Hyaluronic acid (with fibronectin) as a bioimplant for the vocal fold mucosa

Objectives: To measure the viscoelastic shear properties of hyaluronic acid , with and without fibronectin, and to compare them with those of the human vocal fold mucosa and other phonosurgical biomaterials. Methods: Viscoelas tic shear properties of various implantable biomaterials (Teflon, gelatin, collagen, fat, hyaluronic acid, and hyaluronic acid with fibronectin) were measured with a parallel-plate rotational rheometer, Elastic and viscous sh ear properties were quantified as a function of oscillation frequency (0.01 -15 Hz) at 37 degrees C. Results: The shear properties of hyaluronic acid w ere relatively close to those of human vocal fold mucosal tissues reported previously. Hyaluronic acid at specific concentrations (0.5%-1%), with or w ithout fibronectin, was found to exhibit viscous shear properties (viscous shear modulus and dynamic viscosity) similar to those of the average male a nd female vocal fold mucosa. Conclusions: According to a theory that establ ishes the effects of tissue shear properties on, vocal fold oscillation, ph onation threshold pressure (a measure of the ease of phonation) is directly related to the viscous shear modulus of the vibrating vocal fold mucosa. T herefore, our findings suggest that hyaluronic acid, either by itself or mi xed with fibronectin, may be a potentially optimal bioimplant for the surgi cal management of vocal fold mucosal defects and lamina propria deficiencie s (e.g., scarring) from a biomechanical standpoint.