Combined cremaster muscle and inner thigh skin composite flap: a novel experimental flap model in the rat

Unlike the composite musculocutaneous flap models, the combined composite muscle-skin flap model allows evaluating muscle and skin viability independently, because it has an independent blood supply to the muscle and skin component. However, to our knowledge, only two combined muscle-skin flaps have been reported to date. During our cremaster dissection in our laboratory, we perceived a new vessel as a terminal continuation of the pudic-epigastric artery (PEA) on which the cremaster muscle flap is raised. Therefore, we designed this study to determine whether the scrotal and inner thigh skin can be harvested with the cremaster muscle as a combined cremaster muscle-skin composite flap. Thirty male Sprague-Dawley rats were used in this experiment. In five rats, ink study selective to the PEA marked a skin territory. In 15 rats, cremaster muscle and 4 x 3 cm ipsilateral scrotal and medial thigh skin flap was raised on the PEA. Fluorescein study after 4 hours showed fluorescein stain in the skin island. On postoperative day 7, both muscle and skin components of the flaps were viable. Microangiographic study after the flap elevation revealed the vascularity of all components of the flap and clearly identified the branch to the skin island. To the best of our knowledge, this is the first report describing the combined flap model including the cremaster muscle. Our flap seems to have an important advantage over the other combined muscle-skin flap models in terms of the cremaster muscle being suitable for the intravital microscopy. Additionally, the two components of the flap have separate nutrient vessels with adequate length, which gives the flap flexibility in the placement of the skin component in a location distant from the muscle component. The flap may be also be raised as a skin flap without the cremaster muscle. It can be used for different applications, including microcirculatory, pharmacological, physiological, biochemical, and immunological studies as well as for transplantation studies.