Qualitative analysis of neck kinematics during low-speed rear-end impact

Objective. To analyze neck kinematics and loading patterns during rear-end impacts. Design. The motion of each cervical vertebra was captured using a 250 frame/s X-ray system during a whole body rear-end impact. These data were analyzed in order to understand different phases of neck loading during rear-end impact. Background. The mechanism of whiplash injury remains largely unknown. An understanding of the underlying kinematics of whiplash is crucial to the identification of possible injury mechanisms before countermeasures can be designed. Methods. Metallic markers were inserted into the vertebral bodies and spinous processes of each of the seven cervical vertebrae. Relative displacement-time traces between each pair of adjacent cervical vertebrae were calculated from X-ray data. Qualitative analyses of the kinematics of the neck at different phase of impact were performed. Results. The neck experiences compression, tension, shear, flexion and extension at different cervical levels and/or during different stages of the whiplash event. Conclusions. Neck kinematics during whiplash is rather complicated and greatly influenced by the rotation of the thoracic spine, which occurs as a result of the straightening of the kyphotic thoracic curvature.