| Objective:Based on the CT data of the proximal femur,finite element analysis was used to investigate the A3.1 intertrochanteric fracture and the stress and global displacement of the proximal femur and PFNA before and after the reconstruction of the external wall defect.And the stress and global displacement of proximal femur and PFNA with different models of medial wall defects.To explore the clinical significance of medial and lateral wall defects.Methods:After obtaining CT data of proximal femur,the model of A3.1 intertrochanteric fracture was created in Minics,Geomagic,SolidWorks,Ansys and other software,and different models were established on this basis and grouped as follows.1.Reverse intertrochanteric fracture with lateral wall defect,intertrochanteric fracture with lateral wall reconstruction group;2.Intertrochanteric fracture combined with partial defect of medial wall,intertrochanteric fracture combined with complete defect of medial wall;3.Intertrochanteric fracture combined with partial defect of the medial wall and reconstruction of the lateral wall and intertrochanteric fracture combined with complete defect of the medial wall and reconstruction of the lateral wall.Axial stresses of 600N,900N,1200N,1500N and 1800N were applied to the surface of the femoral head after fixation with PFNA.The stress values and overall displacement of femur and PFNA in each model were observed to explore the suggestion for the stability of intertrochanteric fracture.Results:In the first group,in terms of PFNA stress,the femoral lateral wall defect models were 161.83MPa,233.33MPa,300.76MPa,369.05MPa,435.92MPa,respectively.In the femoral lateral wall reconstruction group,135.74MPa,193.41MPa,250.55MPa,304.19MPa and 358.44MPa,respectively.The overall displacement of femoral head in the femoral lateral wall defect model were 6.6973mm,10.038mm,13.381mm,16.718mm,20.053mm,respectively.The overall displacement of PFNA were 6.3649mm,9.5414mm,12.719mm,15.892mm and 19.064mm,respectively.The overall displacement of femur in the lateral wall reconstruction group was 6.6459mm,9.9528mm,13.266mm,16.566mm and 19.873mm,and the overall displacement of PFNA was 6.3179mm,9.4632mm,12,614mm,15.754mm and 18.899mm,respectively.In the second group,the PFNA stress of the group with intertrochanteric fracture combined with partial defect of the medial wall was 177.34MPa,254.96MPa,328.32MPa,404.72MPa and 479.36MPa,respectively.254.81MPa,373.44MPa,491.11MPa,609.87MPa and 727.3MPa respectively in the group of intertrochanteric fracture combined with complete defect of medial wall.The overall displacement of femoral head was 6.6918mm,10.021mm,13.343mm,16.675mm,20.005mm in the group of intertrochanteric fracture combined with partial defect of medial wall.The overall displacement of PFNA was 6.3593mm,9.5251mm,12.685mm,15.854mm and 19.021mm,respectively.The overall displacement of femur in the group of intertrochanteric fracture combined with complete defect of medial wall was 6.7663mm,10.148mm,13.528mm,16.904mm and 20.28mm.The overall displacement of PFNA was 6.4272mm,9.6402mm,12.852mm,16.061mm and 19.269mm,respectively.In the third group,the stress of PFNA in the group with partial defect of the medial wall and reconstruction of the lateral wall was 161.52MPa,229.09MPa,295.68MPa,351.73MPa and 412.86MPa,respectively.218.7MPa,318.91MPa,418.61MPa,519.15MPa and 620.71MPa respectively in the group with complete defect of medial wall and reconstruction of lateral wall.The overall displacement of femoral head in the group with partial defect of medial wall and lateral wall reconstruction were 6.6727mm,10mm,13.322mm,16.628mm and 19.941mm.The overall displacement of PFNA was 6.3421mm,9.5055mm,12.664mm,15.808mm and 18.959mm,respectively.The overall displacement of femur was 6.7462mm,10.12mm,13.49mm,16.856mm,20.217mm in the group with complete defect of medial wall and reconstruction of lateral wall.The overall displacement of PFNA was 6.4082mm,9.6133mm,12.815mm,16.013mm and 19.207mm,respectively.Conclusion:When the proximal femoral locking plate was used to reconstruct the lateral wall,the stress on the intramedullary nail was significantly reduced,thus reducing the occurrence of nail breakage and screw blade cutting and other internal fixation failures.The risk of internal fixation failure was increased when the medial wall defect involved the calcar femur.Reconstruction of the lateral wall can reduce the failure rate of internal fixation when there is an mediall and lateral wall fracture. |
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