Rheology of Vocal Foldx

The purpose of this study was to compare the functional biomechanical properties of some injectable phonosurgical biomaterials commonly used for vocal fold augmentation. Linear viscoelastic shear properties of cross-linked hyaluronic acid (HA; Juvederm®), micronized AlloDerm (Cymetra®), 3% bovine collagen (Atelocollagen), and calcium hydroxylapatite (CaHA; Radiesse®) were determined as functions of frequency covering the phonatory range, and compared to those of the human vocal fold cover. Measurements of elastic shear modulus (G’) and dynamic viscosity (η’) were made up to 250 Hz with a controlled-strain simple-shear rheometer. Linear leastsquares regression was conducted to curve-fit log G’ and log η’ versus log frequency, and statistical analysis was performed with one-way ANOVA. There were statistically significant differences in the magnitudes of G’ and η’ among the phonosurgical materials and the normal human vocal fold cover (p<0.01), whereas there was no significant difference (p<0.05) in pairwise comparisons among all materials and the normal vocal fold cover. The rheometric properties of Juvederm and Atelocollagen were the closest match to those of the vocal fold cover. These findings suggest that none of the tested injectable biomaterials are ideal implants for facilitating the functional vibratory performance of the vocal fold cover. Future studies for the development of materials with optimal viscoelastic properties are warranted.