Architecture of bone tissue and its adaptation to pathological conditions

Brillouin and Raman Micro-Spectroscopy: A Tool for Micro-Mechanical and Structural Characterization of Cortical and Trabecular Bone Tissues

“…However, it is the trabecular tissue organization obtained from the femoral epiphysis and the medullary canal of the diaphysis that shows the greatest differences since the areas among the epiphyseal trabeculae are marked by signals from the red and yellow bone marrow, while in the medullary canal, mainly signatures from the adipocytes can be retrieved. This result agrees with the fact that during growth, the red bone marrow in the medullary cavity is almost totally replaced by adipocytes, thus transforming into yellow adipose tissue, while the hematopoietic cells are preserved only in the epiphyseal region of long bones [4]. This different chemical composition results in a variation of the average elastic modulus (M AVERAGED ) of the cortical tissue from 22.4 ± 0.08 GPa (diaphysis) to 26.3 ± 0.11 GPa (epiphysis) and from 13.4 ± 0.16 GPa (medullary cavity) to 11.6 ± 0.09 GPa (epiphysis) for the trabecular bone, obtained by the calculation of the mean of M AVERAGED values of each spectrum in the ROIs of Figure 5.…”

“…These pieces of evidence agree with the concept that trabecular bone tissue is designed (i) to provide support to the marrow, (ii) to regulate calcium and phosphate ion homeostasis, and (iii) to transfer the load from joints to the compact bone of the cortex of long bones [40]. Thus, the result can potentially come out in a more disordered and less mineralized collagen bundle architecture, likely due to bone remodelling processes [4].…”

“…Its loading plot in the bottom right part of Figure 5f confirms a higher contribution from the heme and carotenoids groups in the epiphyseal region than the diaphyseal one, instead of showing higher content in lipids. A possible explanation of this result can be found in the fact that bone marrow encapsulated among the trabeculae can be constituted by both a yellow and a red part, depending on the main contributors from either lipids or blood precursors, respectively [4].…”

“…From the microscopic point of view, the cortical bone (black square-Figure 1a) is organized in concentric lamella to form the so-called osteon or Haversian system, while in the trabecular bone (red square), the lamellae are settled adjacent one to the other to constitute bony spiculae-i.e., the trabeculae. The spaces among the trabeculae are filled by the bone marrow constituents [4].…”

“…The cortical tissue, constituting the envelope of the whole-bone structure, is formed by the so-called Haversian systems or osteons, cylindrical structures in which the lamellae are concentrically organized around central blood vessels. On the other hand, the trabecular tissue in the inner portion of bones is composed of adjacent lamellae forming bony spicules-i.e., trabeculae-that encapsulate the bone marrow [4]. At the microscopic level, the lamellar structure of both osteons and lamellae are constituted by an extracellular mineralized matrix (ECM) organized in the form of both an ordered phase of mineralized collagen bundles, responsible for lamellar strength and resistance, and a disordered phase, filling the spaces among the fibres and allowing for the survival of cells [5].…”