Division of Dermatologic Surgery, Department of Dermatology, Stanford University School of Medicine, Stanford, CA, USA
Dermatologic surgeons are often faced with the repair of complex facial defects following Mohs micrographic surgery. While the size or absence of critical tissue layers may be daunting, the reconstruction of these complex defects follow similar principles to those for the closure of smaller, simpler defects. There are several issues specific to these closures including whether to delay closure in order to allow wound contraction, thus decreasing the size of the wound. Yet, if the defect is adjacent to a fixed anatomic structure, this may not be an option. The tumescent technique allows for effective anesthesia over large surface areas. Although choosing a method of closure may be specific to the anatomic area, if possible, it is best to choose a “workhorse” flap, e.g. multiple flaps or a flap and a full thickness skin graft. Occasionally, a tunneled pedicle flap may be appropriate. For large areas an artificial skin substitute may be necessary. While tissue expansion has a number of disadvantages, it may be the only option for large defects in immobile anatomic regions. While it would be optimal to close every Mohs defect, it is important to know when to refer a reconstruction that may require general anesthesia and/or hospitalization.
Tumescent, Bilobed, Paramedian, Mohs Defect
Increased public awareness of skin cancer, improved access to dermatologists, and greater availability of Mohs micrographic surgery have combined to decrease the average size of tumors and post-surgical defects. Yet, for a variety of reasons including socio-economic,psychologic, and tumor biology, the dermatologic surgeon may still encounter large facial defects. Previously, otolaryngologists and plastic surgeons repaired these types of defects under general anesthesia. However, dermatologic surgeons can now repair most large defects in an office setting using skin flaps and local anesthesia.
While there isn’t an exact size that determines the intricacy of repair, in general, a complex skin defect may be defined as one that is >50% of a cosmetic unit. Yet, defects are defined not only by their sheer size, but also by missing structures such as mucosal lining, cartilage, fat, and muscle, which are necessary for the subsurface framework.1 Accordingly, small defects on the nose or eyelid that include significant cartilage or posterior lamellar components also require complex closures.
Principles of Closure
When faced with a large repair, often there is a temptation to focus on the size, and to ignore fundamental principles of facial reconstruction. Not surprisingly, following these axioms will often facilitate closure of the surgical wound. These principles include determining if multiple layers must be replaced, locating the reservoir of skin, and maintaining both function and aesthetics.
If multiple layers are involved, the defect may require bulk or bulk-plus structure. For defects requiring bulk alone, muscle, or a fat graft may adequately fill the defect. For structural defects, calvarial bone, rib cartilage, nasal cartilage or auricular cartilage may be used to recreate the subsurface framework. These reconstructions most commonly involve the ear and nose.
Skin may be moved from a single cosmetic unit or from multiple adjacent sites and must be mobile enough to close the defect with minimal tension. When designing a flap to close a large defect, it is essential that the major tension vector is parallel to any nearby free margins to avoid distortion of critical units such as the eyelid, nasal ala, or oral commissure. In addition to placement of the flap incision, integrity of the cosmetic unit, layered closure, and wound eversion will promote a favorable aesthetic result.
To Wait or Not To Wait
The initial decision in closing a large defect is whether to delay the repair. This is often an appropriate strategy. Advantages include wound contraction, which closes the defect by shrinking it, as well as granulation, which improves the survival of delayed flaps and grafts. A disadvantage of delaying closure is that significant contraction may require up to 1 month, thus imposing substantial wound care challenges. Furthermore, contraction of large wounds may result in deformation of nearby structures such as the eyebrow, eyelid, nares, or mouth.
Large head and neck defects are routinely repaired using local anesthesia. The key to these repairs is the use of tumescent anesthesia (0.1% lidocaine with 1:500,000 epinephrine), which provides adequate anesthesia and excellent hemostasis. On rare occasions when patients need additional oral sedation or pain medication, 0.25mg of alprazolam (Xanax®, Pfizer) and one tablet of hydrocodone and acetaminophen (Vicodin®, Abbott) is usually sufficient. Tumescent solution is infiltrated slowly, usually requiring no more than 100mL, and reconstruction is begun after waiting 25–30 minutes. The advantages of tumescent anesthesia are its decreased risk of lidocaine toxicity, excellent hemostasis, and hydrodissection of tissue planes, thereby facilitating flap elevation.2 Nerve blocks and field blocks can also be utilized in conjunction with, or independent of, tumescent anesthesia, but because of redundant sensory nerve distribution on the head and neck, they often fail to achieve a full block when used alone.
