This chapter will classify local flaps according to classic transfer methods. In reality, many local flaps actually are combinations of these classifications.
Advancement flaps have a linear configuration where an adjacent tissue is advanced linearly to cover a primary tissue defect. Advancement flaps are subclassified as simple, single pedicle, bipedicle, and V–Y flaps. These flaps are particularly useful in reconstructing forehead, lip, and eyelid defects.
Single-Pedicle Advancement Flaps
These rectangular flaps are created by making two parallel incisions extending from the border of the defect, ideally along RSTLs when possible (Figure 77–1). A length-to-width ratio of 1:1 to 2:1 is ideal and should not exceed 3:1. The flap and its pedicle are then advanced into the defect. The tension in these flaps is in the direction of the advancement. Undermining around the defect minimizes tension and promotes better scarring along the incisions. Burow's triangles may be used to remove standing cone deformities, which may be excised anywhere along the longer side.
Single-pedicle advancement flap.
Bipedicle Advancement Flaps
These flaps are designed to allow advancement into the adjacent defect in a vector that is perpendicular to the flap axis (Figure 77–2). These flaps are generally used to close a defect in an area of high visibility by moving the defect into an area of low visibility (eg, from the forehead to the scalp).
Bilateral advancement flap.
This flap is unique among advancement flaps in that it is pushed rather than stretched into the defect. The donor flap, which is usually triangular, is advanced, and the resulting donor defect is closed in a straight line. This approach results in a suture line with a Y configuration. A skin island advancement flap is an example of a V–Y advancement flap.
Pivotal flaps are transferred about a pivotal point from the donor site to the defect. Pivotal flaps include rotation, transposition, and interpolation flaps.
In rotation flaps, tissue is moved curvilinearly about a pivot point into an adjacent defect. These flaps are designed so that the leading edge of the flap is also a border of the defect. By doing so, a facial defect is filled by creating another defect that may be closed with less tension or distortion. Burow's triangle at the base may be excised to assist in rotation and closure. Rotation flaps are usually based inferiorly to promote lymphatic drainage. Rotation flaps are commonly used for medium to large defects involving the cheek, neck, and scalp.
The interpolation flap is similar to the transposition flap in that the flap is moved about the pedicle and transposed across intervening tissue; however, with an interpolation flap, the pedicle rests over the intervening tissue. The pedicle must be divided and inset at a second stage after neovascularization occurs. A common interpolation flap is the paramedian forehead flap.
A transposition flap is created so that the donor site is remote from the defect, while the base of the flap is immediately adjacent to the defect. The flap is moved about the pedicle and transposed over the intervening tissue into the defect. Like rotation flaps, transposition flaps exploit skin laxity at a site distant to the surgical defect and redirect the tension of closure. Examples of the transposition flap include the bilobed flap, Z-plasty, and rhombic flap.
The bilobed flap is a double transposition flap consisting of two lobes based on a single pedicle. It is designed to recruit adjacent skin from areas of more laxity to areas of deficiency. The primary lobe is adjacent to the defect and designed to have a diameter equal to that of the defect. The secondary flap is used to repair the primary flap donor site and is approximately one-half the diameter or more of the primary lobe. The secondary donor site is closed primarily.
The traditional design of the bilobed flap was described with a 90° angle of transfer between each lobe, for a total transposition of 180°. Zitelli modified the arcs of rotation to an angle of 45° between each lobe, limiting transposition to 90°, in order to minimize dog ear and trapdoor deformities that can occur with the larger angles (Figure 77–3). The bilobed flap is ideal for reconstructing cutaneous defects <1.5 cm or less in size. These flaps are particularly useful in nasal tip reconstruction. Defects of the nasal ala are generally approached with medially based bilobed flaps, whereas tip defects are closed with laterally based flaps.
Zitelli modification of bilobe flap, resulting in a 90° rotation, minimizes standing cutaneous deformities, and trap-door deformities. (A)—skin defect and flap design. (B)—rotation of flap and closure of the defect.
Disadvantages of the bilobed flap include the curved, complex incision lines, disruption of nasal subunits, and limitation to relatively small defects.
Z-plasty is a double transposition flap consisting of two triangles, each with independent pivot points. One triangular flap is transposed about its pivotal point in a clockwise direction, while the other flap in a counter-clockwise direction, to its triangular recipient site. Wide undermining at the base of each flap is necessary to achieve proper flap movement. For scar revision, the scar should be positioned in and oriented along the central long limb of the Z (Table 77–2).
Table 77–2. Angle Design for Z-Plasty Influences Scar Length. ||Download (.pdf)
Table 77–2. Angle Design for Z-Plasty Influences Scar Length.
|Angle Size||Length Increase|
Z-plasty is used to change the direction of the scar to relieve scar contracture at the expense of lengthening the final length of the scar. The wider the angle of the triangular flaps, the greater the length of the final scar, but this also results in larger standing cutaneous deformities. Flaps with angles of 30°, 45°, and 60° result in elongation of the final scar by approximately 25%, 50%, and 75%, respectively.
While relatively large Z-plasties can be used in the neck, those on the face ideally should be designed so that the limbs are 0.5 cm or less. If the scar being revised is longer than 0.5 cm, multiple Z-plasties should be used. Z-plasty can help reorient scars to be more parallel to RSTLs.
The classic rhombic flap originally described by Limberg is a transposition flap used to repair a rhombus-shaped surgical defect with equal side lengths, two opposing 60° angles and two opposing 120° angles (Figure 77–4). This configuration creates a short diagonal (which bisects the 120° angles) that is equal in length to the sides of the rhombus.
The flap is designed by extending the line of the short diagonal a length equal to the diagonal, which is also the same length as the side of the defect. A second line is then drawn of equal length parallel to either adjacent side of the defect. Every rhombic defect has four potential flaps that can be designed due to having two potential lines drawn in either direction. The point of greatest wound closure tension is at the closure site of the donor defect. Donor site closure should be parallel to the LME and perpendicular to RSTLs.
The Dufourmentel flap is a variation of the classic Limberg rhombic flap. This flap is designed to close rhombic defects with any two opposite angles rather than the 60° and 120° angles. It is particularly useful for repair of rhombic defects with acute angles of 60° to 90° where excision of excess skin is undesirable.
A disadvantage of the rhombic flap is a more visible scar than with other flaps because approximately half of the incisions are not parallel to RSTLs. Rhombic flaps are particularly helpful in repairing defects on the cheek and temple, where skin creases are less prominent.
Borges AF. The rhombic flap. Plast Reconstr Surg. 1981;67:458–466. (Design and technique of a rhombic flap.)
Larrabee WF. Design of local skin flaps. Otolaryngol Clin North Am. 1990;899–923. (Excellent review of the design of local skin flaps.)
Zitelli JA. The bilobe flap for nasal reconstruction. Arch Dermatol. 1989;125:957–959. (Classic paper describing the bilobe flap as described and modified by Zitelli.)