The effect of histological variation on the tensile strength of cortical bone

Under controlled machining, storage and testing conditions the tensile strength of longitudinally orientated specimens of cortical bone is measured over a range of 3 rates of strain. Coefficients of correlation and associated regression curves computed between the strength measurements and the results of a comprehensive photometric analysis of the histological microstructure indicate that naturally occurring cavities in the structure constitute the most significant sites of weakness. The observed strain rate sensitivity of their weakening effect suggests a mechanism of stress concentration to be operative. Clinical significance in such conditions as osteoporosis is indicated.