Chapter 77. Local Skin Flaps in Facial Reconstruction

This chapter presents a basic overview of the approach to reconstruction of cutaneous facial defects with local skin flaps. Emphasis is placed on the understanding of the anatomy, evaluation of a defect, and design of an appropriate local skin flap.

Essentials of Diagnosis

For successful local flap reconstruction of facial defects, the surgeon must have a thorough understanding of thefollowing.

• Biomechanics of soft tissues
• Vascular supply to the face and given skin flap
• Aesthetic subunits and the relaxed skin tension lines of the face (RSTL)
• Dimensions and depth of the defect
• Inherent structural characteristics of the native skin in the area of the defect (ie, thickness and sebaceous character).

Successful reconstruction of facial defects requires a thorough understanding of skin anatomy and physiology, careful analysis of the defect, and meticulous soft tissue techniques. Options for reconstruction should generally proceed from least invasive to most invasive in terms of morbidity. This approach is termed the “reconstructive ladder.” Most facial defects that are too large for primary closure are amenable to local flaps. When planned and executed properly, local flaps allow for rapid reconstruction with a reliable blood supply, minimal morbidity, and excellent cosmesis. This chapter reviews the classification of commonly used local skin flaps and outlines the use of local flaps for facial reconstruction. In considering the appropriate surgical approach for a given defect, the surgeon should not forget that secondary intention healing is a viable option for concave areas of the face.

When possible, local flaps should be designed in the same aesthetic unit as the initial defect. Lines of excision should usually be made parallel to relaxed skin tension lines (RSTL) or along aesthetic borders to optimize scar camouflage. If the defect involves multiple aesthetic subunits, it may be necessary to use a separate flap for each subunit. If more than 50% of a subunit is involved, the defect may be enlarged to reconstruct the entire unit with a flap. Placing incisions parallel to RSTLs reduces tension on wound closure by placing maximal tension into lines of maximal extensibility (LME). Skin tension and its distribution are important to avoid distortion of key facial landmarks such as the eyelid, lip, and the nasal ala.

Local skin flaps can be classified either by their blood supply or by the method of transfer. (Table 77–1)

Flap Blood Supply

Surgeons must be familiar with the vascular supply of a local flap, either random (supplied by the dermal and subdermal vascular plexuses) or axial (supplied by a named artery and vein). Most axial flaps have some random blood supply at their distal ends.

The blood supply to a random skin flap is derived from musculocutaneous perforating arteries near the base of the flap. The distal portion of the flap is perfused by interconnecting subdermal plexuses located at the junction between the deep reticular dermis and subcutaneous fat. These vessels communicate with more superficial dermal plexuses located at the papillary ridge to the dermal–epidermal junction. Rhombic and bilobed flaps are examples of random pattern flaps.

Axial (arterial) pattern skin flaps are perfused by a direct cutaneous artery within the longitudinal axis of the flap. Axial flaps typically have improved survival lengths compared to random pattern flaps due to this vascular supply. The surviving length of axial flaps is related to the length of the cutaneous artery. Flap necrosis secondary to ischemia can occur at the distal portion of the flap if the length exceeds the arterial length, where the flap is dependent on random pattern blood supply. A common example of an axial flap is the paramedian forehead flap, which is supplied by the supratrochlear artery.

This chapter will classify local flaps according to classic transfer methods. In reality, many local flaps actually are combinations of these classifications.

Advancement Flaps

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.

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).

The V–Y 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

Pivotal flaps are transferred about a pivotal point from the donor site to the defect. Pivotal flaps include rotation, transposition, and interpolation flaps.

Rotation 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.

Interpolation Flaps

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.

Transposition Flaps

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.

Bilobed 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.

Disadvantages of the bilobed flap include the curved, complex incision lines, disruption of nasal subunits, and limitation to relatively small defects.

Z-Plasty

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).

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.

Rhombic Flap

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.

Nose

For full thickness defects, three-layered reconstruction generally preserves function and minimizes the contraction. The effect of scar contracture is most prominent at the nasal alar subunit and can cause major deformity and nasal airway obstruction. The nasal subunits should be considered when planning reconstruction. The subunit rule states that if more than 50% of the subunit is removed, the entire subunit should be removed for optimal camouflage of incisions.

In general, defects of the upper two thirds of the nose that involve the dorsal and/or sidewall subunits are reconstructed with thinner, less sebaceous skin than that used in the lower third of the nose. The paramedian forehead flap, an interpolation flap supplied by the supratrochlear artery, provides abundant tissue, with excellent color and texture matching, and it can reliably be used to cover the entire nasal surface. Disadvantages of the flap are the vertical forehead scar, and the limited length in nonhair bearing forehead skin, and the need for a second stage procedure to divide the pedicle.

Defects involving the lower third of the nose can be more challenging to reconstruct due to its complex contours and thicker, more sebaceous, skin. The bilobed flap is an excellent flap for defects smaller than 1.5 cm. Alar notching and retraction may occur if the defect is less than 10 mm from the alar margin. If the entire tip subunit is involved, a paramedian forehead flap should be considered. For subtotal tip defects, a full-thickness skin graft or composite auricular cartilage graft is another option, although this may provide a less desirable color and texture match.

Cheek

Cheek defects can vary in depth and may present as a challenge to match the contour of the surrounding tissue. The skin of the cheek is relatively thick with reasonable elasticity. Primary closure along RSTLs is the simplest and best reconstructive option for small defects. However, for medium-to-large defects, local flap coverage is required.

Simple transposition flaps, including the rhombic flap can be used successfully in the cheek region, but incisions placed perpendicularly to the RSTLs should be avoided. These flaps are generally limited to the lateral aspect of the cheek.

The most common local flap used for cheek reconstruction is the cervico-facial advancement rotation flap. Large amounts of tissue can be recruited from the cheek and cervical skin to cover large defects, without causing significant secondary deformity. The lower medial area of the cheek near the alar-facial junction is frequently amenable to repair with island pedicled flaps.

Forehead

Bilateral advancement, or H-plasty, is a commonly used flap for closing forehead defects. In this procedure, bilateral lateral-to-medial advancement flaps are used to close square or round defects, and the incisions are placed in existing forehead furrows. An O–T flap is a variation of bilateral advancement flaps, which can also be used successfully in the forehead.

We would like to acknowledge Nathan Monhian, MD, Shan R. Baker, MD, and Jeffrey Wise, MD for their contribution to this chapter in the previous editions of CDT.