A comparison of neck injuries in fatal rollover crashes to equivalent cadaver tests. Implications for neck injury criteria in rollover testing

A fundamental issue in developing a valid test protocol to assess occupant safety system performance is identifying relevant biomechanical injury criteria. Head, neck, thorax and lower limb injury criteria have evolved over many decades and are mandated in vehicle safety standards and test protocols. Agreement on head and neck injury criteria for rollover crash tests has not been reached. The specific injury presentations of people retained in the vehicle, but fatally injured in rollover crashes were analysed using NCIS and related files. The biomechanical literature on cadaver tests that involved inverted or largely axial loads to the human neck was reviewed. The injury presentations on a case-by-case basis from the literature were collated. Five papers reporting on 49 cadaver tests were selected. The proportion of in vitro fractures from cervical vertebra 1 to thoracic vertebra 4 was similar, but intervertebral disc, ligament and dislocation injuries were greatest around cervical vertebra 5 (C5). In contrast, the real world injury pattern was bimodal, with injuries occurring both at the occipito-atlantal joint, where the neck articulates with the head, and around C5, in the lordotic region of the cervical spine. This suggests that there may be different injury mechanisms present in the real world than in laboratory impact tests. This needs to be considered in developing a test protocol. Severe traumatic brain injury is another injury that occurs frequently in rollover crashes. Issues around injury mechanisms, taking into account the head and cervical spine, are presented.