Classification of skin-tightening devices

Over the past 2 decades, there has been an explosion in noninvasive and minimally invasive therapies to enhance skin rejuvenation. Characteristics of the aging face include fine rhytids and dynamic rhytids in early aging followed by fixed, deep rhytids both dynamic and static in the glabella area of the forehead and around the eyes. There is a loss of dermal substrate, including functional collagen, elastin, and ground substances. The epidermis tends to thicken and there is general loss of subcutaneous fibrous connectivity with loss of midface soft tissue volume, periosteal absorption, and ptosis of soft tissues, leading to a more prominent naso-labial fold, labial mental lines, the elongation of the lid-cheek junction, and jowls. Superficial epidermal-dermal changes include dyschromias, brown discoloration, hyperpigmentation, erythema, telangiectasia, rosacea, and dark melanin dyschromia, especially in photo-damaged skin. For the past 15 years there has been tremendous growth and development of technologies that address these various aging facial changes.

Older chemical ablative techniques and macrodermabrasion gave way to ablative laser resurfacing, including carbon dioxide and erbium YAG lasers. Full-face laser ablation, although tremendous at rhytid reduction and significant superficial skin tightening, often led to an unacceptable degree of postoperative recovery and erythema, swelling, and downtime, in addition to long-term complications of demarcation, pigmentation abnormalities, and scarring. As the aging population over the past 10 to 15 years has increasingly sought esthetic enhancement procedures, there has also been an increasing desire to seek therapies that have less recovery downtime and morbidity than traditional ablative laser or chemical treatments.

The busy social and professional lives of our patients have necessitated the growth and expansion of a whole minimally invasive or noninvasive area of skin rejuvenation. Enhanced improvements in laser technology design and experiences and procedures around the world have resulted in the evolution of many nonablative technologies that have attempted to simulate the results of ablative carbon dioxide and erbium YAG lasers. Although the downtime and recovery from these nonablative laser and light-based technologies is far more desirable than full ablative lasers, multiple treatments are often required and the long-term results of rhytid reduction, skin tightening, diminishment of pores, and texture irregularities are often subtle at best.

These nonablative laser and light devices work by a photon interaction with a dermal chromophore, melanin, deoxygenated or oxygenated hemoglobin, and/or dermal water. The end pathway of these photon-chromophore interactions is the generation of heat, which may lead to a resolution of the chromophore, a subablative, noncoagulative inflammatory response, and, over time, mild to modest enhanced dermal levels of elastin, collagen, and ground substance. This nonablative, selective photothermolytic remodeling process will often result over several months, in very subtle rhytid improvement, some subtle to moderate tightening or texture improvements, and, depending on the device, improvements in melanin and/or vascular discoloration. Examples of these devices include early infrared devices, such as the Cool Touch Infrared Laser (1320 nm) (Roseville, CA, USA), the 1064 Neodymium Lag Laser, the 1440 ND YAG Laser, the Smooth-beam Infrared Laser (1450 nm diode) (Wayland, MA, USA), as well as numerous intense pulse-light technologies (585 to 1100 nm) and pulse-dye laser technology (585 nm and 595 nm). Virtually every wavelength between 500 nm and 2000 nm has been developed and used in conjunction with some aspect of skin rejuvenation: color correction, skin tightening, or rhytid textural diminishment. Although all of these technologies work to a greater or lesser degree, they often fall far short of the type of skin-tightening results that patients are seeking. The advantages of these noninvasive, nonablative technologies and probably why they have proliferated, is that many esthetic physicians have a comfort level using them. The technical barrier to entry in using these nonablative devices is minimal. Often, nonablative technologies lend themselves well to delegation to nonmedical health professional staff under a physician direction and can be combined with Botox, soft tissue fillers, microdermabrasion, and other minimally invasive techniques to achieve quite pleasing esthetic results. Color correction has been an important part of nonablative enhancement over the past 10 to 15 years. Intense pulse-light photorejuvenation and pulse-dye technologies have dominated the sector of laser technology revolving around correction of vasculature and melanin-based dyschromia.

The need for a nonablative technology that results in significant tissue tightening without disrupting the epidermal-dermal junction, led to the development of nonablative RF skin-tightening technologies. The RF tightening technologies, led by Thermage™ (Solta Medical, Hayward, CA, USA) and, later, by Syneron Medical Ltd (Yokneam Illit, Israel) and other companies, have created a nonablative, transepidermal skin-tightening array of treatment protocols and techniques that have proven to be quite successful in achieving moderate and potentially pleasing skin tightening for patients. In deciding on a method of classifying these RF skin-tightening technologies, a more anatomic approach has been adopted that takes into account the very exciting growth areas of minimally invasive RF skin tightening through the delivery of skin-tightening laser or RF energy to the immediate subdermal space and bypassing altogether or combining at a later date classic transepidermal-dermal RF skin heating. The following list sets out the classification system. One can divide skin-tightening devices into 2 broad categories: transepidermal delivery of energy and subdermal delivery of energy.

