Establishment Of Three-dimensional Finite Element Model For Severe Rigid Scoliosis And Biomechanical Analysis Of PVCR

Objective:The-three-dimensional finite element model of adolescent idiopathic scoliosis was established by Mimics10.01 software,Geomagicl2,UG8.0 3D modeling software and Workbench finite element analysis software with the aid of the real patient’s CT scanning data.The CVSL and biomechanical properties of the model were validated effectively.This model is used to simulate PVCR operation to explore:1.Biomechanical changes and movement of important vertebrae during PVCR orthopedic operation,2.The distribution of stress cloud on orthopedic screws and orthopedic bars and Comparison of preoperative and postoperative vertebral body,pedicle force and displacement distribution nephogram,3.The distribution of force cloud images after intervertebral disc orthopedic surgeryMethods:1.Establishment of severe scoliosis model and optimization of the model using three-dimensional finite element software.In the Mimics10.01 software,the volunteer CT model was successfully imported,and rough model was initially obtained.In Geomagic studio 12 software,the model is optimized to make the model more smooth and close to reality.In the UG8.0 software,intervertebral discs,ribs,sternum handles and pelvis were added to simulate the friction coefficient of the intervertebral joints and costal joints in prone position.2.Validation of the effectiveness of severe scoliosis model:In the Mimics10.01 software,the model is compared with the original patient’s CT to verify the geometric similarity of the model.By establishing the three-dimensional spatial model of the patient’s spine,the CSVL validation is recognized in this study.The data of the spinal coronal and sagittal CSVL four groups were listed in Mimics10.01 and UG8.0 respectively,and the statistical analysis was carried out by statistical software SPSS 19.0.Fine-tuning the deficiencies of the model ensures the consistency of the model established in this study and the actual location of the spine in the patient.Six validation of the model,such as flexion,extension,left bend,right bend,left rotation and right rotation,are applied to the model,and the FSU data of the model are obtained and compared with the previous research results to ensure the effectiveness of the model in mechanics.3.Using PVCR model to simulate the real environment of surgery.Simplify the modeling of real operative beds,skin and muscles.According to the actual situation,the skin of the fixed sternum and pelvis contact site was limited to the operative bed.Ensure the motion between the chest and the vertebral body,And real simulation of joint capsule lubrication,Simulated orthopedics:pedicle screw implantation and placement.According to the pre operation plan,T12 vertebrotomy for patients was resected,The fixed segment is T3-L4,Accurate implantation of pedicle orthopedic screws during operation,and resection the vertebral,Apply an orthopedic force.Results:1.After the orthopedic operation of simulated PVCR,there were three dimensional orthopedic displacement in each vertebral body.After the vertebral body was resected,the continuous spinal column was divided into two segments artificially.First,the two sides of the vertebral body showed a vertical separation trend.On the coronal plane,the upper part of the vertebral resection area tended to move towards the convex side.At the sagittal position,the displacement distance of the lower segment is greater than the upper segment after the resection of the vertebral body.Therefore,the downward trend of the lower segment of the vertebral resection is greater than the upper part,that is,the distal subsidence and the proximal end.2.After the orthopedic operation of simulated PVCR,The stress range of orthopedic bar after simulated PVCR orthopedic surgery is 0.0050214e7 MPa-0.045217 E7 MPa.The maximum stress area is two vertebrae above and below the osteotomy area and the osteotomy area.The stress value is 0.045217 E7 MPa,The next is the orthopedic area,the stress value is 0.03145 E7 MPa-0.040193 E7 MPa.The stress of the orthopedic bar is the smallest.The stress value is 0.0050214e7 MPa-0.025121 E7 MPa.The stress range of orthopedic screws is 3.1108e7 MPa-2.7961e8 MPa.The largest area of stress is pedicle area.The stress of the first orthopedic screw was 2.4577e8 MPa under the excised vertebral column.After simulated PVCR orthopedic surgery,the nail bone junction area was found in the most stress regions of each vertebrae.3.After the orthopedic operation of simulated PVCR,the stress on the T2/3 and the T7/8,T8/9 and T9/10 of the intervertebral disc was larger than that of the other intervertebral discs.The intervertebral disc T2/3 intervertebral disc is more stressed and concentrates on the outer side of the annulus fibrosus.At the end of the correction,the maximum displacement of the intervertebral disc was shifted to the fibrous ring.Conclusions:In this study,CT 3D images were imported to establish a scoliosis model which is in line with the actual condition of the human body and to verify the validity of the model.Based on the model simulation of PVCR operation,intraoperative effects of intraoperative objective objects such as thorax,sternum,pelvis,skin,operating table and joint capsule were investigated.Compared with other similar experiments,it is more realistic to simulate PVCR operation.All segments of this study were implanted with pedicle screws.The size of stress values represented the possibility of pedicle wall fracture or screw rod fracture.The higher the value,the higher the possibility of intraspinal invasion or breaking of the broken rod.After PVCR,the coronal scoliosis was corrected.When the patient’s spine is corrected to the right position,the whole spine moves in the direction of the patient’s head in the direction of Z,and it is also in line with the height of the patient after the orthopedic operation.In the PVCR orthopedics,the spinal cord should be shortened first after complete spinal resection,and the spinal cord tension should be reduced to improve the spinal tolerance to the spinal transposition and the safety of the spinal cord.After PVCR,the osteotomy area is a high-risk area for postoperative plant rupture.Therefore,effective fusion of bone is performed during operation.Patients are strictly advised to avoid heavy physical exercise after operation.After PVCR orthopedic surgery,the intervertebral disc is more stressed and concentrated,and the degeneration of the intervertebral discs is the main factor leading to the occurrence of PJK.