Introduction: Silk-hyaluronic acid (silk-HA), a vocal fold augmentation material used in humans since July 2020 for correcting glottic insufficiency has demonstrated long-term, durable results over 2 years after injection. Collagen ingrowth and fibrosis replacing the Silk-HA scaffold over approximately 18 months is expected and provides the durable effect. Both patients presenting with follow up periods greater than 3 years as well as patients who need additional silk augmentation but were lost to follow up from the pandemic are now available. Outcomes from cases that represent these two groups will be presented.

Methods: Retrospective chart review from patients who underwent Silk-hyaluronic acid vocal fold augmentation from 2020-2021. Patients were divided into two groups. The “reinjection” group is comprised of patients who were reinjected with Silk-HA at least 18 months after their first injection. The “long-term follow-u” includes patients who presented for follow-up at least 3 years after a satisfactory Silk-HA augmentation. Voice Handicap Index-10 (VHI) and videostroboscopic findings were analyzed. Descriptive analysis was performed.

Results: Eight patients met the inclusion criteria for reinjection (62.5% female) - a fibrotic area that had developed was appreciated during needle placement. This made additional augmentation more challenging but not impossible. Four patients had follow-up longer than 3 years. Three (75%) had stable VHI and considered their voice quality stable. Silk-HA augmentation effect was visually unchanged in all four patients (100%).

Conclusion: Silk-HA demonstrates a lasting effect for at least 3 years in a small cohort who underwent some of the earlier Silk-HA augmentations. Patients who required further augmentation with Silk-HA in a delayed fashion (18 months or more after initial augmentation) demonstrate the expected fibrosis where the material was originally injected. This was evident through more challenging transnasal endoscopic needle placement and material delivery.