Over the past several years, the concept and use of fractional laser resurfacing has become commonplace among dermatologists and others looking for novel ways to improve wrinkles and rhytids, textural abnormalities, and improving acne and traumatic scars. The use of fractional laser energy, with both ablative and nonablative laser energies, has become routine for many of us.
The basic premise of these devices is rather simple, and has had dramatic effects in how we approach patients now with their skin concerns. Fractional lasers create small holes in the skin and use the normal nonlaser skin to assist in the healing process that allows for safer treatments for our patients.1
Ablative fractional laser resurfacing has shown its successes in treating skin concerns in 1 to 2 visits on average, and with an associated downtime of anywhere from 5 to 10 days. Nonablative fractional laser energy has also shown its successes, with multiple treatments (average of 4 to 6) over 4 to 6 months to achieve similar results with less downtime per treatment.2 Even with the successes from these treatments, something was missing from our armamentarium that prompted investigators to look at radiofrequency (RF) energy as a source of the fractional treatments. This mainly had to do with the need to easily treat all skin colors, and RF seemed an appropriate energy source to potentially address this issue.
RF fractional devices have been introduced into our energy-based systems and are not dependent on laser light diffusion, chromophore absorption, or light scattering effects. Instead, these devices produce focal thermal damage in the dermis by generating a current between electrodes or by using needles to penetrate into the dermis and then release RF energy.3
This article will review some of the original technology in this field and discuss several newer RF device modalities currently available which has, in some regards, changed how we approach patients with facial concerns of wrinkles, rhytids, textural changes, as well as acne and traumatic scars.
Why has fractional RF become so popular all over the world? It is perhaps because RF energy is color-blind, and therefore can be used safely in all skin types. In fact, as described below, several clinical trials involving these devices were performed in darker-skinned individuals, with very acceptable clinical outcomes and minimal adverse effects. RF devices use thermal energy that is generated by an electric current rather than by laser light. Thus, they are not subject to diffraction or absorption by epidermal chromophores which is the basis of how they may be used safely in all skin types.4 The incidence of adverse events with these RF fractional devices, while remarkably low as compared to traditional laser therapy, do still exist; this fact needs to be remembered by all clinicians using these machines for skin concerns among patients.
The one premise that was defined early on with the fractional RF devices was that there would be minimal epidermal destruction and a concentration of energy into the dermis, which, by virtue of the electrodes or by needles, could be placed at various depths in the dermis to effectively achieve the desired results with the devices. Now, let’s take a look at some of the more common devices and the potential impact they may have have on our fractional energy-based thinking in the coming years.
Article continues on page 2
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Pin Delivery of RF
The first of the devices solely designed for the purpose of fractional RF therapy became known as the eMatrix device from Syneron Candela. The thermal energy for eMatrix is delivered to the skin via an array of multielectrode pins. Two types of pin arrays have been made available for this device, one with 64 pins and one with more density at 144 pins. The pins on the tip of the device have a parallel grid of bipolar RF electrodes that form an array of positively- and negatively-charged electrodes that can deliver up to 1 MHz of RF energy at multiple points. Energies of up to 20 J can be delivered to the skin directly in contact with and below the pin array with intervening tissue intact, thus creating the fractional nature of the treatments.
The pivotal work by Hruza and colleagues5 showed early on that wrinkles and rhytids could be affected significantly with this device. They studied both treatments in patients scheduled for abdominoplasty and in patients with facial wrinkles and rhytids. From the abdominoplasty patients, the histology showed immediate posttreatment demarcated zones of ablation/coagulation/necrosis with depths of injury up to 450 µm. Over 40% of the patients studied showed more than 50% improvement in their skin texture with a series of treatments.
Gold and Biron6 then demonstrated the effectiveness of this device in the treatment of acne scars that led to the FDA approval of eMatrix for these scars. In the study, 15 individuals with mild to moderate acne scars were treated at monthly intervals for 3 months and followed for 3 months after their last RF treatment with the 64-pin tip array. There was a statistically significant improvement in the acne scars treated at the time intervals evaluated and patient satisfaction was high in 67% to 92% of the individuals treated. Adverse events were minimal and limited to transient erythema. This was a significant finding, as postinflammatory hyperpigmentation (PIH) was not observed in this study, and this has been shown to be minimal with these devices in the majority of published clinical trials. Clinical examples of improvement with this device are shown in Figures 1 and 2.
Additional studies also showed success with eMatrix. For example, Bloom and colleagues3 found that with 3 treatments using the 144-pin tip array there was an improvement in rhytids, dyschromias, and textural changes 6 months following the last treatment. Man and Goldberg7 evaluated eMatrix in 15 individuals with darker skin types and observed no PIH in the study cohort. Yeung and colleagues4 evaluated this device in an Asian population and also found improvement in acne scars in the 20 patients who were studied.
The eMatrix became the first in the RF fractional devices that showed promise in treating wrinkles, rhytids, as well as acne and traumatic scars. Along with its efficacy, safety was seen and with minimal downtime noted in most patients. The term sublative rejuvenation was created—less downtime than traditional fractional ablative laser resurfacing with comparable results in many, and more robust treatments than traditional nonablative laser resurfacing, with downtime from 1 to 3 days in most. Phothong and colleagues8 noted that higher energies in Asian skinned individuals demonstrated greater efficacies at 1 month after their series of treatments but that at 3 and 6 months, efficacy was the same with normal and high energies, although more adverse events were observed in those with higher energies.
Since the advent of eMatrix, other devices have come into our energy-based world including Venus Viva from Venus Concept. Venus Viva is a fractional RF device that uses “nano-fractional RF” technology to deliver RF energy into the dermis and a SmartScan scanning device to provide potentially safer energy delivery into the skin. The RF energy with Venus Viva is delivered via an array of small pins that are placed on the skin and with the scanner mode creates up to 160 microwounds per energy pulse with up to 62 mJ per tip of energy. Depths of energy delivered up to 400 µm has been demonstrated with this device. The methodology of Venus Viva is shown in Figure 3.
With this method, patient discomfort is minimized and one sees consistent endpoints with the therapy and reduced downtimes as compared to traditional laser-based fractional resurfacing. The use of the novel scanning device provides customized treatments for each patient allowing the size of the treatment area to be defined as well as the density for each pulse. Again, this allows for safer and more optimized treatments than previous technologies.
Clinical studies have confirmed the effectiveness and satisfaction of the Venus Viva device. Hongcharu and Gold9 looked at 12 female volunteers who had various degrees of facial rhytids, hyperpigmentation, or facial redness. The participants received 1 treatment with Venus Viva and were followed at 1 month after therapy. Standard- and high-resolution macrophotographic analysis showed that Venus Viva was effective in improving skin texture and pigmentation. Ray and Gold10 also looked at Venus Viva and the satisfaction associated with the treatments. Forty-three patients treated (1-3 treatments) were included in their evaluation. On average, 60% of the study participants reported excellent satisfaction scores as a result of treatments with Venus Viva. Examples of the device are shown in Figures 4 and 5.
