Injectable biomaterials for vocal fold augmentation: biomechanical principles, clinical outcomes, and emerging regenerative strategies

Disorders of the vocal folds, including atrophy, scarring, and paralysis, frequently result in glottic insufficiency, impaired phonation, and reduced quality of life. Injection laryngoplasty has become a cornerstone treatment for these conditions by restoring vocal fold volume and improving glottic closure through the injection of biomaterials into the thyroarytenoid muscle or paraglottic space. A variety of injectable biomaterials are currently available, including hyaluronic acid, calcium hydroxylapatite, human collagen, autologous fat or fascia, hematogenous biomaterials, and synthetic polymers such as polydimethylsiloxane. These materials differ considerably in their viscoelastic properties, biocompatibility, degradation kinetics, durability, and capacity for host tissue integration. Hyaluronic acid-based fillers closely mimic the mechanical properties of the vocal fold lamina propria and may support extracellular matrix remodeling, whereas autologous fat and fascia offer longer-lasting augmentation with variable long-term persistence. Despite significant clinical improvements in voice quality and glottis competence, their therapeutic effects remain largely structural, providing passive medialization without restoring native tissue microarchitecture or biomechanical function of the vocal folds. Consequently, next-generation biomaterials are increasingly being designed to combine mechanical support with regenerative functionality by promoting extracellular matrix remodeling, preserving mucosal wave propagation, and enhancing long-term tissue integration. This review provides a translational overview of injectable biomaterials for vocal fold augmentation, integrating their clinical performance with biomechanical properties, biological compatibility, and emerging regenerative strategies for functional vocal fold restoration.