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Introduction
CHAPTER 23 Transposition Flaps
Thuzar M. Shin Jeremy R. Etzkorn Joseph F. Sobanko Christopher J. Miller
SUMMARY
With transposition flaps, the position of the main tension vector is changed from
the primary defect to a more ample adjacent tissue reservoir, and the elevated flap is transposed under little to no tension.
The ability of transposition flaps to push tissue into the defect by redirecting
tension vectors perpendicular to the primary closure direction, coupled with their ability to close a defect using a smaller total surface area than sliding flaps (and the possible added benefit of a broken-up repair line), make these flaps particularly useful for larger facial defects.
Beginner Pearls
The pinch test may be useful to assess both the primary wound and nearby tissue
reservoirs.
Visualizing a rhombic flap as a rotation flap with a large backcut helps illustrate the
consequence of pivotal restraint on flap movement.
Expert Pearls
The takeoff point can influence flap vascularity and length, and is usually at the
midpoint of the defect.
The nasolabial single-lobed transposition flap is useful for reconstructing defects of
the ala, though this flap can appear thick and pincushion without a precise undermining plane and tacking sutures to recreate the alar groove.
Donโt Forget!
The curved lines that result from most transposition flaps require meticulous suturing,
as they rarely fall along cosmetic subunit junctions or relaxed skin tension lines. This attention to detail is particularly critical for successful execution of flaps on sebaceous skin, such as the distal nose.
Taking off from the long axis of an asymmetric defect requires a greater arc of rotation
and flap length, which both threaten the flapโs blood supply. Distal takeoff points narrow the pedicle and compromise the blood supply.
Pitfalls and Cautions
Pincushioning, or trapdoor deformity, may occur with transposition flaps, especially
on the nose. Several etiologies have been suggested, such as excessive flap thickness, inadequate undermining, and circumferential wound contraction. Strategies to minimize pincushioning include appropriately sizing the flap, careful suturing of all anatomic layers, and closing any dead space under the flap. If intralesional corticosteroids do not resolve pincushioning, surgical thinning may be necessary.
Patient Education Points
When recruiting tissue from distant sites, transposition flaps may not match the contour,
texture, and hair density of the defect. Surgeons may counsel patients when additional procedures, such as staged surgery or hair removal, are anticipated.
Transposition flaps that span multiple facial subunits may ablate cosmetic subunit
junction lines. Patients may be prepared for the possibility of staged reconstruction to restore a concave subunit junction, such as the alar groove or melolabial fold.
Billing Pearls
Flap repair codes (140XX series) include the excision component, so it is not
appropriate to bill both an excision and a flap repair code simultaneously.
Mohs codes may be submitted along with flap repair codes, though they may be subject
to the multiple-procedure reduction rule.
When coding a flap, medical necessity is the ultimate arbiter of appropriateness.
CHAPTER 23 Transposition Flaps
INTRODUCTION
Transposition flaps are often useful when tension at the primary defect precludes sideto-side closure or the use of sliding flaps, such as advancement or rotation flaps. To transpose means to switch positions, which aptly describes the flapโs essence, as the position of the main tension vector is changed from the primary defect to a more ample adjacent tissue reservoir, and the elevated flap is transposed into the primary defect under little to no tension. Common transposition flaps include the rhombic (singlelobed), bilobed, and trilobed flaps, though the latter two flaps, in particular, involve a significant rotational component.
The ability of transposition flaps to push tissue into the defect by redirecting tension vectors perpendicular to the primary closure direction, coupled with their ability to close a defect using a smaller total surface area than sliding flaps (and the possible added benefit of a broken-up repair line), make these flaps particularly useful for larger facial defects.