Tissue repair after orbital reconstruction using polypropylene mesh implants: A histological study in dogs / Reparo tecidual após reconstrução de órbita com implante de malha de polipropileno: um estudo histológico em cães

Purpose: This experimental study aimed to assess the histological outcomes of orbit reconstruction with a polypropylene mesh implant in an animal model using dogs. Methods: The right and left orbits of 12 dogs were fractured in order to simulate orbital fractures similar to those occurring in humans as a result of trauma. The orbits were reconstructed with a polypropylene mesh positioned approximately 10 mm beyond the bone defect borders. The 24 orbits were divided into four groups of six: one group was given one polypropylene mesh layer; another group received two layers; a third group was given three polypropylene mesh layers; and the fourth group did not receive any implant (control group). The dogs were divided into clusters of four animals and were euthanized 15, 30, or 60 days after the surgery. The orbit medial wall was removed, and samples were subjected to histological polypropylene mesh analysis by optical microscopy. Data were analyzed using a non-parametric test with a 5% level of significance. Results: It was found that the polypropylene mesh caused a mild to moderate tissular reaction. Conclusion: The implant was well tolerated even with two or three overlapping layers.

Objetivo: Trata-se de estudo experimental em que se reconstruíram os continentes orbitais de 12 cães com implante de tela de polipropileno. Metodologia: Os continentes orbitais foram fraturados simulando as fraturas orbitais que ocorrem em humanos devido ao trauma e reconstruídas com tela de polipropileno cortadas com extensão de cerca de 10mm além da margem do defeito ósseo. Utilizaram-se uma, duas ou três camadas de tela de polipropileno nas órbitas teste e algumas órbitas, somente fraturadas, serviram como controle. Os cães foram sacrificados nos tempos de 15, 30 e 60 dias de pós-operatório; os tecidos das órbitas teste e controle foram removidos e preparados para análise histológica em microscopia óptica. Os resultados obtidos pela análise histológica foram submetidos a análise estatística não paramétrica com 5% de significância. Resultados: A tela de polipropileno causou reação tecidual de leve a moderada nos tecidos. Conclusão: O implante foi bem tolerado, mesmo quando a tela foi superposta em duas ou três camadas.

Removal of Silicon-associated Intraorbital Cyst with Gingival Sulcus Incision

PURPOSE: Alloplastic implants, such as Silastic(R) , Supramid(R) , Porous polyethylene, Teflon(R) have been used to prevent reherniation of orbital tissue and are known to be inert for many years, though complications are infrequently reported many years after their insertion. Complications associated with implants are infrequent, but infection, orbital hemorrhage, implant extrusion, motility restriction, migration of implant causing dacryocystitis, cystic formation have been described. The latter was known as a rare late complication of blow-out fracture repair. METHODS: We report the case of a discovery of a intraorbital hemorrhagic cyst which developed after silicon implant insertion. This patient developed diplopia, unilateral proptosis, exophthalmos, vertical dystopia, ectropion 10 years after repair of blow-out fracture. In this case, orbital CT scan revealed intraorbital cyst surrounding the orbital implant. At surgery, a fibrous capsule surrounded the silicon implant and was filled with mucin pools. RESULTS: Proptosis, diplopia, exophthalmos, ectropion, vertical dystopia were resolved after surgical removal of the cyst and implant. CONCLUSION: This case illustrate that it is important for us to be aware of the complication of cyst formation around the silicon implants.

Comparison of Physical & Histological Change of Alloplastic Implants after Implantation in Rat

Augmentation rhinoplasty is one of the most popular aesthetic procedure in Asians. Numerous alloplastic implants have been used until now, but no accurate comparative analysis about the implant materials has been reported yet. This study in animal model was designed to determine the safety and effectiveness of various implant materials in augmentation rhinoplasty. The 15 x 15 x 2 mm sized square shaped plate of Gore-Tex(R), silicone rubber, and 15 x 15 x 1.5 mm sized Medpor(R) were implanted under panniculus carnosus of the abdomen wall of rat. And tissue specimens including the implant and surrounding soft tissue were obtained by en bloc excision in 6 months after implantation. The implants were estimated in weight and volume, and also the specimens were examined grossly and microscopically. The results revealed that increase of average weight 26.9%, decrease of average volume 55.4% in Gore-Tex(R) implant, increase of each average weight and volume 62.6%, 8.7% in Medpor(R) implant and very slight increase of both average weight and volume 4.7%, 1.1% in silicone rubber implant. Grossly, the Gore-Tex(R) was deformed, Medpor(R) was strongly adherent to surrounding soft tissue and the silicone rubber was well encapsulated and easily peeled off. Microscopically, silicone rubber showed foreign body reaction slightly and there were no inflammatory responses in all alloplastic implants. In our study, silicone rubber showed very proper alloplastic features for augmentation rhinoplasty due to causing no inflammatory response, no physical change, and no deformity.

Hematic cyst formation after repair of blow-out fracture

Alloplastic implants are known to be inert for many years, though complications are infrequently reported many years after their insertion. We report the case of a patient who had undergone a blow-out fracture repair five years before the discovery of a hematic cyst. He had been free of symptoms for the first five years after his orbital floor repair but then developed pain on eyeball movement and persistent vertical diplopia, which finally led to surgical intervention. At surgery, a hematic cyst was found to have formed around the implanted silastic plate. When alloplastic material is used in orbital fracture repair, we should be alert for late complications which may occur many years after surgery.