Article continues on page 3
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Needling Delivery of RF
In addition to fractional RF energy being delivered via electrode pin arrays, the other method for delivery is through the use of needles, with RF energy associated with those needles. Needling RF devices are described as noninsulated or insulated. Both methods have shown effectiveness in a variety of skin concerns.
Invasix-InMode’s Fractora is an RF fractional devices that uses needles to deliver RF energy into the skin. It combines nonablative and ablative RF energy delivery. The tips on the Fractora use variable density and variable length sharp arrays of needles. A variety of Fractora designs can be used to customize treatments for patients based on tip density. One can have high- or low-density epidermal impact, or by depth of the needle ablative injury and RF penetration, from 600 to 3000 µm. Furthermore, one can have the energy delivered via a nonablative tip, a 60-pin 600-µm tip, a 126-pin 600-µm tip, a 24-pin uncoated 3000-µm tip, or a 24-pin silicon-coated 3000-µm tip. The energies delivered are between 10 and 62 mJ per pin, and once again, this allows treatments to be customized to areas of concerns for patients. Clinical studies have confirmed its effectiveness in skin rejuvenation and in acne scars. Mulholland and colleagues11 looked at 20 Caucasian and 30 Asian patients treated with the Fractora device. The outcomes showed improvements in all parameters studied for skin rejuvenation with high patient satisfaction scores. Hellman12 reported on 8 patients with acne scars and noted all patients had improvement in their active acne and acne scars after 4 treatments and a 1 month, on average, follow-up period. Skin biopsies from this study showed reduction in scar depth and new collagen formation with an increase in elastic fibers and adnexal structures noted. In a follow-up report, Hellman13 showed that 4 of the 8 patients who were in the original study returned for a long-term follow-up, from 1 to 2 years, that showed ongoing clinical improvements in these patients.
Recently, my practice published an article in which 11 patients received combination therapy for facial skin rejuvenation using 3 components of the InMode device, which is the platform device of InMode-Invasix.14 Patients received 6 treatments and 2 follow-up visits at 3-week intervals. Three sessions were performed with the Lumecca (intense pulsed light component) alternated with the Forma (deep bulk RF) and the Fractora with the 60-pin tip in a stamping technique with 30% overlap and firm pressure applied. This combination approach showed statistically significant improvement in wrinkles, pigmentation, vascular lesions, and skin laxity.
It is common in today’s energy-based microneedling world to discuss the needling devices in terms of needles that are either insulated or noninsulated needles. The below discussion highlights 2 insulated microneedling devices and one noninsulated microneedle device. The first of these devices to gain popularity is the INTRAcel system (Jeisys), which uses 49 microneedle electrodes in an area of 1 cm2. These are deployed via a mechanical device into the skin, penetrating into the dermis, creating multiple thermal injury columns in the target area being treated. The microneedles can be deployed at depths from 0.5 to 2.0 mm.
Cho and colleagues15 looked at 20 patients with acne scars and enlarged pores treated with this device. Using the 1.5-mm needle and 500 W of power, more than 70% of the patients had improvements in acne scars and shrinkage of their pores. Dermal matrix remodeling and regeneration was determined to be the mechanism of action. Other studies have also demonstrated positive results with the INTRAcel system.16,17 A clinical example of a treated patient is shown in Figure 6.
Another insulated fractional RF device is Lutronic’s Infini—a high-intensity focused bipolar RF device that delivers its RF energy through an array of insulated 200-µm diameter microneedles that are arranged in a 7×7 array, 49 needles, with a total spot size of 10×10 mm. The needle depth can be adjusted from 0.5 to 3.5 mm, which allows customized treatment to the specific area. The device can have energies up to 50 W and exposure times from 10 milliseconds to 1 second.
A pilot study by Clementoni and Munavalli18 looked at 33 patients with mild to moderate facial skin laxity who were treated with Infini. Three treatments were given to each patients, with 3 passes per session, and patients were followed for 6 months following the last treatment. Patients showed a statistically significant improvement in the cervicomental and gnathion angles at follow-up visits. In the global assessment of improvement, 81.8% of the patients achieved moderate or higher improvements and 87% of the patients were very satisfied or better. Cohen and colleagues19 studied 30 patients with Infini and showed positive results for the treatment of the aging neck and face. An example of a patient treated with the Infini device is shown in Figure 7.
EndyMed’s Intensif, a novel noninsulated microneedling device, is also popular. The Intensif handpiece is part of a larger platform device, known as the EndyMed Pro. The Intensif handpiece has a sterilized tip with 25 extra sharp gold-plated microneedles. The needles are 300 µm in diameter can be inserted into the skin from 0 to 3.5 mm with a 0.1 step resolution. There is a step motor to allow smooth and precise insertion of the needles into the skin. This is important to lessen any pain associated with the procedure and helps to minimize epidermal trauma. Power can be adjusted from 0 to 25 W and the pulse duration can be adjusted in 30 millisecond increments. Studies in the literature have demonstrated the effectiveness of this device. Hantash and colleagues20 found that with this technology there is dermal remodeling and generation of new collagen, elastin, and hyaluronic acid. Seo and colleagues21 showed more than 50% overall improvement in 56% of Asian patients treated with the Intensif device. Harth and colleagues showed improvement in animal skin and later in patients with acne scars.22,23 Tanaka24 showed long-term improvements in Asian skin following the use of Intensif. Gold and colleagues25 evaluated 49 patients treated at 3-month intervals and followed for 3 months following their last treatments with the Intensif device for wrinkle reduction and for lifting effects of the lower face. Statistically significant improvement in wrinkling was noted in 65% of the patients while 100% noted some overall improvement. Clinical examples of Intensif are shown in Figures 8 and 9.
Conclusion
Fractional RF with either pins or microneedles has become an important modality for improving wrinkles and rhytids, as well as acne and traumatic scars. The advantages of these devices over traditional laser-based energy devices is that RF energy is color-blind; therefore, it is safe for all skin types and skin colors. This field will continue to grow and further clinical studies are needed to determine optimum settings for the devices and to fully elucidate the differences between the devices.
Dr Gold is medical director of Gold Skin Care Center and Tennessee Clinical Research Center in Nashville, TN.
Disclosure: The author performs research and consult for Syneron-Candela, Venus Concept, Invasix – Inmode, and EndyMed.
References on page 4
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References
1. Manstein D, Herron GS, Sink RK, Tanner H, Anderson RR. Fractional photothermolysis: a new concept for cutaneous remodeling using microscopic patterns of thermal injury. Lasers Surg Med. 2004;34(5):426-438.
2. Gold MH. Update on fractional laser technology. J Clin Aesthet Derm. 2010;3(1):42-50.
3. Bloom BS, Emer J, Goldberg DJ. Assessment of safty and efficacy of a bipolar fractionated radiofrequency device in the treatment of photodamaged skin. J Cosm Laser Ther. 2012;14(5):208-211.
4. Yeung CK, Chan NPY, Shek SYN, Chan HHL. Evaluation of combined fractional laser treatment for acne scars in Asians. Lasers Surg Med. 2012;44(8):622-630.
