Development Of A 6-year-old Child Cervical Spine Model And Injury Investigation Under Vehicle Rear-end Crash Condition

Vehicle crash is a leading reason causing child neck injury.Cervical spinal injuries of children in motor vehicle crashes have high morbidity and mortality rates due to their continuing growth.According to the statistic result,49.4%neck injury was caused by the rear-end collision.Up to date,most studies focused on the adult neck injury in vehicle rear-end collision,however,the studies on the child neck injury are very limited.Therefore,investigating child neck injury in vehicle rear-end collision is very necessary and in favor of child neck protection.An automated method was innovatively developed that can automatically extract and align geometric points from CT scans to accurately represent the complex three-dimensional vertebral geometry.Using these spatial geometric points,a statistical cervical vertebrae geometry model for children aged 3-10 YO was established based on principal component analysis and multivariate regression(PCA&R).According to the statistical model,the vertebra spatial geometry for children of different ages and neck circumferences was predicted,and its variation with age and neck circumference were accounted for.In addition,linear mixed model was used to conduct statistics on the significant effects of age,location and their interaction on anterior-posterior length(APL),transverse process width(TPW),vertebral body circumference(VBC)and height(VBH)of vertebrae for 30 subjects.Based on CT scans and the anatomy structure of a 6 years old child,high quality meshes for cervical vertebrae,intervertebral disc,cartilage,ligament,muscle and other soft tissues were successively developed in TrueGrid and HyperMesh software.The material constitute equation and parameters of each component in the finite element model was defined.The cervical finite element models of segment C0-C2,C4-C5,C6-C7 and the global model were validated against child cadaver tests under quasi-static and dynamic condition tests.The results show that the developed model has a high biofidelity.To evaluate the child neck injury in vehicle rear-end crash using the developed finite element model,first,the dynamic model of dummy-seat was developed in MADYMO to obtain the acceleration curve at the bottom of the cervical spine of dummy;second,the acceleration curve is applied to the finite element model to simulate the rear-end crash condition;third,According to the simulation results,the biomechanical response and the injury metrics of the tissues in the neck finite element model was analyzed;and finally,parametric study was conducted on the changes of seat stiffness and crash pulse to investigate their effects on the neck injury.