Structural Analysis of Novel Design Compression Feature Intramedullary Nail System Used in Treatment of Femoral Neck Bone Fracture

Abstract

In this study, the design, numerical modeling, and static analysis of an intramedullary nail system with a compression feature developed to treat femoral neck fractures and prevent rotational displacement of the fractured parts were performed. Three-dimensional models were created considering the mechanical properties of cortical (stiff) and spongious (soft) bone tissues, and a fracture profile was designed in the femoral head. The nail system, manufactured from Ti6Al4V Grade 23 alloy, was implanted virtually into the femur to achieve stable fixation.

Two material models, isotropic and orthotropic, were used for representing the femur bone, and it was concluded that the orthotropic model provided results more consistent with the literature. Structural analyses of both the intramedullary nail system and femur bone were carried out using the finite element method (FEM) under various loading scenarios representing daily human activities such as walking, stair climbing/descending, standing, sitting, kneeling, and one-leg stance. Additionally, a three-point bending test according to ASTM F1264 standards was simulated to evaluate the rigidity of the nail.

The maximum stress on the nail was obtained as 158.37 MPa during stair climbing and 165.88 MPa during stair descending, while the maximum deformation of 18 mm occurred in the nail system under compression. The results demonstrate that the proposed design ensures high mechanical stability and effective load transfer, providing a promising alternative for femoral neck fracture treatment.