Prefabrication of combined composite (chimeric) flaps in rats

The purpose of this study was to prefabricate a new combined composite (chi meric) flap that consists of four different tissues. The tissues were prefa bricated around two independent pedicles that ultimately join as a single m ain pedicle. In the inguinal area of 36 rats, the saphenous and the superfi cial inferior epigastric (SIE) pedicles were dissected and prepared as vasc ular carriers. A fascial graft and a local muscle flap were wrapped around the saphenous pedicle. The SIE pedicle was then implanted under the abdomin al skin to supply a future skin flap. An ear cartilage graft was also inser ted under the abdominal skin and adjacent to the implanted SIE pedicle. Aft er allowing 2-, 4-, 6-, and 12-week prefabrication periods in different gro ups of nine animals, the prefabricated tissues were raised around two pedic les nourished by the femoral pedicle and then transferred, Flap survival wa s assessed by observation, microangiography and histology, The skin flaps s howed survival rates of 52 +/- 17% (mean +/- standard error of the mean), 6 4 +/- 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 t hat 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-wee k (p < 0.02), and 6- and 2-week (p < 0.05) prefabrication groups. Histologi cally, 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 f laps in these groups. The muscle showed mild (at 2, 4, and 6 weeks) and mod erate (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 prefabr ication.