The Human Neck Modeling And Research Of Neck Injuries In Vehicle Rear-end Impact

The increase of the traffic accident has caused many incommodities to people’s life. Notonly do traffic accidents cause a large number of casualties, but also bring huge economiclosses to the society. The human brain, chest and neck injury caused by traffic accidents arethe main reason of death. Among them, the neck injury is the most vulnerable to all kinds oftraffic accidents injuries. Neck injury not only has a fatality, but often leads to the survivorswith long-term sequelae. And which caused by the rear-end impact accounts for a largeproportion. Plenty of researches have been done by the scholars, but the injury mechanism isstill uncertain. Therefore, we need further study on neck injury.Currently, neck injury researches are promoted through the experiment and simulationmethods. Due to ethical constraints it is still difficult to obtain live samples for theexperiment, meanwhile the mechanical model and the multi-rigid-body model have poorbiological fidelity. With the development of the finite element technology, the finite elementmodel can not only characterize the anatomical structure of human neck, but also cansimulate the biomechanical response of the human body in different external conditions.Therefore, it will be effective to analysis and forecast the neck injuries by using the finiteelement analysis method.A finite element model with detailed anatomical structure of human cervical spine wasestablished in this paper based on the CT scan data of the cervical vertebrae obtained from a50th percentile Chinese male. Which consisted of vertebrae, ligament, intervertebral disc, thefacet joint and muscle groups. Different material properties were defined for those tissuesaccording to the different physiological characteristics and related references.The model was validated by the data from the head-neck drop test conducted byNightingale et al in1996(without muscle tissues)，the frontal impact experiment conductedby Ewing et al in1968and the rear-end impact experiment conducted by Davidsson et al in 1998(with muscle tissues). The results showed that the head-neck finite element model hada consistent mechanics and dynamics with the tests, and the response parameters showedgood agreement with the corridors. The model can simulate the real dynamic response of thehuman cervical spine.The neck injury was studied with the model under the low speed rear-end impactcondition. Through the simulation, the stress curve of vertebrae, intervertebral disc,ligaments and facet joint were obtained respectively. The neck injury position and damagemechanism were predicted by analyzing the stress curve and nephogram. The results showedthat in rear-end car collision, it was likely to cause vertebral fracture、blowout fracture andbursting fracture of the vertebral, central, lateral or hybrid protrusion of intervertebral disc,ligament to tear especially the anterior longitudinal ligament, and pain in facet joint. Finallywe put forward that a well-designed restraint system and the car seat which can effectivelyreduce the neck injury according to the results of the analysis.The study showed that the model established in this paper has a high biological fidelityand validation, which can be used for further research on neck injury mechanism andanalysis of the cervical spine damage in different crash conditions.