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 analyz ed in order to understand different phases of neck loading during rear-end impact. Background. The mechanism of whiplash injury remains largely unknown. An un derstanding of the underlying kinematics of whiplash is crucial to the iden tification of possible injury mechanisms before countermeasures can be desi gned. Methods. Metallic markers were inserted into the vertebral bodies and spino us processes of each of the seven cervical vertebrae. Relative displacement -time traces between each pair of adjacent cervical vertebrae were calculat ed from X-ray data. Qualitative analyses of the kinematics of the neck at d ifferent phase of impact were performed. Results. The neck experiences compression, tension, shear, flexion and exte nsion at different cervical levels and/or during different stages of the wh iplash event. Conclusions. Neck kinematics during whiplash is rather complicated and grea tly influenced by the rotation of the thoracic spine, which occurs as a res ult of the straightening of the kyphotic thoracic curvature. (C) 2000 Elsev ier Science Ltd. All rights reserved.