Chapter 72. Scar Revision

With advances in the knowledge of wound healing, as well as the development of better materials and techniques, many options have become available in the treatment of patients with unsightly scars. Nevertheless, no technique has been devised to allow for total and permanent elimination of scars. Patients should be counseled to understand that the goal of scar revision is to replace one scar for another to improve the appearance and the acceptability of the scar.

The wound healing process is divided into three stages. In the inflammatory phase, the release of inflammatory mediators results in migration of fibroblasts into the wound. During the proliferative phase, an extracellular matrix is formed that comprises proteoglycans, fibronectin, hyaluronic acid, and collagen secreted by fibroblasts. Angiogenesis and re-epithelialization of the wound also occur during the proliferative phase. Collagen and the extracellular matrix mature in the remodeling phase, and the wound contracts. Wound strength reaches 20% of its preinjury strength at 3 weeks. The ultimate tensile strength of the wound is 70–80% of that of the uninjured skin.

Genetic Factors

Genetic factors contributing to poor scar formation are likely to be present in patients with Fitzpatrick skin Types III and above. Darker skins tend to form postinflammatory hyperpigmentation and are more likely to form keloids or hypertrophic scars. Younger skin has more tensile strength, which can lead to widening of the scar, whereas older skin tends to scar better because of a lesser amount of tension on the wound.

Iatrogenic Causes

Iatrogenic causes of poor scar formation include excessive soft tissue trauma while handling the skin, failure to reapproximate and evert the wound edges properly, and closure under excessive tension. Failure to evert the wound edges at the time of closure leads to formation of a depressed scar. Lack of deep support of the wound can lead to excessive tension on wound edges, resulting in a widened scar. Sutures from facial wounds should be removed after 5–7 days. Removing sutures too early or too late may lead to a wide scar or unsightly tracking, respectively. Early treatment with steroids or isotretinoin (Accutane) can adversely affect wound healing. It is recommended that laser resurfacing procedures or elective surgery, especially on the face, be delayed for at least 12–18 months after completing a course of isotretinoin.

Hypertrophic Scar, Keloids, and Widened Scars

Hypertrophic scars are self-limited scars, which hypertrophy within the limits of the wound but above the skin level. Hypertrophic scars are more common than keloids and occur without race predilection and in any age group. Initially, these scars are red, raised, pruritic, and occasionally painful, but they tend to flatten over time. They appear worse at 2 weeks to 2 months after wound closure. In general, hypertrophic scars are more responsive to steroid injections than are keloids.

Keloid scars can be distinguished from hypertrophic scars by spreading beyond the original wound. Keloids have a distinct race predilection to darker skins and occur most often in patients who are 10–30 years old. In contrast to hypertrophic scars, keloid scars remain raised, red, pruritic, and occasionally painful rather than regressing at a few months.

Widened scars are typically flat and depressed and do not have an erythematous or pruritic phase. They occur without race or age tendency and occur most frequently on the body. Wound color typically improves to match the uninjured skin with time.

Histologically, the collagen in both keloids and hypertrophic scars is organized in discrete nodules, frequently obliterating the rete pegs in the papillary dermis of the lesions. While collagen in normal dermis is arranged in discrete fascicles separated by considerable interstitial space, collagen nodules in keloids and in hypertrophic scars appear avascular and unidirectional and are aligned in a highly stressed configuration. Collagen synthesis is greater in keloids than hypertrophic scars. Collagen synthesis is three times greater in keloids than hypertrophic scars and 20 times greater than in normal scars. Keloids immunochemically demonstrate a greater tissue concentration of immunoglobulin G (IgG) relative to hypertrophic scars and normal skin. Disagreement exists about whether hypertrophic scars can be differentiated from keloids using light microscopy. Blackburn and Cosman described eosinophilic refractile hyaline collagen fibers, an increase in mucinous ground substance, and a lack of fibroblasts in keloids. Scanning electron microscopy findings clearly demonstrate the randomly organized sheets of collagen with no obvious relationship to the skin surface in keloid scar formation.

Skin is anisotropic and nonlinear and has time-dependent properties. The term anisotropic indicates that the mechanical properties of skin vary with direction. The relaxed skin tension lines (RSTLs) are the lines of minimal tension of the skin; incisions parallel with these lines are under the least possible tension while healing. Perpendicular to the RSTLs are the lines of maximal extensibility. A fusiform excision parallel with the RSTLs and closed in the direction of the lines of maximal extensibility heals under minimal closing tension and results in the best scar.

Complications of scar revision vary according to the method used. These include local infection, graft or flap necrosis, and further scarring after the revision. Viral reactivation of the herpes zoster virus is a potential complication after dermabrasion or laser resurfacing. Laser resurfacing can also cause postinflammatory hyperpigmentation, which may last several months, or hypopigmentation, which may be difficult to treat. Resurfacing methods that go beyond the deep reticular dermis can cause further scarring instead of improving a scar.

