TITLE: FLAPS FOR FACIAL DEFECTS
SOURCE: UTMB, Grand Rounds Presentation
DATE: 21 October 1998
RESIDENT PHYSICIAN: Robert H. Stroud, M.D.
FACULTY PHYSICIAN: Francis B. Quinn, Jr., M.D., F.A.C.S.
SERIES EDITOR: Francis B. Quinn, Jr., M.D., F.A.C.S.
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"This material was prepared by resident physicians in partial fulfillment of educational requirements established for the Postgraduate Training Program of the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended for clinical use in its present form. It was prepared for the purpose of stimulating group discussion in a conference setting. No warranties, either express or implied, are made with respect to its accuracy, completeness, or timeliness. The material does not necessarily reflect the current or past opinions of members of the UTMB faculty and should not be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion."
Otolaryngologists commonly encounter facial skin defects. They are most frequently a result of the surgical treatment of cutaneous malignancies either by Mohs’ technique or by conventional surgical excision. They may also be the result of trauma. The management of these defects requires a thorough knowledge of all treatment options from healing by secondary intention to microvascular free tissue transfer. The majority of these defects are best repaired using local and regional skin flaps. Defects of the lip, ear, eyelid and nose are the subjects of separate Grand Rounds presentations and will not be discussed in this presentation. The focus of this discussion will be on the anatomy, physiology, design and application of local and regional skin flaps in the reconstruction of facial skin defects.
Basal cell carcinoma is the most common cancer in man. Basal cell as well as squamous cell carcinomas are common on facial skin. The options for treatment of these lesions include electrodessication and currettage, radiation therapy, surgical excision, cryosurgery or chemotherapy. Mohs’ micrographic surgery, introduced in the 1930s, aims to assure complete tumor removal by microscopic examination of 100% of the tumor resection margins. The process begins with excision of the tumor. The specimen is then oriented and sectioned. A map of the tumor with exact relation to the surgical defect is then created. The sections are examined. If tumor is present in any of the excision margins, re-excision is performed only in the area of the positive margin determined from the tumor map. This process in repeated until all histologic sections are free of tumor.
Mohs’ technique is recommended for recurrent cancers, morpheaform, aggressive or sclerotic tumors, those with ill-defined borders or occurring in high risk areas. These include areas that may allow for tumor spread along embryonic fusion planes, fascial planes, perichondrium or periosteum, nerves or vessels. Tumors arising in cosmetically important areas such as the nasal tip or ala, eyelids, lips and ears should also be considered for Mohs’ technique as the maximum amount of tissue is preserved.
Once the lesion is completely excised, decisions regarding the method of reconstruction can be made. It is important to keep as the primary goal the eradication of malignancy and not compromise resection with concerns over reconstruction. The options for reconstruction are multiple, including healing by secondary intention, primary closure, skin grafting, local and regional flaps and free tissue transfer. The reconstruction method should be chosen by considering the patient’s general health, characteristics of the defect, and first and foremost, the patient’s expectations and desires.
The simplest option for management of a skin defect is to allow the wound to heal by secondary intention. This frequently results in a discolored, depressed scar that may distort surrounding structures. Small defects, defects of the medial canthal region, nasal tip or temple may yield excellent results if allowed to heal by secondary intention and this may be the treatment of choice for selected defects.
Only minimally more complicated, primary closure is also a management option. This may be accomplished in smaller defects if the wound margins are sufficiently undermined. The ability to perform closure is usually dependent on the availability and laxity of the surrounding tissue. Primary closure is contraindicated if in doing so, fixed anatomic structures are distorted. Ideally, the long axis of the wound should lie in parallel to the relaxed skin tension lines for optimal cosmetic results.
Skin grafting is another option for the reconstruction of skin and soft tissue defects. Skin grafting yields best results when there is only minimal loss of underlying tissue. Contour deformities often occur if grafts are placed into deep defects. It is often difficult to attain good color and texture matches with skin grafting, but acceptable results can be obtained with donor sites in the supraclavicular and post-auricular areas. Skin grafting is frequently used when tumor recurrence is likely as it allows for surveillance of the tumor site and re-excision should there be a recurrence. Skin grafting has the advantage of supplying a large amount of tissue with minimal donor site morbidity, but has a poorer texture and color match than local flaps.
