Revision medialization thyroplasty with hydroxylapatite implants.

INTRODUCTION Medialization thyroplasty is a useful tool in the management of dysphonia and dysphagia with aspiration secondary to unilateral vocal fold impairment. A variety of implant materials have been used for medialization thyroplasty including silicone elastomer (Silastic, Dow Corning Corporation, Midland, MI), expanded polytetrafluoroethylene (Gore-Tex, Gore, Newark, DE), and hydroxylapatite (VoCoM, Gyrus ENT, Bartlett, TN). Successful revision with like-material replacement of both Silastic and Gore-Tex medialization thyroplasty has previously been reported; however, no similar description exists for hydroxylapatite revisions. The approach to revision is dependant upon the initial implant material due to varying degrees of incorporation of the prosthesis into the surrounding tissues. Histologic examination following implantation of either Silastic or Gore-Tex prostheses in a rabbit model demonstrated fibrous encapsulation. In contrast, following implantation of a hydroxylapatite prosthesis, osteogenesis with lamellar bone formation was identified between the thyroid lamina fenestra and the implant. This osteogenesis, that provides implant stability and decreased potential for migration, also creates difficulty in regard to removal due to loss of tissue planes. This article will address the surgical method of revision medialization thyroplasty when hydroxylapatite has been used as the initial implant material. In addition, we will present previously unpublished retrospective data to support the safety and effectiveness of this revision technique.