A protocol has been proposed for testing seats for whiplash protection, however injury criteria were not chosen. Assuming that whiplash symptoms arise from non-physiological motions of vertebral segments, the ability of proposed criteria to predict peak individual vertebral displacements was determined. Volunteers were subjected to rear impacts while seated in a car seat with head restraint, mounted onto a sled. Then, the seat was replaced by a platform onto which were mounted cadaveric cervico-thoracic spines. Head and T1 accelerations and individual vertebral sagittal (XZ) plane rotations and translations were obtained. Proposed injury criteria were tested for their ability to predict peak intervertebral displacements. Cadaveric specimens had chest and head X (horizontal) and Z (vertical) linear accelerations similar to volunteers whose heads hit the head restraint. The best predictors were: Nd (maximum displacement) shear and peak posterior translation (0.80), Nd extension and peak extension angle (r2 = 0.70), and Nd distraction and peak distraction (0.51). Therefore consideration should be given to a displacement based injury criteria such as Nd. For the covering abstract see ITRD E825082.
Abstract