**3.1 VASER liposuction**

The workhorse of our approach to lipocontouring of the body, including the arms, is using ultrasound-assisted liposuction (UAL) to prepare the fat for smooth extraction with some skin retraction and limited blood loss. We use VASER (Solta Medical, Bothell, WA), which is a third-generation UAL device. Following infiltration of tissues with tumescent fluid, the VASER blunt probe is gently moved through both the superficial and deep layers of fat. VASER uses ultrasonic energy to emulsify the fat for removal by suction-assisted or power-assisted liposuction (SAL, PAL respectively). The emulsification process occurs through a combination of cavitation, mechanical, and thermal effects. The cavitation effect occurs when the VASER probe, vibrating at ultrasonic frequencies, creates microbubbles that implode and release energy that disrupts the fat layer architecture, while preserving the integrity of the fat cells and tissue matrix [4, 7, 8]. The mechanical effect occurs when the vibrating tip comes into contact with adipocytes [4]. We compare this effect to shaking the grapes off of a vine. As a by-product of the high-frequency vibration, thermal energy is created [4], which contributes to a modest amount of skin tightening following liposuction. Care must be exercised to avoid accumulation of excess thermal energy at any one location by keeping the probe in constant smooth motion.

VASER liposuction offers several advantages over traditional liposuction, with respect to smooth fat harvest and minimizing irregularities, improved skin retraction, and limiting blood loss. Traditional forms of liposuction (SAL and PAL) can lead to contour irregularities, especially in the thin, soft tissues of the upper arm and in the superficial fat layer, that present as cannula lines, uneven fat pockets, and potential iatrogenic cellulite-like appearance of the thin internal skin. Loosening of the adipocytes with VASER emulsification prior to aspiration leads to smoother fat extraction as well as the ability to use finer cannulas. Further, the thermal energy from VASER can melt the superficial fat and tighten the fibroseptal network (FSN), leading to an improved arm contour and appearance [9]. VASER liposuction has been shown to result in significantly more (53%) skin retraction relative to SAL (17% skin retraction per liter of liposuction with VASER compared to 11% with SAL) [10]. In cases of negligible fat excess in the arms with limited need for liposuction, we still find VASER to be immensely helpful. The blunt probe of the VASER helps to gently pre-tunnel prior to the use of any other instrumentation (SAL/PAL aspiration or skin tightening with subdermal RF devices) to minimize tissue trauma and create smoother outlines. In addition, the moderate skin tightening effects of VASER can be synergistic with other skin tightening treatments.

By virtue of keeping the tissue matrix and neurovascular networks intact, VASER liposuction can result in 26% reduced blood loss compared to traditional liposuction [10], enhancing patient safety especially when arm liposuction is coupled with other concurrent surgeries or multiple areas of liposuction.

## **3.2 Skin tightening with radiofrequency (RF) devices**

The greatest barrier to arm skin excision procedures has been the need for extended conspicuous scars that limit the choice of arm-bearing clothing, which is the common presenting complaint in the first place. While there is still no replacement for the extent of skin laxity correction that can be achieved by removal of skin, we find that the improvements achieved with minimally-invasive arm contouring methods frequently meet the desired goal of many patients, and at the very least may help shorten the length of any eventual skin excision scars. VASER can provide a modest amount of skin retraction following liposuction as discussed above which may be sufficient in patients with mild skin laxity. In most other cases, we utilize RF technologies devised for skin contractility as an adjunct to lipocontouring.

