In vivo ovine flap model to evaluate surgical infection and tissue necrosis

Although the inciting causes and the end results of soft tissue infection are well described, we have not achieved a quantitative methodistic description of the sequence of events in between. The following study presents an isolated in vivo model which will allow specific manipulations and quantifications of the events of integumentary infection. Pedicle flaps were raised on the buttock of the adult range ewe and it was multiply inoculated with Staphylococcus aureus, and followed for 96 hr. This pedicle contains not only a well-defined artery, vein, and nerve, but also a well-developed efferent lymphatic vessel. In addition, the distal portion of the flap is primarily supplied by a musculocutaneous arterial perforator, making the distal flap a watershed area. Anatomic, radiologic, and vital stain injection studies confirmed these results. The sheep model was found to be superior to the pig model both in terms of its anatomy (the addition of an efferent lymphatic vessel) as well as the disposition of the sheep which was more compliant than that of the pig. We believe that this flap will allow multiple manipulations and provide an in vivo isolated system to study the pathobiology of soft tissue infection.