Bilateral Facet Dislocations With and Without Head Impact Sustained by Restrained Occupants

This paper aims to understand the different injury mechanisms involved with traumatic Bilateral Facet Dislocation (BFD) and fracture of the cervical spine. The intent is to demonstrate and elucidate tensile and compression induced injury mechanisms producing BFD by employing real-world crash investigations in association with all the past laboratory testing and studies done by numerous researchers. The study indicates that in a frontal crash scenario, maintaining the position of the shoulder belt is paramount, and any migration towards the base of the neck allows the fulcrum formation that amplifies distractive moments on the neck producing BFD. Similarly, in a rollover crash scenario, roof intrusion magnitude, and its rate along with roof deformation pattern can impose a rotational constraint on the head and plays a vital role in producing BFD. Roof design must address the formation of pocketing in the roof due to deformations imposing rotational head constraint exposing the neck to buckling and subsequent BFD as the roof intrusion continues.