Nonablative procedures for facial rejuvenation have become increasingly popular. One such method to improve laxity and diminish rhytids is monopolar capacitively coupled radiofrequency (MRF). The authors discuss clinical studies using MRF. The authors also discuss their clinical experiences as well as recommendations for optimal results. MRF using the Thermage CPT system (Solta Medical, Hayward, California) offers minimal downtime with a favorable side-effect profile. Although there are many radiofrequency devices on the market for aesthetic use, MRF has the most clinical trials to date to support its use as an effective, evidence-based modality to improve rhytids and tighten the skin.
The demand for safe and effective modalities to improve laxity and appearance of wrinkles has steadily risen over the last several decades. Although ablative laser technology and surgical treatment, such as rhytidectomy and blepharoplasty, provide a proven, evidence-based method of rejuvenation of aging skin, patients often opt for procedures with less downtime and risk for complications, such as pigmentary changes, scarring, and infection. The development of minimally invasive procedures, such as nonablative laser and radiofrequency (RF) treatments, has boomed since the 1990s, leading to a paradigm shift in the field of aesthetic medicine. Patients are willing to accept less dramatic results if there is minimal recovery and risk.
One such nonablative system, the Thermage CPT (Solta Medical, Hayward, CA, USA) uses monopolar capacitively coupled radiofrequency (MRF) to tighten the skin and reduce laxity. This device garnered US Food and Drug Administration (FDA) approval for the treatment of periorbital wrinkles in 2002, facial rhytids in 2004, and all rhytids in 2005. Although there are other radiofrequency devices on the market, Thermage has the most literature and clinical trials published to date that support monopolar radiofrequency as an effective modality for rejuvenation. Facial contouring and mild to moderate tightening is achieved through volumetric heating and dermal collagen remodeling, and epidermal cooling and the maintenance of an intact epidermis protects the skin from complications, such as infection, scarring, and pigmentary changes.
Mechanism of action
The Thermage CPT system consists of 3 components: a generator, a cryogen unit, and a hand piece connected to a disposable treatment tip ( Figs. 1 and 2 ). The generator provides an alternating electrical current that creates an electric field through the skin that shifts polarity 6 million times per second. The charged particles change their orientation within the electric field. Heat is generated by the tissue resistance to particle movement. Precooling, parallel cooling, and postcooling is delivered via a digitally pulsed cryogen spray on the inside of the treatment tip, thereby protecting the epidermis. For this reason, MRF can safely be performed with all Fitzpatrick skin types (FST). Pressure, current flow, and skin temperature (measured with thermistors inside the treatment tip surface) are monitored using a microprocessor in the treatment tip. Constant feedback from the treatment tip to the computer regulates whether a pulse is fired and the amount of energy fired from the tip. If the treatment tip is not in full contact with the skin surface, or if the skin temperature is too high, a pulse will not be discharged. Heating the dermis to the appropriate temperature while sparing the epidermis is essential for MRF to work and provide the optimal aesthetic result. The MRF system uses the reverse thermal gradient principle in which the epidermis is cooled and preserved while the deeper tissue (including dermal collagen) is heated ( Fig. 3 ). The epidermis is kept at 40°C as the cryogen coolant is delivered. Collagen denaturation occurs at approximately 65°C. Exposure to heating for 10 minutes results in 10% shrinkage of collagen fibers, whereas 60% shrinkage occurs after only 1.5 minutes at 80°C. Thus, the higher the maximum temperature reached during heating, the greater the shrinkage. The MRF system heats the dermis to 65°C to 75°C, which has been confirmed in histologic studies. If suboptimal heat is generated, there will be no significant clinical improvement in laxity or rhytids. If excessive heat is generated, erosions, atrophy, scarring, or pigmentary changes may ensue.