on the forehead and upper lip to hide incision lines along relaxed skin tension lines and cosmetic unit junctions.

Another commonly employed bilateral advancement flap is an O-to-T flap, also termed on A-to-T or a T-plasty, analogous to a bilateral L-plasty. The standing cone is removed from one end of the defect, creating a triangle or transforming on “O” into an “A.” Single incisions extend from the base of this triangular defect, and the two sides of the triangle slide together along this baseline. The T-plasty is best performed with the broad base along a free margin or cosmetic unit junction (e.g., lip, eyebrow).

33.4.3 Crescentic Advancement

The crescentic advancement flap utilizes the removal of a small crescent of tissue along an advancement flap to either better hide the scar line or increase the length of the line to prevent distortion. This flap is particularly useful for the repair of upper lip and perialar

defects. The superior standing cone is removed in a crescentic shape around the ala such that the superior scar line is placed in the perinasal sulcus (Fig. 33.5) [13]. For defects on the upper cutaneous lip, the inferior cone is removed along relaxed skin tension lines (Fig. 33.6) of the upper lip. If the inferior cone approaches the vermillion border, it is best to extend the cone through the vermillion border and terminate it in the wet mucosa to prevent downward distortion of the vermillion. A modification of the crescentic advancement includes the repair of a small, perialar defect of the medial cheek where both cones are removed around the ala, and the entire scar line is placed in the nasal sulcus, similar to the cheek advancement. Another modification of this type of flap is the East–West flap or modified Burow’s advancement flap of Dzubow [14]. This flap is used in nasal tip and supratip defects that are off midline. The Burow’s triangle is designed to extend inferiorly down the midline of the nose into the columella, and the flap is advanced horizontally into place (Fig. 33.7).

a

b

c

Fig. 33.6 Crescentic advancement flap upper lip

33.4.4 Island Pedicle

A subcutaneous island pedicle flap, also referred to as a V–Y advancement flap, may be considered as a variation of an advancement flap that has had all of its connections to the epidermis and dermis severed,

maintaining its blood supply through a subcutaneous tissue pedicle (Fig. 33.8) [15]. The flap is designed within cosmetic units when possible and, as with all repairs, it is optimal for the incision lines to run along cosmetic junctions. The island pedicle flap is frequently used on nasal and perioral closures where free margins are at risk for distortion. The tension vectors of an island pedicle flap are primarily in the same direction as that of a primary closure; however, they are displaced distal to the wound (i.e., superior to the nasal tip, superior or lateral to the vermillion border) and help avoid distortion of the area around the defect.

An island pedicle flap is created by extending two non-parallel tangential incisions to meet at an approximate 30° angle, similar to when planning a Burow’s triangle. The difference is that the incision lines stay essentially parallel for a short distance before converging, creating a slightly larger triangle than would be created with a Burrow’s triangle. This extra length gives tissue that more closely approximates the size of the defect and minimizes local distortion. The triangle may be designed larger or smaller depending on how much tension sharing is desired. Incisions are made into the superficial subcutaneous tissue. The tip and sides of the flap are undermined widely extending outward from the flap in the subcutaneous plane. The triangular flap is also undermined slightly to help mobilize it. The flap is then advanced into the defect and sutured into place. In order for the flap to fit properly into a circular defect, either the corners of the flap must be trimmed or the defect squared off. The flap must be undermined with attention both to the mobility of the tissue as well as to the maintenance of a subcutaneous vascular pedicle. While the initial design should have a broad pedicle, if mobility is limited, the pedicle may be progressively diminished (particularly at the trailing tip of the flap).

When closing defects on the nasal dorsum and tip, a muscular flap is often created laterally on one or both sides. For this musculocutaneous island pedicle flap, undermining is performed both above and below the nasalis muscle. If there is not enough laxity to close the defect without upward tension on the nasal tip, the muscular flap is released horizontally at the superior and inferior edge to create a muscular sling that advances with the flap into place. The muscular attachment gives a robust blood supply to the flap and helps ensure its survival.