Finite Element Analysis of the Septal Cartilage L-Strut

Abstract

Importance: Septoplasty is one of the most commonly performed operations in the head and neck. However, the reasons for septoplasty failure and the additional stress of performing a chondrotomy on the septal cartilage are not well understood. Design, Setting, and Participants: A finite element model of the nasal septum was created using a microcomputed tomography scan of the nasoseptal complex that was reconstructed into a three-dimensional model in silico. Testing included four common chondrotomy designs: Traditional L-strut, double-cornered chondrotomy (DCC), curved L-strut, and the C-curve. Tip displacement was applied in a vector parallel to the caudal strut to simulate nasal tip palpation. Main Outcomes and Measures: With finite element analysis, the maximum principal stress (MPS), von Mises stress (VMS), harvested cartilage volume, and surface area were recorded. Results: The highest MPS for the L-strut, DCC, curved L-strut, and C-curve was identified at the corner of the chondrotomy. The MPS at the corner of the chondrotomy was reduced 44% when comparing the C-curve with the traditional L-strut. The VMS patterns showed compressive stress along the caudal septum in all models, but at the corner, the stresses were highest in the chondrotomies designed with sharp-Angled corners. The VMS showed a 76% decrease when comparing the C-curve with the traditional L-strut. The stress across the anterior septal angle is also higher in models with sharp-Angled corners. Cartilage harvest volumetric and surface area assessments did not show meaningful differences between shapes. Conclusions and Relevance: The highest area of stress is near the transition of the dorsal to caudal septum in all models. Stresses are relatively higher in chondrotomy shapes that contain sharp-Angled corners. The relative reduction in MPS and VMS utilizing a C-curve instead of an L-strut may decrease the likelihood that the septum will deform or fail in this region. The volume and surface area of the C-curve are similar to that of the L-strut technique. Avoiding sharp-Angled corners reduces the stresses at the corner of the chondrotomy and across the anterior septal angle. Using a C-curve may be an improved septoplasty design.