| Objective : 1.A three-dimensional finite element model of the distal radius is established,the axial compressive load condition is simulated in the finite element software,and the force distribution and stress conduction of the model are analyzed.The scientific nature of the finite element model of the distal radius was tested,laying the foundation for subsequent experiments.2.A three-dimensional finite element model of AO A2.2 fracture at the distal radius of the non-bridge external fixator was established,and the axial compression load,dorsal extension load and palm flexion load were simulated in the finite element software,and the stress distribution of the middle and outer fixation frames in the model,the force of the distal fracture block and the displacement of the fracture fracture were analyzed.To verify the scientific nature of the treatment method using non-bridge external fixation frame,the stability of the fixation system provides a strong theoretical basis for clinical treatment.Methods:1.Select a healthy volunteer,perform a CT scan on his forearm,import the obtained data into the MIS＿Medical＿21.0 software,extract the radius model,save the data and then import it into the Geomagic Wrap2017 software,smooth the model,build the contour line,generate fine surface pieces,obtain the distal radius tartar bone model and the radius corticosteroid bone model,and save the data for the next processing.The above model is assembled with the cortical bone model by Boolean operation in Solid Works2019 software,and then the radius model is cut to generate a distal radius model.Open the distal radius model in Abaqus2016 software,assign materials,mesh,create load and boundary conditions,simulate an axial compression load of 100 N,output Job,and get the cloud map display and data.2.Open the distal radius model in Solid Works2019 software,select 25.00 mm from the wrist joint surface of the distal radius,and establish a model of AO A2.2 fracture of the distal radius by cutting method.The device manufacturer obtains the data dimensions of the non-bridged external fixator,builds the non-bridged external fixation model in solid Works2019 software,and then assembles the external fixation frame model with the fracture model through Boolean operations to obtain a complete model.3.The above model is imported into the Abaqus 2016 software,the materials are assigned to each part of the model,and then the interaction is added to the model.All contact surfaces of the external fixation frame are set to the binding state,the contact surface of the steel needle and the fracture model is set to the binding state,and the fracture contact surface is set to sliding,and the friction coefficient is 0.2.Mesh the parts of the model.Create load and boundary conditions.The proximal radius degree of freedom is set to 0 for all operating conditions,and then the axial compression load is simulated at 100 N,the back extension load is 50 N,and the palm bend load is 50 N.Create job analysis(Job1,Job2,Job3),submit the job,and get the final data and cloud map.Result:1.When the three-dimensional finite element model of the distal radius is established to simulate the working conditions of axial compression of 100 N,the stress distribution is mainly on the dorsal side of the radius and at the junction of cortical bone and cancellous bone.2.The stress distribution and displacement of the finite element model of AO AO A2.2 type fracture treated by non-bridging external fixation frame in three working conditions were analyzed.The maximum stress of the model under the three working conditions is concentrated on the distal steel needle,and when the axial compression is 100 N,the stress size of the distal steel needle is56.978 MPa,and the stress size of the fracture block is 16.622 MPa;when the dorsal extension is 50 N,the stress size of the distal steel needle is 258.582 MPa,and the stress size of the fracture block is 43.408 MPa;when the palmar flexion is 50 N,the stress size of the distal steel needle is 115.077 MPa,and the stress size of the fracture block is 31.877 MPa.The displacement of the fracture contact surface is almost zero in axial compression and palm flexion conditions,and the displacement of the fracture contact surface is 3.269 mm in the dorsal extension condition.Conclusion : The three-dimensional finite element model of the distal radius established by the above method is verified and concluded that the model established by the method has objective authenticity and scientific nature,and can be put into experimental research.Finite element analysis of non-bridging external fixation frame treatment of AO AO A2.2 type fracture of the distal radius shows that the stress is mainly concentrated on the distal steel needle of the external fixator,and the displacement of the fracture contact surface is small,which shows that the non-bridging external fixator is firmly fixed,this treatment method is scientific,and we provide data support for clinical treatment. |
