Histomorphometric Study of Tissue Reaction of Gore-Tex Implant in the Rat Model

Lew, Dae Hyun; Kim, Sung Mim; Ahn, Seang Joon; Park, Beoyung Yun

Abstract

To reconstruct the defect caused by losses of bone, cartilage and soft tissue, either autogenous tissue or alloplastic material can be used. Although the autogenous tissue is ideal choice for their reconstruction, the availability and problems associated with donor site morbidity limit its usage. Therefore the alloplastic material have been used widely for tissue replacement. Many synthetic material have been developed for alloplasty; among these, the silicone has been the most popular alloplastic material for plastic surgeon. Inherent problem related to the use of silicone are infection, exposure, implant migration, capsular formation, and poor penetration of bone or soft tissue into the implant. To solve these problems, many effort have been made. From 1970s the porous high density polyethylene(HDPE, Medpor) and expanded polytetrafluorethylene(Gore-Tex), which are porous substance, have been used because those have the advantage of less implant migration by the penetration of connective tissue into the pore, less capsule formation and reduced chance of infection due to high vascularity. The purpose of this study is to compare the tissue reaction of silicone and Medpor with that of Gore-Tex in rats. The 1.0 cm sized square shape plate of silicone, Medpor and Gore-Tex were implanted in the back of rat and bloc tissue specimen were obtained including the implant and their surrounding capsule in 4, 8, 12 weeks after implantation. The specimen were examined grossly and microscopically. The microscopic slide were prepared with H-E and Masson's trichrome stain. Grossly the capsule around the silicone rubber was easily peel off while the capsules around Medpor was strongly adherent to implant and that of Gore-Tex was mildly adherent to implant. Under microscope, the thickness of capsule were compared. 1he capsule of those implants were thicker in 4 weeks then 8, 12 weeks. The capsule of silicone were significant thicker than Medpor and Gore-Tex in 4 weeks (274.8+ 35.1 um vs 119.8+23.2um vs 177.2+27.9 um). Histologically the capsule of silicone and Gore-Tex consist of denser connective tissue and showed lesser foreign body reaction than Medpor. Many multinucleated giant cells were found around the Medpor, while none of them were found around silicone and Gore-Tex. The capsule of Medpor showed more new capillary formation than silicone due to tissue ingrowth into the pore in the implant material so Medpor fixed hardly around the soft tissue and was impossible to remove. But Gore-Tex, that is microporous alloplastic material, have less capsular formation, less foreign body reaction and limited tissue ingrowth and stabilization of implant while at the same time permitting easy removal when necessary. From this study the Gore-tex will be useful alloplastic material in clinical usage by virtue of limited tissue ingrowth and decreased chance of infection, implant migration and capsular formation.