Advancement Flaps in Dermatologic Surgery

Several options are available to the dermatologic surgeon for the closure of surgical defects. The options range from simple side-to-side closure to more complex closures that use skin flaps and grafts. The choice of closure technique depends on the patient, the type of tumor, the location of the wound, and the local tissue characteristics and availability. Indications, techniques, and complications of advancement flaps are discussed in this article.

Related Medscape articles, as follows, may be of interest:

• Forehead and Temple Reconstruction

• Cheek Reconstruction

• Dermatologic Approach to Ear Reconstruction

• Scalp Reconstruction Procedures

• Nasal Reconstruction

• Dermatologic Aspects of Lip Reconstruction

Choosing a repair technique

The first issues to address when choosing a reconstructive approach are to decide if a skin flap has any advantages over a side-to-side closure and to consider other closure options, such as secondary intention healing or skin grafting.

The advantage of a side-to-side closure is that it results in a straight or slightly curved line with little risk of complications, such as necrosis. Secondary intention healing may be the best option for concave areas of the face (eg, conchal bowl, alar groove or rim, melolabial fold, preauricular area, medial canthus), where it can provide an excellent cosmetic result. However, a flap should be considered if excessive tension or anatomical distortion is present or if cosmetic units or relaxed skin tension lines will be breached by a fusiform closure. If tissue movement is insufficient for a flap, a graft may be required. The best tissue match is often obtained with a full-thickness skin graft; however, poorly vascularized areas may only support a split-thickness skin graft. Wounds that involve exposed bone, cartilage, or tendon or wounds in poorly vascularized areas that cannot support grafts may require a flap.

The second issues are the location of potential donor skin and the availability of enough tissue. Locating and assessing donor skin can be accomplished by gently pinching tissue in multiple directions around the defect. Reservoirs of excess tissue include the glabella, the nasal sidewall, and the medial part of the cheek for nasal defects; the temple and the glabella for forehead defects; and the melolabial fold and the cheek for upper lip defects.

General principles of tissue movement

The next decision is to choose the mechanism by which tissue may be moved. Advancement, rotation, and transposition flaps should all be considered. The effect on surrounding structures must be evaluated; in particular, check for any distortion of free margins. A basic knowledge of the terminology of flap dynamics is essential.

Primary motion is movement of the flap into the surgical or primary defect. The defect created by the flap movement creates a secondary defect. The objective of any flap is to close the primary defect, while minimizing the size of the secondary defect.

Secondary motion consists of the elastic forces attempting to return tissue that has been advanced back to its natural position. Secondary motion includes the response of the surrounding tissue to the motion of the flap and to the closure of the primary and secondary defects. The effects of these forces are determined by testing the laxity of the skin under consideration by pressing and stretching the tissue before anesthetic is injected. Undermining the area around the surgical defect may help better define the forces of tension.

Free margins and anatomical units should always be evaluated for possible distortion. Examples of such tests include the snap test on the lower eyelid, which checks for the creation of ectropion. Another test is the application of upward and inward pressure on the nasal bridge (or nose) to determine the potential for elevation of the alar rim.

Finally, the surgeon must determine whether tissue can be moved in a manner that hides the final scars. Scar camouflage is a major advantage of flaps. Suture lines can be placed in facial unit junction lines or in relaxed skin tension lines; such placement often results in barely perceptible scars.

Flap types

Three types of cutaneous flaps are used: advancement, rotation, and transposition. The focus of this article is advancement flaps. In advancement flaps, the primary motion is in a straight line from the donor site to the primary defect, while the secondary motion occurs in the opposite direction. These flaps are best used in areas of tissue redundancy.

The primary goal of an advancement flap is to transfer the tension of the scar that would result from side-to-side closure to a more cosmetically acceptable site. Such sites include relaxed skin tension lines and the boundaries between cosmetic units (eg, melolabial fold, melolabial crease). Dog ear correction scars are displaced from the original defect, and they can also be hidden in cosmetic boundaries or in skin lines.

Mechanics of advancement flaps

The width of any flap is proportional to the width of the defect. The pedicle or base of the flap connects it to the surrounding tissue. The pedicle contains the flap's vascular supply; thus, it is critical to its survival. The location of the pedicle base in relation to the distal aspect of the flap is often used to describe the flap; flaps are superiorly, inferiorly, medially, or laterally based.

