Finite Element Analysis Of Different Internal Fixations For Supracondylar Fracture Of Humerus

Purpose:(1)To establish a 3D model and a reliable finite element model of distal humerus in normal adults.(2)In order to clarify the stress and displacement distribution characteristics of different steel plate fixation methods and provide corresponding suggestions for clinical treatment of this site fracture,the difference of biomechanical stability among parallel double plates,vertical double plates and Y type plate in the treatment of distal humeral fractures under different loading conditions was compared by using computer 3D reconstruction technology and finite element analysis technology.Methods:(1)First,the CT raw data of one volunteer was obtained,the medical image processing software MIMICS 17.0 was used to process the data to obtain the humerus 3D model,and the model was smooth-surfaced using reverse engineering software Geomagic Studio 2012.Then,finite element meshing of the distal humerus model was performed by using the finite element preprocessing software Hypermesh 13.0 and the model was imported into MIMCS 17.0 for material assignment based on CT grayscale values.Finally,according to the previous reports,the finite element analysis software Abaqus 6.14 was used to analyze the finite element model to verify its validity.(2)3D modeling software Solidworks 2012 was used to construct the fracture model of distal humerus.A fracture defect of 10 mm in length was constructed on the supracondylar of humerus.Then,the software was used to build the equal proportion model of parallel double steel plates,vertical double steel plates and Y-shaped steel plate,and these models were assembled with the humeral distal fracture model according to AO principle of fracture treatment,respectively.The finite element preprocessing software was used to mesh the above three kinds of assembly models,the material of the humerus fracture model was assigned based on the grayscale value of CT,and the plate models was given the uniform material assignment.(3)The above three groups of finite element models were imported into the finite element analysis software Abaqus 6.14.The contact relation between the plate screws and the bone was defined as “tie-constraint”.The proximal humerus was completely fixed on the X axis,Y axis and Z axis.The distal humeral articular surface were applied axial load 200 N,bending load 30 N,the lateral supracondylar humerus to impose 30 N varus load.Then,the stress distribution of these implants and the displacement of distal humerus bone were compared with each other.Result:(1)Finite element model of distal humerus of normal adult was successfully established through CT data acquisition,3D reconstruction of images,model surface treatment and meshing.The maximum stress of the model under different axial loads was highly consistent with the results of previous studies,so it showed that the finite element model established in this study was reliable and could be applied in later related research.(2)Three kinds of finite element models of internal fixation of fracture were successfully established through the establishment of the distal humerus fracture model,the establishment of the implants model,the combination of fracture models and implant models and the meshing.(3)In terms of stress distribution and maximum stress,under different mechanical loadings,the stress distribution of parallel double steel plates was the most uniform,the maximum stress value was the lowest,the vertical double steel plates was the second,the stress distribution of Y steel plate was the most concentrated,and the maximum stress value was the highest.In terms of the displacement of the fracture fragments,the displacement of the fracture fragments in the parallel double plates fixation was the smallest under different mechanical loadings,followed by the vertical double plates fixation,and the Y-plate fixation was the largest.Conclusion:(1)In this study,the finite element model of the distal humerus was successfully established by using MIMICS 17.0 software,Geomagic Studio 2012 software and Hypermesh 13.0 software.The method was simple and reliable,and it could be used for related biomechanical studies.(2)In terms of the biomechanical reliability and stability of the fracture fixations,the parallel double steel plates optimal under different mechanical loadings,followed by the vertical double plates,Y-plate was the worst.This provided a powerful reference for the treatment of distal humeral fractures in the selection of appropriate internal fixations.