Local and regional flaps are the most commonly used method for repair of facial defects. Records of the forehead flap for nasal reconstruction have been found as early as 700 BC. Despite recent advances in microsurgical free tissue transfer, the local flap remains the workhorse for the repair of skin defects on the face. Local flaps have many advantages, including an excellent skin color and texture match, most local flaps may be performed as a one stage procedure, and donor sites are frequently able to be closed primarily with little associated morbidity. Their disadvantages include a random blood supply limiting flap length, the potential for distortion of surrounding structures in closure of the donor site, and limited bulk for the repair of deep defects. Distant flaps and free tissue transfer have occasional use in the reconstruction of large or complicated facial defects, but are beyond the scope of this discussion.
It is imperative that the surgeon designing and performing the reconstruction of facial defects with flaps has a working knowledge of blood supply to the skin. Segmental vessels are large, named branches of the aorta that run deep to muscle masses. The segmental arteries give rise to musculocutaneous vessels that run through muscle providing its blood supply, then proceed beyond the muscle to the subcutaneous tissue and skin. There are also direct cutaneous vessels that arise directly from segmental vessels, run on top of the muscle fascia to directly supply the skin. The musculocutaneous arteries within the deep reticular dermis branch into two horizontally oriented microvascular plexi, one at the dermal-subcutaneous junction, and the other more superficial in the papillary dermis. Random flaps derive blood supply from the microvascular plexi, while axial flaps rely on direct cutaneous vessels running superficial to the muscle. Musculocutaneous flaps are supplied by named arteries that lie deep to the muscle mass.
In addition to blood supply, many factors interact to determine a flap’s viability. The skin’s function as a thermoregulator requires that blood flow be highly variable. Much of the regulation of cutaneous blood flow is under the control of the sympathetic nervous system. Arteriovenous shunts exist between arterial and venous circulation and allow bypass of the capillary beds. It is not clear what factors precipitate an increase in the flow through these shunts, but flap viability may be compromised by decreased flow through the capillary bed despite adequate arterial supply and venous drainage.
Skin possesses remarkable elastic properties. These properties are a result collagen and elastin. As force is applied, the elastin content allows for initial stretching. If the force is maintained, additional stretch may be gained as the collagen fibers align in the direction of the force. Once the collagen fibers have been completely aligned, little additional movement is gained. The stress and tension that occur with increased stretch decreases blood flow and can adversely effect a flap’s potential viability. Tension can be reduced with undermining of the wound margins, but careful flap planning is the best method of avoiding excessive tension on wound closure.
The elastic properties of skin are manifest in the creep and stress relaxation phenomena. Creep refers to the observation that if constant force is applied to a skin flap for 5 to 15 minutes, additional length may be gained. Stress relaxation occurs when the skin is placed under constant tension for days to weeks. Skin volume increases to relieve the applied stress. Stress relaxation is the principle behind tissue expansion and serial excision of scars.
A number of other factors have been shown to have effects on flap perfusion. These include cytokines released as a component of the inflammatory response. Leukotriene D4 increases blood flow to the skin and interleukin-1, tumor necrosis factor-a , and platelet activating factor all induce vasodilation. Neutrophils elaborate oxygen free radicals that have been shown to inhibit the vasodilatory effects of nitric oxide generated within the endothelium. This may be partially responsible for reperfusion injury seen in ischemic skin flaps. Thrombosis within the microcirculation has also been implicated in the ischemia-reperfusion injury noted within non-viable skin flaps. It is clear that multiple, poorly understood factors interact to regulate perfusion of the skin and ultimately the success of skin flaps.
Several factors within the patient can be used as predictors of flaps that may be at risk for failure. Advanced age has been shown to decrease flap survival in a rat model. Diabetes, hypertension, atherosclerotic vascular disease and hyperlipidemia all have been suggested as decreasing flap survival. Smoking is well known to adversely affect flap survival and patients should be counseled to not smoke in the immediate post-operative period. Hematoma formation may also be detrimental to flap viability both due to a decrease in blood flow within the flap as a result of pressure from the fluid collection, as well as direct toxicity from factors released during hematoma breakdown. Sound surgical technique can minimize the risk of hematoma formation, but patients should be questioned as to the use of salicylates or non-steroidal anti-inflammatory medications and their use discontinued prior to the planned surgery. Aspirin should be stopped 7-10 days in advance while NSAIDs should be given three times the drug half-life to allow clearance and return of platelet function, usually 24-48 hours being adequate.