To ensure that the pedicle provides adequate blood flow, the length-to-width ratio of the flap should not usually exceed 3:1. The thickness of the flap should be proportional to the depth of the defect, and the flap must comprise at least a thin layer of subdermal fat to include part of the vasculature. Thinning of the distal flap edge to improve wound contour is common; however, thinning should be avoided in patients with a tenuous blood supply, such as those with diabetes or those who smoke.

Longer flaps should be thicker, especially at their base, to include the larger-caliber deep subcutaneous vessels needed to nourish the entire length of the flap. Exceptions to this principle are well-vascularized areas, such as the nasal dorsum or the helix of the ear.

See Intraoperative Details.

Advancement flaps are not indicated for defects in which side-to-side closure is difficult and structural distortion is likely. The exception is a mobile structure, such as the lip. In this situation, a dog ear can be positioned away from the original wound, creating a tension-free closure. Closing the displaced dog ear advances the flap toward the defect, while relieving tension on the flap and the mobile structure. Limiting tension on the defect is imperative for avoiding structural distortion.

Advancement flaps are appropriate for tumors excised with adequate margins or via Mohs surgery, which minimizes the risk of recurrence. If the surgical margins are inadequate and the defect is repaired with a flap, detecting a recurrence may be more difficult, and reexcision of the recurrent tumor may be extensive and disfiguring.

In certain patients, the internist may obtain whatever laboratory studies are deemed necessary to provide medical clearance for the patient prior to surgery.

As with all procedures, a detailed medical history must be obtained prior to performing surgery. The patient's general health status and medical problems (eg, hypertension, diabetes mellitus, cardiac disease, pacemaker, lung disease) should be documented. The surgeon must inquire about any conditions (eg, defective heart valve, congenital heart disease) that may require the use of prophylactic antibiotics prior to surgery. The patient's medications and any allergies to medications must be noted. The patient should be asked about any abnormal scarring, excessive bruising, fainting episodes, seizures, or any problems with prior surgeries. Patients with multiple or complex medical problems may require medical clearance from an internist.

All medications that can interfere with platelet function or the clotting cascade must be identified before surgery. Patients should limit the intake of vitamin E and gingko biloba, both of which may interfere with clotting. Aspirin (salicylic acid) interferes with platelet function by irreversibly blocking the cyclo-oxygenase pathway. Ibuprofen and related medications also affect platelet function, but their effects are reversible. Because nonsteroidal anti-inflammatory agents are commonly used, patients may not identify them on screening questionnaires; therefore, specific questions regarding these medications are necessary. If at all possible, these medications should be discontinued before surgery. Aspirin should be stopped 10 days prior to surgery; other nonsteroidal anti-inflammatory drugs should be discontinued 2-5 days before surgery. Acetaminophen is an excellent analgesic substitute that does not interfere with the clotting mechanism.

Design and types of advancement flaps

The single-arm advancement flap, or Burow wedge flap, involves the removal of 2 cutaneous triangles. The first triangle is at the base of the defect, while the second triangle advances the flap into the defect. The O-to-T or A-to-T advancement flaps consist of Burow wedges on either side of the defect, with dog ears on the same side of the wound. These flaps are selected to limit the effects of primary and secondary motion on anatomical structures and to use the cosmetic units and the skin tension lines to hide incision lines.

H-plasty consists of bilateral rectangular flaps advanced into the defect. This flap may create 4 dog ears, which can be placed in a cosmetically pleasing manner. In some cases, dog ears may be sewn out by using the rule of halves. An advantage of this flap is that the components cancel out secondary motion. In addition, the small size of the flaps allows good blood flow to the distal portion of the flap, reducing the risk of necrosis.

The island pedicle flap takes advantage of areas of increased tissue elasticity, such as the cheeks, the lips, the nasal sidewall, the preauricular area, and the helix of the ear. This flap consists of a V-shaped island of tissue that maintains a narrow pedicle of subcutaneous fat and underlying muscle while it is advanced into the defect.

