Objective:
Glottoplasty, which raises fundamental frequency (F₀) by shortening the effective vibratory length of the vocal folds, is currently one of the most frequently performed pitch-elevation surgeries. Nevertheless, the isolated influence of horizontal suture depth within the vocal fold and of the subglottic extent of the suture line on postoperative voice remains undefined. Using an ex-vivo canine larynx model, we systematically simulated variations in suture depth and subglottic extension and quantified their impact on acoustic and aerodynamic parameters.
Methods:
Experiments were conducted on ex-vivo larynges harvested from mongrel dogs. The study consisted of two independent protocols: (1) Suture-depth variation—single sutures were placed at the anterior one-third of the vocal fold through the mucosal layer (superficial), the vocal ligament (intermediate), or the thyro-arytenoid muscle (deep). (2) Subglottic-extent variation—sutures were progressively extended from the vocal-fold level to the subglottic plane and finally anchored to the thyroid perichondrium, always within the anterior one-third of the glottis. Each preparation was phonated on a calibrated bench-top apparatus driven by standardized airflow. Fundamental frequency (F₀), sound-pressure level (SPL), phonation threshold pressure (PTP), phonation threshold flow (PTF), and the derived phonation threshold power (PTW) were acquired.
Results:
(1) Across the three suture-depth conditions, no significant inter-group differences were observed for F₀, SPL, PTP, PTF, or PTW (all P > 0.05).(2) Among the three subglottic-extent conditions, SPL, PTP, PTF, and PTW likewise showed no significant differences (all P > 0.05), whereas F₀ exhibited a significant group effect (P < 0.05). Post-hoc pairwise comparisons revealed that the thyroid-perichondrium anchorage group achieved a markedly higher F₀ than both the vocal-fold-only and subglottic-suture groups (P 0.05).
Conclusion:
(1) In this ex-vivo model, incremental deepening of the horizontal vocal-fold suture does not provide additional F₀ elevation, indicating limited benefit of deep-layer suturing for pitch raising.(2) Extension of the suture to the thyroid perichondrium significantly increases F₀ without imposing additional aerodynamic load, offering an experimentally grounded modification for clinical glottoplasty.