The ethmoid bone is the ideal graft to strengthen nasal septum L-strut among different grafts: An evaluation based on finite element analysis.

Abstract

In the rhinoplasty of Asian short nose deformity, the surgeon cuts a portion of septal cartilage and retains the nasal septum L-strut, but a deviated nasal septum is formed after the surgery under forces of soft tissue contracture. Although various autologous grafts are used to reinforce the L-strut, there is a lack of objective "mechanical theory" to support the clinical findings in other studies at the present time. A simplified and geometrical finite element model of L-strut reinforced with clinically common materials, including auricular cartilage, nasal septal cartilage, and perpendicular plate of ethmoid, was established. Simulating the mechanical environment of nasal tip in reality, when the force was loaded, the von Mises stress and directional deformation of the L-strut were observed under different widths. Kruskal-Wallis test was used to examine the significance of intergroup differences of L-strut, and P<0.05 indicated statistical significance. All autologous grafts decreased the maximum directional deformation of L-strut, and the variance of nasal tip displacement was reduced; the perpendicular plate of ethmoid showed a distinct effect. The increasing width of the L-strut reduced the maximum displacement of the nasal tip, but the influence of using grafts as a reinforcement to the L-strut was much greater than the residual width (p=0.003). The graft reinforcement significantly increased the stability of the L-strut, which enhanced the resistance to deformation in the long-term action of tension, and the effect of the perpendicular plate of ethmoid to reinforce was significantly better than that of auricular and nasal septal cartilage.