• 
  

  Classification of RF and energy-based skin-tightening devices

  
  
• 1.
  

  Transepidermal Energy Delivery

  
  
  
  
  • a.
    

    Transepidermal Laser Energy Devices

    
    
    
    
    • 
      

      Various wavelengths, pulse durations, and pulse configurations: 585, 595 pulse-dye technology, nm pulse dye, 755 nm, 810 nm, 900, 980 nm diodes, 1064 nm, 1320 nm, 1440 nm, and 1500 nm series lasers

    
    
    
    
  • b.
    

    Infrared lamp technology, 700 nm and 2000 nm infrared lamps

    
    
    
    
    • i.
      

      Sciton SkinTyte (Palo Alto, CA, USA)

      
      
    • ii.
      

      Cutera Titen (Brisbane, CA, USA)

    
    
    
    
  • c.
    

    Monopolar RF energy

    
    
    
    
    • i.
      

      Thermage™ (Solta Medical, Hayward, CA, USA)

      
      
    • ii.
      

      Accent (Caesarea, Israel)

    
    
    
    
  • d.
    

    Bipolar RF energy in combination with other light sources

    
    
    
    
    • i.
      

      Syneron Medical Ltd (Yokneam Illit, Israel) intense pulse light and bi-polar RF

      
      
    • ii.
      

      810 nm diode and bipolar RF

      
      
    • iii.
      

      950 nm diode and bipolar RF

      
      
    • iv.
      

      Infrared lamp bipolar

    
    
    
    
  • e.
    

    Multipolar Transepidermal Skin-Tightening RF Devices

    
    
    
    
    • i.
      

      TriPollar (Pollogen, Tel Aviv, Israel)

      
      
    • ii.
      

      Octopolar, Freeze (Tel Aviv, Israel)

    
    
    
    
  • f.
    

    Intense pulsed light

    
    
    
    
    • i.
      

      500 nm to 1200 nm intense pulse-light systems

      
      
    • ii.
      

      Lumenis Lume 1 (Yokneam, Israel), the Palomar Starluxe (Burlington, MA, USA), Syneron Medical Ltd E-Max (Yokneam Illit, Israel), the Sciton BBL (Palo Alto, CA, USA), the Alma laser Harmony (Caesarea, Israel)

    
    

  
  
  
  
• 2.
  

  Transepidermal Fractional Energy Delivery

  
  
  
  
  • a.
    

    Transepidermal fractional carbon dioxide resurfacing

    
    
    
    
    • i.
      

      Active and DeepFX Lumenis (Yokneam, Israel)

      
      
    • ii.
      

      Fraxel Repair, Solta Medical (Hayward, CA, USA)

      
      
    • iii.
      

      Affrim CO2 Smart Skin, Cynosure (Westford, MA, USA)

    
    
    
    
  • b.
    

    Transepidermal fractional delivery of infrared wavelengths

    
    
    
    
    • i.
      

      Fraxel Renew, Solta Medical (Hayward, CA, USA)

      
      
    • ii.
      

      Affirm MPX 1320/1440, Cynosure (Westford, MA, USA)

      
      
    • iii.
      

      Lux 1540, Palomar (Burlington, MA, USA)

      
      
    • iv.
      

      Matrix IR, Syneron Medical Ltd (Yokneam Illit, Israel)

      
      
    • v.
      

      Fractional Pearl, Cutera (Brisbane, CA, USA)

    
    
    
    
  • c.
    

    Fractional infrared delivery of erbium YAG Er:YSGG (Yttrium Scandium Gallium Garnet)

    
    
    
    
    • i.
      

      Profractional, Sciton (Palo Alto, CA, USA)

    
    
    
    
  • d.
    

    Fractional transepidermal RF energy

    
    
    
    
    • i.
      

      E-Matrix and Matrix RF, Syneron Medical Ltd (Yokneam Illit, Israel)

      
      
    • ii.
      

      Fractora, Invasix (Yokneam, Israel)

    
    

  
  
  
  
• 3.
  

  Subdermal Delivery of Energy

  
  
  
  
  • a.
    

    Subdermal delivery of fiber-optic laser energy

    
    
    
    
    • i.
      

      SmartLipo, Cynosure (Westford, MA, USA)

    
    
    
    
  • b.
    

    Subdermal delivery of RF energy

    
    
    
    
    • i.
      

      BodyTite, NeckTite, FaceTite, and CelluTite RF

      
      
    • ii.
      

      Liposuction and skin-tightening devices, Invasix (Yokneam, Israel).

