Ultrastructural alterations of polytetrafluoroethylene prostheses implanted in abdominal wall provoked by infection: Clinical and experimental study

Infection of an expanded polytetrafluoroethylene (ePTFE) prosthesis after i mplant is a major drawback of its use in current clinical practice. The aim of the present study was to compare the behavior of such prostheses implan ted into New Zealand rabbits with that of prostheses infected after clinica l implant. Experimental implants of ePTFE Soft Tissue Patch were performed to repair defects (7 x 5 cm) created in the abdominal wall of 10 rabbits. P rior to implant the prostheses were contaminated with Staphylococcus aureus . Five animals implanted with noncontaminated ePTFE prostheses served as co ntrols. All the animals were sacrificed at 30 days after implant, For the c linical study, specimens were taken from three ePTFE implants that had been found to be infected after intervention. The clinical and experimental imp lant specimens were processed for light microscopy and scanning electron mi croscopy. Macroscopic and microscopic examination of experimental and clini cal implants revealed alterations to the ePTFE structure, such as areas of fragmentation, fracture lines, and detachment of fine layers of ePTFE that harbored numerous Staphylococcus colonies. Neoformed tissue around contamin ated implants was arranged more loosely, and on occasion large spaces betwe en fibers gave rise to an "unknitted" appearance with respect to the contro l implants. It may be concluded that microporous ePTFE prostheses show simi lar behavior following experimental or clinical implant in the presence of infection. Irreversible changes to the structure of the prosthesis are prod uced owing to colonization of the biomaterial by microorganisms, which in m ost cases necessitates total replacement of the prosthesis.