This article reviews minimally invasive radiofrequency options for skin tightening, focusing on describing their mechanism of action and clinical profile in terms of safety and efficacy and presenting peer-reviewed articles associated with the specific technologies. Treatments offered by minimally invasive radiofrequency devices (fractional, microneedling, temperature-controlled) are increasing in popularity due to the dramatic effects they can have without requiring skin excision, downtime, or even extreme financial burden from the patient’s perspective. Clinical applications thus far have yielded impressive results in treating signs of the aging face and neck, either as stand-alone or as postoperative maintenance treatments.
Key points
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Minimally invasive radiofrequency devices offer significant clinical results in treating a variety of cosmetic indications such as skin laxity and scarring.
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Treatments are safe and effective with no adverse effects or requiring patient downtime.
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Physicians offering minimally invasive radiofrequency treatments need to have intimate knowledge with the different devices and their mechanism of action to provide high-quality clinical care.
Introduction
The scope of radiofrequency (RF) devices used for minimally invasive aesthetic treatments of the face and body is to induce selective dermal injury, leading to tissue wound repair response and coagulation while keeping the overlying epidermis intact. As opposed to noninvasive RF devices that do not disrupt the skin layer, minimally invasive devices exploit a variety of methodologies, such as electrode arrays (pins), insulated or noninsulated microneedles, as well as internal probes to mitigate their effects. This article reviews the new evidence and research of the new-generation RF devices that deliver energy in the immediate subdermal space, leading to significant soft tissue skin contraction and correction of laxity without the need of an excisional or skin-repositioning procedure. Clinical application of these technologies includes skin tightening, reduction of rhytides, scars, striae, and cellulite. Generally, ideal candidates of minimally invasive RF devices are patients that demonstrate more severe skin laxity or dermal irregularities (scars) and are of a darker skin type. Although the treatments are framed and exploited for more serious conditions than mere skin rejuvenation, their safety profile and downtime are comparable with that of noninvasive RF devices. Erythema, slight pain, and bruising may occur but are limited to the treatment area and resolve within weeks of treatment.
Introduction
The scope of radiofrequency (RF) devices used for minimally invasive aesthetic treatments of the face and body is to induce selective dermal injury, leading to tissue wound repair response and coagulation while keeping the overlying epidermis intact. As opposed to noninvasive RF devices that do not disrupt the skin layer, minimally invasive devices exploit a variety of methodologies, such as electrode arrays (pins), insulated or noninsulated microneedles, as well as internal probes to mitigate their effects. This article reviews the new evidence and research of the new-generation RF devices that deliver energy in the immediate subdermal space, leading to significant soft tissue skin contraction and correction of laxity without the need of an excisional or skin-repositioning procedure. Clinical application of these technologies includes skin tightening, reduction of rhytides, scars, striae, and cellulite. Generally, ideal candidates of minimally invasive RF devices are patients that demonstrate more severe skin laxity or dermal irregularities (scars) and are of a darker skin type. Although the treatments are framed and exploited for more serious conditions than mere skin rejuvenation, their safety profile and downtime are comparable with that of noninvasive RF devices. Erythema, slight pain, and bruising may occur but are limited to the treatment area and resolve within weeks of treatment.
Fractional radiofrequency
Fractional RF is a concept transferred from fractional photothermolysis in lasers, albeit with some practical differences. Fractional photothermolysis introduced in 2003 was based on a conceptual shift from treating a continuous plane of tissue to using an array of microscopic columns of spatially confined thermal injury (microscopic thermal zones), whereas the untreated areas of tissue would provide reservoirs fueling a more rapid dermal remodeling process. Histologic studies demonstrated significant neoelastogenesis and neocollagenesis after fractional RF treatments with new dermal tissue replacing denatured collagen within 10 weeks, and increased volume, cellularity, hyaluronic acid, and elastin content in the reticular dermis. Immediate increases in interferon-1β, tumor necrosis factor-α, and matrix metalloproteinase-1 (MMP-13) were noted, followed by increases in MMP-1, heat shock protein 72 (HSP72), HSP47, and transforming growth factor-β by 2 days, and tropoelastin, fibrillin, and procollagen 1 and 3 by day 28. As opposed to fractional photothermolysis that creates thermal injury in dermal columns that taper as they descend, fractional RF creates a pattern that depends on the electrode configuration. Arrays of surface electrodes create zones of dermal injury narrowest at the epidermis, which enlarge conically as they descend until the pattern is truncated by attenuation. Because RF devices function independent of chromophores, they can be used on all skin types with little to no risk of pigment alteration. Several clinical studies have demonstrated the success of fractional RF devices in treating a variety of dermatologic conditions, such as laxity, facial brightness, skin pigmentation, and scar lesions, and indications continue to expand. Devices used in peer-reviewed publications exploiting fractional RF energy delivery using arrays of flat electrodes placed on the epidermis include the eMatrix (Syneron, Irvine, CA, USA) and the Venus Viva (Venus Concept, Toronto, CA, USA).