## *3.2.1 Subdermal application of RF*

A number of studies have demonstrated that neocollagenesis occurs when soft tissues and the dermis are heated to a temperature of 60 to 80°C and skin surface to approximately 40°C [11]. When RF energy is applied subdermally, conversion of RF energy to heat in this temperature range can be achieved, resulting in collagen fiber restructuring and formation as opposed to tissue necrosis. RF energy in the subcutaneous and subdermal space is converted to heat and results in contraction by two mechanisms. First, cleavage of hydrogen bonds in the collagen fibrils results in shrinkage and thickening of the FSN immediately after energy application. Second, the wound healing cascade is initiated, which results in neocollagenesis, angiogenesis, and elastin reorganization with effects on the skin quality observed over the three to four months following treatment [12]. Subdermal RF heating has been shown to result in FSN contraction and soft tissue contraction of up to 47% [13]. A 50% reduction in vertical height of lax pendulous skin and skin surface contraction of 33.5% can be achieved in the arm with RF treatment [9].

There are two categories of subdermal RF devices available for skin tightening: (1) "bulk heating" devices that utilize RF energy for focal tissue heating (such as Thermi and InMode), and (2) a helium-based plasma device that utilizes RF energy to generate a plasma beam as well as creating thermal energy (Renuvion) [14]. These device categories are described below, and their similarities and differences are highlighted.

"Bulk heating" RF was initially introduced as a monopolar device, which consisted of an energy-emitting subdermal probe and required a grounding pad on the body (Thermitight, Thermi, Irving, TX). Since energy is focused at the tip of the probe, heat accumulates in a small region of tissues quickly ("hot spots") and dissipates slowly to surrounding tissues. Tissue heating can therefore be uneven and poorly optimized. An external monitoring device for heating at the skin surface device is required for safety and to avoid burns from hot spots [14]. Newer bulkheating RF technologies utilize bipolar devices with two electrodes, an internal one inserted into the subcutaneous layer and an external one making contact with skin surface, to create a unidirectional transfer of energy through the tissues between the two probes. Since RF energy is directed between the two electrodes, only the

#### *Enhanced Lipocontouring of the Arms DOI: http://dx.doi.org/10.5772/intechopen.98807*

intervening tissue is heating, limiting unintended thermal energy elsewhere. A grounding pad is not required. Bodytite (InMode, Lake Forest, CA) is a commonly used bipolar RF device for skin tightening with body contouring procedures. Bodytite handpiece has built-in internal and external temperature monitors that promote safety and eliminate the need for skin thermal surveillance with a separate camera [11, 15]. Bipolar RF devices circumvent many of the application and safety limitations of the earlier monopolar devices. As such, we no longer utilize subdermal monopolar RF in our practice.

The latest subdermal RF device to enter the market has been Renuvion (formerly branded as J-Plasma; Apyx Medical Corporation, Clearwater, FL). Renuvion utilizes RF energy to create a helium plasma in addition to traditional thermal heating. Briefly, RF energy is delivered to the handpiece to energize an electrode, while helium gas is passed over, creating a helium plasma which delivers heat to the tissues by two methods. First, production of plasma beams, by ionization and rapid neutralization of helium atoms, produces heat directly. Secondly, the plasma beam functions as an effective electrical conductor to transfer a portion of the RF energy directly to the tissues. Heat is generated as the current passes through the resistance of the tissues— a process known as "Joule heating" [14]. The Renuvion plasma beam heats soft tissue targets to temperatures greater than 85°C for less than 0.1 second to achieve desired coagulation and contraction. Unlike bulk heating, tissues surrounding the treatment target remain much cooler allowing for rapid cooling of target zones after treatment application by process of heat conduction and limiting hot spots. The plasma beam conducts through tissues that offer the least path of resistance for flow of RF energy: either through tissue that is closest to the electrode or tissue that has the lowest impedance (easiest for energy to flow through). In the subcutaneous plane, the collagen network of the FSN is typically the closest tissue and is the primary target of the heating and contraction process. As fibers are treated, they coagulate, contract, and present higher impedance. This, coupled with the withdrawal movement of the handpiece, results in the plasma beam quickly alternating between treating different and new tissue targets, which present lower impedance, in a 360° treatment field. The plasma beam efficiently results in focused treatment of FSN to result in maximal tissue contraction and skin tightening without heating the full thickness of the dermis [14].
