and Revision of the Cicatrix
SOURCE: Grand Rounds, Dept of Otolaryngology UTMB
DATE: November 19, 1997
RESIDENT: Herve' LeBoeuf, MD
FACULTY PHYSICIAN: Karen H. Calhoun, MD
SERIES EDITOR: Francis B. Quinn, Jr. MD
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The most important aspect of scar management is prevention. The surgeon must be familiar with the proper manner of planning an incision, meticulous surgical techniques, and wound healing in order to minimize iatrogenic scarring. Sometimes an unavoidable but unacceptable scar exists after a surgical procedure or traumatic injury. The surgeon should possess mastery of several of the techniques of scar camouflage to maximally disguise these scars, especially in the region of the head and neck. The following is a general discussion of the aforementioned principle and techniques.
Knowledge of the lines of tension described in the head and neck region is essential to creating and camouflaging an incision.
Relaxed skin tension lines (RSTL) are different from either Langerís lines or lines of minimal tension. Langer found that puncture wounds made in fresh cadavers assumed a slit or oval configuration as rigor mortis progressed. The woundís long axis was found to correspond to the greatest static tension of the skin. Langer constructed his incision lines to follow the long axes. Even today, Langerís lines are sometimes thought to represent the optimum direction to orient incisions; however, clinical application has shown that this is not true. Langerís lines are now of historical interest only.
Relaxed skin tension lines are those lines that follows the furrows formed when the skin is relaxed. Unlike wrinkle lines, they are not visible features of the skin. They can be found by pinching the skin and observing the furrows and ridges that are formed. Pinching is the most reliable method of finding the RSTL. The forces that cause the RSTL are inherent to the skin itself and the underlying collagen matrix. Although each person has his or her own blueprint for RSTL, the direction of tension lines between individuals is consistent.
The RSTL correspond to the directional pull that exists in relaxed skin. This pull is determined largely by the protrusion of the underlying bone, cartilage, and tissue bulk that the skin covers. Although the RSTL are not caused by the underlying facial musculature, they frequently run perpendicular to them. The RSTL exert a constant tension on the face when it is in repose, even during sleep, and are altered only temporarily by muscle contraction. It is for this reason that incisions made parallel to tension lines heal better than those made tangentially to tension lines.
Cutaneous wound healing may be defined broadly as the interaction of a complex series of phenomena that culminates in the resurfacing, reconstitution, and proportionate restoration of the tensile strength of wounded skin. In many models of wound healing, reepithelization has been taken as the end point of healing. Yet, from a clinical perspective it is important to note that the tensile strength of healing tissue is highly inadequate at the time of epithelial resurfacing. Collagen remodeling and other events that lead to maturation of the scar tissue occur for months after epithelization is complete.
The stages of wound healing can be temporally organized. The vascular phase occurs immediately after wounding and involves early vasoconstriction and later vasodilatation with the release of a slew of important cellular and noncellular blood products into the wound. The inflammatory phase is important for the phagocytosis and debridement of foreign material and the killing of bacteria. In addition, these inflammatory events generate a host of soluble mediators important in the migration of fibroblasts into the wound, and the subsequent production of new collagen. Reepithelization is critical for restoration of the barrier function of the wound. Granulation tissue consists of inflammatory cells, fibroblasts, and neovasculature in a matrix of fibronectin and other glycoproteins, glycosaminoglycans, and collagen. Its formation involves the synthesis of collagen and noncollagen matrix components and the generation of a new vascular system to support growth. Wound contraction (the centripetal movement of the wound edges) is a critical event during the granulation tissue formation period. Finally, for months after scar and matrix are formed they are remodeled with the ultimate goal to decrease the bulk of the scar and improve its tensile strength through realignment of the collagen fibers.
Variables in Wound Healing
There are several principles of incision technique and repair that can dramatically affect the rate of healing. The most important variables to the surgeon are of a mechanical nature and are discussed below.
Incisions in the head and neck region should be made with the sharpest blade available. The scalpel should incise the skin at right angles, except in hair-bearing areas where the incision should be parallel to the hair follicles.
