Importance of intervertebral displacement for whiplash investigations

It is often reported that the physiological rotational limits of adjacent vertebrae in the cervical spine are exceeded in rear-end accidents which play a significant role in Whiplash Associated Disorders (WAD). This paper presents the first analysis of existing experimental and computational intervertebral displacement research. Existing techniques to capture intervertebral displacement in experimental studies can be grouped into three methods: visual targets method, electronic sensors method and X-Ray method. The analysis of intervertebral displacements has led to the development of the intervertebral neck injury criterion (IV-NIC); it has also shown an upward shift of the C5C6 instantaneous axis of rotation and that the flexion changes to extension point between C2 and C4. Furthermore, it is also shown that when a computational model is validated only for the head kinematics, it should not be assumed that the model provides good neck kinematics. Lastly, current rear-impact dummies are incapable of providing true neck kinematics.