A technique for the tensile testing of demineralised bone

The purpose of this study was to devise a method for the tensile testing of the organic component of demineralised bone. It was hoped that the method could be applied to determine whether an observed reduction in the strength of bone in copper-deficient rats could be attributed to a reduction in the cross-linking of collagen. Tensile testing of a fully demineralised specimen proved impossible to perform because of the difficulty in gripping the material, which tended to slide out of its holding clamps. The technique devised involved the demineralisation of only the diaphysis of the bone, leaving the bone ends intact. This enabled the bone to be gripped firmly at both ends in an Instron tensile testing machine. Elongation under loading of the demineralised diaphysis was measured by the Instron and a video recording was made of the elongation of the central portion. The strain was found to be uniform. Tensile strength was found to correlate with copper levels in the liver (r = 0.54, p < 0.05), although no significant differences were found between the strength, the stiffness, or the strain to failure for bone from the copper-deficient animals and bone from the normal controls. The test method itself should be useful in other studies in which the tensile properties of the organic phase of bone need to be measured.