Prefabrication of combined composite (chimeric) flaps in rats.

The purpose of this study was to prefabricate a new combined composite (chimeric) flap that consists of four different tissues. The tissues were prefabricated around two independent pedicles that ultimately join as a single main pedicle. In the inguinal area of 36 rats, the saphenous and the superficial inferior epigastric (SIE) pedicles were dissected and prepared as vascular carriers. A fascial graft and a local muscle flap were wrapped around the saphenous pedicle. The SIE pedicle was then implanted under the abdominal skin to supply a future skin flap. An ear cartilage graft was also inserted under the abdominal skin and adjacent to the implanted SIE pedicle. After allowing 2-, 4-, 6-, and 12-week prefabrication periods in different groups of nine animals, the prefabricated tissues were raised around two pedicles nourished by the femoral pedicle and then transferred. Flap survival was assessed by observation, microangiography and histology. The skin flaps showed survival rates of 52 +/- 17% (mean +/- standard error of the mean), 64 +/- 16%, 86 +/- 11%, and 100 +/- 0% of the total areas in the 2-, 4-, 6-, and 12-week prefabricated flaps respectively. None of the control grafts that were prepared on the contralateral side survived totally. A significant difference was found between the 12- and 2-week (p < 0.008), 12- and 4-week (p < 0.02), and 6- and 2-week (p < 0.05) prefabrication groups. Histologically, fascial and cartilage grafts, and portions of muscle were viable in the 2- and 4-week groups. Also, noticeable necrosis was found in the skin flaps in these groups. The muscle showed mild (at 2, 4, and 6 weeks) and moderate (at 12 weeks) atrophy. After prefabrication for 6 weeks, all tissues demonstrated good survival. This study shows that a combined composite flap can be prefabricated successfully in rats after a 6-week period of prefabrication.