面体 µFEM、（ii）从 32 µm micro-CT 扫描中以 32、64 和 64 µm 下采样生成的 µFEM，以及（iii）具有均匀和不均匀组织模量的 µFEM 之间的小梁表观模量。从 14 个尸体标本的关节窝穹顶的三个空间分辨率的扫描中生成小梁 µFEM。进行了模拟的无约束压缩，并用于计算和比较每个 µFEM 的表观模量。结果发现，考虑材料各向异性的高分辨率图像生成的模型，无论使用六面体还是四面体元素，几乎都是等效的。然而，从下采样扫描中转换的刚度与在下采样分辨率下执行的扫描或考虑小梁材料各向异性的扫描并不等效。材料各向异性最能代表体内小梁骨，为了准确模拟小梁的力学性能，在未来的 µFEM 开发中应考虑材料各向异性。
