Some properties of the organic matrix of a bovine cortical bone sample in various media

Dimensional stability of a demineralized bovine cortical bone sample was found in all media whether EDTA, saline or ethanol and water solutions or even 100% ethanol. A 6% volume shrinkage was observed, in strong contrast to the reported swelling for tail tendon fiber collagen. Sonic velocity was strongly dependent on the state and the medium, varying by a factor greater than 2. The medium appears to contribute strongly to the observed velocity suggesting that the Reuss formalism is applicable with the solid collagen skeleton as one component and the liquid in the pores as the second. Sonic anisotropy was noted although the intensity varied. The radial to axial velocity was greatest (0.93) in saline and least in 100% ethanol (0.80) indicating that the rigidity of the tissue influenced the character of sonic propagation. Two sets of intermolecular linkages are inferred. One set, in common with tendon collagen, controls the elastic properties. A second set in bone collagen maintains dimensional stability.