Keywords
Skin tighteningRadiofrequencySkin laxityJowlsVolume lossAging skinNeck treatmentsNonsurgical skin tighteningMicro-focused ultrasound (MFU)Infra-red (IR)20.1 Skin Tightening Technology
Surgical procedures remain the gold standard but many aesthetic patients would like to have a non-surgical option to tighten their skin. Smooth, taut skin is a sign of youth and since collagen turn over decreases by 6% each decade, the skin slowly and insidiously becomes less supported by the collagen structure, accelerating the appearance of aging (Fabi and Goldman 2014).
While there are only a few technologies currently used to tighten the skin, there are numerous skin tightening devices available to practitioners. These devices are available from manufacturers all over the world and vary in overall efficacy, patient comfort, and delivery options.
Non-surgical skin tightening modalities heat the underlying dermis and subcutaneous fat at controlled depths without harming the superficial layers of skin. Heating the tissue to sufficient temperatures stimulates neo-collagenesis, but if the temperature becomes excessive, irreversible denaturation changes the specific structure of collagen into a random gelatinous form (Greene and Green 2014). This complication from treatments using earlier protocols led to divots and pockets in the skin that needed correction with filler; additionally, there were also a few reported cases of hyperpigmentation (Greene and Green 2014; Friedmann et al. 2018; Wu 2007). With the advancement of newer technologies and protocols, these complications are remote but did gain early media attention and has been referred to as skin “melting” from fat necrosis due to excessive temperature during treatment (Wu 2007).
Non-surgical technologies include radiofrequency (RF), infra-red (IR), and micro-focused ultrasound (MFU), and some devices offer a combination of these. The energy of these devices is transformed into heat mainly by water contained in the tissue and as a result, the energy is dispersed at controlled depths (Dierickx 2006). The depth and width of the heated area can be adjusted by varying parameters of the energy source and, if applicable, corresponding cooling system. Effective treatment temperatures of the skin depend on the device and range from 40 to 70 degrees Celsius (C) or 104–158 degrees Fahrenheit (F). In addition, patient perception of pain is an important indicator of effective energy selection (Dierickx 2006; Dover et al. 2007; Carruthers et al. 2014). Collagen becomes denatured at around 60–65 °C or 140–149 °F and then remodels with additional hyaluronic acid, reticular volume, and elastin content at about 10 weeks (Dierickx 2006; Gutowski 2016; Hantash et al. 2009).
20.1.1 Radiofrequency
Radiofrequency (RF) uses electrical energy to stimulate the cells of the skin to create heat rather than directly transferring heat into the tissues. There are two types of RF electrode configurations available, monopolar and bipolar . The monopolar devices use one active electrode on the skin, whereas the bipolar devices use two electrodes, one placed a short distance from the other over the treatment area, typically encased in a hand-piece. Monopolar RF devices produce heat through a high frequency electric current, which flows through the transducer, through the skin and body structures, and back to a grounding pad on the patient’s body (Carruthers et al. 2014). Typically, RF travels through structures with the highest water content with greatest resistance by fat and generally, monopolar devices penetrate deeper than bipolar devices (Beasley and Weiss 2014). The pain during the treatment is related to the duration of the pulse; therefore, some devices are more painful than others, depending on how the pulses are delivered.
The effect of collagen stimulation appears to be dependent on the temperature and the length of time the heating takes place within the skin; those patients who have higher temperature and treatment times tend to have improved results (Carruthers et al. 2014). Monopolar RF devices have been associated with side effects such as burns and limited improvement in skin laxity, whereas the newer technology of bipolar devices have led to increased efficacy and fewer side effects because of the creation of a closed electrical circuit using both positive and negative electrodes (Nelson et al. 2015).
There are currently two pulse delivery systems in monopolar devices, stamped and dynamic or continuous. The dynamic method is usually less painful because the practitioner is continuously moving the hand-piece, as in the Exilis® device, and the pulses of heat are spread over a larger specific area vs. a smaller more intense pulse of heat (Beasley and Weiss 2014). Also, since melanin is not a target for RF energy, these treatments are safe for all skin types (Greene and Green 2014).
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