The Stress Analysis Of The Three-joint Complex Of The Lower Lumbar Spine At Different Pelvic Incidence

Purpose:Using a method of finite element analysis to evaluate the stress of the bilateral facet joints and intervertebral discs in the L3-S1 segment of individuals with different PI in functional positions(flexion,extension,left and right lateral bending,left and right rotation),which is better to understand the relationship between the spine pelvic sagittal parameters and the degenerative diseases of the lower lumbar spine provides a theoretical basis for biomechanical support and mechanics.Method:According to the inclusion and exclusion criteria established in this study,three volunteers with PI of 27.44°,47.05°,and 62.28° were selected to perform thin-layer scans of the lower lumbar spine-pelvis L1-S1 vertebral body to obtain the test subjects’ Dicom format CT data and establish a finite element model,use the finite element analysis software Abaqus6.13 to analyze the stress of the facet joints and intervertebral discs of the model,and compare the stress of the three-joint complex of the lumbar spine under three different PI models under different torques.difference.result:As the torque increases in the flexion position,the average stress of the lumbar facet joints gradually decreases,and the intradiscal pressure and the maximum Von Mises stress of the annulus fibrosus show an upward trend.The intradiscal pressure of the low PI group is the largest among the three groups.The stress of the facet joints of the lumbar spine in the extension position increases with the increase of the torque.Under the same load condition,the average stress of the facet joints of the high PI group is the largest among the three groups.The stress of the bilateral facet joints is asymmetrical in the left and right lateral bending positions.The average stress of the curved facet joint was greater than that of the contralateral side.There was no significant difference between the three groups.The facet joint stress is smaller than the contralateral side,that is,the average stress of the right facet joint in the left-torsion position is greater than that of the left side.There is no obvious trend in the average stress of the facet joints between the three groups.The intradiscal pressure of the intervertebral disc of high PI group is higher in the L3/4 segment than the other two groups,and the maximum Von Mises stress of the annulus during L5/S1 segment with a higher PI is greater than that of the other two groups.In addition,we also found that the asymmetry of the angle of the facet joint is related to the stress of the facet joint.In the flexion position,the facet joint with the larger angle of the sagittal position also has a higher average stress of the facet joint.Conclusion:The PI is related to the occurrence and development of lumbar degenerative diseases.The stress of the lower lumbar facet joints and fibrous annulus of individuals with a high PI is greater than that of individuals with a low PI and a normal PI,although this condition only occurs in individual segments,but it can also reflect the influence of the PI on the force of the three-joint complex of the lower lumbar spine to a certain extent.This study analyzes the stress of the three-joint complex of the lower lumbar spine from different PI,and provides a reference for the relationship between the spine-pelvic sagittal parameters and spinal degenerative diseases.