The rough handling of tissue and the use of inappropriately bulky instrumentation can lead to crushed skin edges and subsequent devitalization of tissue. This increases the inflammatory reaction around the wound and the chances for secondary infection. Likewise, wounds closed with inappropriately reactive suture material may increase the likelihood of a clinically apparent foreign body reaction and subsequent infection. Skin sutures tied too tightly may lead to tissue ischemia and predispose to infection.
The most important step in wound closure is the dermal suture. After appropriate undermining to relieve tension from the suture line, the dermis should be closed with an interrupted stitch. The knot should be buried. The needle should be inserted so that the distance from the insertion point to the cut edge is greater than the vertical distance from the exit point beneath the skin. The points where the suture enters and exits the subcutaneous tissue on either side of the wound edge should correspond as mush as possible. Appropriate closure of the subcutaneous tissue and dermis will result in eversion and exact alignment of the epidermis. Inappropriate closure at this level can result in inversion of one skin edge or uneven alignment of the skin edges.
Although closure of the epidermis is not as important as dermal closure, careful attention to detail and use of soft-tissue techniques are still necessary. The distance from the cut edge to the entrance point of the needle should be less than the distance from where the needle enters the epithelium to where it exits the cut edge of the subcutaneous tissue. The suture will thus encompass more subcutaneous tissue than epithelium, giving a tendency toward eversion when the knot is tied. After the sutures are removed, the wound will flatten as the forces of scar contracture pull the would edge in.
Excessive bleeding and the formation of a hematoma within the wound not only can mechanically disrupt the wound closure but also can serve as an excellent culture medium for microorganisms. Meticulous hemostasis attained at the time of surgery, along with primary obliteration of dead space should preempt the need for drains in most cases.
A bacterial wound infection is probably the most common cause for prolonged healing. All wounds are contaminated postoperatively by resident bacterial flora. Clinical infection ensues when a critical number of pathogenic organisms are present.
Bacteria slow healing by activating the alternate complement pathway and detrimentally exaggerating and prolonging the inflammatory phase of wound healing. In addition, they elaborate toxins and proteases that can be damaging to cells. Finally, they compete for oxygen and nutrients in the wound matrix. Lactic acid is produced in this hypoxic state and further stimulates the release of damaging proteolytic enzymes.
The predisposition for bacterial secondary infection can be lessened by minimizing the formation of excessive devitalized tissue, by the judicious use of pinpoint cautery, and the gentle handling and closure of skin edges without tension.
Important is the avoidance of foreign bodies, by proper irrigation, debridement and limiting the amount of absorbable suture. A foreign body within the wound serves as an appropriate surface for the activation of the alternate complement pathway and the generation of a prolonged inflammatory response. These events interfere with the subsequent stages of wound repair. Wounds containing foreign material are characterized by low pH and low pO2. As noted above in the discussion of infection, these factors significantly slow wound repair.
Open wounds that are allowed to form a dry, crusted scab heal more slowly than wounds healing in a moist environment (such as that provided by an occlusive dressing). Abundant evidence now exists that an occlusive or semiocclusive wound dressing promotes faster reepithelization.
Local factors such as foreign bodies, infection, or strangulating sutures significantly slow healing by promoting tissue ischemia. Interestingly, however, not all the phases of wound repair are depressed by this relative anoxia. For example, cellular migration and angiogenesis are actually stimulated by local hypoxia in the center of the wound. On the other hand, local hypoxia is detrimental to cellular proliferation, resistance to infection, and collagen production. The cumulative result is delayed healing or nonhealing.
Topical Medications and Dressings
As mentioned above, occlusive or semiocclusive dressings promote faster reepithelization. They may also alter certain aspects of dermal repair. This finding has led to the formulation of a wide range of commercially available occlusive and semiocclusive dressings. Although they differ in certain of their properties, they all provide the moist environment needed for optimal wound repair. They may also help prevent bacterial invasion and wound infection.
