MODELING THE EFFECTS OF POROSITY IN COMPACT BONE TISSUE

拟议研究的主要目的是进一步促进 了解密质骨组织的力学行为， 微观力学水平。 采用微观力学建模技术 广泛而成功地阐明了 纤维结构/性能关系及破坏机理 增强复合材料 他们的潜力在很大程度上 然而，在研究骨骼和其他生物材料方面尚未开发。 一 微观力学模型由一个小的可重复的单位细胞的 明确包含每个离散材料成分的材料。 该单元格旨在捕获基本的微观结构 从平均意义上讲，材料的特性。 的微观结构 哈弗氏密质骨组织类似于纤维增强的 复合材料，所以这种特殊的骨组织类型提供了一个自然的开始， 复合材料细观力学方法的应用要点。 为 哈弗氏骨，次级骨单位形成基本结构元素， 代表纤维成分。 微观力学建模将使 组织形态学效应的可能表征和预测- 度量参数，如孔隙度、哈弗面积百分比、骨单位类型 （胶原纤维方向），矿化和密度上的 骨组织的宏观力学性能。 故知之， 各种病理条件对这些参数的影响，模型 将允许对机械的相应影响进行评估 行为 拟议研究的具体目标是开发和 对哈弗氏密质骨微观力学模型进行测试。 各种方法 明确地将孔隙度纳入模型将被检查。 该项目的合作者将提供详细的实验 结果报告弹性模量测量值作为几个 组织形态学参数（包括孔隙度）。 该车型将 适应，改进，并通过与此直接比较评估 数据 在这一年的项目期间， 用于模型开发和评估。 顺利完成工作 将为后续研究奠定基础， 开发以及广泛的实验测试， 模型验证 目前的项目是必要的， 这种方法的可行性，以保证这种长期的研究。 的 这项研究的最终好处是一个更完整， 对骨力学基础科学的确定性理解。 的 在这一初步努力的重点是孔隙度，因为它的关键 在骨质疏松症引起的许多主要健康问题中的作用， 通过废用、衰老或代谢紊乱。

The broad purpose of the proposed research is to further the understanding of the mechanical behavior of compact bone tissue at the micromechanics level. Micromechanics modeling techniques are used extensively and quite successfully in elucidating fundamental structure/property relationships and failure mechanisms for fiber reinforced composite materials. Their potential remains largely untapped, however, in studying bone and other biological materials. A micromechanics model consists of a small repeatable unit cell of the material that explicitly contains each discrete material constituent. This unit cell is intended to capture the essential microstructural features of the material in an average sense. The microstructure of Haversian compact bone tissue resembles that of a fiber reinforced composite, so this particular bone tissue type offers a natural starting point for applying composite material micromechanics methods. For Haversian bone, secondary osteons form the basic structural element and represent the fiber component. Micromechanics modeling will make possible characterization and prediction of the effects of histomorpho- metric parameters such as porosity, percent Haversian area, osteon type (collage fiber orientation), mineralization, and density on the macroscopic mechanical properties of bone tissue. Thus, knowing the effects of various pathological conditions on these parameters, the model will allow an assessment of the corresponding effects on mechanical behavior. The specific goals of the proposed research are to develop and test a micromechanics model of Haversian compact bone. Various methods for explicitly incorporating porosity into the model will be examined. The Collaborator on the project will provide detailed experimental results reporting elastic modulus measurements as a function of several histomorphometric parameters (including porosity). The model will be adapted, improved, and evaluated through direct comparison with this data. Most of the effort in this one-year project period will be needed for model development and assessment. Successful completion of the work will lay the foundation for follow-up studies involving further model development as well as extensive experimental testing for more definitive model verification. The current project is necessary to establish the feasibility of the method to warrant such longer-term study. The ultimate benefit of this line of research is a more complete and deterministic understanding of the basic science of bone mechanics. The emphasis in this initial effort is on porosity because of its critical role in the many major health problems arising from osteoporosis, whether through disuse, aging, or metabolic disorders.