Subcutaneous island pedicle flaps allow for substantial tissue mobilization. This is accomplished by selectively and carefully disrupting connections to the surrounding tissues to elevate and mobilize a subcutaneous pedicle. A balance must be established between releasing restraint and maintaining a sufficient blood supply to ensure flap viability. Single stage island pedicle flaps have been utilized since the late 19th century,1,2 and an excellent review of the technique was published as early as 1965 by Barron and Emmett.3 It was Esser, who is best known for the original design of the bilobed flap, who first called this an island flap. Because of the geometric outcome of the typical island pedicle flap the most common variant has widely been referred to as a V-Y advancement.4
An island flap design isolates an island of skin on a vascularized deep fatty pedicle,4,5–7 a deep muscular pedicle,8 a lateral fatty pedicle,9–11 a muscular sling,12,13 or a dedicated axial vascular bundle14,15 (Fig. 5.1). The construction of the pedicle determines both the mobility and the vascularization of the flap. The primary motion of an island may be either advancement or transposition.3,16,17 Island flaps may be quite complex and require substantial conceptual understanding. For example, full thickness wounds of the lateral ala may be repaired with turnover nasolabial island flaps that recreate both an internal lining and an external nare.
Island flaps may be nourished by a number of pedicle subtypes. (A) A deep pedicle. (B) A laterally based fatty pedicle. (C) A lateral pedicle based on a muscular sling. (D) A purely vascular pedicle based on a named artery and vein
GEOMETRY AND FLAP DYNAMICS
It is easiest to begin a discussion of island flaps with a simple design, namely the island pedicle advancement flap. As a typical advancement flap, the subcutaneous island pedicle flap may be unilateral or bilateral. In modern usage the unilateral island is more common. The most common design is a deep triangular cutaneous island in which the secondary defect is closed in a V to Y fashion. The first step in island flap creation is the same, no matter how the pedicle will be designed, is an incision along the triangular perimeter of the flap, through dermis and into the superficial subcutaneous fat. This releases superficial lateral restraint from the dermis and disrupts only the relatively insignificant dermal vascular plexus.
The full-thickness dermal release creates the cutaneous island on a broad and deep vascular base. For the most basic island, the surrounding tissues are then undermined beneath dermis, allowing the flap to advance. In practice, this rarely creates enough release to allow the flap to advance and repair the adjacent operative wound, for restraint still exists at ...