| Objective:Based on real double festival period of osteoporotic vertebral compression fractures of preoperative CT data,and hyperextension restoration technique of traditional Chinese medicine combined therapy with PKP holds influence postoperative CT data,based on computer aided modeling platform,rebuild T11-L2 double festival period of OVCF biomechanics of three-dimensional finite element model,and through the finite element software to simulate axial,bending forward,after stretching,on the left side of the curved,bent on the right side,left rotation and right rotation 7 kinds of working conditions of thoracolumbar different anatomical structure of equivalent stress value.The biomechanical effects of T12,L1 compressed vertebrae,soft tissues and adjacent vertebrae before double-level OVCF fracture and after TCM hyperextension and reduction combined with PKP were mainly studied,so as to provide biomechanical support for the clinical treatment strategy of integrated Chinese and Western medicine for double-level thoracolumbra compression fracture.Methods:1.Screening of gansu university of traditional Chinese medicine affiliated hospital of spine surgery in hospital-L2 experiment into standard T11 spinal column chest waist section 1 patients with double segmental OCVF fractures,exclude other spine patients,use of gansu university of traditional Chinese medicine affiliated hospital radiology images of64 row helical CT in patients with vertebral articular process to the T11 L2 vertebral articular process under anatomic areas for continuous thin layer scanning,scanning layer thickness of0.625 mm,Through the interactive image control and transformation platform of the radiology department of the hospital,the scanned CT image data was transformed into the compatibility format of the finite element software interface and stored in DICOM format.2.The three-dimensional finite element model of the thoracic and lumbar spine before double-level OVCF fracture and after TCM hyperextension and reduction combined with PKP treatment was established.Mimics 19.0 was used to extract and transform the original model.GEOMAGIC WARP 2017 software for feature removal,smoothing,and surface solid fitting;Solid Works 2017 software for part structure assembly and subsidiary structure generation;ANSYS Workbench 17.0 software adds material properties,boundary conditions,coordinate and load Settings,and biomechanical analysis.3.Thoracic lumbar segment model of the spine biomechanics analysis: after verifying the effective preoperative double festival period of three-dimensional finite element model and the postoperative joint hyperextension reset PKP holds treatment in TCM based on three-dimensional finite element model,to set boundary conditions and mechanical loads,respectively on the T11 vertebral endplate axial compression load and 500 N 7.5 N · M torque,axial,bending forward,after the simulation of the human body stretch,the left side of the bow,bow on the right side,left rotation and right rotation 7 kinds of motion,detection of double festival period of OVCF preoperative and postoperative fracture vertebral body fracture,adjacent vertebral bodies and the adjacent soft tissue stress gradient distribution modal dispersion.Results:1.Three-dimensional finite element biomechanical models of pre-operative and post-operative two-level OVCF fractures at the T11-L2 level were successfully established in accordance with the biomechanical characteristics of the thoracic and lumbar spine.2.The three-dimensional finite element model of the two-segment OVCF fracture before the operation and the two-segment OVCF fracture after the TCM hyperextension reduction combined with PKP treatment was carried out to simulate the physiological load of the human body,and the same axial load and bending were applied respectively.Rotation torque,it is found that after T12 and L1 vertebral body’s cortical bone,cancellous bone and adjacent vertebral body endplate,the maximum Von Mises equivalent stress peak distribution gradient and distribution area have shifted after the hyperextension reduction combined with PKP treatment.The preoperative stress is concentrated on the anterior edge of the vertebral body of T12 and L1,and the equivalent stress of the anterior edge of the adjacent vertebra increases correspondingly.The tendency of the injured vertebra to continue to compress fractures and adjacent vertebrae fractures is more obvious.After T12 hyperextension reduction combined with PKP treatment Rear.By establishing a three-dimensional finite element biomechanical model of spine thoracolumbar double-segment vertebral compression fracture before operation and after reduction and strengthening fixation,it is found that there are essential differences in the biomechanical distribution rules and characteristics of spine fracture before operation and after reduction and strengthening.After two-segment vertebral compression fracture,the overall biomechanical distribution of the spine is in an unbalanced