Analysis and modeling of micro- or nano-scale structure and microcirculation of bone

骨是骨骼系统的主要组成部分，是富含血管的组织，骨组织结构不仅具有结构体系，而且具有维持骨循环的血管网。在这项研究中，骨的微观结构进行了分析，从承重结构和微循环的血管网络的观点。应用辐射同步辐射CT对皮质骨中由哈佛管和韦氏管组成的网络结构进行了分析，揭示了生长期大鼠胫骨皮质骨中神经管网络结构的双相性变化。有人还发现，稀疏的运河网络的废用介导的负载减少增强。骨小梁的X射线衍射分析和维氏硬度测试表明，松质骨的宏观各向异性来源于骨小梁网络结构的各向异性和骨小梁的取向依赖性。通过纳米压痕实验和傅立叶变换红外光谱显微镜对皮质骨的材料和力学性能进行了研究，证实了骨质量在成年大鼠皮质骨中的重要性。本文建立了一种用摆杆式CCD视频显微镜直接测量骨膜微循环血流量的方法。采用管内对流扩散和均匀化连续介质扩散模型，模拟了骨皮质中材料通过管网中的血管和骨基质中的腔隙-小管系统的传输，并根据骨皮质的管网结构分析了生理材料浓度。将生理窗骨重建仿真模型扩展为废用窗骨细胞凋亡模型和过度使用窗骨重建目标模型的统一模型，并通过仿真研究验证了模型的性能。

Bone, major component of skeletal system, is blood vessel-rich tissue, and the bone tissue structure is not only of structural architecture but also of vascular network for bone circulation. In this study, the microstructure of bone is analyzed from the viewpoints of the load bearing structure and of the vascular network of microcirculation. The network structure consisting of Haversian canal Volkmann's canal in cortical bone was analyzed by using radiation synchrotron CT, and the biphasic structural change of canal network was revealed in the cortical bone of growing rats tibiae. It was also found that the rarefaction of the canal network was enhanced by the disuse-mediated load reduction. The X-ray diffraction analysis and Vickers hardness test for trabeculae showed that the macroscopic anisotropy of cancellous bone was coming from the structural anisotropy of trabecular network structure and from the orientation dependent property of trabeculae as well. The material and mechanical properties of cortical bone was examined using nano-indentation test and FTIR microscopy, and much importance of bone quality is demonstrated in cortical bone of mature rats. A technique was established for the direct blood flow measurement of periosteal microcirculation by using the pensile-type CCD video microscope. The material transport in cortical bone through the blood vessel in canal network and the lacuno-canalicular system in bone matrix was modeled in terms of the convective diffusion in tubes and the diffusion in homogenized continuum, and the physiological material concentration was analyzed based on the canal network structure of cortical bone. Simulation model of bone remodeling for physiological window was extended to a unified model involving models of the osteocyte apoptosis for disuse window and the targeted remodeling for overuse windows, and its capability was examined through a couple of simulation studies.