Radio frequency skin tightening (RF) is an aesthetic technique that uses RF energy to heat tissue and stimulate subdermal collagen production in order to reduce the appearance of fine lines and loose skin. The technique induces production of new collagen and elastin. The process provides an alternative to facelift and other cosmetic surgeries.
The frequencies of radio waves in this group can be anything from 3 kilohertz (kHz) to 300 gigahertz (GHz). The radiofrequency spectrum can be divided into bands, ranging from very low frequency (3-30 kHz) to extremely high frequency (30-300 GHz).
RF energy can be delivered to the skin in a variety of ways, the most common being monopolar, where RF is delivered via a single probe placed on the skin or bipolar, where the RF is delivered from a probe with two electrodes placed over the treatment area. Multipolar devices are also available and are similar to bipolar but consist of three or more electrodes. The depth of penetration when using monopolar RF is dependent on the tissue impedance which varies from person to person and the cross-sectional area of the monopolar probe, whereas the depth of penetration of bipolar RF depends on the distance between the two electrodes on the probe, with increasing distance resulting in increased depth of penetration.
Numerous RF devices have been developed and modified over this time, delivering RF energy by a variety of different means.
In addition to the monopolar and bipolar classification of RF delivery, there are several other variations of delivery systems such as
- fractional or sublative RF, where RF is delivered via a micro microneedle handpiece to physically ablate the skin and deliver deeper bipolar RF;
- phasecontrolled RF, where a two-dimensional or three-dimensional probe is used to deliver RF to a fixed volume area;
- and combination RF therapies that apply light, massage, vacuum or pulsed electromagnetic fields.
Older machines tend to use monopolar, but there is a higher risk of burns and fat atrophy, so most modern machines are bipolar. It has been shown in a randomised trial that the use of RF in combination with dermal filler treatments is safe.
The most common indication for RF in this field is non-ablative skin tightening, with numerous devices designed to fulfil this aim. The lower face is a very commonly treated area. Devices such as Thermage and Pellevé, use RF energy to selectively heat the deep dermis and subcutaneous fibrous septae, causing cleavage of hydrogen bonds in the collagen fibres and subsequent collagen denaturation.
The following inflammatory and proliferatory stages of healing are believed to then stimulate restructuring of collagen fibres, resulting in tightening of the skin over the following months. It has been shown that non-ablative RF treatments require repeated low energy RF treatments rather than a single high energy insult to produce the most noticeable improvements in skin laxity, as lower energies result in less heating and therefore less risk of burns. In addition, the use of lower energies results in a reduction of discomfort and reduced risk of burn injuries. As well as skin tightening, there is evidence that nonablative RF treatments are also effective as a treatment for active acne vulgaris.
The following issues can be solved using fractional RF methods:
- Deep skin tightening
- Reduction of acne scarring
- Improvement of keloid/hypertrophic scars, stretch marks
- Ablation of rosacea/ thread veins
As mentioned above, fractional radiofrequency devices such as Intracel, Fractora and Inifini generally consist of bipolar micro microneedle handpieces of various lengths and needle arrangements, which are used to penetrate the skin physically. These ablate the skin surface to deliver the RF energy deeper into the tissues, causing subdermal electrothermal coagulation without excessive heating of the skin surface (compared to fractional laser, for example). This has the benefit of reduced superficial thermal discomfort and protracted erythema when compared to fractional laser treatments but the same surface ablation.
Deeper tissue stimulation results in the familiar inflammatory changes and post-inflammatory neocollagenesis associated with non-ablative RF treatments but with the additional benefit of ablative resurfacing. This renders it an ideal treatment for problems such as acne scarring, where the skin surface texture is improved, in addition to improving the quality and structure of the deep scar tissue. Fractional RF has also been shown to be an effective treatment for active acne. In addition to skin RF treatments, deeper targeted treatments have become a popular way to reduce cellulite and volume of subcutaneous fat.
COMPLICATIONS & CHALLENGES OF RF TREATMENTS
RF treatments tend to be considered safe in trained hands. The very nature of these treatments, whereby tissues are heated to temperatures in excess of 43°C can potentially result in thermal injury and burns if either excessive energy is used or if there is prolonged contact in a given area to such an extent the tissue integrity is compromised.
Most modern RF handpieces have built-in temperature sensors to prevent such excessive heating. With some older monopolar devices, unintentional and excessive treatment of subcutaneous fat of the face has led to fat atrophy and depressions. This is rare with modern equipment.
As with any aesthetic treatment, RF treatments are not effective in every patient and unrealistic expectations of the scope and possibilities of RF treatments can sometimes be an issue for both patients and practitioners unfamiliar with these treatments. The effectiveness of these treatments is also very operator dependent, with wide variation based on experience and aggressiveness of treatments.
Radiofrequency in aesthetic practice is an effective and relatively safe treatment, which has applications in multiple aesthetic clinical concerns, from skin laxity to cellulite. A huge number of RF devices are available on the market, so it can be difficult to decide which would suit you most. The new multi-modality devices, such as those combining RF with ultrasound or light-based technologies offer exciting and diverse options.