Investigation of bone with synchrotron radiation imaging: from micro to nano

Excerpt

Bone achieves several functions in the organism and exhibits different levels of organization. At the microstructural scale, it is possible to distinguish cortical and cancellous bone being, respectively, a dense external shell and a porous inner material made of thin trabeculae (hundred of micrometers). If the general organization of these microstructures is well described in an anatomy handbook, their particular organization for a given bone may vary with aging, disease, or therapy. At the ultra-structural scale, bone tissue can be seen as an arrangement of bone modeling units (BMU) with different degrees of mineralization, including micrometric or submicrometric porosities such as micro-cracks, osteocyte lacunae, and canalicules. The composition of bone tissue itself is a mixture of collagen (mainly collagen type I), water and mineral (carbonated hydroxyapatite (HA)). The collagen and mineral phases are complementary in the sense that they respectively provide toughness and stiffness. The possible molecular composition of mineral may differ from stochiometric HA with the substitution of some ions. At the nanometric scale, the mineral particles are supposed to be platelets oriented along the main direction of the collagen fibrils. …