TISSUE STRESS VARIABILITY AND STRENGTH IN VERTEBRAL BONE

描述(由申请人提供)：很大比例的老年人口有因骨质疏松而导致脊椎骨折的风险。胸椎12号和腰椎1号骨折构成了这些椎体骨折的大部分。外界因素，如负荷，撇开，骨质量是骨折的主要决定因素。与骨折相关的骨质量的衡量标准是骨强度。然而，目前的骨质量指标，如骨密度，只是骨强度的替代指标，诊断成功率参差不齐。正在开发的具有潜在高诊断价值的新技术利用了骨骼硬度和强度高度相关的观察结果，即骨折前骨骼可以承受的载荷与骨骼在给定载荷下的柔韧性有关。这两个表观性质是如何通过骨骼的微观结构组织联系在一起的，以及骨骼硬度与骨骼强度之间的关系如何，是骨生物学的基本问题。我们认为，松质骨的表观强度和表观刚度之间的密切关系是一种适应的结果，其中组织(骨小梁)的应力大小和变异性通过微观结构组织来控制，从而使组织应力的平均值和分散度相关。该项目将利用显微计算机断层扫描、大型有限元分析和力学测试，在组织和器官水平上确定人类脊柱T4-L5椎体的骨微结构、组织应力分布和骨表观特性之间的关系。该项目的结果将揭示：(I)在T12-L1连接的组织中是否会产生不依赖外部因素的更大水平的破坏性应力；(Ii)组织应力与骨骼表观特性之间的关联是否对患者内部和患者之间的样本选择敏感，(Iii)导致组织中破坏性应力形式的骨骼的微观结构特征，以及(Iv)是否可以使用引入的松质骨组织的概念通过刚度测量来预测器官水平的椎骨强度。这项研究的长期目标是通过更好地了解椎骨的应力调节结构，提高我们诊断和制定预防骨骼疾病和失败的策略的能力。

DESCRIPTION (provided by applicant): A great percentage of the elderly population is at the risk of a vertebral fracture due to osteoporosis. Fractures of thoracic 12 and lumbar 1 constitute the majority of these vertebral fractures. External factors, such as loading, being aside, bone quality is the major determinant of a fracture. The measure of bone quality that is relevant to fracture is bone strength. However, current measures of bone quality, such as bone mineral density, are only surrogates of bone strength and have variable diagnostic success. New technologies with potentially high diagnostic value that are under development make use of the observation that bone stiffness and strength are highly correlated, i. e., how much load the bone can carry before fracture is related to how flexible the bone is under a given load. How these two apparent properties are related through bone's microstructural organization and to what extent bone stiffness is related to bone strength are very fundamental questions of bone biology. We believe that the close relationship between the apparent strength and apparent stiffness of cancellous bone is a result of an adaptation where tissue (trabeculae) stress magnitude and variability is controlled through microstructural organization such that the average and the scatter of the tissue stresses are correlated. This project will determine the relationships between bone microstructure, tissue stress distributions and bone apparent properties at a tissue and organ level for T4-L5 vertebrae from human spines using microcomputed tomography, large-scale finite element analysis and mechanical testing. The results of this project will reveal: (i) whether greater levels of damaging stresses are generated in the tissue from T12-L1 junction independent of external factors, (ii) whether the association between tissue stresses and bone apparent properties is sensitive to the choice of within-patient and between-patient samples, (iii) microstructural features of bone that give rise to damaging forms of stresses in the tissue, and (iv) whether vertebral bone strength at the organ level can be predicted by stiffness measurements using the concepts introduced for cancellous bone tissue. The long-term goal of this research is to enhance our ability to diagnose and develop strategies for prevention of bone disease and failure through a better understanding of the stress-regulated structure of vertebral bone.