RESUMO
Dermal substitutes are used as dermal regeneration templates to reduce scar formation and improve wound healing. Unlike autografts, dermal substitutes lack normal vascular networks. The increased distance required for diffusion of oxygen and nutrients to the autograft following interpositioning of the substitute dramatically affects graft survival. To evaluate the effect of collagen-chitosan scaffold thickness on dermal regeneration, single-layer collagen-chitosan porous scaffolds of 0.5-, 1- and 2-mm thicknesses were fabricated and used to treat full-thickness wounds in a one-stage grafting procedure in a rat model. Skin-graft viability, wound contraction, histological changes, and wound tensile strength were evaluated. The results indicated that the distance for the diffusion of oxygen and nutrients to the autograft in the 2-mm-thick scaffold provided less support for graft take, which resulted in graft necrosis, extensive inflammatory reaction, marked foreign-body reaction (FBR), rapid scaffold degradation, and abnormal collagen deposition and remodeling. In contrast, the thinner scaffolds, especially of that 0.5-mm thickness, promoted earlier angiogenesis, ensuring skin-graft viability with a mild FBR, and ordered fibroblast infiltration and better collagen remodeling. It can be concluded that collagen-chitosan porous scaffolds with a thickness of <1mm are more suitable for dermal regeneration and can be used as dermal templates for treatment of dermal defects using a one-stage grafting procedure.
Assuntos
Materiais Biocompatíveis/química , Quitosana/química , Colágeno Tipo I/química , Regeneração/efeitos dos fármacos , Transplante de Pele/métodos , Pele/efeitos dos fármacos , Alicerces Teciduais , Animais , Materiais Biocompatíveis/efeitos adversos , Materiais Biocompatíveis/farmacologia , Bovinos , Reação a Corpo Estranho/induzido quimicamente , Masculino , Teste de Materiais , Fenômenos Mecânicos , Porosidade , Ratos , Ratos Sprague-Dawley , Pele/citologia , Pele/metabolismo , Transplante de Pele/efeitos adversos , Sobrevivência de Tecidos/efeitos dos fármacosRESUMO
<p><b>OBJECTIVE</b>To introduce an operation for fingertip reconstruction.</p><p><b>METHODS</b>The vascularity of the reverse dorsal island flap is augmented by performing an arteriovenous anastomosis between the dorsal vein in the flap and a digital artery at the fingertip. The flap was used in ten patients for reconstruction of their fingertip defects.</p><p><b>RESULTS</b>All the ten flaps survived and the appearance was good.</p><p><b>CONCLUSION</b>The method is easy except for the necessity of performing standard microvascular surgery. The flap is a good option for repairing fingertip defects.</p>
