To demonstrate foreign body and chronic inflammatory reaction of commercially available
injection materials using the rabbit vocal fold paralysis model.
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.
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).
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.