Finite Element Analysis And Biomechanical Study On The Effect Of Different Portions Facetectomy Performed By Percutaneous Endoscopy On The Stability Of Lumbar Spine

Part one: Finite element analysis on the effect of different portions facetectomy performed by percutaneous endoscopy on the stability of lumbar spine.Objective: The finite element method was used to compare and analyze the range of motion of the lumbar spine model after the facetectomy of different parts of the percutaneous interforaminal endoscopy,the proportion of the facet joints after the facetectomy of different parts,the maximum stress change of the adjacent segment of the intervertebral disc,and the maximum stress changes in bilateral facet joints.Methods: Based on the CT data of 5 adult male volunteers with no previous lumbar spine disease,three-dimensional reconstruction was performed with software such as Mimics 15.0 and Ansys 13.0 to obtain five three-dimensional finite element models of L3-S1 segments.Select 5 needle insertion points on the superior facet joint of L5 on the left side of the finite element model,and simulate the use of a trephine with an outer diameter of 8.5mm to perform facetectomy through different needle insertion points.The first insertion point represented the apex of the superior facet joint,the second was the midpoint on the ventral side of the superior facet joint,and the third was the lowest point on the ventral side of the superior facet joint.The fourth and fifth insertion points were the points on the dorsal side of the superior facet joint where the second and third insertion points had been translated to radius(8.5mm/2)of the ring saw distant.Provide physiological loading conditions for each finite element model,simulate facetectomy through different needle insertion points,and record the left joint of the L5 vertebral body under six conditions of flexion,extension,left and right flexion,and left and right rotation of each finite element model.The volume of the process resection,the pressure in the facet joints on the left and right sides of the L5 vertebral body,the pressure in the intervertebral disc of the L4/5 segment,and the range of motion of the lumbar spine.Results: After the second needle point facetectomy was formed,compared with the unresected group,the maximum stress of the L4/5 disc under various loads was not statistically significant(P>0.05);The difference in maximum stress under right rotation load is statistically significant(P<0.05);The difference in the maximum stress between the right facet joint of L5 under left rotation loads was statistically significant(P<0.05);The range of motion of the lumbar spine was not statistically significant under different loads(P>0.05).Conclusion: The finite element analysis can simulate the percutaneous transforaminal facetectomy and reflects the biomechanical changes of the lumbar spine after facetectomy.When performing percutaneous transforaminal facetectomy through the second needle point,the midpoint of the ventral edge of the facet joint,has the least impact on the biomechanics of the lumbar spine,and is suitable as the best procedure for facetectomy.Part two: Biomechanical study on the effect of different portions facetectomy performed by percutaneous endoscopy on the stability of lumbar spine.Objective: To investigate the effect of different portions facetectomy performed by percutaneous endoscopy on the biomechanical stability of lumbar spine.Methods: Based on the experimental results of the previous finite element analysis,3 needle insertion points with the most clinical significance were selected for the study.Select 40 fresh calf spine lumbar section(L3-L6)specimens,use a trephine with an inner diameter of 8.5mm to perform unilateral lumbar facetectomy through 3 commonly used clinical needle points,according to whether the facetectomy and the different injection points of the sudden formation were randomly divided into 4 groups,including 3experimental groups and 1 control group,each with 10 specimens.Control group:complete calf spine model.Group A: calf spine model with facetectomy through the apex of the superior facet joint.Group B: calf spine model with facetectomy through the midpoint of the ventral edge of the superior facet joint.Group C: calf spine model with facetectomy through the lowest point of the ventral edge of the superior facet joint.The biomechanical universal material tester was used to measure the lumbar spine mobility and the maximum stress of the L4/5 intervertebral disc under physiological load,under physiologic load,extension,lateral flexion and lateral rotation.Results: 1.Compared with the control group,the range of motion of the lumbar spine of the specimens in group A had no statistically significant difference in the six exercises of flexion,extension,lateral flexion and lateral rotation(P>0.05),but L4/5 The maximum stress of the intervertebral disc was significantly different during extension(P<0.05).2.Compared with the control group,the range of motion of the lumbar spine and the maximum stress of the L4/5 segment of the intervertebral disc of the B group model were not statistically different under the six sports conditions of flexion,extension,left and right flexion and left and right rotation(P >0.05).3.Compared with the control group,the range of motion of the lumbar spine of the C group model increased significantly when rotating left and right compared with the control group,and the difference was statistically significant(P<0.05).The maximum stress of the L4/5 intervertebral disc of the C group model was lower than that of the control group,but extension and left-right rotation increased significantly,and the difference was statistically significant(P<0.05).Conclusion: In the biomechanical test that simulates the facetectomy of different parts of the percutaneous intervertebral endoscopy,the B group model is the calf spine model that undergoes facetectomy through the midpoint of the ventral edge of the superior facet joint.And the maximum stress of the L4/5 intervertebral disc has no significant change compared with the control model.Therefore,it can be concluded that compared with other commonly used clinical needle entry points,unilateral partial facetectomy through the midpoint of the upper facet joint has the least impact on the biomechanics of the lumbar spine.