Finite Elementanalysis And Experimental Study Of Cervical Intervertebral PLA Fusion Cage

Cervical spine is an important part of the human body.It connects the head and thoracic vertebra and plays an important role in human movement.With the development of word,the problems of cervical vertebra are increasing,and the probability of occurrence of cervical spondylosis is higher and higher.Currently anterior cervical bone graft decompression surgery is often used in the treatment of cervical spondylosis which requires the support of the fusion device.However,fusion device has not been unified due to its controversial structure and material.For the above fusion device problem,according to the shape of the endplate and the distribution of compressive strength to design cervical intervertebral fusion cage,the three-dimension modeling of fusion cage is completed in pro-e5.0,and PLA(PLA)material is selected.Complete cervical C5-C6 finite element model and PLA fusion cage model are established by Mimics10.0?reverse modeling software and meshing software.Analyzing five anti-squat index including range of motion?deformation displacement?vertebral body stress?stress of the cranial endplates of C6 and fuse to complete the finite element analysis under flexion?extension?left bending?right bending?left axial rotation?right axial rotation six working conditions.The results show that the motion of the fusion device decreases in each working condition after implantation,and the maximum is flexion and the minimum is axial rotation working condition;When different loads are applied to the PLA fusion model,the overall displacement will occur,with the maximum change in the extension condition and the minimum displacement in the left axial rotation condition;The maximum stress in each vertebra increases correspondingly,but it is in a safe range;The stress distribution of vertebral body and the cranial endplate of C6 are uniform,and no stress concentration occurs,indicating that no damage to the vertebral body and the cranial endplate are caused after the implantation of the fusion device;Through the stress distribution of the fuse,it is found that the stress of the fuse is uniform and there is no stress concentration,and in addition the maximum stress is extension?flexion?right bending?left bending?left axial rotation?right axial rotation successively.In order to further verify the reliability of finite element analysis and the mechanical properties of PLA fusion unit,The PLA fusion cage is printed by 3D printing technology,and the animal specimens are loaded under axial compression?flexion?extension?right bending?left bending working conditions with experimental instruments WDW-10 electronic universal testing machine to complete the experimental study of the complete model and the fusion set model.At the same time,the finite element loading method is determined according to the experimental test,and the finite element simulation of the complete model and the fusing set is carried out.Finally the load-displacement curves of axial compression?flexion?extension?left and right bending are plotted,and the axial stiffness are calculated.The results show that the load-displacement curve of flexion condition is linear,and the other working conditionsare nonlinear,and the finite element changes linearly.Relative to the complete model,the displacement of fusion device set after implantation decreases and axial stiffness increases,which indicate that the stability of the cervical spine is improved after the implantation of the fusion cage.At the maximum load,the displacement of each working condition is respectively left bending?extension?right bending?flexion and axial compressionin the experimental test;Finally the strength test and fatigue test of PLA fusion unit are carried out by the experimental instrument EUT-1020 electronic universal testing machine,the failure load of PLA fusion cage is measured,and the structure of PLA fusion cage is not obviously damaged or deformed under cyclic loading.According to the finite element simulation part and experimental tests part,it can be seen that the PLA fusion has better anti-sinking ability and can provide better initial stability and anti-compression performance,and meets the basic biomechanical requirements.Therefore it can provide some reference for the treatment of cervical spondylosis and the design of fusion device.