Stress and Strain Analysis of Femur in Taylor Spatial Frame

Correction of femur deformity can be accomplished using both external and internal fixtures. The advantages of using circular external fixture include less soft tissue injury, better bone alignment and enhanced strain on cutting section, which causes less healing time. This paper focuses on experimental and Finite Element Analysis (FEA) study of circular external fixture, including two rings and six adjustable struts, with six degrees of freedom (Taylor Spatial Frame (TSF)). Femur 3d model was created using Mimics® software while FEA was accomplished using ABAQUS® software. The FEA was based on the assumptions, that the bone is loaded equal to a standing person load. The femur model was assumed to be isotropic and homogeneous in both cortical and spongy phases. FEA results were verified by corresponding strain measured in experimental tests. Based on these results, the maximum value of stress occurs in the location of pins and half-pins. Moreover, the maximum stress in the connection location of pins is higher than those of half-pins. Results show that substitution of half-pins with pins, in the points with maximum stress, causes reduction of stress and thus the pain is reduced.