14 Reconstruction of the Lip
Summary
The human lip has many important functions and dynamic, complex anatomic relationships. The ideal reconstruction requires a strong understanding of the techniques available to the surgeon. The proper selection of technique demands a nuanced review of the literature as well as meticulous planning and execution. It is important to optimize both the function and appearance of lips in oral reconstruction.
14.1 Introduction
The lip is a major defining feature of the human face. It is a complex, dynamic soft-tissue structure that represents a major facial aesthetic subunit. The lip has many functions, including speech production, tactile sensation, facial expression, communication, and maintenance of an oral seal. Facial surgeons are often tasked with reconstructing various defects in this region. A thorough understanding of lip anatomy is important to enable the best reconstructive outcome. This chapter is a review of the reconstructive options available for surgeons who repair defects of the lip.
14.2 Background
As with many modern surgical reconstruction techniques, lip reconstruction has a rich and far-reaching history. Early reports of lip repairs are included in an ancient book Sushruta Samhitawritten by Sushruta sometime between 600 and 1,000 BC. 1 , 2 Advances in lip reconstruction were relatively stagnant until the 16th century, when Italian surgeon Gaspare Tagliacozzi developed reconstructive techniques using pedicled arm flaps to the nose and lip. 3 Later, in the 18th and 19th centuries, cross-lip techniques were pioneered by Johann Gustaaf Hjertzeel, Sabattini, Abbe, and Estander. 4 , 5 In the 19th century, German Victor von Bruns introduced the vermilionectomy for lip malignancy in early H- and T-plasty and superiorly based flaps for lower lip reconstruction. It was also during this time period that Dieffenbach may have first introduced vermillion reconstruction using a pedicled cheek mucosa. 6 More recently, Walton and Bunkis 7 and Sakai et al 8 were the first to publish microsurgical reconstructive techniques of the upper and lower lips. These pioneers established the basis for our modern techniques.
14.3 Anatomic Considerations/Relevant Anatomy
The face can be divided into vertical thirds from menton to trichion. The lip is positioned in the bottom third of the face, situated between the menton and the subnasale. The lip is bounded by the nose superiorly, labiomental crease inferiorly, and melolabial crease bilaterally. The lip is one of the seven aesthetic units of the face. The surgical anatomy can further be divided into the white lip and red lip. In contrast to lip mucosa, which is pink, the vermillion represents the darker colored fleshy folds and exists as a dry transition zone between the skin and mucous membrane. The upper vermillion is usually thinner than lower vermillion in both men and women. 9 The upper lip is also on average 15 to 17% larger than the lower lip. 9 , 10
14.3.1 The Upper White Lip
The upper lip can be further broken down into the philtral dimple, philtrum columns or ridges, melolabial/nasolabial folds, Cupid’s bow, and vermilion border (see ▶ Fig. 14.1). The Cupid’s bow is located at the midline upper lip and is classically V-shaped. The philtral columns or ridges represent the vertical raised tissue extending from the apices of the Cupid’s bow to the nose. The philtral dimple is the depression between the columns. The upper lip can similarly be divided into the philtrum centrally and two lateral upper lip components to the right and left of the philtrum. 11
14.3.2 The Vermillion
The vermillion is distinct in that it is devoid of minor salivary glands or eccrine glands, which are normally found throughout the oral cavity and its epithelium is thinner than that of oral mucosa. The rich vascular bed and a thin layer of keratinized stratified squamous epithelium of the vermillion are also responsible for its more red/rosy color. 12 The wet line (also known as the red line) represents the distinct transition between the intraoral labial mucosa and the transition zone of the vermillion. The tubercle or procheilon is the area of the upper lip that is prominent centrally.
14.3.3 Lip Function
The lips play a vital role in many aspects of our daily lives. They are important for tactile sensation, oral communication, and facial expression. The lips have a critical role in forming bilabial and labiodental sounds. Bilabial sounds “b,” “m,” “w,” and “p” are formed from the action of both lips. Labiodental sounds “f,” “v,” and “c” are formed from the interaction of the lips and teeth. 13 The lips also shape the mouth, creating a visual cue that aids communication for deaf or hearing-impaired patients in particular. One of the other vital functions of the lips is to prevent leakage of fluid or air. Without this type of oral competence, the patient will lack the ability to form the natural food/liquid barrier primarily at the lower and lateral lip regions, thus resulting in drooling. Lip adduction and food bolus containment is also necessary to initiate the oral phase of swallowing. A strong understanding of the lip functions and components, including nervous, muscular, arterial, mucosa, skin, and vascular components, must be mastered in order to optimize reconstruction.