Nonsurgical Measures

Intralesional Agents

For many years, corticosteroid injection has been established in the reduction of hypertrophic scars and keloids. Common preparations include triamcinolone acetonide (Kenalog) and triamcinolone diacetate (Aristocort). Steroids decrease fibroblast proliferation, reduce blood vessel formation, and interfere with fibrosis by inhibiting extracellular matrix protein gene expression (downregulates pro-α1 collagen gene). By decreasing the production of collagen, a smaller scar is created. Doses ranging from 5 mg/mL to 40 mg/mL are injected at 3- to 6-week intervals. Typically, multiple injections are required to obtain the desired benefit. Complications of steroid injection include atrophy of the subcutaneous layer, granuloma formation, pigmentary changes, and development of telangiectasias.

New intralesional treatments have included the use of antimitotic agents such as bleomycin and 5-fluorouracil (5-FU). Small doses of these drugs may be injected into hypertrophic scar tissue with good results. Intralesional injections of 5-FU in combination with triamcinolone acetonide plus concomitant use of a pulsed-dye laser have had good results. Injections can be performed as frequently as three times per week. Injections of bleomycin into a keloid using a multipuncture technique have also shown some promise in scar flattening and preventing recurrence. Antimitotic medications should not be administered to pregnant women.

Soft Tissue Fillers

Atrophic and depressed scars may also be treated with injectable fillers in an attempt to provide bulk in areas of tissue deficiency. The most commonly used agents include nonanimal stabilized hyaluronic acid (Restylane, Juvederm, Captique, Elevess), animal based hyaluronic acid (Hylaform), hydroxyapatite (Radiesse), bovine collagen (Zyderm, Zyplast), pooled human collagen (micronized AlloDerm or Cymetra, CosmoDerm, CosmoPlast), autologous dermis, and fat. These biologically derived materials provide temporary correction (2–12 months). Synthetic materials such as expanded polytetrafluoroethylene (e-PTFE, GoreTex, SoftForm, UltraSoft, Advanta) may also be used to provide a filling effect in depressed areas. Injectable Fibrel and silicone are no longer in widespread use.

Silicone Sheeting, Hydration, and Compression

Silicone has been used with relative success in the management of hypertrophic scars, although its mechanism of action is not clearly understood. Although it was initially hypothesized to work through pressure over the scar tissue, the efficacy of silicone has been demonstrated even in nonpressure dressings. It appears that hydration, or rather the ability of silicone to prevent wound desiccation, is a contributing mechanism. Hydration inhibits the in vitro production of collagen and glycosaminoglycans by fibroblasts. Silicone sheeting can be worn daily for as long as 12–24 hours daily, although its application is somewhat cumbersome. An alternative to silicone sheeting, silicone gel can be applied onto the scar. Both silicone gel and silicone sheeting have shown positive results in the reduction of scar size and erythema.

Continuous pressure at 80 mm Hg provided by tight-fitting dressings has been shown to prevent and modify scar formation. The potential mechanisms of action are local tissue hypoxia and reduction of the intralesional population of mast cells, which may affect fibroblast growth.

Pulsed-Dye Laser

The pulsed-dye 585-nm-wavelength laser can be effective in reducing scar erythema by reducing neovascularization. Several treatments are usually required using a low to moderate fluence (5.0–7.0 J/cm2) with no overlap. Hypertrophic scars may also shrink with this treatment as a result of a reduction in the number and activity of fibroblasts.

Dermabrasion

Raised, depressed, or hyperpigmented scars may benefit from superficial abrasion of the skin, which blends the scar with its surrounding tissue by changing the texture, color, and depth of the scar. The technique of resurfacing depends on the nature of the deformity. The goal of this technique is to even out any uneven surfaces. The depth of the dermabrasion depends on the depth of the scar. However, dermabrasion should not go beyond the reticular dermis; otherwise, greater scarring or hypopigmentation will result.

Laser Resurfacing

Laser resurfacing has replaced mechanical dermabrasion in many practices. One advantage of laser resurfacing over mechanical dermabrasion is that the depth of penetration is easier to control. Another advantage is that there is no aerosolization of skin and blood, thereby lowering the risk of viral transmission. The thermal damage that results from laser resurfacing is advantageous in that it produces collagen contracture of 20–60%. However, the postoperative period of laser resurfacing is marked by prolonged erythema. The most common lasers in use for resurfacing are the high-energy pulsed CO2 laser, which produces photothermal injury, and the erbium:YAG laser, which results in photomechanical injury to the skin. Combining different laser modalities, such as the pulsed-dye and CO2 lasers, may provide an added advantage in scar improvement.

