Finite Element Analysis Of The Adolescent Idiopathic Scoliosis After Lenke5 Thoracolumbar Orthopedics

Objective To establish a three-dimensional finite element model of the T3 ? L5 segment of the spine of a 15-year-old normal male and a 15-year-old male Lenke5 AIS posterior bilateral pedicle screw fixation(after orthopedic)to study the spine T3? of Lenke5 AIS patients,the stress distribution of L5 segment after orthopedics,and analysis of the difference with the normal spine stress distribution.Materials and methods Samples were collected at the Second Affiliated Hospital of Inner Mongolia Medical University.Normal spine was collected by CT imaging imaging examination,and post-orthopedic spine was collected by spinal surgery.CT imaging imaging data of patients after orthopedic treatment.the collected CT data in the DICOM format wereimported into Mimics16.01 image processing software to read the image,and extracted the vertebral dense bone and cancellous bone,and then reconstructed the respective three-dimensional geometric model,and then undergoed smooth processing,surface fitting,etc.Each model was imported into Geomagic Studio 2015 software to generate solid models,and then Hypermesh 14.0 software was used for meshing,material attribute definition and assignment,and definition of constraints,and then the normal and orthopedic spine were generated by Abaqus 6.14 finite element software.Finite element model for analysis.the normal and orthopedic spine T3 ? L5 segment of each vertebral articular process,pedicle,intervertebral disc and titanium rod were analyzed under six conditions of flexion,extension,left flexion,right flexion,left rotation,right rotation The five stress concentration points were analyzed statistically using SPSS 22.0.(1)the stress difference between the superior articular process,pedicle and intervertebral disc under six working conditions after orthopaedic and normal spine T3 ? L5 segments were compared(2)the maximum stress area of the titanium rods from T3 to L5 after orthopaedic spine.were analyzedResults 1.Based on CT imaging data and based on the actual shape of the modeled object,successfully a normal and an orthopedic spine T3 ? L5 segment 3D finite element model were established,each model includes 10 thoracic vertebrae,5 lumbar vertebrae,14 intervertebral discs,anterior longitudinal ligament,ligamentum flavum,supraspinous ligament,interspinous ligament,intertransverse ligament and other structures.Each model uses a tetrahedral element type.The normal spine model includes 1256874 elements and 1851946 nodes;the orthopedic spine model includes1256907 elements and 1852307 nodes.2.Under the conditions of forward flexion,posterior extension,left flexion,and right flexion,the normal spine T3 ? L5 segment displacement gradually decreases;after orthopedic spine thoracolumbar displacement does not change;under left and right rotation conditions,The displacement of the normal spine and thoracic spine is greater than that of the lumbar spine,and there is no change in the displacement of the spine,thorax and lumbar spine after orthopedics.3.Under the condition of flexion and extension,the normal spine T3 ? T5,L1 ? L5 vertebrae anterior margin stress is greater;after orthopedic thoracic spine stress is greater;in the left and right flexion conditions,the normal spine T3 ? The stress on both sides of the vertebrae of T5,L1?L5 is greater;the stress of the thoracic spine after orthopaedic is greater than that of the lumbar spine;under the left and right rotation conditions,the stress of the anterior edge of the normal vertebrae T3?T5vertebrae is greater,and the posterior orthopedic vertebrae T3 ? L5 lamina and Titanium rods have greater stress.4.Under the six working conditions,the normal and orthopedic spine T3 ? T5 segment left and right upper articular processes,the left and right pedicle stress changes first decreased,then increased,then decreased,then increased,Finally,the trend is reduced;the stress is larger at T6?T8 and L1?L3.5.Under the six working conditions,the normal and orthopedic spine T3/4 ? L4/5intervertebral disc anterior,posterior,left,and right edge stress changes first decreased,then increased,then decreased,and then increased Large,and finally reduce the trend;in T6/7,T7/8,T8/9,L1/2,L2/3 stress are larger.6.Under six working conditions,the titanium rod has the greatest stress at T11(lower vertebrae of thoracic curve)and T12(upper vertebrae of lumbar curve),especially under left andright rotation conditions.Conclusions 1.Under six working conditions,the displacement between the vertebrae of the spine is small after orthopaedics.2.Under six working conditions,the normal and orthopedic spine has a higher stress on the articular process,pedicle,and intervertebral disc at the physiological curvature.3.Titanium rods have the greatest stress at the lower vertebrae of the thoracic curve and the upper vertebrae of the lumbar curve,especially under left and right rotation conditions.