Three Different Types Of Interbody Fusion Cage In TLIF: A Finite Element Analysis

Purposes: At present,lumbar interbody fusion is becoming more and more mature clinically.There are many types of lumbar interbody fusion devices.In terms of morphology,more bullet-shaped interbody fusion devices,kidney-shaped interbody fusion devices and wedge-shaped interbody fusion devices are used.Different types of interbody fusion devices have different stress,shear bearing degree and stability on the endplate.At present,there are many researches on interbody fusion devices made of different materials and single fusion device,but there are relatively few comparative researches on interbody fusion devices made of the same material and with different shapes,which have no definite guiding significance for clinical selection.This experiment uses finite element analysis to analyze the biomechanical characteristics and evaluation of three lumbar interbody fusion devices made of the same material and with different shapes after interbody implantation through lumbar interbody fusion via intervertebral foramen,expecting to play a guiding significance to a certain extent in the reasonable selection of interbody fusion devices in clinic.Methods: according to the inclusion criteria,Select suitable volunteers and use CT machine to collect patient imaging data.use finite element software to make three-dimensional finite element spine model,to make interbody fusion of three different shapes,and to make various ligaments,intervertebral discs,assign values of parameter characteristics,and verify the effectiveness of the model by comparing with authoritative data.Based on the established three-dimensional finite element model,the models of bilateral pedicle screws combined with three different shapes of cage are established respectively.By using the finite element analysis method,the constraints,such as preload and motion additional force of the three-dimensional model,are set up.And corresponding data are obtained to compare the stress and deformation displacement of the three models.Results: Through collecting CT imaging data of volunteers,different intervertebral fusion devices are modeled and converted into three types of digital models,and further meta-limited data working condition analysis is carried out under six movement modes of forward flexion,backward extension,left flexion,right flexion,left rotation and right rotation.Under the application of vertical mechanical load and moment,the average stress analysis of L5 upper endplate is bullet-shaped > wedge-shaped > kidney-shaped,and the deformation displacement comparison of three intervertebral fusion devices is bullet-shaped > kidney-shaped > wedge-shaped.Conclusion: In this paper,the mechanical analysis and deformation displacement measurement of three models are carried out.The stress of bullet shaped cage on the upper endplate is larger,and the deformation displacement is higher than that of kidney shaped and wedge-shaped.The results showed that bullet shaped cage was more likely to cause fracture of endplate than kidney shaped and wedge-shaped cage.