A simple design sensitivity analysis approach is employed for structural shape design. Since this method is based on Finite Element Method, it easily applys to the complicated body shapes. Design sensitivity coefficients are calculated at some nodal points on the boundary or at the interface of different materials from the stiffness matrices of the structure in Finite Element Method. These sensitivity coefficients are used to redesign the boundary or interface of the structural system to reduce the local stress concentration occurring on the structure based on steepest descent. A simplified model of intramedullary fixation structures was studied using this amplified design sensitivity analysis approach giving improved structural shape.