Cheeks

The cheek is one of the cosmetic units with the fewest potential danger zones. The facial nerve and its branches, in particular, the marginal mandibular nerve and the temporal nerve, are at highest risk. Anterior to the facial artery, the marginal mandibular branch lies above the mandible, but it is covered by only a thin layer of skin, subcutaneous fat, and the platysma muscle. The temporal nerve is most vulnerable where it crosses the zygomatic arch and enters the temple region. The relatively deep location of the parotid duct makes injury to it unlikely. On the cheek, 3 areas hide scars well: the nasofacial sulcus, the melolabial line, and the pretragal sulcus. The free margins at risk for distortion are the lower eyelid, the upper lip, and the oral commissures.[1]

Advancement flaps can be used for reconstruction of defects of the preauricular area by using tissue from the cheek and the neck. Medial cheek defects can be repaired by medial advancement of lateral cheek tissue, and tension is best placed horizontally. Defects of the upper medial cheek can be repaired by advancement of tissue from the inferior cheek by using incisions along the nasofacial sulcus and the melolabial groove. See the images below.

Forehead and eyebrows

Rectangular advancement flaps work well on either the eyebrow or the forehead. At times, the need for vertically oriented dog ears can be limited by using the rule of halves to suture the flap into place. A-to-T flaps are also appropriate for the hairline and for the lower parts of the forehead. Horizontal lines can be placed in creases or along the boundaries between cosmetic units (eg, in the junction between the forehead and the eyebrow or upper eyelid). Special considerations when operating on the forehead include the following[2, 3, 4] :

• Greater wound tension than in other cosmetic units because of less available tissue

• Importance of maintaining cosmetic boundaries, such as the hairline

• Avoidance of the temporal branch of the facial nerve (which tends to be deeper over the forehead and more superficial over the zygomatic arch) and, if possible, the supraorbital and supratrochlear nerves and the anterior branch of the temporal artery laterally

• Placement of surgical scars in the hairline brow and along relaxed skin tension lines

Tissue reservoirs on the forehead include the glabella and, most importantly, the temple region.

Eyebrow reconstruction is best achieved by using bilateral rectangular advancement flaps, which avoid a long scar that transgresses cosmetic boundaries and repair the eyebrow with hair-bearing skin. In addition, scars may be hidden in the upper eyelid crease and along horizontal forehead lines.

See the images below.

Upper lip

Advancement flaps are useful for repairing defects on the upper lip. A larger defect on the lateral upper lip can be corrected by using a Burow advancement flap with the lower dog ear pole displaced toward the oral commissure or the melolabial fold. Closure of the lower triangle advances the flap toward the lip wound. Burow triangles are nicely hidden in the cheek and the nasal alar junction and lateral to the oral commissure. Although this flap can flatten the melolabial groove, this effect can be minimized by using a periosteal suspension suture to the piriform aperture of the maxilla to help create a new groove. A-to-T advancement flaps can easily repair smaller defects on the upper lip.[5]

Symmetric reconstruction of the apical triangle of the upper lip can be achieved by making an incision extending from the alar crease along the nasal sill, and along the cutaneous upper lip. This modification creates a sliding flap that assists in recreating the apical triangle, thereby preserving facial symmetry.[6]

Inferolaterally placed (relative to the nose) island pedicle flaps that allow 2 of 3 closure lines to be hidden in the alar crease and the nasolabial fold can repair superolateral defects. A modified approach to alar crescent flap closure has been reported.[7, 8] See the images shown below.

Wounds that straddle the cutaneous portion and the vermilion of the lip may at times be elegantly repaired with double V-to-Y advancement flaps, using the adjacent mucosal tissue to repair the vermilion and the adjacent lip skin to repair the cutaneous portion of the defect.[9]

Nose

Burow wedge advancement flaps may be used to repair lower midline dorsal defects of the nose if placed immediately adjacent to the defect. Advancement flaps consisting of only nasal skin are usually not used in reconstruction of the upper part of the nose because only limited amounts of skin are available. Lateral nasal sidewall defects close to the nasofacial sulcus can be repaired with advancement flaps that use cheek tissue. Incisions can be hidden in the infraorbital crease and in the melolabial groove. Advancement of the skin of the nasal dorsum and root can be used for tip and supratip defects. However, this type of repair can elevate the nasal tip and change the nasal contour.[10, 11, 12] A columellar advancement flap has been described for small midline nasal defects.[13] More recently, use of bilateral advancement flaps for a defect of the caudal lateral nasal tip adjacent to the alar groove has been reported. However, as the authors point out, if the tension vectors are not carefully designed, distortion of the alar rim or nasal tip can occur.[14]

Ear

Defects of the helix can be repaired by using a Burow advancement flap that creates a dog ear behind the ear and a second potential dog ear of the ear lobe. Chondrocutaneous flaps can be helpful in repairing full-thickness defects.

