Head kinematics during in vitro whiplash simulation.

Knowledge of precise head kinematics during whiplash trauma is important for identifying possible injury mechanisms and their prevention. This study reports a comprehensive data set describing head kinematic response to horizontal accelerations simulating whiplash. Seven isolated fresh human cervical spine specimens (C0 to T1 or C7), each carrying a surrogate head designed to represent a 50th percentile human head, were mounted on the sled and subjected to incremental trauma by horizontal sled accelerations of 2.5, 4.5, 6.5, 8.5, and 10.5 g. Sled and head kinematics were measured with potentiometers and accelerometers. The incremental sled accelerations resulted in average (standard deviations) sled velocity changes (delta V) ranging from 5.8 (0.2) to 15.8 (0.2) km/h. Generally, all the peak head kinematic parameters increased with increasing sled acceleration, except for the peak head angular displacement, which decreased. In the initial phase of a whiplash trauma, the head translated posteriorly with respect to T1, without rotation. In the later phase, the head rotated backwards, but much less than its physiological limit. Maximum head rotation of 31.5 (23.9) degrees occurred in a 2.5 g trauma class, and this was less than the maximum physiological head extension of 55.1 (13.3) degrees. Head kinematics expressed in the T1 or shoulder coordinate system is better suited to study potential neck injury in whiplash.