Advanced analysis and control of bone microstructure based on a materials scientific study including microbeam x-ray diffraction

Bone tissue is predominantly composed of biological apatite (BAp) crystals and collagen (Col) fibers, which shows hierarchical structure at various scale levels. Therefore, to design and develop implants suitable for bone replacement, both bone mineral density (BMD) and bone anisotropic microstructure should be investigated. From the viewpoint of materials scientific study, the bone microstructure based on the orientation degree of BAp c-axis which is dependent upon the bone portion, turnover, cell arrangement, etc., was clarified in intact, pathological and regenerated bones. For the analysis of BAp orientation, the microbeam X-ray diffraction method is quite effective on the basis of crystallography of anisotropic hexagonal BAp crystal. Moreover, this method is applicable even to a small region of several 10 μm or more on a side. Therefore, advanced design of implants for bone replacement should take into account anisotropic bone microstructure containing preferential alignment of BAp/Col.