14.3.4 Nervous Components
The lips contain a high density of nervous system structures. In fact, when studying the homunculus or pictorially mapped representation of brain sensation, the lips are proportioned larger than almost any body part. This is due to the many brain cells dedicated to lip sensation and movement. The motor innervation of the lip is provided by the facial nerves, which generally enter the facial muscles on the deep surface. 14
The sensory afferents are provided by the maxillary and mandibular divisions of the trigeminal nerve. The mental branch of the mandibular division provides sensation to the lower lip, which is important when judging food temperature and texture. Disruption of the nervous afferents and efferent may result in dyskinetic motion or inadvertent lip injury due to lack of sensation (e.g., biting, burns).
14.3.5 Muscular Components
The lip has several muscular components. The main muscle of the lip is the orbicularis oris, which provides the major sphincter control of the mouth. The varied muscle fiber orientation allows for dynamic expression and shaping of complex movements. The risorius, depressor anguli oris, depressor labii inferior, mentalis, buccinator, zygomaticus major, zygomaticus minor, nasalis, and depressor septi all attach to the orbicularis oris. Muscles of facial expression also insert adjacent to the oral commissure, forming a complex of muscle and connective tissue known as the modiolus.
As with any muscle group in the body, knowing the origin, insertion points, and muscle orientation allows one to predict the muscle’s action and vector forces. The deep perioral musculature provides oral cavity sphincter function, in contrast to the fine control allowed by the superficial muscles. Orbicularis oris muscle fibers decussate at the midline and insert into the dermis 5 mm from the midline, thus creating the philtral columns. 15 The philtral groove has no dermal attachment and therefore appears concave. 15
14.3.6 Arterial and Venous Supply
The arterial supply to the lips is primarily based off the facial artery system, a branch of the external carotid artery. The facial artery divides to form the inferior labial artery and superior labial artery. The proximal facial artery crosses the mandible to reach the face deep to the risorius/zygomaticus major and superficial to the buccinator muscle. The superior labial artery gives off the angular artery, which continues its course superiorly. This artery has several points of anastomosis to the contralateral side and buccal artery branches. The artery has a variable course either between the orbicularis muscle or between the muscle and mucosa. 16 Classically, it is found between 1 and 2 cm from the oral commissure. 17 The artery has been found to travel through the orbicularis oris muscle in half of patients and been found higher in the central parts of the upper lip. 12
The inferior labial artery branches from the facial artery near the oral commissure. It runs deep to the depressor angularis oris and to the orbicularis oris. This artery also forms an anastomosis with the contralateral side. The inferior labial artery may not always be present. Dissection studies have demonstrated variability in the presence of this artery from 10 to 64%. 16 , 18
There are additional vascular contributions to the lip from the maxillary artery. Both the buccal artery and the inferior alveolar artery are terminal branches of the maxillary artery and supply the lip region. The mental branch of the inferior alveolar artery finds its path to the lower lip after it courses along the mental foramen with the mental nerve. The buccal artery courses from the infraorbital region to the superficial face, paralleling the facial artery across the lateral oral region.
The veins draining the lip travel with the arterial supply and in the upper lip may be included in the “danger triangle,” which may drain to the cavernous sinus via the ophthalmic veins from facial veins. 19 This is the reason that infections in the upper lip region have the theoretical ability to cause intracranial infections.
14.3.7 Lymphatic Drainage
The lymphatic patterns of the lips must also be understood given the oncologic implications of many lip defects that result from malignancy. The lymphatic drainage from the latter upper lip drains to the submandibular nodes, periparotid nodes, and possibly to the submental nodes. 20 The upper and middle lip may drain to the submandibular, periparotid, and submental nodes. The lower lip drains bilaterally to the submental nodes in the center and submandibular and perifacial nodes laterally. 20
14.4 Reconstructive Procedures by Defect and Anatomical Site
14.4.1 Partial-Thickness Red Lip Defect (Vermillion Reconstruction)
Superficial lesions of the vermillion may be treated with vermilionectomy without sacrifice of deeper muscular layers. These defects present a unique clinical challenge for surgeons. The human eye is attracted to contrast in both color and shape; the vermillion has both of these attributes. Irregularities in the vermillion border are amplified as the human eye is drawn to the lips in conversation. Meticulous reapproximation of the oral/red lip interface minimizes what might otherwise be conspicuous repairs.
Primary Closure
Defects across the vermillion border and into the cutaneous (white) lip may be closed primarily. Again, it is important to closely and accurately reapproximate the vermillion border. A common technique to allow for the identification of the vermillion edge is the placement of hatch marks with a scalpel blade sharply, although the authors prefer marking with methylene blue or a skin marking pen. Vertical mattress sutures are often utilized at the vermillion border to optimize outcome.
