An increasing number of patients are disappointed with scarring following aesthetic procedures. Multiple studies have been published with regard to methods to reduce their formation. However, most of the current approaches to improve scarring have considerable side-effects and results can vary aesthetically. Therefore, it is always preferable to try and prevent scar formation rather than have to treat keloid or hypertrophic problems at a later date. In this article, the authors review a variety of different cream and gel-based strategies, as well as more invasive treatments and their ability to improve the aesthetic appearance of fresh and older scars. However, most of the products presently available on the market lack convincing scientific data with regard to their efficacy. Therefore, it remains paramount for the physician to be aware of the basic knowledge of healing mechanisms and skin anatomy, as well as an appreciation of suture material and wound closure techniques to minimise the risk of postoperative scarring.
Scars form following any insult to the deep dermis as a result of the complex physiologic wound healing cascade. Usually, fresh scars appear reddish, sometimes itchy and slightly elevated, eventually turning to flat, frequently depigmented scars without further symptoms, over a number of months (Figure 1). A study by Bond and colleagues, examining the natural history of scar redness and maturation after incisional and excisional wounds, demonstrated that the majority of scars fade at approximately 7 months1 They also showed that a considerable proportion of scars displayed persistent redness at 12 months, in the absence of features suggestive of hypertrophic or keloid scarring, advocating the term ‘rubor perseverans’ to describe the physiologic redness of a normal scar as it matures beyond the first month1.
Genetic susceptibility, specific anatomic locations, prolonged inflammation and delayed epithelialisation may increase the risk of developing unpleasant scarring such as hypertrophic scars or keloids after even minor surgical or laser procedures, particularly in predisposed individuals (Table 1, Figure 2). As defined by Mancini (in 1962) and Peacock (in 1970), both scar types rise above skin level, but while hypertrophic scars do not extend beyond the initial site of injury, keloids typically project beyond the original wound margins2, 3. Both lesions represent aberrations in the fundamental processes of wound healing, where there is an obvious imbalance between the anabolic and catabolic phases, ultimately resulting in these characteristically raised, reddish and itchy scars that are frequently disturbing to the patient both physically and psychologically4.
In the majority of cases, hypertrophic scars develop in wounds at anatomic locations with high tension, such as shoulders, neck, presternum, knees and ankles5-7, while anterior chest, shoulders, earlobes, upper arms and cheeks have a higher preference for keloid formation. Eyelids, cornea, palms, mucous membranes, genitalia and soles are generally less affected8. Keloid and hypertrophic scars are equal in gender distribution and have the highest incidence in the second to third decades of life9,10. Keloid formation affects individuals of all races (except albino), but darker-skinned individuals have been found to be more susceptible to keloid formation, with an incidence of 6–16% in African populations8,11. In Chinese populations, the incidence of keloids has been reported to be three times more common compared with Caucasian patients, and that patients of Chinese ethnicity are slightly more prone to keloids compared with darker-skinned Indians and Malays12. The concept of a genetic predisposition to keloids is therefore widely accepted and has been elucidated in a number of studies13-15, although no single keloid gene has been identified thus far. Keloid growth may also be stimulated by a number of hormones, as some studies suggest a higher incidence of keloid formation during puberty and pregnancy, with a decrease in size after menopause10,16,17.
Multiple studies on hypertrophic scar or keloid formation have led to a range of therapeutic strategies in order to improve scar formation and have been reviewed in a plethora of articles8,18-21. However, most of the current approaches to improve scarring have considerable side-effects and results can vary aesthetically. Therefore, it is always preferable to try and prevent scar formation rather than have to treat problems at a later date.
Surgical approaches for the prevention of unpleasant scarring
Avoiding all unnecessary wounds in patients, who are keloid or hypertrophic scar-prone, remains an obvious but imperfect solution. As delayed epithelialisation beyond 10-14 days is known to increase the incidence of hypertrophic scarring dramatically18, the achievement of rapid epithelialisation is essential to avoid excessive scar formation. In particular, wounds subjected to tension as a result of motion, body location, or loss of tissue are at an increased risk of scar hypertrophy and spreading, and patients should be informed of this important matter prior to surgery22.