It was initially believed that by maintaining a 1:1 length to width ratio a skin flap’s viable length could be extended. This tenet has not held true however. The surviving length of the flap is determined by perfusion pressure within the feeding vessels and intravascular resistance. By widening the flap’s base, additional vessels with the same perfusion pressure are added without appreciable change in the intravascular resistance. Thus no advantage is gained by widening the base. Today, most authors agree that a length to width ratio of 3:1 to 4:1 frequently provides viable random pattern flaps on the face and scalp.
The delay phenomenon has also been shown to increase flap survival by 50 to 100%. It describes the effect noted if the skin flap is partially incised and undermined (but not transposed) approximately 1-2 weeks prior to transposition. The physiologic mechanism for this phenomenon is not clear, but is likely related to a rearrangement of the vascular architecture within the flap. The basic technique used for random flaps is to incise the long axis of the flap and undermine the length while not dividing the ends. After 1-2 weeks, the distal end is divided and the flap transposed. An axial flap may benefit from simply incising the flap margins without undermining. The beneficial effect of the delay phenomenon is felt to be lost if transposition is delayed beyond 3 weeks to 3 months.
It is clear that multiple factors interact to regulate skin perfusion. While not currently clearly understood, further research may gain better techniques for controlling perfusion of the flap. Perhaps pharmacologic interventions will become available to aid in promoting perfusion by manipulating the actions of cytokines and other vasoregulatory substances.
As stated previously, flaps are classified based upon the derivation of their blood supply. Random flaps are supplied by the dermal and sub-dermal microvascular plexi that arise from musculocutaneous perforating vessels. The majority of local skin flaps are random pattern. Axial flaps derive their blood supply from named subcutaneous vessels that run superficial to the muscle and directly supply the dermis and skin. Several flaps used in the reconstruction of facial defects including the nasolabial, median and paramedian forehead flaps fall within this classification.
Local flaps are also classified by their movement. Rotation flaps rotate in an arc about a pivot point. A true rotation flap is semicircular. When applying rotation flaps, it is important to remember that the flap becomes functionally shorter as it is rotated and therefore must be designed longer than the defect. A back cut may be performed at the base of the flap if needed to elongate the short edge, but this should be done judiciously as vascular supply is decreased.
A transposition flap is a type of rotation flap that pivots about a point with an area of partially intact skin intervening. The rhomboid, bilobed and nasolabial flaps are examples of transposition flaps and are some of the most widely utilized.
Interpolated flaps transpose tissue from a donor site that is separated from the defect by an area of intact skin. The flap’s pedicle passes either over or under the intervening tissue and may be divided after adequate blood supply is established at the recipient site. Examples of interpolated flaps include the subcutaneous island flap, as well as some forehead and nasolabial flaps. These flaps usually have an axial pattern.
Advancement flaps are perhaps the simplest type of flap to perform. The primary movement is linear after wide undermining of the wound margins. Monopedicle flaps are usually rectangular and advance from one side of a defect. Bilateral flaps may be advance from both sides of a defect and are particularly useful in defects of the forehead and lips. It is often necessary to excise Burow’s triangles from the flap base to assure smooth closure. The V-to-Y flap is a variation of the advancement flap that is frequently derived from the glabellar or nasolabial regions.
When considering the reconstruction of facial defects, all potential options should be considered and discussed with the patient. In general, primary closure or local flap reconstruction provides superior cosmetic results. Many patients do not desire any further surgery and are willing to accept a poor cosmetic outcome by allowing a defect to heal by secondary intention. In addition, some patients have an absolute contraindication to further intervention. Drs. Calhoun, Seikaly and Quinn have designed and tested a paradigm that has proven to be useful as a guide to the management of facial defects.
When evaluating a patient with a facial defect, all possible treatment options should be discussed. If there is an absolute contraindication to surgery, healing by secondary intention is the default treatment option. If there is no contraindication to further surgery but the patient refuses further intervention, the implications of their decision should be discussed, including the possibility of poor cosmetic results and potential for the distortion of surrounding structures due to wound contraction. Defects of the nasal ala, lip or eyelid may result in especially poor cosmetic and functional deficits if allowed to heal by secondary intention. If the patient accepts the potential for a poor result, healing by secondary intention is appropriate. If after counseling the patient does not wish to risk the poor results, then other management options may be considered. If the defect is less than 1 cm in a concave area such as the medial canthus or temple, healing by secondary intention generally yields excellent results. If not, the defect should be evaluated for primary closure. This can be accomplished if the defect is long and narrow and oriented with the relaxed skin tension lines or if it can be made so by undermining and excision to an elliptical shape. If approximation after undermining does not result in distortion of fixed anatomic structures such as the eyelid, oral commissure or nasal ala, primary closure is the best treatment option.
