Response of the Cervical Spine to Superior-Inferior Head Impact 811005
A test series using 12 unembalmed cadavers was conducted to investigate factors affecting the creation of cervical spine damage due to impact to the top of the head. The test subjects were instrumented to measure head, T8 thoracic spine, and sternum acceleration responses. Photographic targets on the head and torso allowed analysis of impact motions from high-speed movies.
The stationary test subject was struck by a guided, moving impactor mass of 56 Kg at 4.6-5.6 m/s. The impactor striking surface consisted of a biaxial load cell with padding to vary the contact force-time characteristics of the head/impactor. The orientation of the head, cervical spine, and torso was adjusted relative to the impactor axis to investigate the effect of spinal configurations on the damage patterns. Load and acceleration data are presented as functions of time and as functions of frequency in the form of mechanical impedance.
Damage to the cervical spine was produced in all but one test, including fractures of the spinous processes, laminae, transverse processes, and the bodies of the vertebrae as well as ruptured discs and torn ligaments. Both anterior and posterior damage was produced and the sites of the damage ranged from C2 to T4. The peak forces produced during the impacts ranged from 1.8 kN to 11.1 kN.
The limited response data of this pilot study do not allow any specific conclusions with regard to cervical spine tolerance levels. However, it does attest to the influence of spinal configuration and impact conditions on both response and damage of the spine due to crown impact.