Bone has remarkable mechanical properties as a result of its complex hierarchical structure. The micromechanical behaviour of bone is governed by many factors including degree of mineralization, hydration and microstructure. The ability of bone to bear and transfer load is explored in this thesis. Primarily three different types of trabecular bone were investigated;​ antler, bovine and human osteoporotic bone. Using high-energy synchrotron x-rays from a Third Generation source elastic strains in the apatite crystals of trabecular bone were quantified for the first time during in situ loading in compression. The anisotropic accumulation of strain in the a- and c- axes of the apatite crystals is related to the transfer of load from parallel to non-parallel aligned trabeculae with increasing stress. Antler trabecular bone is modelled as an elastomeric open-cell foam due to the severe buckling that the trabeculae can undergo at relatively high far-field strains. Changes in the micromechanical behaviour and load transfer efficiency were explored as a function of hydration. Dehydrated bone is found to be less efficient at transferring load to non-parallel trabecular struts due to the brittle fracture of struts. Thus, dehydrated and hydrated trabecular bone are considered to behave like brittle and plastic open-cell foams respectively. The degraded architecture of osteoporotic bone results in increased elastic strains accumulating in parallel-aligned struts and poor load partitioning behaviour due to the large number of transverse ‘supporting’ struts being missing.

The diffraction technique was also applied to bovine plexiform bone where the use of wide-angle and small-angle x-ray detectors allowed changes in the apatite and collagen phases to be measured simultaneously. Based on the findings it is suggested that with increasing stress, load is transferred from lamellar to the more mineralised woven regions of the bone.

A range of techniques including nanoindentation (for which a custom technique was developed for testing hydrated bone), x-ray microtomography under in situ compression, and image-based finite element modelling were used to characterise the bone samples under study and support and supplement findings.