Montgomery's Aperture: An External Anatomic Landmark for Surgical Identification of the Anterior Commissure

Abstract

Objectives: This study evaluates the consistency of palpable identification of an external landmark for the anterior commissure (AC), termed Montgomery's aperture (MA), in cadaveric and surgical settings.

Methods: Part 1: In human cadaveric larynges, palpation of the external laryngeal framework was used to identify MA by three blinded otolaryngologists. The vertical height (VH) of the thyroid cartilage and distance from MA to the inferior border of the thyroid cartilage were measured, larynges were bisected, and the AC was identified and measured. Surface anatomy was demonstrated visually using 3D imaging. Part 2: Retrospectively collected case series used palpation of MA in thyroplasty type 1 (TT1) and compared the result to ½ VH.

Results: Part 1: MA was identified in seven cadavers by three surgeons. In four of seven MA was palpated at the location of AC. The average difference between the AC and MA was -0.95 ± 0.96 mm. The average difference between AC and ½VH was 0.08 ± 0.72 mm. Part 2: In 49 patients (57% females) who underwent TT1, MA correlated within ½VH in 67% of cases. MA was inferior to ½VH in 27% of cases, on average 1.08 mm ± 0.51 mm below ½VH. MA was not palpable in 6% (3 of 49) of patients.

Conclusion: We define the MA as the external indentation or flattening of the thyroid cartilage located within 1 millimeter inferior or at ½ VH of the thyroid cartilage. MA is a reliable, reproducible, palpable landmark for the anterior commissure. It serves as an important landmark that can be used in laryngoplastic surgery in which accurate prediction of the glottis is important.

Keywords: Anterior commissure; Larynx; Montgomery's aperture; Surgical landmark; Thyroplasty.