Scars are the result of connective tissue that has replaced lost substance in the dermis or deeper tissue due to injury or disease as part of a normative process. Scar characteristics, such as shape and size, are determined by previous damage. Scars can be thin or atrophic, boxcar, or may develop into a hypertrophic scar or keloid.
TOPICAL TREATMENT OF SCARS
Topical therapies for scars have gained popularity among both physicians and patients for their ease of use, widespread availability, and relatively low cost. This section will review pressure therapy, silicone sheeting, onion-extract gels, topical vitamin preparations, imiquimod cream, and topical corticosteroids for the treatment of scars.
Despite a paucity of controlled studies supporting its efficacy, pressure dressings have long been a mainstay in the prevention and minimization of hypertrophic scars and keloids.1 The proposed mechanism of action of pressure dressings centers upon the acceleration of wound maturation through several pressure-related effects, including thinning of the dermis, decreased edema, and reduction of blood flow and oxygen through the compression of small vessels.2 The hypoxic environment created by continuous pressure is thought to decrease collagen formation and increase collagen lysis through the induction of enzymes and cytokines that promote extracellular matrix remodeling.3
Pressure dressings provide the most clinical benefit in the early, active stages of scarring, becoming less efficacious after 6 months.2 These custom-made elastic garments are worn for approximately 1 year, with replacement dressings applied every 6 to 8 weeks. While inexpensive, the disadvantages of this form of therapy are primarily related to patient compliance due to discomfort and inconvenience. The dressings must be worn at all times and are cumbersome in areas of anatomic depression or associated with frequent motion, such as flexural areas. In addition, they carry the potential for skin breakdown and ulceration if the pressure is too great or unevenly distributed. Furthermore, there is no consensus on the optimal pressure to achieve maximal efficacy while maintaining minimal adverse effects. Current thought asserts that a pressure of 25 mm Hg is sufficient; however, recent evidence has shown that pressures much lower than this have been associated with improved clinical outcomes.4
Silicone Elastomer Sheeting
Silicone elastomer sheeting has been used in scar management since the early 1980s.5 The exact mechanism by which silicone sheeting improves hypertrophic scars and keloids has not yet been completely elucidated. It is hypothesized that its beneficial effects occur primarily through occlusion and hydration. Resultant decreases in capillary activity, hyperemia, and fibroblast-induced collagen deposition aid in extracellular matrix remodeling and improvement in the clinical appearance of scars.6
Silicone gel sheeting should be worn for 12 to 24 hours a day for at least 2 to 3 months to be effective. Daily cleaning may be required to ...