Pedicled Mucosal Grafts
Mucosa from the tongue may be pedicled to the lip mucosa and later divided, producing good results. Numerous authors have described the use of dorsal tongue sutured to the vermilionectomy defect. The dorsal aspect of the tongue is used to prevent subsequent tongue tethering and nerve injury. The flap is then divided 3 to 4 weeks after inset. The tongue mucosa subsequently becomes smooth and closely resembles the normal red lip. The resultant lip flap is prone to drying and generally improves with time. 21 Free mucosal grafts from various donor sources have also been successfully accomplished for large defects of the upper and lower vermillion. 22
Mucosal Advancement Flaps
Mucosal advancement flaps have been used for more than 150 years for reconstruction of lip defects. Mucosal defects may be closed after vermilionectomy by advancing the vestibular or buccal mucosa to the cutaneous lip. 6 , 23 The mucosa may be undermined and freed in a submucosal plane with releasing incisions in the oral cavity to gain length. This reconstructive technique can produce very good cosmetic results, but tissue thinning and internal lip rotation are occasional sequelae. Volume deficiency may be addressed with fat or filler injections, but lip rotation is best addressed by anticipating and preventing it at the time of the primary operation. This reconstruction can also impart an unnatural wet appearance to portions of the vermillion, as well as result in a deeper red appearance. It is important to preoperatively counsel patients regarding these expected changes.
Vermillion Mucosal V-Y Advancement Flap
This technique can be used to advance small to medium-sized areas of mucosa to close vermillion defects. With this technique, a wedge-shaped portion of the mucosa is designed to be equal or slightly larger in width to the size of the defect, and then tapers to the apex of the V within the oral vestibular mucosa. The mucosal flap is generally elevated along with the orbicularis oris muscle underlying the flap in order to preserve vascularity. Although this technique transfers well-vascularized tissue, it has the risk of producing a trap door deformity, an area of raised or bulging tissue that can result from lymphatic or venous obstruction, scar hypertrophy, or excessive fatty or redundant tissue.
Cross-Lip Mucosal Flap
It has been proposed that disproportion between the upper and lower lip contributes significantly to the lip deformity following reconstruction. 24 By borrowing tissue from the larger and more redundant lower lip, this size disparity can be minimized. This is the main principle behind the cross-lip mucosal flap, which is a technique that can be used to repair large upper vermillion defects. The flap is raised from the contralateral lower lip mucosa onto the buccal mucosa beyond the commissure and pedicled at the midline. Following this, the vermillion flap is then sutured to the upper lip defect. The pedicle is divided in 7 to 10 days and trimmed. The upper and lower lips are then closed. 25
Facial Artery Musculomucosal Flap
The upper or lower lip vermillion may be reconstructed with this robust composite flap in a bilateral or unilateral manner. Intraoral mucosa is harvested from the lateral cheek as a composite flap along with the axial blood supply from the facial artery, lateral to the buccinator. 26 The flap is designed after using a doppler to identify the course of the facial artery, with its course marked along the mucosa with a pen. After the trajectory of the facial artery is marked, the borders of the flap are designed such that the flap is centered over the artery. This flap may be inferior or superiorly based depending on orientation and vascular supply. We often find it useful to make mucosal incisions with a colorado-tipped monopolar cautery. Following mucosal incision and muscular division, the distal (or proximal facial artery in superiorly based flaps) is identified and ligated. The flap is raised with the mucosa, submucosa and small amount of buccinator muscle. Satisfactory lip volume is achieved with this technique. Careful attention should be paid not to injure Stensen’s duct and to restrict the anterior aspect of the flap to 1 cm posterior to the commissure to ensure no external cosmetic deformity (▶ Fig. 14.2).
14.4.2 Partial-Thickness Cutaneous Reconstruction
Lip soft-tissue defects that do not involve the deeper muscular layers may be closed with little lip function implications. A focus on cosmetic outcome is the primary emphasis when reconstructing these defects. Again, the principles of respecting aesthetic subunits must be followed. All of the following closures involve dissection of skin and subcutaneous tissues overlying the muscles of facial expression/orbicularis oris.
Primary Closure
Cutaneous lip lesions may be primarily closed with tissue advancement. The defect may be made fusiform in nature and then closed without standing cutaneous cones. The closure must be oriented parallel to relaxed skin tension lines. 27 These lines usually are perpendicular to the underlying muscle direction. In young patients, the surgeon may study pictures of the patient’s older relatives to best determine the direction of closure. 27 This closure technique has the disadvantage of flattening the Cupid’s bow or distortion of the vermillion border. Some authors suggest up to 50% of the cutaneous upper lip may be closed primarily. 17 To avoid extension into the chin for a lengthy closure, an M-plasty may be designed.
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