The effect of ultrasonically determined anisotropy on longitudinal fracture of cortical bone.

This study examines the effects of density and microstructural anisotropy on longitudinal crack propagation in compact bone. Bovine cortical bone samples were demineralized by acid, producing specimens with a wide range of bone density. Ultrasound velocity was measured in the radial and longitudinal directions of each specimen using a pulse transmission technique. A proposed microstructural anisotropy parameter based on these ultrasound velocities was introduced and evaluated. The critical stress intensity factors K(IC) of these specimens were determined by mechanical fracture toughness tests. A linear regression study demonstrated that assessment of fracture toughness was precisely achieved by the combined effect of density and microstructural anisotropy of compact bone (r2 = 0.951, p < 0.0001).