THE DISTRIBUTION OF COLLAGEN-APATITE ORIENTATION IN BONE MICROSTRUCTURES

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 研究中心，而研究中心不一定是研究者所在的机构。 这项工作的特点是一个基本方面的人骨的微观结构，有关骨折的启动和逮捕。它解决了是否接近骨细胞陷窝的基本组件的方向影响继发性骨微生物力学。新的数据在骨关节腔周围区域的胶原-磷灰石的方向，和以前的数据胶原蛋白的方向远离骨关节腔周围区域，被纳入一种新的模拟次生骨，以研究方向如何与应变和应力在机械测试。我们使用Datastar上的Abaqus软件创建了一系列所谓的次级骨单位的有限元模型，次级骨单位是人体骨骼的基本单位，长度可达0.5 mm。模型包括模拟骨细胞陷窝的椭圆体。模拟的骨陷窝的数量在7到70之间。骨陷窝的位置可以由操作者选择，也可以根据骨单位中实验观察到的分布进行分配。椭球体附近的元素的机械性能模拟的胶原-磷灰石的取向，我们已经观察到在孤立的层状标本在共聚焦显微镜下。我们已经完成了模拟的实验力学行为的骨标本在拉伸和压缩有关的胶原-磷灰石的取向和存在的孔隙度在弹性阶段。对现有的胶原蛋白取向分布算法进行改进，避免了阶梯函数，使胶原蛋白取向在三维空间中保持连续性。这是为了增加模拟与实验观察的一致性。这一点特别重要，因为取向分布的不连续性可能产生错误的应变。Maple软件将在PC上使用，以准备Abaqus软件在Datastar上运行的输入文件。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This work characterizes a fundamental aspect of human bone micro-structure, pertinent to fracture initiation and arrest. It addresses whether orientation of elementary components proximate to osteocyte lacunae influences secondary osteon micro-biomechanics. New data at the perilacunar region concerning orientation of collagen-apatite, and prior data on collagen orientation away from the perilacunar region, were incorporated in a novel simulation of secondary osteon to investigate how orientation relates to strains and stresses during mechanical testing. We have created a series of finite element models, using Abaqus software on Datastar, of so-called secondary osteons, basic units of human skeleton which .measure up to 0.5 mm in length. The models include ellipsoids that simulate osteocyte lacunae. The number of the simulated lacunae ranges between 7 and 70. The positions of lacunae can be chosen by the operator or assigned to follow experimentally observed distributions in the osteon. The mechanical properties of the elements adjacent to the ellipsoids simulate the collagen-apatite orientation that we have observed in isolated lamellar specimens under confocal microscopy. We have completed the simulation of the experimental mechanical behavior of osteon specimens under tension and compression in relation to collagen-apatite orientation and presence of porosity during the elastic phase. The current algorithm for collagen orientation distribution will be improved to avoid step-functions and allow continuity of collagen orientation in three-dimension. This is to increase adherence of simulation to experimental observations. This is a particular important point because discontinuities in the orientation distribution may create erroneous strains. Maple software will be used on PC's to prepare the input files for Abaqus software to run on Datastar.