5. Hruza G, Taub AF, Collier SL, Mulholland SR. Skin rejuvenation and wrinkle reduction using a fractional radiofrequency system. J Drugs Dermatol. 2009;8(3):259-265.
6. Gold MH, Biron JA. Treatment of acne scars by fractional bipolar radiofrequency energy. J Cosm Laser Ther. 2012;14(4):172-178.
7. Man J, Goldberg DJ. Safety and efficacy of fractional bipolar radiofrequency treatment in Fitzpatrick skin types V-VI. J Cosm Laser Ther. 2012;14(4):179-183.
8. Phothong W, Wanitphakdeedecha R, Sathaworawong A, Manuskiatti W. High versus moderate energy use of bipolar fractional radiofrequency in the treatment of acne scars: a pilot split-face double-blinded randomized control trial pilot study. Lasers Med Sci. 2016;31(2):229-234.
9. Hongcharu W, Gold MH. Expanding the clinical application of fractional radiofrequency treatment: Findings on rhytids, hyperpigmentation, rosacea, and acne redness. J Drugs Dermatol. 2015;14(11):1298-1304.
10. Ray M, Gold MH. A retrospective study of patient satisfaction following a trial of nano-fractional RF treatment. J Drugs Dermatol. 2015;14(11):1268-1271.
11. Mulholland RS, Ahn DH, Kreindel M, Paul M. Fractional ablative radio-frequency resurfacing in Asian and Caucasian skin: A novel method for deep radiofrequency fractional skin rejuvenation. J Cosm Dermatol Sci App. 2012;2(3):144-150.
12. Hellman J. Retrospective study of the use of a fractional radio frequency ablative device in the treatment of acne vulgaris and related acne scars. J Cosmet Dermatol Sci App. 2015;5(4):311-316.
13. Hellman J. Long term follow-up results of a fractional radio frequency ablative treatment of acne vulgaris and related acne scars. J Cosmet Dermatol Sci App. 2016;6(3):100-104.
14. Gold MH, Biron JA, Sensing W. Facial skin rejuvenation by combination treatment of IPL followed by continuous and fractional radiofrequency. J Cosm Laser Ther. 2016;18(1):2-6.
15. Cho SI, Chung BY, Choi MG, et al. Evaluation of the clinical efficacy of fractional radiofrequency microneedle treatment in acne scars and large facial pores. Dermatol Surg. 2012;38(7 Pt 1):1017-1024.
16. Lim SD, Yeo UCY, Kim IH, Choi CW, Kim WS. Evaluation of the wound healing response after deep dermal heating by fractional micro-needle radiofrequency device. J Drugs Dermatol. 2013;12(9):1044-1049.
17. Seung JL, Yeo UC, Wee SH, et al. Consensus recommendations on the use of a fractional radiofrequency microneedle and its applications in dermatologic laser surgery. Med Lasers. 2014; 3(1):5-10.
18. Clementoni MT, Munavalli GS. Fractional high intensity focused radiofrequency in the treatment of mild to moderate laxity of the lower face and neck: A pilot study. Lasers Surg Med. 2016;48(5):461-470.
19. Cohen JL, Weiner SF, Pozner KN, et al. Multi-center pilot study to evaluate the safety profile of high energy fractionated radiofrequency with insulated microneedles to multiple levels of the dermis. J Drugs Dermatol. 2016;15(11):1308-1312.
20. Hantash BM, Ubeid AA, Chang H, Kafi R, Renton B. Bipolar fractional radiofrequency treatment induces neoelastogenesis and neocollagenesis. Lasers Surg Med. 2009;41(1):1-9.
21. Seo KY, Yoon MS, Kim DH, Lee HJ. Skin rejuvenation by microneedle fractional radiofrequency treatment in Asian skin; clinical and histological analysis. Lasers Surg Med. 2012;44(8):631-636.
22. Harth Y, Elman M, Ackerman E, Frank I. Depressed acne scars – effective, minimal downtime treatment with a novel smooth motion non-insulated microneedle radiofrequency technology. J Cosmet Dermatol Sci App. 2014;4(3):212-218.
23. Harth Y, Frank I. In vivo histological evaluation of non-insulated microneedle radiofrequency applicator with novel fractionated pulse mode. J Drugs Dermatol. 2013;12(12):1430-1433.
24. Tanaka Y. Long-term three-dimensional volumetric assessment of skin tightening using sharply tapered non-insulated microneedle radiofrequency applicator with novel fractionated pulse mode in Asians. Lasers Surg Med. 2015;47(8):626-633.
25. Gold M, Taylor M, Rothaus K, Tanaka Y. Non-insulated smooth motion, micro-needles RF fractional treatment for wrinkle reduction and lifting of the lower face: International study. Lasers Surg Med. 2016;48(8):727-733.
Over the past several years, the concept and use of fractional laser resurfacing has become commonplace among dermatologists and others looking for novel ways to improve wrinkles and rhytids, textural abnormalities, and improving acne and traumatic scars. The use of fractional laser energy, with both ablative and nonablative laser energies, has become routine for many of us.
The basic premise of these devices is rather simple, and has had dramatic effects in how we approach patients now with their skin concerns. Fractional lasers create small holes in the skin and use the normal nonlaser skin to assist in the healing process that allows for safer treatments for our patients.1
Ablative fractional laser resurfacing has shown its successes in treating skin concerns in 1 to 2 visits on average, and with an associated downtime of anywhere from 5 to 10 days. Nonablative fractional laser energy has also shown its successes, with multiple treatments (average of 4 to 6) over 4 to 6 months to achieve similar results with less downtime per treatment.2 Even with the successes from these treatments, something was missing from our armamentarium that prompted investigators to look at radiofrequency (RF) energy as a source of the fractional treatments. This mainly had to do with the need to easily treat all skin colors, and RF seemed an appropriate energy source to potentially address this issue.
RF fractional devices have been introduced into our energy-based systems and are not dependent on laser light diffusion, chromophore absorption, or light scattering effects. Instead, these devices produce focal thermal damage in the dermis by generating a current between electrodes or by using needles to penetrate into the dermis and then release RF energy.3
This article will review some of the original technology in this field and discuss several newer RF device modalities currently available which has, in some regards, changed how we approach patients with facial concerns of wrinkles, rhytids, textural changes, as well as acne and traumatic scars.
Why has fractional RF become so popular all over the world? It is perhaps because RF energy is color-blind, and therefore can be used safely in all skin types. In fact, as described below, several clinical trials involving these devices were performed in darker-skinned individuals, with very acceptable clinical outcomes and minimal adverse effects. RF devices use thermal energy that is generated by an electric current rather than by laser light. Thus, they are not subject to diffraction or absorption by epidermal chromophores which is the basis of how they may be used safely in all skin types.4 The incidence of adverse events with these RF fractional devices, while remarkably low as compared to traditional laser therapy, do still exist; this fact needs to be remembered by all clinicians using these machines for skin concerns among patients.
