Micro-Mechanical Modeling of Trabecular Bone

描述（由申请人提供）：骨小梁的显微结构类型（板状与杆状）在确定骨小梁强度方面至关重要，而骨小梁在衰老和骨质疏松症中发生从板状到杆状的显著变化。该生物工程研究资助项目旨在开发一种基于骨小梁muCT和muMRI图像的数字拓扑分析（DTA）的新型形态学和微观力学建模方法，具体目标如下：具体目标1：对人尸体椎骨、胫骨近端和股骨近端的松质骨样本进行muCT和muMRI成像，并进行单轴压缩试验以实验性地确定人骨小梁的机械性能。具体目标二：对muCT和muMRI图像进行基于非线性体素的muFE分析，并对单个骨小梁进行基于DTA的分割，以量化骨小梁失效的微观力学。具体目标3：对muCT和muMRI图像进行基于DTA的形态学分析，并将新的形态学参数与实验测定的人骨小梁机械特性相关联。具体目标4：基于muCT和muMRI图像的DTA分割开发简化的板/棒muFE模型，并将简化的板/棒模型的非线性预测与基于体素的模型的非线性预测进行比较;使用简化的muFE模型对整个椎体进行非线性muFE分析，并将简化模型的非线性预测与将在UC Berkeley进行的基于体素的模型的非线性预测进行比较（支持NTH项目）。在执行上述具体目标的过程中，我们将测试以下假设： 假设1：独立于解剖部位，屈服开始于小梁杆，然后在小梁骨失效的后期阶段在小梁板和杆中均匀分布。 假设二：骨小梁的力学性能可以通过基于单个骨小梁棒/板的DTA分割的形态学参数来预测。 假设三：松质骨的机械特性和微观力学预测与成像模式（muCT与muMRI）和模型类型（体素与简化板/棒）无关。 新的骨小梁微观结构的形态学和微观力学建模工具将被开发用于在个体骨小梁水平上研究整个人骨的失效机制和骨折风险评估。

DESCRIPTION (provided by applicant): The microstructural type of trabeculae (plate-like vs. rod-like) is critical in determining the strength of trabecular bone while a dramatic change of trabeculae from plate-like to rod-like occurs in aging and osteoporosis. This Bioengineering Research Grant is to develop a novel morphological and micro-mechanical modeling method based on digital topological analysis (DTA) of muCT and muMRI images of trabecular bone with the following specific aims: Specific Aim 1: To perform muCT and muMRI imaging on trabecular bone specimens from human cadaveric vertebrae, proximal tibiae, and proximal femurs, and to perform uniaxial compression tests to experimentally determine mechanical properties of human trabecular bone. Specific Aim 2: To perform non-linear voxel based muFE analyses on muCT and muMRI images and DTA based segmentations for individual trabeculae to quantify micromechanics of trabecular bone failure. Specific Aim 3: To perform DTA based morphological analyses on muCT and muMRI images and correlate new morphological parameters to experimentally determined mechanical properties of human trabecular bone. Specific Aim 4: To develop reduced plate/rod muFE models based on DTA segmentation of both muCT and muMRI images and to compare nonlinear predictions of reduced plate/rod models with those of voxel based models; To perform nonlinear muFE analyses of whole vertebral bodies using reduced muFE models and to compare nonlinear predictions of reduced models with those of voxel based models to be performed at UC Berkeley (supported NTH project). In the process of performing the above specific aims, we will test the following hypotheses: Hypothesis 1: Independent of anatomic sites, yielding is initiated in trabecular rods and then is equally distributed in both trabecular plates and rods at later stages in trabecular bone failure. Hypothesis 2: Mechanical properties of trabecular bone can be predicted by morphological parameters based on DTA segmentation of individual trabecular rods/plates. Hypothesis 3: The predictions of mechanical properties and micromechanics of trabecular bone are independent of imaging modalities (muCT vs. muMRI) and model types (voxel vs. reduced plate/rod). New morphological and micromechanical modeling tools of trabecular bone microstructure will be developed for studying failure mechanisms and fracture risk assessment for a whole human bone at an individual trabecula level.