Biomechanics of femur fractures secondary to gunshot wounds
Smith, H.W.; Wheatley, K.K.
Journal of Trauma 24(11): 970-977
Nonlethal gunshot wounds to the femur produce 4 classical types of fractures. The drill-hole, incomplete and butterfly fractures have been described in both clinical and experimental settings. The remote spiral fracture, sometimes attributed to the fall on the femur after wounding, is unique to the weight-loaded femur. A mathematical model relying on the beam in bending and the mechanics of a cylindrical shell is offered. An experimental method utilizing an apparatus (the osteoclast) designed to apply torsion, bending or combined forces to cadaveric long bones is discussed. Femur failure proximal or distal to the impact site of a projectile is a function of stress risers operating at relatively great distances. Predictable primary and secondary peak moment location for fracture are illustrated.