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Page 4 of 7 Catinis et al. Plast Aesthet Res 2020;7:9 I http://dx.doi.org/10.20517/2347-9264.2019.68

Figure 3. The right photo shows the patient three months after her second treatment with the protocol

formation of heat. In this way, RF produces thermal injury in the dermis, while preserving the integrity
[4,5]
of the epidermis . The controlled heating of the dermis induces immediate collagen denaturation and
subsequent fibroblast activation, leading to synthesis of new collagen and elastin fibers [4,6,7] . The heat-
induced contraction of the dermal layer tightens the skin while also increasing skin elasticity. The extent
of tissue remodeling and contraction is dependent on a number of different variables. These include the
depth of energy delivery, the time the desired temperature is maintained, the conductivity of the target
[4]
tissue, and the frequency used . It has also been shown that the heat generated by RF can induce apoptosis
of subcutaneous adipocytes [4,8,11] . This finding has led to the extensive use of RF in body contouring and fat
reduction, in addition to the treatment of skin laxity.

[12]
A novel two-treatment protocol using radiofrequency was proposed by McDaniel et al. in 2014. Each
treatment began with 6 min on the lower face (sub malar region to the mandible), followed by treatment
of the submentum for 4 min. The lower face was then treated again for 6 min, with 3 min spent on the sub
malar region and 3 min spent on the mandible. Next, the submentum was treated again for 4 min. These
steps were then repeated on the contralateral face. The two treatments were spaced 10-14 days apart. This
approach demonstrated a marked improvement in skin laxity in the majority of subjects. The treatments
were well tolerated by patients, with no reported side effects. Ninety-two percent of subjects showed
measurable improvement in the tightness of their skin after being evaluated three months post-treatment,
demonstrating that maintaining a lower skin temperature over a longer period of time produces more
favorable results. The data obtained in this study also confirmed an overall improvement in skin density
(19% increase in three months) as well as improvements in dermal collagen and elastin deposition.

Ultrasound functions through the emission of high frequency sound waves within the tissue. The
propagating sound waves excite charged molecules in the dermal layer and cause them to oscillate. By
increasing the energy of the underlying molecules, US results in the generation of heat in a similar manner
[4,8]
to RF, leading to collagen denaturation and remodeling . When administered in combination with RF,
US aids in efficiently and evenly dissipating the thermal energy to deeper skin layers by altering tissue
[4]
resistance .