The neck injury criterion: future considerations.

The cost of whiplash injuries--both in dollars spent for medical care and disability, and in terms of human suffering--are quite high in westernized nations. This is of particular interest both from a public health perspective and a general societal one because the disorder is theoretically preventable: in the very least it can be minimized. This can be achieved with crash prevention strategies and improvements in vehicle safety design--especially with more effective seat back and head restraint systems. Toward the goal of developing a gold standard for safety research in this area, a neck injury criterion (NIC) was proposed by Boström et al. in 1996 (Boström O., Svennson, M.Y., Aldman, B. et al., 1996. In: Proceedings of the International Conference on the Biomechanics of Impact, Dublin, Ireland). This criterion considers the relative horizontal acceleration and velocity between the bottom (T1) and top (C1) of the cervical spine and has face validity based on current literature. However, the NIC has still not been subjected to rigorous scientific investigation or validation in terms of its representativeness of human occupant injury. Such investigation should specifically consider, first, whether the NIC provides an adequate proxy for all potential neck injuries due to whiplash and, secondly, whether the proposed threshold value of 15 m2/s2 is an appropriate level for the stated goal. Based on a review of recent literature, recent human volunteer crash tests by Wheeler et al. and the those of the Spine Research Institute of San Diego, and based on mathematical MADYMO analysis of the first real world crash pulse data, it appears that the threshold for acute injury in the general population is likely to require a lowering of the originally proposed NIC value, and additional parameters, such as considering a forward rebound phase or neck extension criteria may be necessary. The conclusions of this paper should be considered preliminary because the numbers of crash test subjects and real world injury victims does not allow for rigorous statistical analysis. Certainly, ongoing work will be necessary to investigate this further and larger scale analysis of more onboard crash data will prove invaluable.