Elastic modulus and strength of emu cortical bone.

The emu (Dromaius novaehollandiae) shows potential as a unique animal model for replicating the femoral head collapse process seen in end-stage human osteonecrosis. Since the collapse phenomenon (and interventions to prevent it) involve mechanical processes, it is important to elucidate the similarities and differences of emus versus humans in terms of hip joint biomechanics. A first step for comparison is the intrinsic mechanical properties of the respective bone tissues, as reflected in cortical bone flexural stiffness and strength. In four-point bending, emu cortical bone was found to have an elastic modulus of 13.1 GPa. Its yield stress was determined to be 113 MPa and the ultimate strength was 146 MPa. Emu cortical bone's elastic modulus was similar to that of other avian species, and falls approximately 25% below that of the human (17.3 GPa).