An experimental study in bio-ballistics: Femoral fractures produced by projectiles—II Shaft impacts

To determine the response of human cortical bone to projectile impact, 364 projectile impact tests were conducted on the shafts of embalmed human femurs. Chrome steel spherical projectiles in two diameters, 0·250 and 0·406 in., were employed to differentiate the effects of projectiles of varied sizes and masses in impacts at the same velocity. It was found that the larger projectiles expended significantly more energy in fracturing a femur than the smaller projectiles did at an identical impact velocity. Also, when impacts in which larger and smaller spheres possessed identical kinetic energies were compared, it was found that the larger spheres still expended more energy in fracturing the femur. Finally, it was clearly demonstrated by these experiments that impacts to cortical bone of the femoral shaft by either size projectile caused greater energy expenditure than impacts to the distal end of the femur, which is composed almost entirely of cancellous bone.