Stiffness of compact bone: effects of porosity and density.

Stiffness of compact bone is found to be highly and nonlinearly dependent on its porosity, its complement, bone volume fraction and apparent density. Elastic modulus decreases as a power (0.55) of increasing porosity and increases both as a power of increasing bone tissue volume (10.92) and increasing apparent density (7.4). These data indicate that small changes in the amount or density of compact bone tissue exert a more pronounced influence on its stiffness than would similar changes in trabecular bone.