Finite element analysis of hollow nail internal fixation for Pauwels type Ⅰ femoral neck frac-tures
Objective To analyze the biomechanical characteristics of hollow nail internal fixation for Pau-wels type Ⅰ fractures of the femoral neck through finite element(FE)analysis by modeling 3 hollow screws located at different spatial distributions.Methods A healthy male volunteer who underwent physical examination in our hospital was selected to undergo thin layer scan of the femoral head to the distal end of the femur using a 128-row spiral CT scanner.Then a femoral model in line with human structure was preliminarily constructed.The femoral shaft center was taken as the reference,a perpendicular line was drawn,and the fracture line was located at the cen-ter of the femoral neck at an angle of 30° to construct the model of Pauwels type Ⅰ femoral neck fractures.The SolidWorks 2021 software was adopted to establish the fixation model by 3 hollow nails at five different spatial distri-butions:respectively an inverted equilateral triangle,an inverted isosceles triangle,an inverted acute angle triangle,an inverted right angle triangle,and an inverted obtuse angle triangle.Thereafter,import the assembly model into the Ansys 2021R1 software and establish an FE model.The maximum stress peak of the femur model and internal fix-ators at different spatial distributions of the 3 screws were evaluated,and the maximum displacement of the femur and internal fixators were analyzed.Results The stress concentration areas in the proximal femur of different screw spa-tial distributions were all located below the fracture area of the femoral neck,with the stress peak of the inverted equilateral triangle configuration being the smallest,at 18.674 MPa.The overall stress of the fixators in different spatial screw distributions was located in the middle section of the proximal femoral ventral screw,with the stress peak of the inverted equilateral triangle configuration being the smallest,at 46.484 MPa.The overall displacement of different spatial screw distributions at the femoral neck fracture was located at the stress-loading site of the femoral head.The displacement of the inverted equilateral triangle configuration was the smallest,at 0.72517 mm.The dis-placement of the fixators in different spatial distribution fixation models was located at the stress-loading site of the femoral head.The displacement of the inverted equilateral triangle configuration was the smallest,at 0.68933 mm.Conclusion Hollow screws at different spatial distribution exhibit different biomechanical characteristics in the treatment of Pauwels type Ⅰ femoral neck fractures.The inverted equilateral triangle configuration reveals the stron-gest stress dispersion ability,the smallest displacement,and the best mechanical stability.
Femoral neck fracturePauwels type ⅠFinite element analysisHollow nailsInternal fixa-tionBiomechanics
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