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

点击翻译按钮获取中文摘要

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.