Intratrabecular distribution of tissue stiffness and mineralization in developing trabecular bone.

The purpose of this study was to investigate the relation between bone tissue stiffness and degree of mineralization distribution and to examine possible changes during prenatal development. Understanding this may provide insight into adaptation processes and into deformation mechanisms of the bone microstructure. Mandibular condyles from four fetal and newborn pigs were used. Tissue stiffness was measured using nanoindentation, the degree of mineralization with microCT. Eight indents were made over the trabecular width of 15 trabeculae in each specimen, leading to a total of 960 indents. Subsequently, the degree of mineralization of these locations was determined. Intratrabecular variations in bone tissue stiffness and degree of mineralization showed a similar pattern; low at trabecular surfaces and higher in the cores. A strong correlation was found between the two variables, which remained unchanged during development. It was concluded that bone tissue in fetal and newborn trabecular cores resembles adult trabecular bone tissue properties and is distributed in a regular radial pattern in trabeculae. For the first time, it was shown that the intratrabecular tissue stiffness develops along the same path as the degree of mineralization. Knowledge regarding intratrabecular tissue stiffness and mineralization results in a better understanding of trabecular bone mechanical behavior on a structural and tissue level.