The one premise that was defined early on with the fractional RF devices was that there would be minimal epidermal destruction and a concentration of energy into the dermis, which, by virtue of the electrodes or by needles, could be placed at various depths in the dermis to effectively achieve the desired results with the devices. Now, let’s take a look at some of the more common devices and the potential impact they may have have on our fractional energy-based thinking in the coming years.
Article continues on page 2
{{pagebreak}}
Pin Delivery of RF
The first of the devices solely designed for the purpose of fractional RF therapy became known as the eMatrix device from Syneron Candela. The thermal energy for eMatrix is delivered to the skin via an array of multielectrode pins. Two types of pin arrays have been made available for this device, one with 64 pins and one with more density at 144 pins. The pins on the tip of the device have a parallel grid of bipolar RF electrodes that form an array of positively- and negatively-charged electrodes that can deliver up to 1 MHz of RF energy at multiple points. Energies of up to 20 J can be delivered to the skin directly in contact with and below the pin array with intervening tissue intact, thus creating the fractional nature of the treatments.
The pivotal work by Hruza and colleagues5 showed early on that wrinkles and rhytids could be affected significantly with this device. They studied both treatments in patients scheduled for abdominoplasty and in patients with facial wrinkles and rhytids. From the abdominoplasty patients, the histology showed immediate posttreatment demarcated zones of ablation/coagulation/necrosis with depths of injury up to 450 µm. Over 40% of the patients studied showed more than 50% improvement in their skin texture with a series of treatments.
Gold and Biron6 then demonstrated the effectiveness of this device in the treatment of acne scars that led to the FDA approval of eMatrix for these scars. In the study, 15 individuals with mild to moderate acne scars were treated at monthly intervals for 3 months and followed for 3 months after their last RF treatment with the 64-pin tip array. There was a statistically significant improvement in the acne scars treated at the time intervals evaluated and patient satisfaction was high in 67% to 92% of the individuals treated. Adverse events were minimal and limited to transient erythema. This was a significant finding, as postinflammatory hyperpigmentation (PIH) was not observed in this study, and this has been shown to be minimal with these devices in the majority of published clinical trials. Clinical examples of improvement with this device are shown in Figures 1 and 2.
Additional studies also showed success with eMatrix. For example, Bloom and colleagues3 found that with 3 treatments using the 144-pin tip array there was an improvement in rhytids, dyschromias, and textural changes 6 months following the last treatment. Man and Goldberg7 evaluated eMatrix in 15 individuals with darker skin types and observed no PIH in the study cohort. Yeung and colleagues4 evaluated this device in an Asian population and also found improvement in acne scars in the 20 patients who were studied.
The eMatrix became the first in the RF fractional devices that showed promise in treating wrinkles, rhytids, as well as acne and traumatic scars. Along with its efficacy, safety was seen and with minimal downtime noted in most patients. The term sublative rejuvenation was created—less downtime than traditional fractional ablative laser resurfacing with comparable results in many, and more robust treatments than traditional nonablative laser resurfacing, with downtime from 1 to 3 days in most. Phothong and colleagues8 noted that higher energies in Asian skinned individuals demonstrated greater efficacies at 1 month after their series of treatments but that at 3 and 6 months, efficacy was the same with normal and high energies, although more adverse events were observed in those with higher energies.
Since the advent of eMatrix, other devices have come into our energy-based world including Venus Viva from Venus Concept. Venus Viva is a fractional RF device that uses “nano-fractional RF” technology to deliver RF energy into the dermis and a SmartScan scanning device to provide potentially safer energy delivery into the skin. The RF energy with Venus Viva is delivered via an array of small pins that are placed on the skin and with the scanner mode creates up to 160 microwounds per energy pulse with up to 62 mJ per tip of energy. Depths of energy delivered up to 400 µm has been demonstrated with this device. The methodology of Venus Viva is shown in Figure 3.
With this method, patient discomfort is minimized and one sees consistent endpoints with the therapy and reduced downtimes as compared to traditional laser-based fractional resurfacing. The use of the novel scanning device provides customized treatments for each patient allowing the size of the treatment area to be defined as well as the density for each pulse. Again, this allows for safer and more optimized treatments than previous technologies.
Clinical studies have confirmed the effectiveness and satisfaction of the Venus Viva device. Hongcharu and Gold9 looked at 12 female volunteers who had various degrees of facial rhytids, hyperpigmentation, or facial redness. The participants received 1 treatment with Venus Viva and were followed at 1 month after therapy. Standard- and high-resolution macrophotographic analysis showed that Venus Viva was effective in improving skin texture and pigmentation. Ray and Gold10 also looked at Venus Viva and the satisfaction associated with the treatments. Forty-three patients treated (1-3 treatments) were included in their evaluation. On average, 60% of the study participants reported excellent satisfaction scores as a result of treatments with Venus Viva. Examples of the device are shown in Figures 4 and 5.
Article continues on page 3
{{pagebreak}}
Needling Delivery of RF
In addition to fractional RF energy being delivered via electrode pin arrays, the other method for delivery is through the use of needles, with RF energy associated with those needles. Needling RF devices are described as noninsulated or insulated. Both methods have shown effectiveness in a variety of skin concerns.
Invasix-InMode’s Fractora is an RF fractional devices that uses needles to deliver RF energy into the skin. It combines nonablative and ablative RF energy delivery. The tips on the Fractora use variable density and variable length sharp arrays of needles. A variety of Fractora designs can be used to customize treatments for patients based on tip density. One can have high- or low-density epidermal impact, or by depth of the needle ablative injury and RF penetration, from 600 to 3000 µm. Furthermore, one can have the energy delivered via a nonablative tip, a 60-pin 600-µm tip, a 126-pin 600-µm tip, a 24-pin uncoated 3000-µm tip, or a 24-pin silicon-coated 3000-µm tip. The energies delivered are between 10 and 62 mJ per pin, and once again, this allows treatments to be customized to areas of concerns for patients. Clinical studies have confirmed its effectiveness in skin rejuvenation and in acne scars. Mulholland and colleagues11 looked at 20 Caucasian and 30 Asian patients treated with the Fractora device. The outcomes showed improvements in all parameters studied for skin rejuvenation with high patient satisfaction scores. Hellman12 reported on 8 patients with acne scars and noted all patients had improvement in their active acne and acne scars after 4 treatments and a 1 month, on average, follow-up period. Skin biopsies from this study showed reduction in scar depth and new collagen formation with an increase in elastic fibers and adnexal structures noted. In a follow-up report, Hellman13 showed that 4 of the 8 patients who were in the original study returned for a long-term follow-up, from 1 to 2 years, that showed ongoing clinical improvements in these patients.
Recently, my practice published an article in which 11 patients received combination therapy for facial skin rejuvenation using 3 components of the InMode device, which is the platform device of InMode-Invasix.14 Patients received 6 treatments and 2 follow-up visits at 3-week intervals. Three sessions were performed with the Lumecca (intense pulsed light component) alternated with the Forma (deep bulk RF) and the Fractora with the 60-pin tip in a stamping technique with 30% overlap and firm pressure applied. This combination approach showed statistically significant improvement in wrinkles, pigmentation, vascular lesions, and skin laxity.