If unable to close the wound primarily, but the patient does not wish to risk the possibility of a poor cosmetic outcome that may result from healing by secondary intention, surgical options include skin grafting or local flap closure. If the patient is a smoker, diabetic or patient on NSAIDS or salicylates, they should be fully informed of the increased risk of flap failure. Provided the patient understands, flap closure is appropriate. If the patient does not accept the risks, the more reliable skin graft is appropriate. Many patients will desire the simplest solution at the expense of better cosmesis rather than undergo a more involved procedure and opt for skin grafting. Once the patient understands the risks of local flap closure and has a defect that is unable to be closed primarily, local flap reconstruction will provide the best functional and cosmetic outcomes in most instances.
Once it is decided that local flap reconstruction is the best management option, the anatomic location should be evaluated for the best flap design. The face is composed of multiple aesthetic units including the forehead, periorbital, nasal, cheek and chin. Flaps usually provide the best color and texture match if derived from the same aesthetic unit. As a general rule, flaps should be designed so that the majority of the incisions fall parallel to the relaxed skin tension lines. Incisions are also less conspicuous if placed along the junction of aesthetic units and long straight scars should be avoided unless hidden within the hairline, an aesthetic junction line, deep skin crease or shadow area.
Forehead defects of small size are often able to be closed primarily after fusiform excision. Multiple deep skin creases within this area provide excellent camouflage for incisions. Defects of moderate size can be closed with advancement, rotation or transposition flaps. Care should be taken to avoid distortion of the eyebrow and incisions should be placed within skin creases when possible. Unilateral or bilateral advancement flaps are frequently useful in the area in and around the eyebrows. The hairline provides an excellent barrier in which to hide incisions and A-to-T flaps are often used in central superior or temple defects. Rhomboid flaps are also quite useful for defects of the temple region. Care should be taken to avoid the transposition of hair-bearing skin into a non-hair bearing area and to avoid the distortion of the hairline, as this can be very conspicuous.
As stated previously, defects of the medial canthus that are small frequently heal by secondary intention with very acceptable cosmetic results. If the eyelid is involved, reconstruction is usually required but is beyond the scope of this discussion. Larger defects of the medial canthal region are frequently reconstructed with transposition flaps from the glabellar region.
Defects of the nose present a particular challenge in reconstruction due its cosmetic importance and central location on the face. Skin of the upper nose is thinner and more mobile than that of the lower nose. Defects of the upper nose are frequently able to be reconstructed using bilobed, rhombic and similar transposition flaps. The dorsal nasal flap is a V-to-Y advancement flap from the glabellar region that is often useful in reconstructing defects of the mid-dorsum. Wounds of the superior and lateral nose are often reconstructed using any one of many rotation, transposition and advancement flaps from the glabellar area. Care must be taken in using the glabellar region as a donor site, as this area is not always and hairless and the transposition of hair-bearing skin onto the nasal dorsum can be quite conspicuous.
Several flaps have been described for the reconstruction of defects of the lower nose. The midline forehead flap is commonly used for reconstructing defects of the nasal tip, ala, columella and dorsum. This is an axial pattern flap based on the supratrochlear artery with a pedicle that must be divided at approximately 3 weeks. It has proven to be very reliable for the reconstruction of various nasal defects. The nasolabial flap is derived from excess tissue present adjacent to the nasolabial fold on the medial cheek. Some authors classify the nasolabial flap as a random pattern flap while other describe it as an axial flap based on the angular artery. It may be based either superiorly or inferiorly, and is useful in the coverage of defects of the nasal dorsum, alae, tip and columella. Defects involving the lateral nose and extending onto the cheek are frequently reconstructed using rotation flaps from the cheek. A large amount of tissue is available as the skin of the entire cheek may be elevated if necessary, and incisions are able to placed along the junctions of aesthetic units at the lateral edge of the nose, in the nasolabial fold and along the infraorbital rim.
Defects of the nose frequently are full-thickness and require reconstruction of the internal nasal lining and bony or cartilaginous framework. Many of the above mentioned flaps may be turned upon themselves to provide a nasal lining. Often, composite grafts are required for the reconstruction of defects of the bone and cartilage. These reconstructions are beyond the scope of this presentation and will be addressed in a dedicated Grand Rounds presentation.