    
    

  
  

This anatomic classification is significant because a clinician can now divide the skin-tightening opportunities using RF energy sources and laser devices into those that deliver their energy across the epidermal-dermal junction, resulting in nonablative treatment of the epidermal-dermal junction, or a complete dermal ablative procedure through traditional ablative carbon dioxide and erbium YAG technology, or a fractional transepidermal nonablative and/or ablative experience. All of these devices will interact with dermal water, resulting in a photothermalytic thermal response and, depending on whether the device is principally ablative, nonablative coagulative, or a combination, an inflammatory stimulus of various magnitudes will affect the tissue. The more ablative devices will require an epidermal-repair process and some remodeling of the ablated or coagulative nonablative injury to the dermal substrate. Generally, the more ablative the laser or photon device, the better the tightening results will be.

Into this transepidermal delivery of laser energy has evolved the transepidermal delivery of RF energy. Through minimal to no epidermal-dermal ablation, one can deliver RF energy into the dermis, where, rather than targeting traditional chromophores, such as hemoglobin, melanin, or water, all molecules in the RF pathways are oscillated 1 million to 6 million times per second. It is the resistance to RF traveling through tissue that results in molecular oscillation and thermal energy. RF, either fractional or nonfractional, can be selective and targeted in different depths of the dermis and combined with other energy sources.

The subdermal space has recently become the focus of an intense excitement for skin-tightening technologies and esthetic physicians. As reviewed in this article, new evidence and research has shown that if the energy source, either a laser-based or RF-based device, is placed in the immediate subdermal space, significant soft tissue skin contraction and correction of laxity can be induced without an excisional procedure or epidermal-dermal ablation. With this new subdermal delivery of RF, the kind of nonexcisional skin-tightening results that many patients are looking for is approached, without seeking the gold standard excisional rhytidectomy or skin-repositioning procedures. The maturation in the transepidermal delivery of monopolar RF (Thermage™) has given patients and clinicians noninvasive options for skin tightening when even subdermal, nonexcisional delivery techniques remain too aggressive.

Basic science of RF skin tightening

The basic science of skin tightening is really the basic science of controlled dermal heat generation, which is the common final pathway for laser and RF devices. In standard chemical ablation, the chemical agent results in a nonthermal chemical dissolution and coagulation of the associated dermal proteins and the wound healing that occurs over several weeks results in new collagen, elastin, and skin tightening. As the ablative chemical and dermabrasion techniques gave rise to ablative carbon dioxide and erbium YAG lasers, so does the promise of more selective depth control and precision injury. The photothermolytic process involved the photons (10,600 nm for carbon disoxide and 2940 nm for erbium) being attracted to dermal water, resulting in ablative and nonablative coagulative disruption. Immediate disruption of the collagen triple helix accounted for immediate, “on-the-table” skin-tightening effects and then a secondary tightening effect over 6 months from secondary neocollagenesis, elastin, and ground substance production. The original ablative laser technologies were associated with excessive patient morbidity, potential complications and patient downtime, and resulted in the growth and development of nonablative technologies that attempted to affect the collagen triple helix the same as the more ablative laser wavelengths. The proliferation of wavelengths and energies from intense pulsed light, pulse dye, the infrared diodes, and infrared heating lamps resulted in a nonablated, intact epidermal-dermal junction, whereas dermal water was the principal chromophore for the infrared devices. Hemoglobin and melanin were the chromophores for very near infrared and invisible skin-tightening light devices. Although there was some superficial papillary dermal collagen and ground substance response to these devices, the clinical results were often difficult to see with standard photography and follow-up results. Unless the results were a correction of vascular or melanin dyschromia’s discernable tightening and textural improvement, results were difficult to detect.

With the evolution, growth, and refinement of Thermage™ and monopolar transepidermal RF technology, moderate, consistent, and pleasing skin tightening can be achieved very reproducibly and comfortably. Since the inception and release of Thermage™ in 2002, the evolution to what type of monopolar nonablative RF skin tightening was available in 2010 (the time of this writing) is a testament to a company that has been very much committed to basic science research and understanding the evolution of the effect of RF on biologic tissues. Over the past 8 years, advances have been seen in tip geometry and shape. Although there are other nonablative transepidermal RF devices available, Thermage™ remains the number 1 monopolar RF delivery system in the world. Thermage™ also has the most abundant nonablative, RF peer-reviewed science behind it and in this article is the main focus of the transepidermal discussion of RF energy delivery for skin tightening. Thermage™ consists of 3 important components: a generator, a coolant, and an applicator tip. Refined and patented delivery of the monopolar RF energy occurs across a thin membrane. Synchronous cryogen-based cooling and a very sophisticated volumetric delivery of RF energy, depending on the tip size and configuration and pulse configuration, heat a specific volumetric amount of papillary superficial reticular dermis. Over the past 8 years, refinement in Thermage™ tip sizes has improved treatment time. Elegant studies of preauricular biopsies before rhytidectomy have shown that multiple passes at lower Thermage™ fluences result in better, more significant, and enhanced collagen and elastin ground substance production and tissue tightening than fewer passes and higher fluence.

