Three-dimensional finite element analysis of mechanical stability of double screw internal fixation for talar neck fracture / 中华创伤杂志

ABSTRACT

Objective The three-dimensional finite element analysis was done to analyze the mechanical stability of double screw internal fixation for talus neck fracture,the methods with different approaches and different placement methods as well as the optimal biomechanical environment of fracture section were discussed so as to provide reliable mechanical arguments for the selection of clinical internal fixators.Methods The acquired male adult ankle CT data were imported into Mimics for 3D reconstruction of the ankle joint model.After the model was fitted with the surface by Geomagic software,the model was imported into Solidwork software to establish the talus neck fracture model and the corresponding screw.The fixtures were assembled with the anterior-posterior parallel double screw,the anterior-posterior cross-double screw,the posterior-anterior parallel double screw,and the posterioranterior cross-double screw,respectively.The model data were imported to Abaqus 6.14 for analysis and calculation,followed by the meshing pretreatment using software Hypermesh 13.0.The Von Mises stress distribution of the lag screw and displacement of the fracture end were observed under different fixation modes.Results In the displacement and stress cloud diagrams of the fracture ends of the four groups,the displacement peaks of the fractures of the anterior to posterior double-screw parallel and cross-fixed groups were 0.399 3 mm and 0.418 6 mm,and the peak pressures were 7.721 MPa and 8.124 MPa,respectively.The displacement peaks of posterior to anterior double-screw parallel and cross-groups were 0.418 3 mm and 0.418 5 mm,the fracture end peak pressures were 4.848 MPa and 5.692 MPa,respectively.In the screw stress cloud diagram of the four internal fixation modes,the Von Mises stress peaks of the anterior-posterior parallel screw group and cross-screw group were 45.11 MPa and 50.18 MPa,and those of the posterior-anterior parallel screw group and cross-screw group were 30.65 MPa and 37.68 MPa,respectively.Conclusion In the posterior-anterior parallel screw fixation,the fracture end has the lowest stress,and the screw has dispersive stress and the stress peak is the lowest,which is superior to other three groups.Therefore,the posterior-anterior screw is better than anterior-posterior fixation,and the parallel fixation is better than cross fixation.