Prediction of the Post Yield Behavior of Bone

骨屈服后行为的预测

• 批准号: 7076382
• 负责人: Xiaodu Wang
• 金额: $ 18.47万
• 依托单位: UNIVERSITY OF TEXAS SAN ANTONIO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-15 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7076382
• 关键词: aging; bioengineering /biomedical engineering; biomechanics; biomimetics; bone fracture; bone imaging /visualization /scanning; bone regeneration; collagen; computer simulation; genetically modified animals; laboratory mouse; model design /development; molecular dynamics; nanotechnology; normal ossification; osteogenesis; osteoporosis; skeletal stress

DESCRIPTION (provided by applicant): The increased skeletal propensity to fracture is a major concern in health care of elderly populations due to the deteriorated bone quality. Cellular and/or molecular changes in bone due to aging or diseases are most likely reflected in the ultrastructure and material properties of bone constituents (i.e., mineral and collagen phases), which would eventually affect the post-yield behavior (microdamage formation) and the quality of the tissue. As a major measure of bone quality, the toughness of bone is mainly determined by the post-yield behavior of the tissue. Previous studies have demonstrated that the post-yield deformation of bone is most likely realized through the formation of two types of microdamages: microcrack and diffuse damage. Thus, elucidating the generating mechanisms of these microdamages and its relationship with bone constituents would significantly facilitate the understanding of age and disease related bone fractures. Although the ultrastructural and material properties of bone constituents is most likely related to the microdamage formation in bone, the underlying mechanism is poorly understood. To address this issue, the present study proposes a novel probabilistic damage model of mineral-collagen composites that can be used to study the mechanism of the tensile post-yield behavior (i.e., nano/microdamage formation) for bone tissues, and further to assess the contribution of ultrastructural and material properties of the bone constituents to the process. The hypothesis of this study is that microdamage formation (microcrack or diffuse damage) in bone is dependent on the ultrastructural and material properties of collagen fibrils and mineral matrix in the tissue. Two specific aims will be addressed as follows: Aim1: To develop a probabilistic failure model of mineral-collagen fibril composite to predict the mechanisms of damage formation in bone (i.e., either microcrack or diffuse damage) as a function of ultrastructural and material properties of mineral and collagen constituents: To do so, micromechanics combined with the probabilistic damage mechanics approaches will be used to develop a probabilistic damage model of mineral-collagen fibril composites. Using this novel model, patterns of microdamage progression as a function of ultrastructural and material properties of bone constituents will be examined. Aim 2: To verify the probabilistic failure model using bone samples from several mice models: Several mice models (i.e., C57BL/6, C3HE/H, and oim mice) with varied properties of the mineral and collagen phases will be utilized to test the effects of ultrastructural and material properties of the mineral and collagen phases on the post-yield behavior of bone (i.e., microdamage formation). These experimental data will be compared with the predictions by the mechanistic model developed in Aim 1. This study will, for the first time, provide a novel probabilistic damage mechanics approach to examine the effect of ultrastructural and material properties of bone constituents on the post-yield behavior of bone. Moreover, this model will provide significant insights into the underlying mechanism of age and disease related bone fractures. Elucidating these fundamental issues is not only scientifically important, but also give rise to the future development of strategies in prediction and prevention of age-related and osteoporotic bone fractures.

描述（由申请方提供）：由于骨质恶化，骨骼骨折倾向增加是老年人群医疗保健中的一个主要问题。由于老化或疾病引起的骨中的细胞和/或分子变化最有可能反映在骨成分的超微结构和材料性质中（即，矿物质和胶原相），这最终会影响屈服后行为（微损伤形成）和组织质量。作为骨质量的主要量度，骨的韧性主要由组织的屈服后行为决定。以往的研究表明，骨的屈服后变形很可能是通过形成两种类型的微损伤实现的：微裂纹和扩散损伤。因此，阐明这些微损伤的产生机制及其与骨成分的关系，将大大有助于理解与年龄和疾病相关的骨折。虽然骨成分的超微结构和材料特性最有可能与骨中的微损伤形成有关，但其潜在机制知之甚少。为了解决这个问题，本研究提出了一种新的矿物-胶原复合材料的概率损伤模型，可用于研究拉伸屈服后行为的机制（即，纳米/微米损伤形成），并进一步评估骨成分的超微结构和材料性质对该过程的贡献。本研究的假设是，骨中的微损伤形成（微裂纹或弥漫性损伤）取决于组织中胶原纤维和矿物质基质的超微结构和材料特性。两个具体的目标将解决如下：目标1：建立一个概率失效模型的矿物胶原纤维复合材料，以预测损伤形成的机制在骨（即，无论是微裂纹或扩散损伤）作为矿物和胶原成分的超微结构和材料特性的函数：为此，将使用结合概率损伤力学方法的微观力学来开发矿物-胶原纤维复合材料的概率损伤模型。使用这种新的模型，微损伤进展的功能，骨成分的超微结构和材料特性的模式将被检查。目的2：使用来自几种小鼠模型的骨样本验证概率失效模型：几种小鼠模型（即，C57 BL/6、C3 HE/H和oim小鼠）的骨组织中，将利用具有不同性质的矿物质和胶原蛋白相的骨组织来测试矿物质和胶原蛋白相的超微结构和材料性质对骨的屈服后行为的影响（即，微损伤形成）。这些实验数据将与目标1中开发的机械模型的预测进行比较。这项研究将首次提供一种新的概率损伤力学方法来研究骨成分的超微结构和材料特性对骨屈服后行为的影响。此外，该模型将为年龄和疾病相关骨折的潜在机制提供重要见解。阐明这些基本问题不仅在科学上具有重要意义，而且也会引起未来发展的预测和预防与年龄相关的骨折和骨质疏松性骨折的策略。