Reports on the use of fractional CO₂ lasers to improve skin dyschromia, rhytides, and textural irregularities have increased. However, there is little mention of their impact on patients with traumatic or postoperative scars. Most reconstructive surgical interventions, such as conventional laser resurfacing and mechanical dermabrasion, focus on timing with respect to the return of tissue mechanical stability, which can potentially destabilize a healing tissue bed or disrupt the protective epidermal barrier prior to the sealing of the incision.

We present our experience with the use of fractional CO₂ lasers during early treatment times after surgery or trauma to reduce the formation of scars, and discuss the efficacy and safety of such an approach.

Forty-three patients, (20 men and 23 women) aged 22 to 54 years (average age, 33 years), were recruited through the department of plastic surgery, Soonchunhyang Hospital, for study eligibility from March 2010 to April 2012. All patients had facial trauma that was repaired surgically at our hospital. The Fitzpatrick skin types of the patients ranged from III to V.

Laser treatment was initiated about 4 weeks after injury at 4-week intervals. Five treatments were performed, and photographs were taken during every treatment session.

We used a fractional CO₂ laser (LineXel; UTI Co. Ltd, Seoul, Korea) system. The laser procedure was performed with a pulse duration of 140-300 milliseconds (for the scarred region: 160–400 µs), with a distance of 0.8–0.9 mm, degree 1th. A 2.5% licocaine/prilocaine cream was used as a topical anesthetic and applied to the treated areas under occlusion 1 hour before treatment.

Prior to treatment and 5 months after the final treatment, the patient and treating physician completed scar-rating scales. Patients were surveyed about their overall level of satisfaction using the following choices: very satisfied, satisfied, slightly satisfied, and unsatisfied. The 10 independent physicians scored the scars using the Vancouver Scar Scale (VSS), which includes pigmentation (0 =normal, 1 =hypopigmented, 2 =mixed pigmentation, and 3 =hyperpigmented), pliability (0 =normal, 1 =supple, 2 =yielding, 3=firm, 4=ropes, and 5=contracture), height (0=flat, 1= <2 mm, 2=2–5 mm, 3= ≥5 mm), and vascularity (0=normal, 1=pink, 2=red, and 3=purple) [1]. The score for each parameter was assessed separately, and all four scores were added and averaged. The pliability and height scores were determined by considering clinical photos and medical records.

Statistical analyses of comparisons between the pre- and post-treatment VSS scores were performed using the Wilcoxon signedrank test and SPSS statistical software (SPSS Inc., version 17.0, Chicago, IL, USA).

Subjects had statistically significant improvement in scar quality after treatment, as measured by both patient and physicians (Fig. 1, 2). Clinical observations showed diminished scar bulk with reductions in scar height and textural improvements. Additionally, many patients observed skin pigmentation improvement and pliability, as demonstrated by the VSS, which was evaluated by 10 physicians blinded to the patients. The mean VSS scores were 5.93, (standard deviation 2.00) before treatment and 1.58 (standard deviation 0.84) 5 months after the final treatment. After laser treatment, the mean VSS values decreased significantly (P<0.05), and all patients reported subjective improvements, beginning with their initial visit to the end of treatment (Table 1). Looking at each parameter individually, every parameter responded favorably to CO₂ fractional laser treatment. Outstanding achievement is defined as the score of each parameter reaching its lowest scores, representing near-normal skin (Fig. 3). No adverse effects or complications, such as wound disruption, postinflammatory hyperpigmentation, or dyspigmentation, occurred in the present study.

Skin injuries, such as lacerations or abrasions, due to trauma or surgery are relatively common, and patients are very concerned about scar formation. In the best situation, the scar can take up to 1 year to mature before fading into the surrounding skin. On the other hand, some scars remained red and became hard, or worse, became hypertrophic.

The first step in the treatment of excessive scarring is early recognition and institution of therapy after surgery or trauma. Meticulous handling, suturing, and wound management are mandatory. Many different scar prevention therapies, such as silicone gel sheeting, pressure therapy, cryotherapy, and lasers have been used previously with mixed results.