See the images below.

The most common complication of an advancement flap is undersizing the flap. In general, the ability of the advancement flap to cover a defect is not much better than that of a comparable fusiform closure.

Avoiding distortion of free margins, such as the eyelid, the lip, and the eyebrow, is of utmost importance when using advancement flaps. Careful planning of the flap, as well as intraoperative testing for potential distortions, is essential.

Ecchymosis and edema can occur up to 24 hours after the procedure and result from surgical trauma. Surgery on the scalp or the forehead usually leads to ecchymoses of the upper eyelid before affecting the lower eyelid. Cheek surgery may result in a bruise on the jaw line. Ecchymoses do not affect the final outcome, and they spontaneously resolve; however, they can be alarming to the patient, and reassurance may be necessary.

Most bleeding complications are the result of drug-related coagulopathy (see Preoperative details) or faulty intraoperative hemostasis. In addition, excessive postoperative activity can result in bleeding.

As anesthesia wears off, bleeding may occur along the suture line. If bleeding cannot be controlled by applying simple pressure for approximately 15 minutes, the sutures must be removed and hemostasis achieved. At this time, the surgeon may reinject the site with a local anesthetic containing epinephrine or apply an epinephrine-soaked cotton sponge on the wound bed. Subsequent application of a pressure dressing also aids in hemostasis.

Occult bleeding may emanate from the muscles used in facial expression and from blood vessels between the fat lobules deep in the subcutaneous tissue. If bleeding persists, placing a drain or widening suture gaps to allow blood to egress to an absorbent dressing is necessary to prevent hematoma formation.

If a hematoma is discovered in the first 24 hours after surgery, if it is symptomatic, or if it appears to be endangering the flap, it should be immediately evacuated and the wound resutured.

Infections

Signs of infection include erythema, edema, tenderness, and exudation from the suture line. Bacterial culture and sensitivities should be obtained prior to initiating systemic therapy. If necessary, the sutures should be removed and replaced by adhesive strips. In addition, wounds with copious drainage should be irrigated with sodium chloride solution, and a wick fashioned from plain gauze should be inserted into the wound to aid in drainage. The wound should be allowed to heal by secondary intention.

Lengthy procedures or those in which the wound remains open for a long period before closure may merit prophylactic antibiotics. Some surgeons consider the axilla, the ear, and the groin to be at high risk for infection and routinely administer prophylactic antibiotics prior to and/or after the procedure. In addition, diabetes mellitus and immunosuppression due to illness or drugs may be indications for antibiotic prophylaxis. To be of value in patients with diabetes or immunosuppression, antibiotics must be adequately concentrated in the tissue prior to the procedure. Thus, oral antibiotics should be administered 24 hours prior to surgery.

Dehiscence

Dehiscence may be caused by infection or hematoma. In addition, it may be iatrogenic as a result of premature suture removal or lack of placement of required subcutaneous sutures. If dehiscence results from inadequate tensile strength at suture removal, simply resuturing the wound is sufficient; however, wounds complicated by infection, ischemia, or necrosis should be allowed to heal by secondary intention.

Necrosis

Any factor that compromises the flap's subdermal plexus blood supply may cause ischemia and subsequent tissue necrosis. The most important causes include faulty flap design or increased wound tension. Flaps that necrose are allowed to heal by secondary intention.

Anatomical considerations

Neck flaps have an increased risk of hematoma formation because all patients inadvertently move their necks. The surgeon should avoid trauma to superficially located motor nerves, including the terminal branches of the facial nerve, the spinal accessory nerve, and the digital nerves. The superficially located parotid gland and the sensory greater auricular nerve should also be avoided. Because sensory nerves terminate in the skin, some degree of numbness and/or dysesthesia is not unexpected. These sensory abnormalities are temporary and usually resolve or diminish within 3-6 months after surgery.