| Objective: The mechanism of degenerative lumbar load distribution and lumbar degeneration was explored by digital orthopedic finite element analysis.The stress distribution of lumbar vertebrae in normal volunteers,lumbar disc herniation patients,fusion and non-fusion patients and two surgical retreats were compared.The improvement of the stress of the lumbar vertebrae provides a scientific research method for clinical research.From the perspective of mechanics,the degenerative mechanism of the lumbar spine is further explained,and the stress distribution of lumbar non-fusion surgery and lumbar fusion surgery is evaluated which is closer to the normal lumbar vertebrae,and which procedure is better for the stress reduction of the degenerated lumbar vertebrae.Methods: Lumbar PLIF fusion surgery and lumbar Dynesys dynamic fixation non-fusion surgery are representative of lumbar fusion surgery and lumbar non-fusion surgery.Four volunteers of similar age and gender were selected from the clinical trial.The four volunteers were normal lumbar vertebrae,lumbar disc herniation,patients with lumbar spine PLIF fusion surgery and lumbar spine Dynesys dynamic fixation after non-fusion surgery.The CT images of the four volunteers were collected and output in DICOM format,then inverted into Mimics 17.0 for image segmentation.The created 3D model was imported into Geomagic Studio 12 for noise reduction,smoothing,paving,repairing polygon meshes,etc.In the precision surface module,the solid model required for finite element analysis is obtained.The mesh is divided into hypermesh12.0 in STP format to mesh the model,material assignment,etc.,and the stress distribution of lumbar vertebrae in the neutral position of lumbar disc herniation is simulated by workbench 17.0.Then,the forces of the four sets of models in the neutral position,the lateral bend position,the flexion position and the rotation position are simulated separately,and the static finite element analysis is performed to observe the whole model in different states,L4-5,L3-4 The stress distribution of the intervertebral disc and the equivalent stress value,the corresponding test results are obtained.Results: The finite element analysis of degenerative lumbar spine showed that the stress of intervertebral disc mainly concentrated on the posterior part of the annulus fibrosus.The degenerative annulus fibrosus was easy become thin under stress,thus affecting the lumbar stability.Comparing the equivalent stress values of the lumbar vertebrae and intervertebral discs in the neutral position,lateral bending position,flexion position and rotational position,the overall equivalent stress values of the lumbar vertebrae in the neutral position,lateral bending position,flexion position and rotational position were found.From the largest to the small,the patients were normal volunteers,non-fusion patients,patients after fusion,and patients with degeneration of lumbar disc herniation.The equivalent stress values of L3-4 in the neutral position,lateral bending position,flexion position and rotational position are from normal to normal volunteers,non-fusion patients,patients with lumbar disc herniation,and patients after fusion.The equivalent stress values of L4-5 in the neutral position,lateral bending position,flexion position and rotational position are normal volunteers,non-fusion patients,fusion patients,and lumbar disc herniation patients.Conclusion: The finite element analysis method can be applied to the study of lumbar stress distribution.Comparing the results of finite element analysis of 4 groups of lumbar vertebrae,it was found that lumbar disc herniation in lumbar disc herniation was mainly concentrated in the posterior part of the intervertebral disc.The distribution of lumbar vertebrae after non-fusion was closer to the normal lumbar vertebrae than the lumbar vertebrae after fusion.In terms of stress distribution results of finite element analysis,lumbar non-fusion surgery has certain advantages over fusion surgery. |
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