Effects of stress concentrations on the fatigue life of bovine cortical bone: finite element predicted peak stress and stressed volume

Mechanical fatigue is the predominant etiology of stress fracture but the mechanism governing the fatigue failure of bone is poorly understood. Recent work from our lab suggests that intracortical microarchitecture is strongly associated with the fatigue life of bone. Vascular canals induce stress concentrations that may increase the magnitude and volume of highly stressed material within the bone matrix. This study examined the relationship between peak stress or stressed volume and the fatigue life of bovine cortical bone. Four samples were cyclically loaded in compression until failure and microCT-based FE models were created to estimate the peak stress and stressed volume. Peak stress explained 66% of the variance in fatigue life, while stressed volume explained 81% suggesting that the fatigue failure of bone is related to both the magnitude and size of stress concentrations.