Over the years, transepidermal, monopolar Thermage™ delivery of RF energy has become a much more patient-acceptable procedure with less pain and recovery. The monopolar energy delivered by the Thermage™ tip is delivered to a specific volumetric amount of the dermis or subcutaneous space. RF energy does not rely on a classic chromophore or chromophore photon interaction, as in the laser-based technologies but rather it is the resistance to RF energy traveling through tissue that results in generation of heat. It is the volumetric generation of heat through the oscillatory vibration of molecules along the resistant pathways of RF that results in energy. The RF energy can be used on all skin types and is chromophore independent. The clinical results of Thermage™ monopolar RF energy is discussed in the next section on clinical outcomes.

The basic science of subdermal thermal energy delivery is a very new area of intense clinical interest. Barry DiBernardo, in his seminal work on subdermal delivery of fiber-optic laser energy, specifically a 1064 nm laser fiber, Smart Lipo, Cynosure, was able to show that subdermal delivery of thermal energy resulted in significant tissue tightening using quantitative and reliable techniques. Studies were able to show that area contraction of the skin of 17% can occur over 3 months following subdermal thermal laser energy delivery. That degree of soft tissue area contraction is a very significant amount of soft tissue tightening given that this skin tightening occurs in a nonexcisional fashion. The subdermal laser heating is indeed minimally invasive, as opposed to noninvasive, as local anesthesia must be used and a stab access port must be created to insert the heating device under the skin and into tissue. Most esthetic surgeons who inject a large volume of fillers, make small excisions and are comfortable with human facial anatomy, and are capable of local anesthesia and subdermal delivery of a laser fiber. There is an increased complication rate and risks to subdermal laser and RF delivery. What Dr DiBernardo was able to show was that by keeping the epidermal temperatures at 40 to 42°C and a subreticular dermal temperature of 50 to 55°C, the result is a nonablative, coagulative disruption of deep reticular collagen fibers and that a neocollagenesis, which was biopsy proven, occurs over the subsequent 3 to 6 months with significant measurable and quantitative skin and tissue tightening.

The basic science behind the delivery of this subdermal thermal laser energy is quite straightforward. The laser emits a wavelength of light, which can be from 900 nm up to 1400 nm, and in the presence of local anesthesia and subdermal tumescent fluid, the infrared laser photon will be attracted to the chromophore’s water and to a lesser extent, hemoglobin and adipose tissue. These chromophores interact with the photons, resulting in a selective photothermolytic response and release of heat. When the tissue heats to critical temperatures higher than 50 to 55°C, it will result in a nonablative coagulative disruption of collagen and then new collagen forms and tissue tightening occurs over approximately 3 to 6 months.

Taking this subdermal laser-tightening paradigm further, Invasix (Yokneam, Israel) introduced into the marketplace a bipolar RF hand piece and device, which is a novel and proprietary technology that attempts to simulate both the nonablative, transepidermal delivery effects of Thermage™ and the subdermal laser heating effect achieved with a laser fiber optic. There are various Invasix applicators and configurations of the hand pieces, depending on where the internal electrode will be inserted, which can be a very small bipolar hand piece for the face called FaceTite, or neck device called NeckTite, or a much larger device for the body called BodyTite. Each applicator consists of an internal RF probe. This probe can be a hollow RF-emitting suction cannula, if it is to be used for body fat aspiration, used for corporeal body liposuction, or, in the face and neck, it can be a nonaspirating, very small internal RF probe designed to pass directly under the dermis. The internal electrode-probe is coated with Teflon so only the tip emits RF energy. The RF energy from the internal probe then travels directionally in a confined way up to the external electrode, which travels smoothly, in tandem with the internal electrode along the skin ( Fig. 1 ). Unlike a monopolar system, which needs to have a return electrode pad somewhere on the body, this bipolar electrode configuration from Invasix allows intense internal RF energy to create heat in the subcutaneous or subdermal space around the internal electrode-probe, while gentle transepidermal dermal heating occurs from the external electrode, which serves as the return electrode for the internally generated RF current (see Fig. 1 ). This unique device, therefore, allows physicians to deliver transepidermal “monopolar” Thermage™ nonablative-type RF heating to the mid and deep dermis and then a more significant RF thermal experience to the septofascial cutaneous structures in the hypodermis, resulting in matrix-tightening effects in the subdermal and subcutaneous spaces. The various Invasix bipolar applicators, FaceTite, NeckTite, and BodyTite, can be performed under local anesthesia and, like subdermal laser fiber delivery, a physician needs to be skilled in the art of applying anesthesia and know the relevant subcutaneous structures to avoid.

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