During the last 15 years demographic changes have resulted in increased demand for aesthetic procedures to address the effects of intrinsic aging, excessive sun exposure, and other factors that contribute to unwanted skin laxity and an accelerated appearance of rhytids. This has driven an increase in the popularity of energy based devices for the treatment of a variety of skin conditions over recent years.

To reduce the symptoms of skin aging, physicians have turned to a number of treatment options, ranging in degree of invasiveness and side-effect profile. These include treatment with topical retinoids, chemical peels, microdermabrasion, non-invasive and invasive energy based devices, and surgical reconstruction.

Unlike ablative lasers, fractional laser treatment has been shown to be clinically efficient in managing acne scars and other dermatologic diseases with cosmetic problems without causing direct damage to the epidermis. Although conventional fractional treatment has the disadvantages of inaccurate depth control and possible indirect damage to the epidermis, recently introduced, minimally invasive, fractional microneedle radiofrequency (MRF) devices have been used to overcome such problems by creating radiofrequency (RF) thermal zones with minimal epidermal injury.

Using the microneedle delivery system, it is possible to deliver an exact amount of RF energy at accurate depths at the discretion of the operator. After damage to the reticular dermis, long-term dermal remodeling, neoelastogenesis, and neocollagenesis result in dermal thickening.

About 10 years ago, the FDA approved fractional RF for skin rejuvenation, which can achieve fractional and contiguous treatment patterns while sparing epidermis and key adnexal structures that contribute to rapid healing. In addition to the skin rejuvenation, fractional RF has been reported to induce textural improvement in terms of skin smoothness and tightness.

Fractional radiofrequency with microneedling in acne scars

Acne can result in a variety of subtypes of scars depending on the depth and severity of the inciting inflammation. Atrophic scarring limited to the epidermis and papillary dermis results in superficial macular scarring, which may be erythematous or hyperpigmented. Involvement of the reticular dermis can result in sinuses, ice-pick scars, boxcar scars, rolling scars, hypertrophic scars, and keloidal scars. Ice-pick scars have a narrow aperture and penetrate deep into the dermis or subcutaneous tissue. Boxcar scars have sharp cliff-drop-like vertical margins and a larger, flatter base. Boxcar scars can be further subdivided into superficial and deep boxcar scars. Rolling scars occur from dermal tethering to the underlying superficial musculoaponeurotic system, with the appearance of gently sloping edges. Finally, fat atrophy can result from inflammation of the subcutaneous tissue, independent of injectable corticosteroids. Chemical peels, subcision, augmentation using fillers, ablative and non-ablative lasers, dermabrasion, dermal grafting, punch excision, punch elevation, punch grafting, and surgical excision are all available for the treatment of acne scarring. Many lasers were used in treating acne scarring such as the Pulsed dye laser, long pulse 1064?nm Nd:YAG, Non-fractionated 1320nm Nd:YAG, fractionated 1450nm diode, Fractional Er:YAG and fractional Co2 lasers.

The standard treatment for acne scarring is traditional, full-face Co2 or er:yAg laser resurfacing, with studies showing more favourable results with Co2 lasers. The non-fractionated, high-energy, pulsed Co2 laser improves acne scars by an average of 80% with a single treatment.

Although ablative laser resurfacing produces the most dramatic improvement in acne scarring and texture, there is a significant risk of dyspigmentation, scarring, infection, and prolonged healing.

The first publication of fractionated laser resurfacing was in 2004 by Manstein et al. Fractional photothermolysis had the advantage over ablative laser resurfacing owing to a shorter recovery; lack of general aesthesia; and lower risk of scarring, dyspigmentation and infection.

Although originally described for rejuvenation of the ageing face, this concept was soon applied to acne scarring. In a small cohort of skin types IV to VI, 80% of patients had a minimum of 50% to 75% improvement in acne scarring after five treatments each month of the study using the fractionated 1550nm erbium-doped laser.

A recent meta-analysis reported acne scars improved at least 50% with four to five treatments each month with a fractionated non-ablative laser. After the development of fractionated non-ablative lasers, fractionated ablative lasers emerged. Cho et al found an average of 60% improvement after a single treatment with a fractionated Co2 laser and in a study by Chapas et al, two to three treatments with a fractionated Co2 laser improved acne scarring by an average of 66.8%.

Peterson et al reported improvements in acne scarring and texture of more than 60% with five treatments a month using a combination of fractionated laser with RF device and a fractionated bipolar RF device. The improvement of scarring is comparable with those of other non-ablative fractionated lasers. Rolling scars and boxcar scars improved more dramatically than ice-pick scars.

One of the greatest advantages of MRF is its safety in all skin types. Patients with Fitzpatrick skin types IV to VI have limited options for the improvement of acne scarring because of a greater incidence of post inflammatory hypopigmentation (PIH), which most commonly appears 3 to 4 weeks after laser surgery.

All currently available fractionated lasers must be used conservatively in skin types IV and V and are generally not advisable in skin type VI unless in the hands of an advanced laser surgeon. It is advisable to decrease the fluence, density, and number of passes when treating darker skin types. The epidermis sustains two to 14 times as much damage with other available non-ablative and ablative fractionated lasers compared to the fractional RF, leading to a higher incidence of dyspigmentation. No subjects treated with fractional RF displayed PIH. In another study, there was a significant improvement in investigator-rated acne scarring, texture, and pigmentation. Patient satisfaction scores did not improve, although patient overall improvement scores did. It was speculated that the patients had higher expectations of the device upon study entry. Although patients showed improvement, these high expectations were not met, as reflected in the lack of significant improvement in patient satisfaction scores. The fractionated bipolar RF device was better tolerated than the fractionated laser with RF device. Five treatments were administered every 30 days, but more treatment sessions may be required to produce more substantial clinical and patient-perceived results. Treatments every 5 to 6 months may be needed to achieve patient satisfaction in cases of acne scarring.