Rabbit femora and ulnae were tested to fracture in a torsion loading experiment. Various mechanical parameters were determined under five loading rates ranging from 0.003 to 13.2 radians per second. The maximum torque, maximum torsional deformation, energy absorbed to fracture, and torsional stiffness all increased with the rate of deformation, reached a maximum, and then declined. The bones absorbed 67 per cent more energy, had 33 per cent more torque and torsional deformation, and 5 per cent more stiffness at the highest rate of deformation as compared with the lowest.
From the Engineering Laboratory for Musculoskeletal Diseases, Section of Orthopaedic Surgery, Yale University School of Medicine, New Haven