Studies on mechanical strength of bone. I. Torsional strength of normal rabbit tibio-fibular bone.

A method is described for testing torsional strength in small cortical bones at low velocities. The linearity and precision of the testing equipment, and the effect of the dimensions and chemical composition of the bone on torsional properties are analysed. Rabbit tibio-fibular bones exhibited right-to-left differences in energy absorption capacity (up to 10.0 per cent), torsional rigidity (7.1 per cent), torque moment at fracture (6.3 per cent) and angular deformation (5.7 per cent). The scatter in energy absorption was more dependent on differences in angular deformation (strain) than on differences in torque moment (stress). No statistically significant dominance of either side could be observed. The biomechanical properties of the bones were dependent on the body weight of the test animal and the transverse dimensions of the bone, but were not influenced by the small variations measured in the chemical composition of normal bone.