7 - Transposition Flaps

Abstract

A transposition flap is a random-pattern flap that borrows skin laxity from an adjacent area to fill a defect in an area with little or no skin laxity. If performed correctly, the result of this flap is a change of the tension vectors in the region, leading to improved cosmetic and functional outcomes over what would be an otherwise tense closure. This technique is especially valuable in preventing the distortion of free margins. The flap gains its name from the “transposition” or movement of a flap of donor tissue up and over normal/uninvolved tissue to its resting place within the surgical defect. The flap movement is often rotational in nature from its pedicle base to the surgical defect. Great care must be taken in the design of the flap as to not overrotate or put excessive tension on the flap such that the vascular pedicle is compromised. Transposition flaps are advantageous in that they can often be smaller than comparable repairs using advancement or rotational flaps, and the geometric design used eliminates long suture lines, which can otherwise distort the natural curvature and appearance of the repair region. In addition, the transposition flap adds another method by which nearby tissue matching the defect area closest in color and texture can be used in the repair. The most common transposition flaps in cutaneous surgery include rhombic flaps (single-lobed flaps), bilobed flaps, and banner flaps, such as the nasolabial flap. Knowledge of the tissue dynamics used in these three basic transposition flaps can be carried over to the planning and execution of numerous flap variations, including note flaps, trilobed flaps, and tetralobed flaps. Although sometimes technically complex in their design and execution, in the hands of a skilled surgeon, transposition flaps can produce a beautiful surgical outcome without distortion of free margins.