TISSUE STRESS VARIABILITY AND STRENGTH IN VERTEBRAL BONE

描述（由申请人提供）：由于骨质疏松症，老年人群中有很大比例存在椎骨骨折的风险。胸椎骨折12例，腰椎骨折1例，占这些椎骨骨折的大多数。撇开外部因素如负荷不谈，骨质量是骨折的主要决定因素.与骨折相关的骨质量的量度是骨强度。然而，目前骨质量的测量，如骨矿物质密度，只是骨强度的替代品，并具有可变的诊断成功率。正在开发的具有潜在高诊断价值的新技术利用了骨硬度和强度高度相关的观察结果，即。例如，骨折前骨能承受多大的负荷与骨在给定负荷下的柔韧性有关。这两个表观性质如何通过骨的微观结构组织相关，以及骨刚度与骨强度在多大程度上相关，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适应的结果，其中组织（骨小梁）应力大小和可变性通过微观结构组织控制，使得组织应力的平均值和分散度相关。本项目将使用微型计算机断层扫描、大规模有限元分析和力学测试，确定人体脊柱T4-L5椎骨组织和器官水平上骨微观结构、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）是否在组织中从T12-L1连接处独立于外部因素产生更高水平的破坏性应力，（ii）组织应力和骨表观性质之间的关联是否对患者内和患者间样品的选择敏感，（iii）引起组织中破坏性形式的应力的骨的微观结构特征，以及（iv）在器官水平的椎骨强度是否可以通过使用针对松质骨组织引入的概念的刚度测量来预测。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疾病和骨衰竭的策略的能力。

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.