Effect of Window Geometry on Strength of Shaft Part of Femur Bone

Abstract

Femur bone is known as the largest and longest bone in human body. It bears most of the body weight during activities such as standing, walking, and running. This study investigates impact of the geometry of the window perforated in the shaft part of this bone on its strength. Four window geometries, including square, circle, trapezoid and triangle were employed in order to assess yield stress under tension, compressive 3-point bending, 4-point bending and torsional loadings. 5 mm interval CT scan images were employed for modeling the femur bone. Analyses were performed in ANSYS finite element code. Trapezoidal window showed much better resistance in 3-point bending and axial loadings compared to other window geometries, while it showed the weaker performance in torsional and 4-point bending loads. However, the femur bone is very unlikely to be loaded in 4-point bending. Moreover, in torsion, the femur bone with trapezoidal window was only 12% weaker than the femur bone with circular window (in axial loading, the femur bone with trapezoidal window had 33.6% higher strength than the bone with circular window). Therefore, summing up all the results of this study, it is suggested to use trapezoidal as the most appropriate window type for orthopedic surgeries.