CONTINUOUS MOTION ANALYSIS OF THE HEAD-NECK COMPLEX UNDER IMPACT

The objective of the present study was to analyze the localized kinema tic biodynamics of the human head-neck complex under impact loading. U nembalmed human cadaveric head-neck complexes were subjected to axial compressive forces delivered using an electrohydraulic testing device. The head-neck complex was aligned along the stiffest-axis; musculatur e was simulated using preloaded springs and cables; and retroreflectiv e targets were inserted into the vertebral body, the facet joint artic ulation, and the spinous process at every level of the cervical column . At dynamic loading rates (1.8-5.1 m/min), mid to lower cervical spin e injuries consistently occurred in these preparations. Continuous mot ion analysis of the components (vertebral body, intervertebral disk, f acet joint, and the spinous process) at all levels of the cervical spi ne showed the temporal order of the transfer of the external load. Inj uries documented by computed tomography and cryomicrotomy techniques c orrelated with the kinematics of the structure. The application of dyn amic loading to the head-neck complex coupled with high-speed, continu ous-motion analysis of the intervertebral components of the entire cer vical column makes possible the definition of the temporal kinematic m echanics that are fundamental to the understanding of the biodynamics of cervical spine trauma. Using these procedures, we have correlated t he kinematics with the onset and pattern of neck injury secondary to i mpact forces.