Finite Element Analysis Of PFNA-Ⅱ Treatment 31-A3 Intertrochanteric Fracture Reaming And Non-reaming

Objective:The mechanical distribution characteristics of reamed and unreamed femoral intertrochanteric fractures treated with PFNA-Ⅱ were analyzed by finite element method.Methods:A healthy volunteer was included.The femur was scanned by CT to obtain the DICOM format file,which was imported into the Mimics software to extract the three-dimensional model of the femur and saved to the stl file format.The polygonal optimization of the three-dimensional model of femur is carried out by using Geomagic Wrap software,and then the solid model of femur is obtained by precise curved surface command box operation,and the solid model of femur is derived as stp.The femoral model was obtained by assembling bone cortex and cancellous bone into Solid Works software.The fracture lines were drawn and osteotomized to get A3.1,A3.2 and A3.3intertrochanteric fracture models,which were assembled with intramedullary nails of9 mm,11mm diameter and 170 mm length,respectively.Non-reaming was simulated with9 mm intramedullary nail and reaming was simulated with 11 mm intramedullary nail.Save three sets of six models in stp format.Import stp format files into Hypermesh and convert them to inp format files for export.Then import the inp file into the Mimics software for femur material assignment,and finally export the Ansys pretreatment file.The six model files are imported into the Ansys software to give the intramedullary nail material attributes,set the interaction relationship of each contact surface,define the load and boundary conditions,and solve the problem.The stress distribution of femur,the stress distribution of internal fixation,the displacement of femur and the displacement of internal fixation were observed in different models.Results:1)The femoral stress of all types of fractures fixed with reamed intramedullary nails was lower than that of non-reamed intramedullary nails,and the maximum stress of A3.3fractures was greater than that of A3.1 and A3.2 fractures.2)The internal fixation stress of all types of fractures with reamed intramedullary nail fixation was greater than that of non-reamed intramedullary nail fixation,and the maximum internal fixation stress of A3.3 type fractures was greater than that of A3.1 type and A3.2 type.3)All types of fractures were fixed by reaming or non-reaming intramedullary nails.The displacement of femur and internal fixation was similar,and the displacement of A3.3 type fracture was greater than that of A3.2 type and A3.1 type.Conclusion:Reaming and non-reaming have little influence on the displacement of femur and internal fixation,but have great influence on stress.With reamed intramedullary nail fixation,the stress of femur decreased,the overall stress of internal fixation increased,and the stress of distal locking nail decreased.Compared with non-reamed intramedullary nail,reamed intramedullary nail may provide better therapeutic effect.