Furthermore, local emollients applied to the wound may affect wound repair. Even the bases in which these agents are compounded may accelerate or diminish the rates of epithelization.
Few scars are as objectionable to a patient as those found on the face. Whether they are the result of trauma, burns, or surgery, the main goal of the patient is their elimination. As it is not possible to remove a scar completely, the surgeonís goal in revision should be to improve the scar and thus camouflage its presence on the face.
An ideal scar, following complete healing and maturation, should possess all of the following characteristics. It should be (1) flat and level with the surrounding skin; (2) of good color match with the surrounding skin; (3) narrow; (4) parallel to RSTL; and (5) without straight, unbroken lines that can be easily followed with the eye.
As stated previously, no scar can be eliminated completely, no matter how great the desire on the part of the patient or surgeon that this be accomplished. The surgeon should stress to the patient that improvement is the goal of procedures performed in scar revision, and that there will always be a scar; the revision is designed to try to render the scar as inconspicuous as possible.
Scars that are amenable to revision are (1) widened; (2) perpendicular to RSTL; (3) interrupting an aesthetic unit of the face; (4) webbed, (5) pin-cushioned; (6) hypertrophied; (7) adjacent to, but not lying in, a favorable site; (8) long, unbroken, and not within RSTL; or (9) causing distortion of facial features or anatomic function.
The timing of scar revision is variable. Every scar will show some improvement for up to 1 to 3 years without revision. Traditionally, patients were told to wait 6 to 12 months before discussion revision of a scar. That is still true of scars that are thin, in favorable locations, or are of a natural configuration that the surgeon knows will lend itself well to camouflage with maturation. A scar that is uneven, shows a marked step-off, or is obviously poorly positioned may be revised as early as 2 months after the original closure. If it is possible to tell early that a scar will not improve with maturation, there is not a compelling reason to make the patient wait. In fact, early revision with realignment of the scar may allow it to mature more rapidly.
Probably the most common technique employed in removing small lesions of the skin is the fusiform excision, also called a linear excision with straight-line closure. These excisions should be performed only on a hypertrophied scar lying within the RSTL.
This technique is useful for existing scars, such as pitted acne scars or pox scars, that can be excised, with the tradeoff being a pit for a small, straight-line scar that falls within RSTL.
Meticulous attention must be paid to closure in fusiform excision, and care should be taken to follow the natural skin lines as they gently curve, rather than creating a straight line where none normally exists.
Small, existing scars that lie close to RSTL or another favorable site may be repositioned with excision and undermining techniques. Scars on the midface can sometimes be moved to the nasolabial crease, those on the forehead to the hairline, and those on the lateral cheek into the preauricular crease. However, if the symmetry of the facial contour is grossly distorted by this pseudo-rhytidectomy care should be taken to "tighten" the contralateral facial features.
Partial Serial Excision
Large scars or lesions, such as congenital hairy nevi or old skin or grafts, that cannot be eliminated in one procedure without causing distortion or gross asymmetry can often be approached by using the method of partial serial excision. By removing a portion of the lesion and advancing only the normal adjacent skin, the lesion can, over several procedures, often be totally eliminated.
Tissue expanders may be useful in serial excision. If they can be placed in such a way that only normal skin is expanded, more coverage may be obtained with each surgical procedure.
Altering Scar Polarity
Z-plasty is the oldest, simplest, and most versatile of the zigzag closures. The Z-plasty has been described for use in scar elongation, for release of scar contracture, and for changing the direction of a scar.
The classic Z-plasty has 60-degree angles and three limbs of equal length. Undermining the two flaps created by incising these limbs and transposing them increases the length of the scar by 75%. Z-plasties employing other angles are used, most commonly with two 30 degree angles yielding a 25% length increase or two 45-degree angles giving a 50% increase in length.
Z-plasties are useful in breaking up straight-line scars that cross RSTL. Multiple Z-plasties are often useful in the revision of small flaps on the face that may have healed with a pin-cushioned appearance. Placing several Zs around the curve of the flap, allowing interdigitation of flap skin with adjacent skin, provides excellent camouflage, especially when later followed by light dermabrasion.
