Biomechanical comparison of four internal fixation approaches for Pauwels type Ⅲ femoral neck fractures using finite...

The optimal fixation method for Pauwels type Ⅲ femoral neck fractures remains controversial. The finite element study aimed to compare the biomechanical performance of four internal fixation techniques: Interlocking Hip Screw (IHS), Femoral Neck System (FNS), Biplane Double-Supported Screw Fixation (BDSF), and Four Cannulated Screws (FCS).

A full-length computed tomography (CT) scan of one volunteer's femur was selected and analyzed by Mimics. The femur model was reconstructed with Geomagic Studio, while SolidWorks enabled modeling of both the Pauwels Ⅲ fracture pattern and four implants. We used ANSYS Workbench to simulate the response of femoral neck fracture-implant assemblies under three static axial loads applied along the mechanical axis of the femur. We analyzed femoral and implant displacements, along with Von Mises stress distributions and peak values.

Under all loading conditions, femoral displacement decreased progressively from the femoral head to the distal fixation site. The IHS group demonstrated the smallest peak femoral displacement. Stress distribution in the femur was similar across all groups, concentrated medially at the femoral neck and fracture site. Implant displacement was lowest in the IHS group. The IHS and FNS groups exhibited comparable stress distributions and peak values, both of which were higher than those in the BDSF and FCS groups.

The study revealed that the IHS offers superior stability for the fracture, with enhanced shear force resistance and improved stress distribution. While these findings support the potential clinical application of the IHS, further confirmation through clinical trials is necessary.