A full-thickness defect limited to less than one-third the width of the vermilion and the underlying orbicularis muscle can be closed by creating an advancement flap from the remaining vermilion (Fig. 9.5). A full-thickness incision is made along the vermilion border incorporating the labial artery in the flap. The vermilion portion of the orbicularis oris muscle is also included in the flap. The length of the incision must be kept sufficient to allow for adequate stretch of the flap to cover the entire defect.

Defects greater than one-third the width of the vermilion can be closed using a single pedicle cross-lip vermilion flap (Fig. 9.6) or a bipedicled vermilion flap from the opposite lip. This flap is based on the axial blood supply from the labial artery and is performed in the similar manner to the bipedicled mucosal flap described above except the orbicularis muscle and labial artery are incorporated into the flap.

Partial-thickness cutaneous defects of the lips occur more commonly in the upper lip than in the lower lip due to the higher prevalence of basal cell carcinoma in the upper lip region. The principles of reconstruction for partial-thickness lip defects are similar to those for other facial subunits. Strict attention to the relaxed skin tension lines (RSTLs) and the borders of the lip and perioral subunits are paramount to an esthetic outcome. The RSTLs for the lips course in a radiant fashion around the mouth and reflect the perioral rhytids of older patients. These lines are oriented perpendicular to the underlying orbicularis oris fibers. The borders of the lip subunits include the nasolabial creases, nasal sill, alar bases, philtral columns, vermilion borders, and labiomental crease. Incisions that are placed parallel to or along the RSTLs and borders of the esthetic subunits are less conspicuous than those placed perpendicular to these lines. Moreover, it is preferable to confine tissue transfer within the esthetic region of the lips, unless this causes excessive distortion of surrounding structures such as the nasolabial crease.

The reconstructive ladder gives a useful framework that stratifies options by level of complexity and includes primary closure, healing by secondary intention, skin grafting, local flaps, regional flaps, and microvascular free flap. There are no absolute indications for a particular reconstructive method, and preferences vary by individual surgeon and geographic regions. Microvascular free flaps are usually reserved for a massive composite defect and are rarely used for partial-thickness cutaneous defects and are discussed in detail elsewhere in the textbook and later in this chapter.

Some small cutaneous defects along the nasolabial crease away from the lip vermilion may be left to heal by secondary intention. Wounds near the lip or large defects may exhibit excessive wound contraction and distortion of the vermilion if led to heal by secondary intention. Skin grafts are used for small defects only when local flap reconstruction is not readily available. The lip is a relatively mobile tissue, necessitating proper immobilization of skin grafts for successful take. Preferred skin donor sites include the supraclavicular region and the postauricular region due to their good color match with the facial skin. Full-thickness skin grafts are preferred over split-thickness skin grafts because of their better color match and lower tendency for secondary contracture [26].

Most surgeons prefer to reconstruct cutaneous lip defects by primary closure or with local flaps due to their superior esthetic results. Small cutaneous lesions can be excised in an elliptical fashion and closed primarily. The elliptical excision is oriented with its long axis along the anatomic subunit borders or the RSTLs of that region of the lip. A vertical closure extending beyond the vermilion border may contract and result in pull from the vermilion border. If possible, incisions for primary closure should stop before crossing the vermilion border using a W-plasty. Likewise, elliptical excisions should avoid extension beyond the nasolabial or mental crease lines using a W-plasty. A W-plasty may also reduce tissue redundancies, particularly near the free margin of the lip. Cutaneous defects near the vermilion border can also be closed in an A-T fashion, which entails creation of a triangular defect with its base along the cutaneous-vermilion junction for excision of a lesion. On both sides of the triangular defect, the incision is extended along the cutaneous-vermilion junction to develop two rotational flaps. The final T-shaped closure has favorable scars in RSTLs and along the anatomic subunit borders.

Local flaps offer a functional recovery, high success rate, and excellent esthetic outcomes for large size wounds not amenable to primary closure. Local flaps can be categorized into transpositional flaps, rotational flaps, and advancement flaps. In addition, Burow’s triangles can be incorporated into a flap design as needed to prevent a “dog-ear” deformity. In any local flap design, it is preferred to line up as many closure lines with the RSTLs or the anatomic subunit borders as possible.

Simple excision of a small lip cancer often results in a full-thickness semicircular defect. As long as the defect is less than 30 % of the lip, it can be primarily closed without tension. However, this type of closure results in puckering or notching of the lip margin. Therefore, additional tissue should be trimmed to make the defect either “V”-shaped or pentagonal (Figs. 9.7 and 9.8). This method is similar to the excision of a circular lesion on a skin with an elliptical incision to facilitate closure without a “dog ear.” The orbicularis oris muscle on both sides of the defect must be sutured together in order to reestablish the continuity of the oral sphincter. After sturdy closure of the orbicularis oris muscle, the vermilion-cutaneous junctions on both sides are carefully reapproximated and sutured. The accuracy of this realignment is crucial to the esthetic outcome of the reconstruction. A “step-off” along the vermilion-cutaneous junction can be easily recognized as a flaw to human eyes. Some surgeons elect to tattoo the vermilion border or the white line before injection of local anesthetics with a tuberculin syringe and methylene blue because of tissue blanching and distortion [5]. The rest of the mucosa, vermilion, and skin of the chin are then closed. After closure of the wound, placement of steri-strips can minimize tension across the closure.

When the defect is in the midline of the lip, the width of the vermilion on each side of the defect should be equal. However, because the vermilion tapers laterally, lateral defects usually have a mismatch in the vermilion width between two sides of the defect. This problem can be solved by making the incision along the lateral limb of the “V” in an oblique fashion, increasing the width of the lateral vermilion to match the wider medial vermilion (Fig. 9.9).

For larger defects that extends further inferiorly on the lower lip, either a “W”-shaped excision or a shield-shaped excision may result in less tissue loss, permitting primary closure. Moreover, a “W” excision allows primary closure without violating the labiomental crease and chin subunit (Fig. 9.10).

When lip resections result in a rectangular defect, advancement flaps from the adjacent tissue can be performed with a primary closure (Fig. 9.11). Excision can be planned so that the base of the rectangle is placed along the mental crease or nasal sill for better esthetic results. Burow’s triangle excisions are usually necessary at the lateral limits to prevent “dog-ear deformities.” The orbicularis oris is reapproximated with resorbable sutures, recreating the complete ring of oral sphincter. The mucosal margins are reapproximated and sutured with resorbable sutures in an everted fashion to provide a watertight mucosal seal. The skin is closed with nylon or prolene sutures with meticulous realignment of the vermilion border (Fig. 9.12) [3].

Medium defects are defined as approximately 30–80 % of the vermilion width. Most of these defects are satisfactorily reconstructed by redistribution of the remaining lip tissue without any need for regional or distant flaps (Fig. 9.13).