Besides the irregularization of a scar that can be achieved with Z-plasty, this technique also serves to neutralize the forces acting to cause contracture of a straight-line wound, spreading the forces over several directions allowing little tension in any single direction.
W-plasty is an irregularization technique used to treat antitension line scars and consists of excising consecutive small triangles on each side of a wound or scar and imbricating the resultant triangular flaps. The advantages of a W-plasty are that it generally employs segments with shorter limbs than Z-plasty and does not cause overall lengthening of a scar. Its usefulness is greatest on the forehead, cheeks, chin, and nose, while the Z-plasty is more appropriate to areas about the eyes and mouth. One disadvantage of the W-plasty is that it requires the excision of small amounts of skin and, therefore, allows no gain of tissue in tight areas.
Geometric Broken Line Closure
The geometric broken line closure (GBLC) is a scar irregularization technique with a bit more sophistication than the W-plasty. The design of GBLC comprises a series of random, irregular, geometric shapes cut from one side of a wound and interdigitated with the mirror image of this pattern on the opposite side. The triangles, half-circles, rectangles, and squares should be no longer than 6 mm in any dimension for improved camouflage.
The GBLC is most useful for long, unbroken scars that cross RSTL. Closure of a GBLC is facilitated by careful dermal suturing to remove tension from the skin, and by the use of a running, locked skin suture. As with Z-plasty and W-plasty, dermabrasion 6 or more weeks after GBLC provides optimal camouflage. The GBLC is time consuming to execute and, if improperly designed, can worsen a scar, but there are few other disadvantages to its use.
Dermabrasion is an old technique first described before World War I. It provides a superficial skin injury (to the level of the papillary dermis) that heals by re-epithelialization from adnexal structures in the reticular dermis.
Shallow, crater-like facial scars are often treated with dermabrasion. The scar is not removed, but the surrounding tissue is brought down to a level closer to that of the depressed region. This allows the lesion to blend into the surrounding normal skin because less of a shadow is created by the depression to draw attention to the scar. Mildly elevated immature scars also benefit from localized dermabrasion.
Dermabrasion can be used in conjunction with other scar revision techniques in a sequential fashion. As stated previously, running Z-plasty, W-plasty, and GBLC are generally followed at 6 to 12 weeks by dermabrasion to better blend the new scar with the surrounding skin.
Adjuncts to Healing
Although the proper choice of a scar revision technique, careful execution, and meticulous closure are all necessary to a good surgical result, there are also several adjunctive measures that can be employed to optimize the outcome of healing after revision.
Immobilization of the revised wound is advisable and should be carried out for as long as the patient will tolerate it. The use of antitension taping using skin strips is useful, especially in areas of facial animation.
The use of antibiotic ointment along incision lines and on denuded and dermabraded areas prevents drying, skin desiccation, and crusting, all of which may prolong healing. It is recommended that ointment should used at least two weeks on sutured wounds, and longer if necessary on open wounds, such as those following shave excisions and dermabrasion.
After scar revision, or while awaiting primary healing of a wound that may need to be revised, topical application of steroid creams, retinoids, vitamin preparations, and over-the-counter emollients may be of use. Information on the efficacy of these preparations for this purpose is anecdotal, but harmful effects do not seem to occur; therefore, the use of these agents need not be discouraged in patients wishing to try them.
Similarity, massage of a new scar, once initial epithelial healing has occurred, may serve to realign collagen fibers in the scar and allow it to soften more rapidly.
Adjuncts to Camouflage
During the healing phase following scar revision, especially while the scar is erythematous and indurated, professional assistance in the application of cosmetics may be desirable. Similarly, hair styling may also serve to camouflage particular scars and may not be something the patient instinctively knows how to optimize. Through the art of makeup application and hair styling, desirable features may be enhanced and attention drawn away from those that are less appealing. In many patients, this can be a significant aid to regaining self-esteem and to the acceptance of facial scars.
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