state,and the biomechanical stress distribution of different structural units of the spine is extremely unbalanced under the conditions of axial compression,flexion,extension,left and right scoliosis and rotation.In the active state of flexion and bending,the maximum stress of the cortical bone of the L1 vertebral body is 74.798 Mpa,the maximum stress of the cancellous bone of the T12 vertebral body is 2.5816 Mpa,the maximum stress of the T12-L1 intervertebral disc is 3.973 Mpa,and the upper endplate of the L1 vertebral body is the largest The stress is 13.598 Mpa,and the maximum stress of the right facet joint of L1-2 is21.842 Mpa.In the post-extension state,the vertebral cortical bone,cancellous bone,intervertebral disc,cartilage endplate and facet joints received less stress stimulation,respectively 99.232 Mpa,0.7807 Mpa,3.973 Mpa,3.2182 Mpa and 4.2637Mpa;In the post-extension state,the cells with the smallest spine stress distribution are located in the cortical bone of the L2 vertebral body,the cancellous bone of the L2 vertebral body,the T11-12 intervertebral disc,and the facet joint on the left side of L1-2.It can be seen that after a vertebral body compression fracture,the different structural units of the spine have the greatest stress stimulation in the forward flexion state.It is not recommended to bend forward after the compression fracture is imposed,and in the post-extension state,the different structural units of the spine The biomechanical stress is the smallest,which indirectly confirms the biomechanical safety and reliability of the application of TCM hyperextension reduction treatment after spinal fracture.Vertebral compression fractures were treated with TCM hyperextension reduction combined with PKP.The height of the vertebral body was restored and the biomechanical balance of the spine was restored.The biomechanical stimulation of different structural units of the spine was significantly reduced compared with preoperatively,and the tendency of local stress concentration was relieved..In the flexion state,the maximum stress of the cortical bone of the vertebral body is reduced from99.232 Mpa before the operation to 34.705 Mpa after the operation;the maximum stress of the cancellous bone of the T12 vertebral body is reduced from 2.5816 Mpa before the operation to1.2085 Mpa after the operation;T12-The maximum stress of L1 intervertebral disc was reduced from 3.973 Mpa before operation to 2.049 Mpa after operation;the upper endplate of L1 vertebral body dropped from 13.598 Mpa before operation to 6.0292 Mpa after operation.Therefore,after vertebral body compression fracture,it passes through After hyperextension reduction combined with vertebral body intensive treatment,the biomechanical form of the spine was reconstructed,and the overall biomechanical imbalance of the spine was restored.Conclusion:1.Based on the real CT images of patients,the computer-aided modeling platform can be used to better establish the biomechanical three-dimensional finite element model of osteoporotic vertebral compression fracture.The model has strong validity and reliability and is suitable for biomechanical analysis requirements.2.Double segmental spinal thoracic lumbar vertebral compression fractures after overall biomechanical stability of the imbalances,spinal structure unit and local stress concentration phenomenon is very prominent,especially in forward bends,axial compression and lateral bending rotation process,the spinal column chest waist section of vertebral body,cartilage endplate,intervertebral disc and articular cartilage degenerative change trend and risk increase;However,in the state of posterior extension activity,the overall structural unit stress distribution of the thoracolumbar segment is small,which indirectly confirms the biomechanical safety of the traditional Chinese medicine posterior extension reduction technique after the occurrence of the two-segment vertebral compression fracture.In addition,the increased local stress in the thoracolumbar vertebral bodies,cartilage endplates,intervertebral discs,facet joints and other structural units may provide a biomechanical explanation for the fracture of adjacent vertebral bodies,degenerative changes of the lumbar spine,and chronic low back pain following compression fractures.3.Double segment vertebral compression fractures after hyperextension reduction after joint vertebral strengthening treatment,the structure of the spinal column chest waist section as a whole unit of biomechanical stress distribution trend than preoperative decreases,and the stress distribution trend is more even,reconstruction of the thoracolumbar spine injury vertebral anatomical morphology and biomechanical stability,slows down the spinal degenerative change and injured vertebra adjacent vertebral fracture risk again,of course,better strengthen reset,degree of injured vertebral reset relations with clinical symptoms still need further consideration. |
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