Fractional laser resurfacing (Fraxel SR) has been in use in treatment of scars, as well as dyschromia and poor skin texture. This approach is based on fractional photothermolysis. Unlike in CO2 laser resurfacing, the fractionated method creates patterns of microscopic laser spots of 70 to 100 μm in diameter, called microthermal zones. Each laser spot is surrounded by healthy tissue, and most melanocytes and stem cells in papillary dermis are spared. This method avoids many of the side effects associated with traditional laser resurfacing and results in rapid re-epithelialization of the dermis and collagen remodeling. A recent survey of patients undergoing fractionated resurfacing shows great satisfaction among patients who had the procedures for deep acne scars.

Camouflage

Many patients who seek scar revisions may not be able to camouflage the scar or have minimal knowledge of available camouflage techniques. Makeup, hair, and accessories can sometimes offer excellent coverage of the scar. Newer makeup materials and techniques allow for better and more complete coverage of unsightly defects. Opaque cosmetics with a slightly low tone, which disguises the erythema of scars, generally provide better results.

Preoperative Considerations

Patient Expectations

As with any cosmetic procedure, the patient's motivations and expectations for seeking corrective surgery should be carefully considered. In general, well-informed patients with realistic expectations have better overall outcomes. A patient should understand that scar revision is a process to improve the appearance of the scar by adjusting, repositioning, or narrowing the scar and that complete elimination of the scar is impossible at this point. However, the physician should be sensitive to the fact that the scar may represent a traumatic experience to the patient. If the revision does not meet the patient's expectations, the patient may suffer additional trauma. Occasionally, psychological counseling should be recommended in conjunction with scar revision.

Timing of Scar Revision

Scars in the inflammatory phase are prone to hypertrophy. The initial scar can be expected to change due to collagen remodeling and collagen fiber reorientation. Although collagen remodeling continues for 1–3 years, most significant changes occur in the first 4–6 months, and an average of 6 months' delay before revision is reasonable. Nevertheless, in clinical situations, where skin edges are grossly misaligned or the scar lies in an unfavorable direction, scar revision may prove beneficial as early as 2 months.

Scar Analysis

Before embarking on a revision, the primary scar, and its desired location when revised, should be carefully analyzed. Scars can be classified according to their location, etiology, size, shape, contour, and color. Cosmetically favorable scars are similar in color to the surrounding tissue. They are also fine, flat, and well positioned in the face. Scars that are located in the periphery of the face, at a transition line between two cosmetic subunits, or directly in the midline are less conspicuous. The lack of one or more of these qualities results in an unsightly scar. Noticeable scars are wide, raised, or depressed, or are often hyperpigmented or hypopigmented compared with the adjacent skin. They may cut across different subunits or lie in an unfavorable direction. A scar contracture in sensitive areas—for example, at the vermilion or the eyelid—can distort adjacent structures and create cosmetic or functional deformities.

Surgical Measures

Appropriate scar management begins at the time of injury. Good surgical technique is essential for normal wound healing. Crushing the skin edges, tying sutures too tightly, and cauterizing too excessively may result in local tissue inflammation, necrosis, and poor scarring. Adequate wound humidity and coverage are also important for minimizing scar formation. Studies suggest that epithelial cells migrate more readily with adequate surface moisture. If the wound is kept moist, particularly with an occlusive dressing, migration proceeds more directly and efficiently. Local tissue ischemia caused by infection, hematoma, foreign bodies, anemia, or poor surgical technique may slow wound healing. In addition, local wound infection prolongs wound healing. Bacteria delay normal healing phases by directly damaging cells of wound repair by prolonging the inflammatory phase as well as competing for oxygen and nutrients within the tissue. Surgical excision of hypertrophic scars or keloids may lead to recurrence rates of 45–100%.

Primary Excision and Straight-Line Closure

The most common technique in the revision of scars 2 cm or shorter is primary excision and linear closure. Typically, with this procedure, a small margin of normal skin in the periphery of the scar is excised with the scar in a fusiform fashion, and the defect is closed in a linear fashion. The optimal length-to-width ratio to prevent standing cone deformities while maintaining the minimum length of the new scar is 3:1. The wound edges should be undermined to reduce the tension on the closure line. The defect is then closed in two layers, with subdermal absorbable sutures to minimize tension and fine monofilament sutures, such as 5.0 or 6.0 nylon or polypropylene, for the superficial layer. Wound eversion should be meticulously achieved.

With large scars, where total excision of the scar is not practical, serial excisions of the central portion of the scar with advancement of the peripheral tissue can be useful. A minimum period of 6 weeks should be allowed between each two excisions.

Small and pitted or depressed scars, such as deep acne scars, can be revised by punch excision and primary closure with wound eversion. As an alternative, small, full-thickness skin grafts can be placed into the defects and secured in position with sutures, bolstering techniques, or both.