Although scar remodeling and clinical improvement continue to occur 2 to 3 years after surgery, many patients desire scar treatment as soon as possible. Many procedures are postponed until at least 2 to 3 months following surgery, when it is felt that the wound has healed at least 60%.

The use of lasers prophylactically against scarring during the early post-traumatic period is relatively new. The use of pulsed-dye laser (PDL) to suppress scars during the early postoperative period has been described. Keyvan et al. reported that PDL treatment on day of suture removal, prevents erythema and hypertrophic scars [2]. Theresa et al. demonstrated that PDL treatment selectively achieves photothermolysis of scar microvessels [3].

Ablative lasers used for skin resurfacing, such as CO₂ and Er-YAG lasers, can greatly improve the appearance of scars. Significant adverse effects limit their use, so nonablative lasers have been developed as a safer alternative therapy, but outcomes are unsatisfactory. Recently, ablative CO₂ fractional lasers have gained popularity; because of their high pulses of energy, this approach results in negligible adverse effects and leaves the epidermal architecture surrounding each coagulated, microtreated area intact. While not clearly explaining the mechanism, some authors have hypothesized about how the laser affects the scar remodeling phase after trauma or surgery. One hypothesis concerns thermal injury to the dermis (during which disulfide bond disruption occurs due to tissue heating) where neocollagenesis and remodeling transpire [4]. Another hypothesis focuses on the stimulation of growth factors and cytokines by lasers [5], or the initiation of collagen signaling cascades [6]. Laser-induced hypoxia may also play a role in treatment effects [7].

Conventional laser resurfacing and mechanical dermabrasion can potentially destabilize a healing tissue bed or disrupt the protective epidermal barrier prior to the sealing of the incision. Therefore, the optimal time for treatment is during the premature phase of scar formation, 6 to 8 weeks postinjury. However, newer, nonablative, pulsed, or fractionated lasers place minimal mechanical stress on the tissues, making an argument for earlier treatments. Earlier intervention can theoretically alter the inflammatory phase of wound healing and change fibroblast migration, leading to a reduction in the appearance of scars [8].

In this study, we used ablative CO₂ fractional lasers to treat scars especially during early stages of scar remodeling. We initiated laser use 4 weeks after injury, which is the early remodeling phase, during which the extracellular matrix is dynamic, balanced between synthesis and degradation. The main feature of this phase is the deposition of collagen in an organized, well-mannered network. Net collagen synthesis continues for at least 4 to 5 weeks after injury (Fig. 4) [9]. The timing we chose is based on clinical exams performed around 4 weeks after injury, during which dehydration occurs and the scar becomes firm and rigid. At this point, we applied a laser to minimize undesirable cosmetic results, such as hypertrophy, increased erythema, and hard, contracted scars. This approach was an effective and safe method for improving the appearance of scars. Jung et al. [4] used a fractional CO₂ laser for thyroidectomy scars and chose to treat patients with lasers 2 to 3 weeks after surgery because they thought that re-epithelization would be complete at that point.

Further histological studies are needed to assess whether fractional CO₂ lasers improve existing scars or has any preventative capability; a split-scar study would also help compare the effects of lasers with the natural healing of these scars. Bond and colleagues evaluated the maturation of incisional scars on the inner aspect of the upper arm. During the first 1 and 3 postoperative months, the scars displayed a greater number of blood vessels and fibroblasts than normal skin with an immature extracellular matrix. Four months after the incision, the collagen fibers became thicker and denser, with less cellularity and lower blood vessel density in the area of the scar [10].

In our small population study, we noted improvements in traumatic or postoperative scars after early treatment with a fractional CO₂ laser. Although we did not compare the treatment group with a control group, early treatment using a fractional CO₂ laser may prevent scar formation and can rapidly improve the appearance of scars, as we used the VSS to provide an objective measurement of scarring.

This study shows that the use of early fractional CO₂ lasers 4 weeks after surgery or trauma is an effective and safe method to minimize scar formation.