This study explores the dynamics of head and cervical spine impact with the specific goals of determining the effects of head inertia and impact surface on injury risk. Head impact experiments were performed using unembalmed head and neck specimens from 22 cadavers. These included impacts onto compliant and rigid surfaces with the surface oriented to produce both flexion and extension attitudes. Tests were conducted using a drop track system to produce impact velocities on the order of 3.2 m/s. Injuries occurred 2 to 30 msec following head impact and prior to significant head motion.These experiments demonstrate that in the absence of head pocketing, the head mass can provide sufficient constraint to cause cervical spine injury.The buckling modes illustrate the kinematic complexity of cervical spinedynamics, and may explain why injuries can occur at different vertebral levels and with widely varying mechanism in compressive head impacts. The experiments also suggest that highly deformable padded contact surfaces should be employed carefully in environments where there is the risk for cervical spine injury. However, the orientation of the head, neck, and torso relative to the impact surface is of greater significance. (A)
Abstract