Ablative Fractional Laser
The AFL creates a pixilated pattern of injury throughout the epidermis and dermis of the treatment area. Ablative fractional laser platforms include the 10,600-nm CO2 and 2940-nm erbium-doped YAG lasers, both targeting intracellular water. The AFL vaporizes columns of tissue, leaving minute vertical channels with narrow rims of protein coagulation referred to as microscopic treatment zones (MTZs).6 Scar collagen analysis after AFL treatment has shown a profile resembling unaffected skin.7 Consistently, patients report improvements in stiffness, range of motion, pain, pruritus, pigmentation, and erythema.Physician observers also have reported similar improvements in these end points.8,9 Recently, interim data from a prospective controlled trial were presented showing objective improvements in dermal thickness, elasticity, and extensibility after 3 treatments with the CO2 AFL.6 The UltraPulse CO2 laser (Lumenis) is the most well-studied and widely available AFL for scar therapy and as such we will outline common treatment parameters with this device. Of note, treatment end points may be generalized to any AFL.
The DeepFX UltraPulse configuration is utilized to achieve deep AFL therapy and has a fixed pulse width of 0.8 milliseconds, slightly less than the thermal relaxation time of the skin. The diameter of the MTZs is 120 µm, and MTZ density for scar treatment ranges from 1% to 10% with a goal depth of at least 80% of scar thickness. Maximal penetration of the AFL is 4 mm, which is directly proportional to fluence. The goal of deep AFL is the removal of scar tissue to facilitate remodeling and neocollagenesis. Superficial fractional ablation can then be achieved utilizing the ActiveFX UltraPulse configuration generating a 1.3-mm MTZ spot size. We commonly use a treatment level of 3 (82% density). Typical treatment energy ranges from 80 to 125 mJ, which correlates with depths of approximately 50 to 115 µm. With both configurations, the size and shape of the treatment area can be customized to the scar. In addition, frequency may be adjusted to control the speed of treatment while balancing the risk of bulk heating. The goal of superficial AFL is to minimize scar surface irregularities and ensure blending of deep AFL treatment. Once AFL treatment is complete, local pharmacotherapy can then be employed.
Pharmacotherapy
Intralesional corticosteroids have long represented the standard of care for hypertrophic scars, with concentrations between 2.5 and 40 mg/mL that are titrated to scar thickness and location to avoid unwanted atrophy. Visual blanching of the scar represents the clinical end point for treatment. Corticosteroids act by inhibiting fibroblast proliferation and enhancing collagen degradation.10 5-Fluorouracil (5-FU) also is used in scar management. In addition to inhibiting fibroblast proliferation and inducing fibroblast apoptosis, 5-FU inhibits myofibroblast proliferation, which is helpful in the prevention and treatment of scar contracture.11 As monotherapy, weekly injections with 1 to 3 mL of 50 mg/mL 5-FU has been safe and effective. Combination intralesional corticosteroid and 5-FU therapy has been reported and is associated with improved scar regression, reduced reoccurrence, and fewer side effects.11 In our experience, a 1:1 suspension is effective with appropriate titration of the corticosteroid component. Although less well defined, topical application of pharmacotherapy and massage to the newly created MTZs appears beneficial and offers another option for delivery of corticosteroids and 5-FU, in addition to a number of promising medications such as bimatoprost, poly-L-lactic acid, timolol, and rapamycin.12
Conclusion
Advances in laser surgery and our understanding of wound healing have created a paradigm shift in the treatment approach to trauma and burn scars. In lieu of extensive scar excisions, the summarized multimodal regimen emphasizing tissue conservation and autologous remodeling is gaining favor in the military, academic medical centers, and scar centers of excellence, but patients are finding local access to care difficult. Dermatologists are uniquely positioned to cost-effectively deliver this care in the outpatient setting utilizing devices and techniques they already possess. With the end goal of optimization of functional, symptomatic, and aesthetic state of the patient, it is critical that dermatologists seize this opportunity to truly make a difference for the military and civilian patients that need it most.