The cheek is an area with abundant soft tissue and skin laxity. This gives the surgeon many options with which to reconstruct skin defects. Small to moderate sized defects may be closed with any of a number of advancement, rotation and transposition flaps. The ability to widely undermine makes advancement flaps useful and primary closure is frequently possible. The rhomboid and bilobed flaps are perhaps the most frequently employed flaps for closure of lateral cheek defects and are very versatile in their applications. Larger defects of the medial and lateral cheek are often best reconstructed using cheek and cervicofacial rotation-advancement flaps. Incisions can be camouflaged along the lateral nasal border, infraorbital rim and preauricular skin crease. As always, incisions should be placed parallel to the relaxed skin tension lines when possible, and caution should be used to avoid injury to the facial nerve and parotid duct.
Defects of the chin often present difficult due to a loss of the thick subcutaneous tissue in the region. Abundant tissue is available however, and many rotation, advancement and transposition flaps prove useful. The prominent sublabial crease that forms the superior border of this unit is useful in scar camouflage. Incisions crossing this crease should be avoided however, as this may lead to a webbed scar across the concavity.
It is obvious that numerous reconstruction options exist and different anatomic components of the face present varying challenges in reconstruction. Many flaps have wide application while some have very limited indications. In order to make the best choice for closure of a skin defect the surgeon must have multiple options at his disposal and consider all available alternatives.
Postoperative management after local flap reconstruction is usually uncomplicated. Wound care with gentle cleansing and the application of topical antibiotics is usually all that is required. If desired, a clean gauze dressing may be applied. If a vascular pedicle is exposed as in the midline forehead flap, it may be loosely wrapped with antibiotic impregnated gauze such as Xeroform to avoid dessication. Sutures should be removed at 5-7 days postoperatively.
Wound infections are uncommon, but when they occur are managed with drainage and local wound care. The prevention of hematoma formation has been previously discussed, and should be drained if noted postoperatively and any excessive bleeding controlled to avoid reaccumulation. Flap failure, either partial or total is a common postoperative concern. Partial necrosis of the distal flap is relatively common and usually requires nothing more than local wound care and expectant management. Debridement is infrequently needed. Flaps that are noted to be cyanotic in the immediate postoperative period frequently have insufficient venous drainage. This may be due to excessive tension in wound closure or kinking of the vascular pedicle. If necessary, tight sutures should be removed or the vascular pedicle explored. Multiple punctures in the flap using a small gauge hypodermic needle may relieve venous hypertension. The application of heparin soaked gauze may also be effective. It is rarely necessary to replace to flap to its donor site and delay the transposition. Leeches are effective in relieving venous congestion and may be applied until collateral circulation develops.
Patients’ expectations regarding cosmetic outcome varies widely and they should be given a realistic representation of scarring during preoperative counseling. In the event of poor cosmetic results, multiple options exist for scar revision and camouflage. The most frequently employed method of scar alteration is dermabrasion. It is commonly used to smooth height differences between the flap and surrounding skin. It also may be useful in areas with thick sebaceous skin such as the nasal tip. Best results are obtained if performed 6-12 weeks postoperatively.
Surgical intervention for scar revision is best delayed for greater than 6 months while scar maturation is occurring. Patients may require significant reassurance during this period, but typically accept this waiting period if well informed. Revisions undertaken before final scar maturation should be reserved for those patients with significant functional impairment. If after this period of time the scar is unacceptable, several surgical interventions may improve outcome. Simple excision is perhaps the least complicated to perform and produces good results when applied to widened scars that parallel the relaxed skin tension lines or lie within the borders of aesthetic units. Serial excision is often indicated in areas of limited skin laxity. This technique may also be combined with tissue expansion if needed to attain additional coverage of large wounds. Long straight scars may be made less conspicuous by excision and re-closure with W-plasty or geometric broken line closure. Z-plasty effectively lengthens and changes the direction of a scar and is useful in the revision of contracted scars. It may be applied at the time of initial operation to allow the long axis of incisions to lie in parallel with the lines of relaxed skin tension and thus improve cosmetic outcome primarily.
Defects of the facial skin are a commonly occurring problem faced by the otolaryngologist, most frequently resulting from the surgical removal of cutaneous malignancy. The reconstruction of these defects requires a thorough knowledge of the anatomy and physiology of the skin. All reconstructive options should be considered in each situation and surgical intervention carefully planned. Both surgeon and patient should maintain realistic expectations and sound oncologic principle adhered to at all times. Outcomes pleasing to both the patient and surgeon are the rewards of a well-planned and carefully executed reconstruction.
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