Utility and safety of commercially available injection laryngoplasty materials in a rabbit model.

OBJECTIVE: To demonstrate foreign body and chronic inflammatory reaction of commercially available injection materials using the rabbit vocal fold paralysis model. STUDY DESIGN: Animal study. METHODS: The left recurrent laryngeal nerve was identified and divided at the tracheoesophageal groove. Amounts (100 µL) of phosphate-buffered saline (PBS), polyacrylamide hydrogel (Aquamid; Ferrosan A/S, Søborg, Denmark), calcium hydroxyapatite (Radiesse; BioForm Medical Inc., San Mateo, CA), or hyaluronic acid derivative (Rofilan; Rofil Medical International, Breda, Netherlands) were injected into the left vocalis muscle. Six months later, the larynx was harvested. Hematoxylin/eosin and Masson trichrome staining were performed to compare inflammatory and foreign body reactions, granuloma development, and relative vocal fold areas among groups. RESULTS: Compared with the PBS (control) group, the Aquamid, Radiesse, and Rofilan groups exhibited only mild chronic inflammatory reactions that did not significantly differ among groups, or from controls (P > 0.05). However, the Aquamid and Radiesse groups exhibited moderate foreign body reactions that were significantly greater than those of controls (P < 0.05). No foreign body granuloma formed in any group. All test groups exhibited significant increases in vocal fold areas at 6 months (P < 0.05). CONCLUSIONS: Although commercially available injection materials induced more foreign body reactions than a control injection of PBS, no foreign body granuloma developed and the augmented vocal fold area was maintained until 6 months after injection.