Choosing the Flap
Deciding on the flap is partly dependent on the location of the wound, the lines of relaxation, and how the flap will affect fixed structures. In general, if one has a favored “workhorse” flap, it is often wise to use this method of tissue transfer because of its geometric familiarity. Additionally, scar camouflage is an important consideration for large defects. For defects on the cheek, this can often be achieved by using a rhombic flap with its relatively short, angular lines or with a cervico-facial rotation flap whose lines are confined to the periphery of the face. A bilobed flap is another alternative with its secondary lobes mostly hidden pre- and postauricularly.3
The depth of the wound also needs to be considered. A deep cheek defect may require an island pedicle flap with substantial fat or a muscular component. In both the lip and eyelid, multiple layers must be replaced when missing in order to restore both bulk and function. Full thickness lip defects may require a Karapandzic flap or, for more lateral defects, a staged Abbe-Estlander flap.4 Complex eyelid repairs may necessitate a lid sharing procedure such as the Hughes flap.
Repair of nasal defects follows the axiom of “replacing like with like.” For large nasal defects, this philosophy mandates replication of the inner lining, recreation of a subsurface framework, and restoration of proper skin thickness, texture, and color.5
For patients who have large, skin-only, tip and supratip defects, a birhombic repair or a Peng flap may suffice.6 When performing large flaps with multiple incision lines and wide undermining, addition of a cartilage brace is often beneficial even when the framework is intact. This helps prevent nasal valve compromise from extensive wound contraction.
For moderately large defects involving the nasal ala or lower sidewall, the one-stage Spear flap is an elegant method,7 although it often requires revision, thereby essentially converting it into a two-stage procedure. Alternatively, a staged melolabial flap provides a reasonable color match and a good vascular supply which enables detailed contouring. Traditionally, when this flap is contoured, it is defatted and inset. In selected patients with thin alar and narrow rims, the authors have shave-contoured the flap, which precisely recreates the rim.
For larger defects involving an entire nasal subunit or more, the paramedian forehead flap is often the repair of choice. Despite its complex design, it is a hardy flap, with a vascular supply based primarily on the supratrochlear artery along with branches of the infratrochlear artery.8 When recreating the alar rim, it is necessary to insert cartilage struts using auricular cartilage from either the conchal bowl or the anti-helix. The paramedian forehead flap is then used for coverage. Traditionally, this flap is divided and contoured at 3 weeks. In selected patients, the authors have divided the flap at 1 week and contoured at 3 weeks, improving patient quality of life.
While it can be tempting to repair a large defect with only a skin graft, the long-term results and health consequences of a large skin graft can relegate the patient to years of disfigurement, and difficulty breathing from contraction of the graft.
Combinations of Flaps/Grafts
Although it is always preferable to close a wound in one session, for large defects, delayed flaps can provide more reliable vascularization and superior long-term aesthetic results compared with skin grafting. On the scalp in particular, multiple rotation flaps in the form of a pinwheel may be needed to close a large defect.9 Bilateral transposition flaps can also close a large defect without causing significant alopecia. In other locations such as the cheek or forehead, a combination of flaps and a full thickness skin graft may be needed to close a large wound. Strategically, the full thickness skin graft can be taken from the dog ear created by the flap.10
Tunneling Pedicle Flaps
Though not as common in dermatologic surgery, plastic surgeons commonly use tunneled pedicle flaps for large head and neck defects. For regional repair on the forehead, a tunneled pedicle flap based on a branch of the superficial temporal artery can be raised laterally, and tunneled to cover a medial defect.11 Similarly, for a large nasal root defect, a glabellar flap based on the supratrochlear artery can be easily manipulated to cover fairly sizeable defects. The drawbacks of tunneled flaps include the relatively limited distance that they can travel and the common presence of a ridge above the pedicle, which negatively affects the final esthetics.
Tissue expansion has been frequently used in the past for large areas with immobile skin such as the scalp and forehead.12 This technique is effective, but significantly delays closure and can increase patient morbidity. In brief, the method involves dissection of a pocket and insertion of a silicone expander which is then filled with saline. Volume is added on a weekly basis for up to 2 months until the desired expansion is reached. The expander is removed, and the appropriate flap is performed. In addition to having to undergo an additional procedure, the expander is temporarily disfiguring, and there is a risk of infection.
Skin Grafts/Artificial Equivalents
For large defects on the head and neck, skin grafts are best used in conjunction with a skin flap since, in the large majority of patients, the use of large skin grafts alone will lead to inferior cosmesis. In patients with very large defects on the scalp and no contiguous donor site for tissue transfer, a split-thickness skin graft may be indicated. For smaller facial defects, the use of artificial skin substitutes, such as Apligraf® (Organogenesis) and Integra™ (Integra Lifesciences) have been reported as effective coverage methods.13 For deeper wounds, it is important to layer the Integra™ to fill the volume deficit, and if desired, Apligraf® can be applied on top of the Integra™.
