Research On Reverse Modeling As Well As Finite Element Analysis Of Human Lumbar Based On CT Image

In order to understand the stress of human lumbar and intervertebral disc, the breakingpoints of after implanted pedicle screw fixation system were found in different states. Thelumbar L₄-L₅segment three-dimensional model was reversed from CT image in Mimics.The model was repaired in the engineering design software UG NX. Then, it was analyzedat different kinds of load conditions in the finite element analysis software AnsysWorkbench, it can obtained the stress and displacement of the lumbar and intervertebraldisc. Finally, the strength was checked and provide theoretical support for medical.In the course of the study, first of all, the normal human lumbar L₄-L₅segment3Dmodel was reconstructed from CT tomography images in the Mimics. Then, theintervertebral disc that included annulus fibrosus and nucleus pulposus was establishedand assembled in L₄-L₅.It simulated the real structure of the human lumbar spine. It wasimported into Ansys Workbench through the UG and Ansys Workbench seamless interface.Then, the model was assigned and analyzed, it can obtained the equivalent stress anddisplacement of lumbar and intervertebral disc in upright, flexion, rotation. The resultsshow that, the maximum displacement occurs in the anterior portion of the L₄vertebraand in the front of intervertebral disc surface. While the small joint contact area fromcoronal to the sagittal plane, it was easy to damage by load, so the maximum stressoccurred near the L₄facet, which the maximum is28.211MPa in rotated. Secondly, themodel was simplified. The strength result in upright was checked by the theory of materialmechanics formula. The results show that, the finite element analysis results are close tothe theoretical results, and the relative error is small, the calculating results are reliable,and provide a theoretical reference for clinical medicine. Finally, the model of lumbar thatimplanted pedicle screw fixation system was established and finite element analysis, then,it can obtained the equivalent stress and displacement of lumbar and intervertebral disc inupright, flexion, rotation. The results show that, the maximum stress occurs in the middleof screws, it indicated the pedicle screws can alleviated the vertebral bearing burden, andit can decreased the deformation of lumbar spine.