Biomechanical comparison using finite element analysis of different screw configurations in the fixation of femoral neck fractures

K Gok,S Inal

doi:10.5194/ms-6-173-2015

Abstract

Abstract. In this research, biomechanical behaviors of five different configurations of screws used for stabilization of femoral neck fracture under axial loading have been examined, and which configuration is best has been investigated. A point cloud was obtained after scanning the human femoral model with a three dimensional (3-D) scanner, and this point cloud was converted to a 3-D femoral model by Geomagic Studio software. Femoral neck fracture was modeled by SolidWorks software for five different configurations: dual parallel, triple parallel, triangle, inverted triangle and square, and computer-aided numerical analysis of different configurations were carried out by ANSYS Workbench finite element analysis (FEA) software. For each configuration, mesh process, loading status (axial), boundary conditions and material model were applied in finite element analysis software. Von Mises stress values in the upper and lower proximity of the femur and screws were calculated. According to FEA results, it was particularly advantageous to use the fixation type of triangle configuration. The lowest values are found as 223.32 MPa at the lower, 63.34 MPa at the upper proximity and 493.24 MPa at the screws in triangle configuration. This showed that this configuration creates minimum stress at the upper and lower proximity of the fracture line. Clinically, we believe that the lowest stress values which are created by triangle configuration encompass the most advantageous method. In clinical practices, it is believed that using more than three screws does not provide any benefit. Furthermore, the highest stresses are as follows: at upper proximity 394.79 MPa in triple parallel configuration, for lower proximity 651.2 MPa in square configuration and for screw 2459 MPa in inverted triangle.

Highlights

IntroductionAs a result of these traumas, femoral neck fractures may occur in the skeletal system
In our daily life, people can be faced with undesired traumas
These stress values have been evaluated according to the von Mises criteria

Summary

Introduction

As a result of these traumas, femoral neck fractures may occur in the skeletal system. The different configurations of screw fixation are used for stabilization of femoral neck fractures. The question of the best fixation type in surgical treatment of femoral neck fractures is still subject of debate today (Basso et al, 2012; Deneka et al, 1997; Filipov, 2011; Martens et al, 1979; Zdero et al, 2010). Screw fixations of these fractures have been described as appropriate, there are only few studies that contain evidence based on biomechanics regarding which configuration or how many screws result in better stabilization (Audekercke et al, 1979; Cody et al, 2000; Martens et al, 1979; Springer et al, 1991; Swiontkowski et al, 1987).

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Discussion

Conclusion