Finite Element Analysis Of Biomechanical Characteristics Of Adjacent Intervertebral Discs After Posterior Lumbar Intervertebral Graft Fusion And Internal Fixation

ObjectiveThree kinds of three-dimensional finite element models including L3-5 model(normal model),L4-5 laminectomy model,L4-5 laminectomy model,L4-5 laminectomy model,cage fusion model and pedicle screw internal fixation model were established to simulate human lumbar vertebrae in flexion,extension,left and right lateral bending and left and right axial rotation The biomechanical ’changes of adjacent segments in the three models were compared from the mechanical point of view.MethodsCT image data of lumbar spine of a normal adult(DICOM format)were collected and imported into mimics17.0 software,Geomagic wrap2017 software,UG modeling software and abaqus6.14 software to establish L3-5 model(normal model),L4-5 laminectomy model,nucleus pulposus removal model,L4-5 laminectomy model,intervertebral cage fusion model and pedicle screw fixation model.The maximum bulging value and maximum invagination value of L3-4 intervertebral disc,and the stress peak value of L3-4 annulus fibrosus were compared when the three models applied loads in all directions to simulate human movement.Resultscompared with L4-5 model,L4-5 model with laminectomy,cage fusion,pedicle screw fixation and normal model,the maximum bulging value and maximum invagination value of L3-4 disc in L4-5 model were significantly increased,and L4-5 model with laminectomy,cage fusion and pedicle screw fixation were larger than normal model,the difference was statistically significant(P<0.05).Compared with normal model,L4-5 model with laminectomy,cage fusion and pedicle screw fixation had significantly higher stress peak in annulus fibrosus of L3-4 than that of L4-5 model with laminectomy,and L4-5 model with laminectomy,cage fusion and pedicle screw fixation had significantly higher stress peak in annulus fibrosus than that of normal model,The difference was statistically significant(P<0.05).Conclusionposterior lumbar interbody fusion and internal fixation can cause the biomechanical changes of adjacent segment intervertebral disc,that is,aggravate the degeneration of adjacent segment intervertebral disc.Figure 14 Table 4...