Five unembalmed intact human cadavers (four small females and one large male) were subjected to rear impact simulations. Two female specimens were tested at 4.3 m/s (mean) and the other two were tested at 6.8 m/s (mean), and the male specimen was subjected to 6.6 m/s velocity. Tests were conducted to examine head-neck injuries. Injuries were documented using x-ray, computed tomography (CT) and cryomicrotomy techniques. One female specimen tested at 4.1 m/s did not sustain injury. However, injuries to joint-related structures were documented in the other four specimens. Head cg accelerations, angular accelerations, forces and moments at occipital condyles agreed with literature and, in general, reached their respective maximum values in the extension phase. The peak compressive force at the occipital condyles preceded peak shear and tension forces. Peak compressive forces were lower than peak tension and shear forces at the occipital condyles. The maximum tension force appeared to depend more on velocity than the other two components. The suggested neck injury criterion (NIC) limit (15 m2/s2) was exceeded in all specimens. Axial force and bending moment data were used to evaluate various neck injury criteria. The risk of Abbreviated Injury Scale (AIS) equal to or greater than 3 neck injury for the combined tension-extension criteria was 30% in one female specimen tested at 6.8 m/s. For the other specimens the risk of AIS equal to or greater than 3 neck injury was less than 5% using all criteria.
Abstract