It has been proposed that the amount of energy transferred to the bone during a high velocity projectile injury determines the extent of bony injury. We studied the validity of this theory Fresh rear skeletally mature deer femurs were subjected to progressively increasing velocity projectile injuries within a pneumatic ballistic chamber with non-deforming steel spheres capturing the energy transferred. Analysis of fracture severity was performed including micro computer tomography analysis of micro-fractures. The effect of projectile caliber size was then analyzed.

Characteristic fractures patterns were observed with fracture lines extending radially from the impact site, often propagating longitudinally along the sample. It was found that a greater energy transfer resulted in more severe fracture for a given projectile. However, fractures of differing severity were produced by different projectiles for similar energy transfer. Neither specific energy transfer nor energy density could explain this phenomenon.

Although energy transfer plays a role in ballistic fracture, it is not the sole determinant. Other factors such as contact surface area, projectile mass and angle of impact may need to be considered.