Modeling And Verification Of Neck Model Including Atlanto-Occipital And Atlantoaxial Joints

The human spine supports the body’s weight and protects the spinal cord.Cervical spine injuries are the most common type of all spinal injuries in various types of traffic accidents.There are many ways to study neck injury.Fenite element models are the most economical and effective method of researching neck injury.There are seven vertebrae(C1-C7)in the human cervical spine,which can be divided into the upper cervical spine(C1-C2)and the lower cervical spine(C3-C7).It is one of the most complicated structures in the human spine.The upper cervical spine contains the atlantooccipital joint and atlantoaxial joint.The forward flexion and extension of the neck are mainly realized by the atlantooccipital joint,and the rotation movement is mainly performed by the atlantoaxial joint.The lower cervical vertebra of the human body plays an important role in stabilizing the movement of the neck.When neck injury occurs,though clinical studies can describe kinematics,the actual forces on the cervical spine or the forces on the soft tissues around the cervical spine(such as discs)cannot be obtained directly from these studies.Finite element modeling can more effectively evaluate the stress and strain in the complex deformation of vertebrae,ligaments,and other soft tissues,and has been widely used in spine biomechanics research.This article focuses on the existing neck models for modeling the neck joints.The following studies were carried out:(1)Based on the CT scan data of the 50 th percentile male volunteers in China and related medical literature,software such as Mimics,Geomagic and other softwares were used to establish a geometric model of the human cervical and cervical spine,and important geometric features such as the articular surface of the vertebrae were expressed.Finite element meshing was performed on the model using Hypermesh software,and a new cervical finite element model was established.The accuracy of the model was improved compared with the previous cervical finite element model.(2)Apply torque to the model in two different experiments,compare the angles of movement of the atlantooccipital joint and atlantoaxial joint with the experimental results,and find out the factors that affect the movement of the model,namely the six ligaments of the atlantooccipital joint and atlantoaxial.(3)Study on optimization of vertebral ligament material properties.According to the characteristics of the upper cervical ligament relaxation,the six cervical ligament relaxation values are variables,and the minimum value of the median value of the forward flexion and extension motion and the angle of the lateral flexion motion are the optimization goals.The optimized Latin hypercube test design,The Kriging agent model and multi-objective optimization method were used to optimize the six ligament characteristic curves,and the ligament material characteristic curves suitable for the 50 th percentile male in China were obtained,which is closer to the experimental results of the corpse motion angle compared with previous models.(4)The neck model established in this paper is combined with the previous head model to establish a finite element model of the head and neck,and the effectiveness of two different models without muscle and muscle is verified.The simulation results show that the results of the neck finite element model established in this paper are in good agreement with the experimental results.The neck finite element model established in this paper are in good agreement with the results of cadaver tests,and have a high degree of biomimicry,which can be used for the study of human neck injury.