When To Refer
The question of when to refer is more complicated than it appears. In addition to the size of the defect, it depends on factors such as the skill of the dermatologic surgeon, and the health of the patient. Generally, nasal defects involving the sinuses and upper nasal defects that require calvarial bone would be appropriate to refer to an otolaryngologist. Similarly, though many dermatologic surgeons repair eyelid defects, patients who have full thickness defects >50% of the lid may be best served by an oculoplastic surgeon. Extensive deep facial defects that involve multiple cosmetic subunits and have no discernible donor site may require a large regional muscle flap, such as a pectoralis flap or a free tissue transfer by either an otolaryngologist or a plastic surgeon. Full thickness lip defects, in which the repair will significantly decrease stoma size, require hospitalization. If they involve the oral cavity they may have more favorable results from an otolaryngologist or oral maxillo-facial surgeon. Finally, near total auricular defects that require rib grafts should generally be referred to a plastic or facial plastic surgeon.
A helpful technique for closing large wounds is the use of suspension sutures, also known as plication sutures. These sutures are commonly used in rhytidectomies to approximate deeper tissues and reduce wound tension. In brief, the technique involves an anchoring stitch to a stable structure such as the fascia or periosteum, and then taking a bite of tissue 1-2cm away from the initial bite, with approximation of these “edges” in a buried fashion.14 Large defects may require several plication sutures. They can work well on the cheek, particularly when performing a cervico-facial rotation flap. In this situation, plication sutures can also be used to elevate the malar fat pad in order to recreate the malar eminence.
Intraoperative tissue expansion may also be of value in closing a large defect. This type of expansion can be accomplished with either towel clamps or a series of temporary nonabsorbable sutures.15 Using this technique for as little as 30 minutes will lengthen enough of the collagen fibers to permit a better approximation of the skin edges. While this technique alone does not significantly aid closure of large defects, a combination of this type of expansion along with plication sutures and an appropriate flap will generally result in a satisfactory outcome. If the wound still will not close, a partial closure in many cases may be appropriate, followed by final closure in 2-3 weeks.
- Menick FJ. Reconstruction of the nose. In: Baker SR, Swanson NA, eds. Local flaps in facial reconstruction. St. Louis: Mosby p305-44 (1995).
- Acosta AE. Clinical parameters of tumescent anesthesia in skin cancer reconstructive surgery. A review of 86 patients. Arch Dermatol 133(4):451-4 (1997 Apr).
- Ricks M, Cook J. Extranasal applications of the bilobed flap. Dermatol Surg 31(8 Pt 1):941-8 (2005 Aug).
- Kroll SS. Staged sequential flap reconstruction for large lower lip defects. Plast Reconstr Surg 88(4):620-5 (1991 Oct).
- Burget GC, Menick FJ. The subunit principle in nasal reconstruction. Plast Reconstr Surg 76(2):239-47 (1985 Aug).
- Rowe D, Warshawski L, Carruthers A. The Peng flap. The flap of choice for the convex curve of the central nasal tip. Dermatol Surg 21(2):149-52 (1995 Feb).
- Spear SL, Kroll SS, Romm S. A new twist to the nasolabial flap for reconstruction of lateral alar defects. Plast Reconstr Surg 79(6):915-20 (1987 Jun).
- Shumrick KA, Smith TL. The anatomic basis for the design of forehead flaps in nasal reconstruction. Arch Otolaryngol Head Neck Surg 118(4):373-9 (1992 Apr).
- Vecchione TR, Griffith L. Closure of scalp defects by using multiple flaps in a pinwheel design. Plast Reconstr Surg 62(1):74-7 (1978 Jul).
- Kaufman AJ. Adjacent-tissue skin grafts for reconstruction. Dermatol Surg 30(10):1349-53 (2004 Oct).
- Guerrerosantos J. Frontalis musculocutaneous island flap for coverage of forehead defect. Plast Reconstr Surg 105(1):18-22 (2000 Jan).
- Hoffmann JF. Tissue expansion in the head and neck. Facial Plast Surg Clin North Am 13(2):315-24 (2005 May).
- Gohari S, Gambla C, Heale M, et al. Evaluation of tissue-engineered skin (human skin substitute) and secondary intention healing in the treatment of full thickness wounds after Mohs micrographic or excisional surgery. Dermatol Surg 28(12):1107-14 (2002 Dec).
- Robinson JK. Suspension sutures in facial reconstruction. Dermatol Surg 29(4):386-93 (2003 Apr).
- Chandawarkar RY, Cervino AL, Pennington GA. Intraoperative acute tissue expansion revisited: a valuable tool for challenging skin defects. Dermatol Surg 29(8):834-8 (2003 Aug).