Histopathologic study of minced and injected expanded polytetrafluoroethylene (Gore-Tex) in quadriceps muscle of rats for injection laryngoplasty

Objective Gore-Tex has not yet been used as an injection material, and no animal study has been performed. The purpose of this study was to investigate the histopathological and volumetric changes of minced and injected expanded polytetrafluoroethylene (Gore-Tex) in the quadriceps muscle of rats to find out its possibility as an injection material in future injection laryngoplasty. Design A prospective study was performed in 13 Wistar rats. Methods The 50 ± 5 mg Gore-Tex vascular graft was minced until it was fine enough to pass through a 16G injection cannula. To create viscosity in order to avoid precipitation, minced Gore-Tex was mixed with sodium hyaluronate (SH) gel. 0.5 ml of this mixture was injected into the middle part of the right quadriceps muscle of each subject. Then, pure SH (0.5 ml) was injected into the middle part of the left quadriceps muscle of each subject. To compare the volumetric and histopathological changes of the injection area occupied by the materials over the time, two rats were sacrificed 1 day after the procedure, four rats after 1 month, four rats after 3 months and three rats after 6 months. Results In pure SH: SH was observed as an effusion in the muscle of one subject on the first day only. We did not detect SH in the muscle in the first, third and sixth months and, as a result, there was no augmentation. Inflammation and fibrosis was not detected in any of these applications of SH. In minced Gore-Tex + SH gel mixture: SH was again eliminated from the muscle in a very short period of time, but the remaining Gore-Tex created a 15.8% volumetric gain. Fibrosis and capsule formation began in the first month and, in the sixth month; we observed connective tissue surrounding the Gore-Tex material. Ingrowth of connective tissue into the Gore-Tex, though not present in the first month, occurred partially in the third and significantly in the sixth month. In addition, we observed foreign body granuloma formation after the third month. Conclusions Pure SH, though easily applicable, was immediately eliminated leaving no trace. In the relatively difficult applications of Gore-Tex mixed with SH, however, there was residual Gore-Tex present in all subjects throughout the study. Gore-Tex may be an applicable material for injection laryngoplasty.