It is common in today’s energy-based microneedling world to discuss the needling devices in terms of needles that are either insulated or noninsulated needles. The below discussion highlights 2 insulated microneedling devices and one noninsulated microneedle device. The first of these devices to gain popularity is the INTRAcel system (Jeisys), which uses 49 microneedle electrodes in an area of 1 cm2. These are deployed via a mechanical device into the skin, penetrating into the dermis, creating multiple thermal injury columns in the target area being treated. The microneedles can be deployed at depths from 0.5 to 2.0 mm.
Cho and colleagues15 looked at 20 patients with acne scars and enlarged pores treated with this device. Using the 1.5-mm needle and 500 W of power, more than 70% of the patients had improvements in acne scars and shrinkage of their pores. Dermal matrix remodeling and regeneration was determined to be the mechanism of action. Other studies have also demonstrated positive results with the INTRAcel system.16,17 A clinical example of a treated patient is shown in Figure 6.
Another insulated fractional RF device is Lutronic’s Infini—a high-intensity focused bipolar RF device that delivers its RF energy through an array of insulated 200-µm diameter microneedles that are arranged in a 7×7 array, 49 needles, with a total spot size of 10×10 mm. The needle depth can be adjusted from 0.5 to 3.5 mm, which allows customized treatment to the specific area. The device can have energies up to 50 W and exposure times from 10 milliseconds to 1 second.
A pilot study by Clementoni and Munavalli18 looked at 33 patients with mild to moderate facial skin laxity who were treated with Infini. Three treatments were given to each patients, with 3 passes per session, and patients were followed for 6 months following the last treatment. Patients showed a statistically significant improvement in the cervicomental and gnathion angles at follow-up visits. In the global assessment of improvement, 81.8% of the patients achieved moderate or higher improvements and 87% of the patients were very satisfied or better. Cohen and colleagues19 studied 30 patients with Infini and showed positive results for the treatment of the aging neck and face. An example of a patient treated with the Infini device is shown in Figure 7.
EndyMed’s Intensif, a novel noninsulated microneedling device, is also popular. The Intensif handpiece is part of a larger platform device, known as the EndyMed Pro. The Intensif handpiece has a sterilized tip with 25 extra sharp gold-plated microneedles. The needles are 300 µm in diameter can be inserted into the skin from 0 to 3.5 mm with a 0.1 step resolution. There is a step motor to allow smooth and precise insertion of the needles into the skin. This is important to lessen any pain associated with the procedure and helps to minimize epidermal trauma. Power can be adjusted from 0 to 25 W and the pulse duration can be adjusted in 30 millisecond increments. Studies in the literature have demonstrated the effectiveness of this device. Hantash and colleagues20 found that with this technology there is dermal remodeling and generation of new collagen, elastin, and hyaluronic acid. Seo and colleagues21 showed more than 50% overall improvement in 56% of Asian patients treated with the Intensif device. Harth and colleagues showed improvement in animal skin and later in patients with acne scars.22,23 Tanaka24 showed long-term improvements in Asian skin following the use of Intensif. Gold and colleagues25 evaluated 49 patients treated at 3-month intervals and followed for 3 months following their last treatments with the Intensif device for wrinkle reduction and for lifting effects of the lower face. Statistically significant improvement in wrinkling was noted in 65% of the patients while 100% noted some overall improvement. Clinical examples of Intensif are shown in Figures 8 and 9.
Conclusion
Fractional RF with either pins or microneedles has become an important modality for improving wrinkles and rhytids, as well as acne and traumatic scars. The advantages of these devices over traditional laser-based energy devices is that RF energy is color-blind; therefore, it is safe for all skin types and skin colors. This field will continue to grow and further clinical studies are needed to determine optimum settings for the devices and to fully elucidate the differences between the devices.
Dr Gold is medical director of Gold Skin Care Center and Tennessee Clinical Research Center in Nashville, TN.
Disclosure: The author performs research and consult for Syneron-Candela, Venus Concept, Invasix – Inmode, and EndyMed.
References on page 4
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References
1. Manstein D, Herron GS, Sink RK, Tanner H, Anderson RR. Fractional photothermolysis: a new concept for cutaneous remodeling using microscopic patterns of thermal injury. Lasers Surg Med. 2004;34(5):426-438.
2. Gold MH. Update on fractional laser technology. J Clin Aesthet Derm. 2010;3(1):42-50.
3. Bloom BS, Emer J, Goldberg DJ. Assessment of safty and efficacy of a bipolar fractionated radiofrequency device in the treatment of photodamaged skin. J Cosm Laser Ther. 2012;14(5):208-211.
4. Yeung CK, Chan NPY, Shek SYN, Chan HHL. Evaluation of combined fractional laser treatment for acne scars in Asians. Lasers Surg Med. 2012;44(8):622-630.
5. Hruza G, Taub AF, Collier SL, Mulholland SR. Skin rejuvenation and wrinkle reduction using a fractional radiofrequency system. J Drugs Dermatol. 2009;8(3):259-265.
6. Gold MH, Biron JA. Treatment of acne scars by fractional bipolar radiofrequency energy. J Cosm Laser Ther. 2012;14(4):172-178.
7. Man J, Goldberg DJ. Safety and efficacy of fractional bipolar radiofrequency treatment in Fitzpatrick skin types V-VI. J Cosm Laser Ther. 2012;14(4):179-183.
8. Phothong W, Wanitphakdeedecha R, Sathaworawong A, Manuskiatti W. High versus moderate energy use of bipolar fractional radiofrequency in the treatment of acne scars: a pilot split-face double-blinded randomized control trial pilot study. Lasers Med Sci. 2016;31(2):229-234.
9. Hongcharu W, Gold MH. Expanding the clinical application of fractional radiofrequency treatment: Findings on rhytids, hyperpigmentation, rosacea, and acne redness. J Drugs Dermatol. 2015;14(11):1298-1304.
10. Ray M, Gold MH. A retrospective study of patient satisfaction following a trial of nano-fractional RF treatment. J Drugs Dermatol. 2015;14(11):1268-1271.
11. Mulholland RS, Ahn DH, Kreindel M, Paul M. Fractional ablative radio-frequency resurfacing in Asian and Caucasian skin: A novel method for deep radiofrequency fractional skin rejuvenation. J Cosm Dermatol Sci App. 2012;2(3):144-150.
12. Hellman J. Retrospective study of the use of a fractional radio frequency ablative device in the treatment of acne vulgaris and related acne scars. J Cosmet Dermatol Sci App. 2015;5(4):311-316.
13. Hellman J. Long term follow-up results of a fractional radio frequency ablative treatment of acne vulgaris and related acne scars. J Cosmet Dermatol Sci App. 2016;6(3):100-104.
14. Gold MH, Biron JA, Sensing W. Facial skin rejuvenation by combination treatment of IPL followed by continuous and fractional radiofrequency. J Cosm Laser Ther. 2016;18(1):2-6.
15. Cho SI, Chung BY, Choi MG, et al. Evaluation of the clinical efficacy of fractional radiofrequency microneedle treatment in acne scars and large facial pores. Dermatol Surg. 2012;38(7 Pt 1):1017-1024.
