Evaluation for Mechanism of Diffuse Damage in Cortical Bone

Abstract

There is a kind of bone damage called “diffuse damage”, which initiates before “linear cracks” initiate. Huja and Burr reported that the diffuse damage was related to the bone remodeling. However, studies about quantification of the diffuse damage have not fully been done. In this study, the diffuse damage was produced by the static or cyclic three-point bending. The occurrence and progression of diffuse damage were observed as an increase in fluorescence intensity by the confocal laser scanning microscope (CLSM), and a change in stiffness from the initial condition was evaluated. The beam specimens were prepared from the adult porcine femoral plexiform bone. By static bending, the diffuse damage estimated as an increase in fluorescence intensity increased rapidly just after the relationship between stress and strain became non-linear. In addition, by SEM image of diffuse damage, it was suggested that microstructure of diffuse damage was not crack-like structure. By cyclic bending with low strain amplitude of 2 500 microstrain, the stiffness of all specimens was finally lost up to 10%, but in some specimens, the stiffness was increased at the initial stage before stiffness loss.