Fate of the TRAM Flap after Abdominoplasty in a Rat Model

Abstract

During a classical abdominoplasty, all musculocutaneous perforators from the deep inferior epigastric vessels are normally divided. Even if somehow neovascularization could relink the abdominal skin and rectus abdominis muscles, reestablishing these same discrete perforators would be unlikely because of the barrier effect of the abdominal wall fascia. Therefore, a lower transverse rectus abdominis musculocutaneous (TRAM) flap intuitively should not regain sufficient vascularity for viability after a prior abdominoplasty, and a history of the latter should be expected to be a major contraindication for this procedure. Nevertheless, anecdotal observations of successful lower TRAM flaps following abdominoplasty seem to contradict our basic principles, which may need better further elucidation. Consequently, this two-stage study in Sprague-Dawley rats was undertaken, initially performing an abdominoplasty in all rats. This was followed 1 or 10 months later by the creation of an unipedicled superiorly based TRAM flap that incorporated virtually all of the abdominal skin. From our identical historical TRAM flap control (n = 5) except without prior abdominoplasty, 72.8 +/- 12.83 percent of this area survived. TRAM flaps raised 1 month after the abdominoplasty (n = 6) had 2.2 +/- 3.4 percent or essentially no viability. Unexpectedly, the long-term group (n = 7) demonstrated 13.7 +/- 10.0 percent viability, ranging from 0 to 30 percent. Both groups of TRAM flaps after abdominoplasty had a flap survival area significantly less than that of the control by two-tailed group t test (p < 0.001), and that of the long-term group area was significantly greater than that of the short-term (p = 0.022). Lead oxide studies 10 months after abdominoplasty revealed no irrefutable evidence of the reestablishment of rectus abdominis perforators to the integument, although obviously some reconnections had formed at the microcirculatory level to partially revascularize some flaps. The range of viability of the long-term rat TRAM flaps documented that for the majority, surviving surface area was minuscule even following a delay equivalent to a human decade after abdominoplasty (1 rat month - 1.1 human years), yet rarely sufficient revascularization did indeed occur, which could explain the prior unusual clinical successes. However, the basic principle that a TRAM flap raised following a classical abdominoplasty at any time would be a risky maneuver seems to still be a valid concept.