16. Lim SD, Yeo UCY, Kim IH, Choi CW, Kim WS. Evaluation of the wound healing response after deep dermal heating by fractional micro-needle radiofrequency device. J Drugs Dermatol. 2013;12(9):1044-1049.
17. Seung JL, Yeo UC, Wee SH, et al. Consensus recommendations on the use of a fractional radiofrequency microneedle and its applications in dermatologic laser surgery. Med Lasers. 2014; 3(1):5-10.
18. Clementoni MT, Munavalli GS. Fractional high intensity focused radiofrequency in the treatment of mild to moderate laxity of the lower face and neck: A pilot study. Lasers Surg Med. 2016;48(5):461-470.
19. Cohen JL, Weiner SF, Pozner KN, et al. Multi-center pilot study to evaluate the safety profile of high energy fractionated radiofrequency with insulated microneedles to multiple levels of the dermis. J Drugs Dermatol. 2016;15(11):1308-1312.
20. Hantash BM, Ubeid AA, Chang H, Kafi R, Renton B. Bipolar fractional radiofrequency treatment induces neoelastogenesis and neocollagenesis. Lasers Surg Med. 2009;41(1):1-9.
21. Seo KY, Yoon MS, Kim DH, Lee HJ. Skin rejuvenation by microneedle fractional radiofrequency treatment in Asian skin; clinical and histological analysis. Lasers Surg Med. 2012;44(8):631-636.
22. Harth Y, Elman M, Ackerman E, Frank I. Depressed acne scars – effective, minimal downtime treatment with a novel smooth motion non-insulated microneedle radiofrequency technology. J Cosmet Dermatol Sci App. 2014;4(3):212-218.
23. Harth Y, Frank I. In vivo histological evaluation of non-insulated microneedle radiofrequency applicator with novel fractionated pulse mode. J Drugs Dermatol. 2013;12(12):1430-1433.
24. Tanaka Y. Long-term three-dimensional volumetric assessment of skin tightening using sharply tapered non-insulated microneedle radiofrequency applicator with novel fractionated pulse mode in Asians. Lasers Surg Med. 2015;47(8):626-633.
25. Gold M, Taylor M, Rothaus K, Tanaka Y. Non-insulated smooth motion, micro-needles RF fractional treatment for wrinkle reduction and lifting of the lower face: International study. Lasers Surg Med. 2016;48(8):727-733.
Over the past several years, the concept and use of fractional laser resurfacing has become commonplace among dermatologists and others looking for novel ways to improve wrinkles and rhytids, textural abnormalities, and improving acne and traumatic scars. The use of fractional laser energy, with both ablative and nonablative laser energies, has become routine for many of us.
The basic premise of these devices is rather simple, and has had dramatic effects in how we approach patients now with their skin concerns. Fractional lasers create small holes in the skin and use the normal nonlaser skin to assist in the healing process that allows for safer treatments for our patients.1
Ablative fractional laser resurfacing has shown its successes in treating skin concerns in 1 to 2 visits on average, and with an associated downtime of anywhere from 5 to 10 days. Nonablative fractional laser energy has also shown its successes, with multiple treatments (average of 4 to 6) over 4 to 6 months to achieve similar results with less downtime per treatment.2 Even with the successes from these treatments, something was missing from our armamentarium that prompted investigators to look at radiofrequency (RF) energy as a source of the fractional treatments. This mainly had to do with the need to easily treat all skin colors, and RF seemed an appropriate energy source to potentially address this issue.
RF fractional devices have been introduced into our energy-based systems and are not dependent on laser light diffusion, chromophore absorption, or light scattering effects. Instead, these devices produce focal thermal damage in the dermis by generating a current between electrodes or by using needles to penetrate into the dermis and then release RF energy.3
This article will review some of the original technology in this field and discuss several newer RF device modalities currently available which has, in some regards, changed how we approach patients with facial concerns of wrinkles, rhytids, textural changes, as well as acne and traumatic scars.
Why has fractional RF become so popular all over the world? It is perhaps because RF energy is color-blind, and therefore can be used safely in all skin types. In fact, as described below, several clinical trials involving these devices were performed in darker-skinned individuals, with very acceptable clinical outcomes and minimal adverse effects. RF devices use thermal energy that is generated by an electric current rather than by laser light. Thus, they are not subject to diffraction or absorption by epidermal chromophores which is the basis of how they may be used safely in all skin types.4 The incidence of adverse events with these RF fractional devices, while remarkably low as compared to traditional laser therapy, do still exist; this fact needs to be remembered by all clinicians using these machines for skin concerns among patients.
The one premise that was defined early on with the fractional RF devices was that there would be minimal epidermal destruction and a concentration of energy into the dermis, which, by virtue of the electrodes or by needles, could be placed at various depths in the dermis to effectively achieve the desired results with the devices. Now, let’s take a look at some of the more common devices and the potential impact they may have have on our fractional energy-based thinking in the coming years.
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Pin Delivery of RF
The first of the devices solely designed for the purpose of fractional RF therapy became known as the eMatrix device from Syneron Candela. The thermal energy for eMatrix is delivered to the skin via an array of multielectrode pins. Two types of pin arrays have been made available for this device, one with 64 pins and one with more density at 144 pins. The pins on the tip of the device have a parallel grid of bipolar RF electrodes that form an array of positively- and negatively-charged electrodes that can deliver up to 1 MHz of RF energy at multiple points. Energies of up to 20 J can be delivered to the skin directly in contact with and below the pin array with intervening tissue intact, thus creating the fractional nature of the treatments.
The pivotal work by Hruza and colleagues5 showed early on that wrinkles and rhytids could be affected significantly with this device. They studied both treatments in patients scheduled for abdominoplasty and in patients with facial wrinkles and rhytids. From the abdominoplasty patients, the histology showed immediate posttreatment demarcated zones of ablation/coagulation/necrosis with depths of injury up to 450 µm. Over 40% of the patients studied showed more than 50% improvement in their skin texture with a series of treatments.
Gold and Biron6 then demonstrated the effectiveness of this device in the treatment of acne scars that led to the FDA approval of eMatrix for these scars. In the study, 15 individuals with mild to moderate acne scars were treated at monthly intervals for 3 months and followed for 3 months after their last RF treatment with the 64-pin tip array. There was a statistically significant improvement in the acne scars treated at the time intervals evaluated and patient satisfaction was high in 67% to 92% of the individuals treated. Adverse events were minimal and limited to transient erythema. This was a significant finding, as postinflammatory hyperpigmentation (PIH) was not observed in this study, and this has been shown to be minimal with these devices in the majority of published clinical trials. Clinical examples of improvement with this device are shown in Figures 1 and 2.
Additional studies also showed success with eMatrix. For example, Bloom and colleagues3 found that with 3 treatments using the 144-pin tip array there was an improvement in rhytids, dyschromias, and textural changes 6 months following the last treatment. Man and Goldberg7 evaluated eMatrix in 15 individuals with darker skin types and observed no PIH in the study cohort. Yeung and colleagues4 evaluated this device in an Asian population and also found improvement in acne scars in the 20 patients who were studied.
