Dynamic parallel traction theoretical model for the application and validation in femoral neck fractures - a finite element analysis.

Abstract

This study aims to validate the application effects of a novel theoretical model of dynamic parallel traction in the treatment of femoral neck fractures through three-dimensional finite element analysis. By simulating the femoral neck fracture model, we explore the promotional effect of dynamic parallel traction on fracture healing. A digital 3D femur model was constructed using high-resolution computed tomography data of the lower limbs of a 70-year-old elderly subject. An axial compression of 500N was applied at different traction angles (0°, 10°, 20°, 30°, 40°, 50°). The equivalent stress distribution and deformation of the femur geometric model were calculated at each angle under the six <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math> angles. Statistical analysis was performed using One-Way ANOVA. At the parallel angle ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 0°), the maximum stress on the entire femur occurred at the trochanteric fossa, with a value of 7.945 MPa ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 0°). The maximum deformation was at the fovea capitis, with a value of 104.13 mm ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 0°). As the traction angle gradually increased ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 10°, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 20°, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 30°, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 40°, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 50°), the maximum stress shifted gradually to the medial cortex of the femoral shaft, with values of 11.236 MPa ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 10°), 15.196 MPa ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 20°), 19.263 MPa ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 30°), 23.149 MPa ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 40°), and 26.311 MPa ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 50°). The maximum deformation remained at the fovea capitis but increased to 131.87 mm ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 10°), 181.96 mm ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 20°), 228.2 mm ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 30°), 271.15 mm ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 40°), and 307.41 mm ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>α</mi></mrow> </math>  = 50°). One-Way ANOVA revealed that traction angle significantly influenced the stress distribution (F = 4.419, p = 0.0022) and deformation magnitude (F = 4.023, p = 0.0040) at the proximal femur, indicating that traction angle is a critical factor affecting stress distribution and deformation. With the increase of the traction angle, the mechanical properties of the proximal femur decrease, indicating an increased risk of non-union and complications. Additionally, the study proves the effectiveness of the "dynamic parallel traction" theory.