W-Plasty

The W-plasty is a series of connected, triangular advancement flaps mirrored along the length of the scar. A W-plasty, unlike a Z-plasty, incorporates shorter limbs and does not result in an overall change in the length of the scar. Unfavorable scars that are short and located in forgiving locations, such as the forehead or cheeks, scars that lie perpendicular to RSTLs, pretrichial scars, and scars over curved surfaces such as the inferior mandibular border are particularly good indications of W-plasty. This procedure can make the scar less conspicuous by making it irregular and thus more difficult for the observing eye to track. It also disrupts wound contracture with its irregular pattern.

In designing a W-plasty, dots representing the apices of the triangles are placed 3–5 mm from the scar edge. These dots should be spaced 5–6 mm apart, and each limb of the triangle should be 3–5 mm in length. The angle of the apex of each triangle should be determined by its relationship to the RSTLs, making one of the limbs of the triangle parallel with these lines. The ends of the W-plasty should be less than 30° to avoid standing cone deformities. Alternately, an M-plasty can be used at the ends to prevent extending the excision. The scar is excised, the adjacent tissue is undermined, and the wound is closed with a two-layer closure. Horizontal mattress sutures can be used to enhance wound eversion.

Geometric Broken-Line Closure

Geometric broken-line closure (GBLC) differs from W-plasty in that, instead of using a series of triangles, it includes other alternating geometric shapes, such as squares and semicircles, along with triangles (Figure 72–1). Scars that respond well to GBLC are those that are relatively long and 45° or greater from RSTLs. Scars that are perpendicular to these lines have the best cosmetic result using GBLC. GBLC is slightly more challenging than W-plasty, but the principles and techniques are otherwise identical.

Z-Plasty

The Z-plasty consists of two transposition-advancement flaps designed to accomplish three goals: (1) change scar direction, (2) interrupt scar linearity, and (3) lengthen scar contracture (Figure 72–2). Z-pasty is particularly beneficial if it can reorient a scar with RSTLs or in a natural junction between facial esthetic units. Similarly, with this technique, a long scar can be broken up into several smaller components to allow better camouflage (Figure 72–3). Finally, scars that cause distortion of facial features due to scar contracture are good candidates for revision using Z-plasty.

A main advantage of Z-plasty over other techniques, such as W-plasty, is that usually no additional normal skin needs to be removed. A properly planned Z-plasty results in minimal distortion of surrounding structures. Moreover, it can counter the forces of scar contracture, thus correcting webbed or contracted scars that distort anatomic landmarks.

Precise preoperative planning of this technique is an essential requirement for its success. In its classic description, Z-plasty consists of one central and two peripheral limbs in the shape of a Z, such that two triangular flaps of equal size are created. All three limbs are of equal length, and the central limb consists of the scar that is to be lengthened and realigned. The orientation of the final scar can be determined by the direction in which the lateral limbs are placed and by varying the angles of the lateral limbs in relation to the central limb. The most commonly used angles are 30°, 45°, and 60°, which produce lengthening of the scar of 25%, 50%, and 75%, respectively. For long scars for which a single Z-plasty may produce long, linear scars, multiple Z-plasties can be used along the scar.

In performing this technique, the scar is excised along the central limb and the peripheral limbs are incised. The two triangular flaps and the surrounding tissue are mobilized, and the flaps are transposed and advanced. After meticulous hemostasis, the flaps are closed using tension-reducing techniques and eversion. A passive drain with pressure dressing may be necessary to reduce the dead space and the chance of fluid accumulation under the flaps.

Skin Grafts

Full-thickness skin grafts can be used in a variety of ways in scar revision. Scars can be simply excised and grafted with a full-thickness graft. Skin grafts can also be used to fill skin defects after punch excision of deep or depressed scars. Contracted scars in the lower eyelid that lead to ectropion often require replacement of the anterior lamellar defect using a full-thickness graft. Defects in the upper eyelid causing lag ophthalmus can be repaired in a similar fashion using skin grafts.

Flaps

Flaps can be beneficial in a variety of ways in scar revision. In general, they can be used when the best option in scar revision is complete excision of the scar and reconstruction of the defect with a local flap. For example, a small scar of the nasal tip may be excised and repaired using a bilobed flap, just as one might repair a defect after ablation of a malignant growth in the same area. (For a more comprehensive discussion of local flaps, see Chapter 77, Local & Regional Flaps in Head & Neck Reconstruction.)

Most scars may be improved using a variety of scar revision techniques. Essentials of wound care are as important after the revision to achieve optimal outcomes. However, a scar may require several revision procedures before an outcome acceptable to the patient is achieved. The need for multiple procedures should be clearly discussed with the patient.