The eMatrix became the first in the RF fractional devices that showed promise in treating wrinkles, rhytids, as well as acne and traumatic scars. Along with its efficacy, safety was seen and with minimal downtime noted in most patients. The term sublative rejuvenation was created—less downtime than traditional fractional ablative laser resurfacing with comparable results in many, and more robust treatments than traditional nonablative laser resurfacing, with downtime from 1 to 3 days in most. Phothong and colleagues8 noted that higher energies in Asian skinned individuals demonstrated greater efficacies at 1 month after their series of treatments but that at 3 and 6 months, efficacy was the same with normal and high energies, although more adverse events were observed in those with higher energies.
Since the advent of eMatrix, other devices have come into our energy-based world including Venus Viva from Venus Concept. Venus Viva is a fractional RF device that uses “nano-fractional RF” technology to deliver RF energy into the dermis and a SmartScan scanning device to provide potentially safer energy delivery into the skin. The RF energy with Venus Viva is delivered via an array of small pins that are placed on the skin and with the scanner mode creates up to 160 microwounds per energy pulse with up to 62 mJ per tip of energy. Depths of energy delivered up to 400 µm has been demonstrated with this device. The methodology of Venus Viva is shown in Figure 3.
With this method, patient discomfort is minimized and one sees consistent endpoints with the therapy and reduced downtimes as compared to traditional laser-based fractional resurfacing. The use of the novel scanning device provides customized treatments for each patient allowing the size of the treatment area to be defined as well as the density for each pulse. Again, this allows for safer and more optimized treatments than previous technologies.
Clinical studies have confirmed the effectiveness and satisfaction of the Venus Viva device. Hongcharu and Gold9 looked at 12 female volunteers who had various degrees of facial rhytids, hyperpigmentation, or facial redness. The participants received 1 treatment with Venus Viva and were followed at 1 month after therapy. Standard- and high-resolution macrophotographic analysis showed that Venus Viva was effective in improving skin texture and pigmentation. Ray and Gold10 also looked at Venus Viva and the satisfaction associated with the treatments. Forty-three patients treated (1-3 treatments) were included in their evaluation. On average, 60% of the study participants reported excellent satisfaction scores as a result of treatments with Venus Viva. Examples of the device are shown in Figures 4 and 5.
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Needling Delivery of RF
In addition to fractional RF energy being delivered via electrode pin arrays, the other method for delivery is through the use of needles, with RF energy associated with those needles. Needling RF devices are described as noninsulated or insulated. Both methods have shown effectiveness in a variety of skin concerns.
Invasix-InMode’s Fractora is an RF fractional devices that uses needles to deliver RF energy into the skin. It combines nonablative and ablative RF energy delivery. The tips on the Fractora use variable density and variable length sharp arrays of needles. A variety of Fractora designs can be used to customize treatments for patients based on tip density. One can have high- or low-density epidermal impact, or by depth of the needle ablative injury and RF penetration, from 600 to 3000 µm. Furthermore, one can have the energy delivered via a nonablative tip, a 60-pin 600-µm tip, a 126-pin 600-µm tip, a 24-pin uncoated 3000-µm tip, or a 24-pin silicon-coated 3000-µm tip. The energies delivered are between 10 and 62 mJ per pin, and once again, this allows treatments to be customized to areas of concerns for patients. Clinical studies have confirmed its effectiveness in skin rejuvenation and in acne scars. Mulholland and colleagues11 looked at 20 Caucasian and 30 Asian patients treated with the Fractora device. The outcomes showed improvements in all parameters studied for skin rejuvenation with high patient satisfaction scores. Hellman12 reported on 8 patients with acne scars and noted all patients had improvement in their active acne and acne scars after 4 treatments and a 1 month, on average, follow-up period. Skin biopsies from this study showed reduction in scar depth and new collagen formation with an increase in elastic fibers and adnexal structures noted. In a follow-up report, Hellman13 showed that 4 of the 8 patients who were in the original study returned for a long-term follow-up, from 1 to 2 years, that showed ongoing clinical improvements in these patients.
Recently, my practice published an article in which 11 patients received combination therapy for facial skin rejuvenation using 3 components of the InMode device, which is the platform device of InMode-Invasix.14 Patients received 6 treatments and 2 follow-up visits at 3-week intervals. Three sessions were performed with the Lumecca (intense pulsed light component) alternated with the Forma (deep bulk RF) and the Fractora with the 60-pin tip in a stamping technique with 30% overlap and firm pressure applied. This combination approach showed statistically significant improvement in wrinkles, pigmentation, vascular lesions, and skin laxity.
It is common in today’s energy-based microneedling world to discuss the needling devices in terms of needles that are either insulated or noninsulated needles. The below discussion highlights 2 insulated microneedling devices and one noninsulated microneedle device. The first of these devices to gain popularity is the INTRAcel system (Jeisys), which uses 49 microneedle electrodes in an area of 1 cm2. These are deployed via a mechanical device into the skin, penetrating into the dermis, creating multiple thermal injury columns in the target area being treated. The microneedles can be deployed at depths from 0.5 to 2.0 mm.
Cho and colleagues15 looked at 20 patients with acne scars and enlarged pores treated with this device. Using the 1.5-mm needle and 500 W of power, more than 70% of the patients had improvements in acne scars and shrinkage of their pores. Dermal matrix remodeling and regeneration was determined to be the mechanism of action. Other studies have also demonstrated positive results with the INTRAcel system.16,17 A clinical example of a treated patient is shown in Figure 6.
Another insulated fractional RF device is Lutronic’s Infini—a high-intensity focused bipolar RF device that delivers its RF energy through an array of insulated 200-µm diameter microneedles that are arranged in a 7×7 array, 49 needles, with a total spot size of 10×10 mm. The needle depth can be adjusted from 0.5 to 3.5 mm, which allows customized treatment to the specific area. The device can have energies up to 50 W and exposure times from 10 milliseconds to 1 second.
A pilot study by Clementoni and Munavalli18 looked at 33 patients with mild to moderate facial skin laxity who were treated with Infini. Three treatments were given to each patients, with 3 passes per session, and patients were followed for 6 months following the last treatment. Patients showed a statistically significant improvement in the cervicomental and gnathion angles at follow-up visits. In the global assessment of improvement, 81.8% of the patients achieved moderate or higher improvements and 87% of the patients were very satisfied or better. Cohen and colleagues19 studied 30 patients with Infini and showed positive results for the treatment of the aging neck and face. An example of a patient treated with the Infini device is shown in Figure 7.
