抄録
An ultra-microindenter was utilized for the evaluation of the local mechanical properties of bone tissue. The tangents of loading and unloading curve, A and D, were adopted as the parameters for the hardness and stiffness, respectively. An anisotropy due to the orientation of collagen fibers between sagittal and transverse planes of rabbit tibia was observed under the loading condition of 19.6 mN. When the indentation load was lowed, fragile properties of the hydroxyapatite could be evaluated. This technique was further used for the rat caudal vertebrae during mechanical adaptation in order to investigate in-plane distribution of the local mechanical property. Decrease of A and increase of 1/D were observed near the periosteum in the cortex, indicating that immature bone was formed and mineralized progressively. Additionally, higher A and lower 1/D under articular cartilage of the loaded rat suggested that the subchondral bone stiffened for it to adapt to the mechanical stimulation.
