Neck injuries in car collisions - a review covering a possible injury mechanism and the development of a new rear-impact dummy

A review of a few Swedish research projects on soft tissue neck injuries in car collisions is presented together with some new results. Efforts to det ermine neck injury mechanisms was based on a hypothesis stating that injuri es to the nerve root region in the cervical spine are a result of transient pressure gradients in the spinal canal during rapid neck bending. In exper imental neck trauma research on animals, pressure gradients were observed a nd indications of nerve cell membrane dysfunction were found in the cervica l spinal ganglia. The experiments covered neck extension, flexion and later al bending. A theoretical model in which fluid flow was predicted to cause the transient pressure gradients was developed and a neck injury criterion based on Navier-Stokes Equations was applied on the flow model. The theory behind the Neck Injury Criterion indicates that the neck injury occurs earl y on in the rearward motion of the head relative to the torso in a rear-end collision. Thus the relative horizontal acceleration and velocity between the head and the torso should be restricted during the early head-neck moti on to avoid neck injury. A Bio-fidelic Rear Impact Dummy (BioRID) was devel oped in several steps and validated against volunteer test results. The new dummy was partly based on the Hybrid III dummy. It had a new articulated s pine with curvature and range of motion resembling that of a human being. A new crash dummy and a neck injury criterion will be very important compone nts in a future rear-impact crash test procedure. (C) 2000 Elsevier Science Ltd. All rights reserved.