EndyMed’s Intensif, a novel noninsulated microneedling device, is also popular. The Intensif handpiece is part of a larger platform device, known as the EndyMed Pro. The Intensif handpiece has a sterilized tip with 25 extra sharp gold-plated microneedles. The needles are 300 µm in diameter can be inserted into the skin from 0 to 3.5 mm with a 0.1 step resolution. There is a step motor to allow smooth and precise insertion of the needles into the skin. This is important to lessen any pain associated with the procedure and helps to minimize epidermal trauma. Power can be adjusted from 0 to 25 W and the pulse duration can be adjusted in 30 millisecond increments. Studies in the literature have demonstrated the effectiveness of this device. Hantash and colleagues20 found that with this technology there is dermal remodeling and generation of new collagen, elastin, and hyaluronic acid. Seo and colleagues21 showed more than 50% overall improvement in 56% of Asian patients treated with the Intensif device. Harth and colleagues showed improvement in animal skin and later in patients with acne scars.22,23 Tanaka24 showed long-term improvements in Asian skin following the use of Intensif. Gold and colleagues25 evaluated 49 patients treated at 3-month intervals and followed for 3 months following their last treatments with the Intensif device for wrinkle reduction and for lifting effects of the lower face. Statistically significant improvement in wrinkling was noted in 65% of the patients while 100% noted some overall improvement. Clinical examples of Intensif are shown in Figures 8 and 9.
Conclusion
Fractional RF with either pins or microneedles has become an important modality for improving wrinkles and rhytids, as well as acne and traumatic scars. The advantages of these devices over traditional laser-based energy devices is that RF energy is color-blind; therefore, it is safe for all skin types and skin colors. This field will continue to grow and further clinical studies are needed to determine optimum settings for the devices and to fully elucidate the differences between the devices.
Dr Gold is medical director of Gold Skin Care Center and Tennessee Clinical Research Center in Nashville, TN.
Disclosure: The author performs research and consult for Syneron-Candela, Venus Concept, Invasix – Inmode, and EndyMed.
References on page 4
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References
1. Manstein D, Herron GS, Sink RK, Tanner H, Anderson RR. Fractional photothermolysis: a new concept for cutaneous remodeling using microscopic patterns of thermal injury. Lasers Surg Med. 2004;34(5):426-438.
2. Gold MH. Update on fractional laser technology. J Clin Aesthet Derm. 2010;3(1):42-50.
3. Bloom BS, Emer J, Goldberg DJ. Assessment of safty and efficacy of a bipolar fractionated radiofrequency device in the treatment of photodamaged skin. J Cosm Laser Ther. 2012;14(5):208-211.
4. Yeung CK, Chan NPY, Shek SYN, Chan HHL. Evaluation of combined fractional laser treatment for acne scars in Asians. Lasers Surg Med. 2012;44(8):622-630.
5. Hruza G, Taub AF, Collier SL, Mulholland SR. Skin rejuvenation and wrinkle reduction using a fractional radiofrequency system. J Drugs Dermatol. 2009;8(3):259-265.
6. Gold MH, Biron JA. Treatment of acne scars by fractional bipolar radiofrequency energy. J Cosm Laser Ther. 2012;14(4):172-178.
7. Man J, Goldberg DJ. Safety and efficacy of fractional bipolar radiofrequency treatment in Fitzpatrick skin types V-VI. J Cosm Laser Ther. 2012;14(4):179-183.
8. Phothong W, Wanitphakdeedecha R, Sathaworawong A, Manuskiatti W. High versus moderate energy use of bipolar fractional radiofrequency in the treatment of acne scars: a pilot split-face double-blinded randomized control trial pilot study. Lasers Med Sci. 2016;31(2):229-234.
9. Hongcharu W, Gold MH. Expanding the clinical application of fractional radiofrequency treatment: Findings on rhytids, hyperpigmentation, rosacea, and acne redness. J Drugs Dermatol. 2015;14(11):1298-1304.
10. Ray M, Gold MH. A retrospective study of patient satisfaction following a trial of nano-fractional RF treatment. J Drugs Dermatol. 2015;14(11):1268-1271.
11. Mulholland RS, Ahn DH, Kreindel M, Paul M. Fractional ablative radio-frequency resurfacing in Asian and Caucasian skin: A novel method for deep radiofrequency fractional skin rejuvenation. J Cosm Dermatol Sci App. 2012;2(3):144-150.
12. Hellman J. Retrospective study of the use of a fractional radio frequency ablative device in the treatment of acne vulgaris and related acne scars. J Cosmet Dermatol Sci App. 2015;5(4):311-316.
13. Hellman J. Long term follow-up results of a fractional radio frequency ablative treatment of acne vulgaris and related acne scars. J Cosmet Dermatol Sci App. 2016;6(3):100-104.
14. Gold MH, Biron JA, Sensing W. Facial skin rejuvenation by combination treatment of IPL followed by continuous and fractional radiofrequency. J Cosm Laser Ther. 2016;18(1):2-6.
15. Cho SI, Chung BY, Choi MG, et al. Evaluation of the clinical efficacy of fractional radiofrequency microneedle treatment in acne scars and large facial pores. Dermatol Surg. 2012;38(7 Pt 1):1017-1024.
16. Lim SD, Yeo UCY, Kim IH, Choi CW, Kim WS. Evaluation of the wound healing response after deep dermal heating by fractional micro-needle radiofrequency device. J Drugs Dermatol. 2013;12(9):1044-1049.
17. Seung JL, Yeo UC, Wee SH, et al. Consensus recommendations on the use of a fractional radiofrequency microneedle and its applications in dermatologic laser surgery. Med Lasers. 2014; 3(1):5-10.
18. Clementoni MT, Munavalli GS. Fractional high intensity focused radiofrequency in the treatment of mild to moderate laxity of the lower face and neck: A pilot study. Lasers Surg Med. 2016;48(5):461-470.
19. Cohen JL, Weiner SF, Pozner KN, et al. Multi-center pilot study to evaluate the safety profile of high energy fractionated radiofrequency with insulated microneedles to multiple levels of the dermis. J Drugs Dermatol. 2016;15(11):1308-1312.
20. Hantash BM, Ubeid AA, Chang H, Kafi R, Renton B. Bipolar fractional radiofrequency treatment induces neoelastogenesis and neocollagenesis. Lasers Surg Med. 2009;41(1):1-9.
21. Seo KY, Yoon MS, Kim DH, Lee HJ. Skin rejuvenation by microneedle fractional radiofrequency treatment in Asian skin; clinical and histological analysis. Lasers Surg Med. 2012;44(8):631-636.
22. Harth Y, Elman M, Ackerman E, Frank I. Depressed acne scars – effective, minimal downtime treatment with a novel smooth motion non-insulated microneedle radiofrequency technology. J Cosmet Dermatol Sci App. 2014;4(3):212-218.
23. Harth Y, Frank I. In vivo histological evaluation of non-insulated microneedle radiofrequency applicator with novel fractionated pulse mode. J Drugs Dermatol. 2013;12(12):1430-1433.
24. Tanaka Y. Long-term three-dimensional volumetric assessment of skin tightening using sharply tapered non-insulated microneedle radiofrequency applicator with novel fractionated pulse mode in Asians. Lasers Surg Med. 2015;47(8):626-633.
25. Gold M, Taylor M, Rothaus K, Tanaka Y. Non-insulated smooth motion, micro-needles RF fractional treatment for wrinkle reduction and lifting of the lower face: International study. Lasers Surg Med. 2016;48(8):727-733.