Using a fixed placement of 64 electrodes, the eMatrix device can penetrate up to 450 μm in the dermis, delivering energy of 10 J to 20 J (60–100 mJ/pin) ( Fig. 1 ). This pattern of thermal injury has been termed “sublative,” referring to its effect beneath the ablated zone at the epidermis, with only 5% of the epidermis affected ( Fig. 2 ). A clinical study conducted in 33 patients treated with 3 sessions of eMatrix for photoaging, skin laxity, and rhytides showed that greater than half of patients, skin types II–IV, experienced more than 40% improvement in texture and 80% of patients were satisfied. Significant improvement in skin tightness, brightness, and overall appearance was reported in a study of 26 Asian women treated with the eMatrix device as well as 15 patients with darker skin types V–VI, without any postinflammatory pigmentary alteration. Moreover, a recent study combining the eMatrix sublative rejuvenation procedure at the low-energy setting with elure antipigment topical applied immediately after the RF treatment resulted in significant improvement in facial pigmentation and global rejuvenation with minimal side effects. Significant efficacy of this device has been shown for the treatment of acne scars ( Fig. 3 ). A study of 30 subjects treated with eMatrix for 4 sessions showed 10% to 50% and 20% to 70% improvement in acne scars at the end of 2 and 6 months, respectively. In another study of 10 patients with acne scars and skin types I–V, significant clinical improvement accompanied by high patient satisfaction was noted. A recent split-face study exploring the efficacy of high energy (100 mJ/pin) versus moderate energy (60 mJ/pin) of bipolar fractional RF in treatment of atrophic acne scar in 30 Asians receiving 4 monthly sessions showed that the global acne scar score in both the high-energy and the moderate-energy side was significantly reduced at 1-, 3-, and 6-month follow-up visits, but results were visible at the 1-month follow-up visit in the high-energy side, whereas side effects were slightly more intense with the high-energy setting. Numerous other small studies have echoed the findings of clinical improvement following a regimen of 3 treatments with eMatrix, patient satisfaction, safety in Asian and African American patients, and no significant adverse events ( Fig. 4 ).
Another new-generation RF device that in the authors’ personal experience delivers excellent clinical results, patient satisfaction, and safety profile is the Venus Viva (Venus Concept). The device incorporates both SmartScan tip technology and nanofractional RF. The SmartScan tip provides more than 1000 pulses of energy, penetration depths of up to 500 μm, and multiple options for pattern selections, whereas the nanofractional technology provides targeted density control of the heated zone by delivering the RF energy individually through 160 pins per tip, with 62 mJ per pin and a small footprint per pin (150 × 20 μm) ( Figs. 5 and 6 ). This device is thought to offer increased efficacy due to the operator ability to control both power and pulse duration, which results in improved control of tissue ablation or coagulation ratio, whereas the reduced pin footprint is thought to be associated with decreases in reported side effects from the treatment. Clinical studies have demonstrated the efficacy of the Venus Viva device for the treatment of various skin conditions, including striae, acne scarring, irregular texture, rhytides, hyperpigmentation, and skin laxity, and the typical protocol includes 1 to 3 treatments at 2-week intervals ( Figs. 7 and 8 ). A recent retrospective study of 43 healthy adult volunteers receiving 1 to 3 treatments with the Venus Viva for various facial dermatologic conditions, such as rhytides, hyperpigmentation, or redness, demonstrated improvement of clinical results and high patient satisfaction at the 3-month follow-up. A different study in 12 female patients showed that following a single treatment with Venus Viva, there were positive effects on excess facial pigmentation, texture, and wrinkling for all subjects as evaluated by visual comparison of images taken at follow-up to those taken prior to treatment. These findings support the hypothesis that although fractional RF does not target specific chromophores, by promoting the formation of new dermal proteins enabling the appearance of smoother, clearer skin, this technology may be used in the treatment of pigmentary disorders such as melasma and rosacea. Further clinical studies are however necessary to substantiate the safety and efficacy of nanofractional RF for the treatment of these conditions.
