| Object:(1)To establish a three-dimensional digital model of thoracic and lumbar fractures by two-dimensional images acquiring by CT scanning.The customized external fixator is made through 3D printing technology,according to the digital design of the external fixator for thoracic and lumbar fractures.(2)The three-dimensional finite element model(T12-L4)of thoracic and lumbar fractures was established,and the biomechanical changes and the effect on the stability of the spinal of the external fixation of the thoracic and lumbar fractures were investigated by using the finite element method.(3)Patients with thoracic and lumbar fractures were treated by there methods.The follow-up results of three methods were observed.Group A was treated by manual reduction and fixed with a 3d printing external fixation.Group B was operated by open reduction and pedicle screw fixation.Group C was treated by manual reduction and bed rest.Materials and Methods:(1)A 3D model was established according to the CT data of case of L1 fracture satisfactory reconstructive under analgesia.The digital model was saved and imported to Mimics,a 3D reconstruction software.3D model for bone,skin and muscle was established after organize cutting.The new model of the support plate for the back of the external fixation was designed by importing the digital data into 3-matic.Reintroduce the 3D model in Mimics software,export it in the format of*.STL and print it through 3D printer.Assemble it and wear it.(2)A 3D model was established according to the CT data of case of L1 fracture satisfactory reconstructive under analgesia.3D imaging was performed with DICOM data by the computer.The 3D finite element model of the spinal functional unit ofT12-L4,including the bone,the fibrous rings of the intervertebral disc,the nucleus pulposus,the cartilaginous endplate,and the ligaments,was established with the relevant software of Mimics,Ansys,Geomagic Studio and Hpermesh.The force of thoracic and lumbar fractures was simulated,and the stress distribution of spinal functional units was analyzed.A model of wearing the external fixation was established on the basis of the former model.the vertebral body and intervertebral disc stress and displacement under the five situation of stand,forward bend,stretch,lateral flexion and rotation were analyzed,wearing different tightness.(3)Retrospective analysis of 60 patients suffering with simple thoracic and lumbar fractures with three different treatment regimens.Evaluation of anterior vertebral body compression(AVBC),Cobb Angle,the waist pain score(VAS)and The Oswestry Disability Index(ODI)of each group before and after treatment.The advantages and disadvantages of the three treatment regimens were compared within the group and between groups.Results:(1)The study constructed the 3D digital model of the thoracic and lumbar fractures by CT scan,after designed by the software such as 3-matic,the customized external fixators were manufactured by 3D printing,which has the advantages of personalized design,precisely fixation and light weight.(2)In this study,we utilized the software to establish the finite element models of the thoracic and lumbar fractures and the external fixators.The models not only has the same shape with the real injured thoracic and lumbar,but also has very good geometrical similarity.We verified the validity of the finite element models of thoracic and lumbar fractures.By comparing the models with or without external fractures,the study confirm the external fixators can reduce the displacement and stress of the injured vertebral in anteflexion,retroflexion,lateral bending and rotation.And this new type of external fixators is safe,which does not increase the risk for vertebral fracture and lumbar disk herniation.(3)After three different treatments applied,all patients gained obvious improvement in AVBC,Cobb Angle,lumbar pain(VAS score)and ODI(P<0.05).In the comparison between groups,the AVBC in group C was worse than group B(p<0.05).The loss value of AVBC in group A was significantly superior to group C(p<0.05).There was no significant difference between the three treatments at the end of the follow-up period(p>0.05).Conclusion:This study intended to utilize advanced science and technology(3D printing technology to the design and manufacture external fixators),combining with digital image technology and the method of mathematical physics(Finite Element Method)to establish finite element model and biomechanical analysis,to study,analyze and elaborate the traditional Chinese medicine treatment(reduction with external fixators).which was proved to be efficient in the long history.This study not only utilized the modern technology to study the traditional Chinese medicine treatment,but manufactured the new type of customized thoracic and lumbar external fixators.The fixators,which characterized as individuality and precision,is based on the CT data of thoracic and lumbar fracture patients,and with the help of computer design,3D printing,the customized product can fix the fractures effectively,help patients to get fields early,and reduce complications.It is a safe and effective external fixator for the treatment of simple thoracolumbar fracture. |
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