Bone Hierarchical Structure: Heterogeneity and Uniformity

Abstract

Bone has a complex hierarchical structure with structural integration from nm to cm. The understanding of bone structure is developing rapidly due to improvements in available methodologies that allow unravelling structures across several length scales. These methods include advances in electron microscopy, in particular, focused ion beam scanning electron microscopy (FIB-SEM), confocal laser scanning microscopy techniques, X-ray imaging, X-ray diffraction tomography (XRD-CT), and tensor tomography (small angle X-ray scattering tensor tomgraphy, SAXS-TT and wide angle X-ray scattering tensor tomgraphy, WAXS-TT). Special emphasis is placed on the latter X-ray techniques that are emerging into powerful tools. Through a review of selected recent results on the structure of the bone matrix as well as the lacuno-canalicular network housing the osteocyte cells of bone, it is proposed that bone is more heterogeneous than typically described and that local variation in composition and crystallography may play a significant role in bone biology in health and disease.