Next-generation Septal Contouring in Aesthetic Rhinoplasty: A Structural Viewpoint.

Abstract

Aesthetic rhinoplasty is a challenge of both architecture and engineering. While aesthetic appeal is conspicuous, sound geometric design, even load distribution, and foundational stability are the concealed principles of durable results. Additional challenges faced by the rhinoplasty surgeon include complex material properties, variable boundary conditions, and irregular stresses.1 Septal cartilage remains the prime source of graft material in aesthetic rhinoplasty. Surgical pioneers including Ingals (1882), Kreig (1889), Freer (1902), and Killian (1905) advocated preservation of the dorsal and caudal extent of the septum—a configuration that has become known as the “L-strut.”2 Oral tradition advocates preservation of dorsal and caudal limbs of 10–15 mm width. However, borrowing from the foundations to adorn the façade is structurally dubious while cartilage yield correlates poorly with external nasal projection.3 Problematically, the L-strut comprises the thinnest portions of the septum yet supports the lower two-thirds of the nose. Structural failure causes nasal collapse, saddle deformity, tip deviation, and nasal valve dysfunction. Warping or fracture of the thin right angle is encountered in up to 40% of revision surgeries.4 Curiously, the structural competence of a right angled L-strut evaded scrutiny until recently. This probably reflects the sense of rigor and purpose with which the modern rhinoplasty community are reappraising their craft to meet heightened functional and aesthetic expectations.5 In 2007, human cadaveric septal L-struts were first investigated by finite element modeling to better understand surgical failure.6 Subsequent investigations added greater complexity and sophistication to the understanding of L-strut biomechanics and how failure might be mitigated through improved surgical design.7 Our assimilation of the collective computational evidence supports the replacement of the L-strut with a delta-shaped strut.1 It is interesting to speculate on the reasons for the enduring appeal of the L-strut. There is inevitably a learning curve when faced with a paradigm shift, and thus, a powerful motivator for change is necessary. Many of us who have embraced an approach based on structural preservation have done so only after stepping out of the comfort zone when faced with the evidence from our own clinical observations. Moreover, as aestheticians rather than bioengineers, we are averse to analyzing structural failure from a mathematical point of view. The philosophy of structural optimization has merged with the trends toward elevation of the soft tissue envelope in the subperichondrial/subperiosteal plane, preservation of the nasal dorsum, and advances in suture-based manipulation of the lower lateral cartilages into a new philosophical approach to primary aesthetic rhinoplasty.8 These founding principles are risk-averse in that they preserve the structural integrity of the nose, avoiding the need for complex reconstructive rhinoplasty for primary failures.5 Thus, although the tenacious popularity of the L-strut is acknowledged, it is hard to justify from a structural point of view. Rather, the computationally sound “delta strut,” with optimized axial load distribution and foundational stability, is better placed to support aesthetic remodeling and withstand the vicissitudes of time. As preservation techniques gain traction within the rhinoplasty community, the preeminence of the L-strut will become increasingly challenged until a new paradigm is established. ACKNOWLEDGMENTS This article does not contain any studies with human participants or animals performed by any of the authors. For this type of study, informed consent is not required. DISCLOSURE G.E. Glass is a member of the British Association of Aesthetic Plastic Surgeons. All the authors have no financial interest to declare in relation to the content of this article.