Fractional Radiofrequency (RF) is a newer resurfacing approach. Fractional RF uses an array of microneedle electrodes arranged in pairs between which bipolar RF energy is delivered. Thermal lesions are delivered in a non-homogenous fractional form directly to the reticular dermis. The area directly in contact with and below the array of microneedles is selectively heated, while the areas in between the targeted areas are left intact.

Mechanism of Action

The fractionally delivered energy creates zones of affected skin adjacent to unaffected areas. The treated areas result in thermal damage to the deep dermal collagen and subsequent wound healing. This leads to dermal remodeling and new collagen, elastin, and hyaluronic acid formation. The unaffected areas located in between affected areas initially maintain skin integrity but in the long term, serve as a reservoir of cells that promote and accelerate wound healing.

Device Properties

Fractional RF devices consist of a handheld applicator with a disposable tip. The tip contains parallel rows of bipolar arranged electrode pins, forming an array of positively and negatively charged electrodes. The RF energy flows between each pair of positively and negatively charge electrode pins, so that each pair forms a closed circuit of bipolar RF current. The volume of each lesion is defined by the geometry of the microneedle electrode pairs.

Evidence-Based Efficacy and Side Effects

Fractional RF has been used mainly for skin rejuvenation. A prospective multicenter study was conducted on 35 subjects who received three treatments with fractional RF on their entire face. Clinical improvement was assessed at 4 weeks after the last treatment using photographic analysis. Eighty three percent of patients show improvement in skin brightness, 87% in skin tightness, and 90% in smoothness and wrinkling. There was a trend toward less degree of wrinkling and elastosis but this difference was not statistically significant. Eighty percent of patients were satisfied with their treatment. Side effects included minimal pain in 87% of patients, moderate pain in four patients, and one patient with severe pain. One patient experienced prolonged edema and another had temporary erythema.

In a randomized blinded trial, 15 patients with facial skin laxity completed one fractional RF treatment. Five independent blinded evaluators graded 3 and 6 month photographs. The improvement relative to baseline in facial laxity was 16%. Side effects included transient erythema, mild edema, and mild to moderate purpura that resolved in 5-10 days. The patients who underwent fractional RF were compared to 6 patients who underwent a surgical face lift. These patients demonstrated a 49% improvement in skin laxity relative to baseline, compared to 16% in patients treated with fractional RF.

A recent study evaluated the relationship between subjective clinical improvement scores with objective measures of mechanical properties of the skin in 44 patients treated with a fractional radiofrequency device. Clinical improvement in skin laxity and wrinkles were graded using a standard scoring system by three independent clinicians at 3 and 6 months after treatment. Objective evaluation consisted of elasticity measurement using a skin probe. At 3 months after treatment, a statistically significant improvement in elastometry measurements was observed which correlated to a 2.6-year improvement in skin property. Subjective clinical improvement in skin laxity and wrinkles was subjectively observed, which corresponded to a statistically significant improvement of 1.42 grades in Fitzpatrick scale for wrinkles and 0.66 grades in Alexiades scale for laxity.

Limitations

It appears that fractional RF treatments are a safe, tolerable, and effective modality for wrinkle and facial laxity reduction. The most common side effects include erythema and edema, which are transient, and patient discomfort does not seem to be a major disadvantage. Compared to the gold standard of rhytid reduction, the surgical facelift, studies suggest that this nonablative method is inferior, but is associated with less downtime and side effects.

In conclusion, non-ablative radiofrequency devices have broad applications in the field of aesthetic medicine. Results have overall been favorable but many studies are non-randomized, non-comparative trials that use subjective means for evaluation. The few studies that have used objective means for evaluation do report improvement.

Overall, nonablative radiofrequency is a safe, tolerable, and effective tool for skin rejuvenation. They produce modest results that should serve as an alternative but not as an equivalent substitute to surgery. The major significant advantage of this modality compared to ablative and surgical treatments is the lower rate of side effects and less downtime required after treatment.

Questions still remain regarding the ideal treatment parameters, specifically energy levels and number of passes that should be employed for optimal results. More controlled randomized comparative clinical trials are necessary to elucidate the most effective way to use these devices for their various clinical applications. Furthermore, the comparative safety and efficacy among the multiple monopolar, bipolar and fractional radiofrequency devices has not been established.