Effect of protective helmet mass on head/neck dynamics.

The crash helmet which provides protection against injury due to direct head impact may actually contribute to injury in indirect head impact (e.g., hyperflexion or "whiplash") situations because of the added mass of the helmet on the head/neck system. It has been suggested that it may be possible to reduce this hyperflexion/hyperextension injury hazard while retaining the beneficial protection against direct impact through use of the helmet restraining collars, such as styrofoam or inflatable airbags. These claims are quantitatively and qualitatively examined and discussed in this paper. The UCIN HEAD/NECK computer stimulation model is used for the quantitative analysis. It is shown that the helmet can indeed contribute to the hyperflexion/hyperextension injury hazard and that the proposed restraining devices can potentially provide protection against this hazard.