**9.2 Irregularities**

One of the most significant challenges with any form of body contouring, but particularly in the arm where there is less fat and high public visibility, is avoidance of irregularities and unsightly adhesions. Failure to address loose skin or poor quality in the appearance of skin can set the patient up for an undesirable or unrealistic outcome. The key to smooth liposuction is to recognize the superficial and deep adipose layers and make sure to debulk only the deep layer. Liposuction of the superficial layer of fat will result in visible divots and difficult-to-correct irregularities and asymmetries. Of course, when done carefully, superficial liposuction and purposeful creation of contours and shadows is the underlying principle and technique of muscular etching. We advise all surgeons to master lipocontouring of the deep fatty layer of the arm prior to attempting muscular etching. When performing muscular etching, less is more. It is also important to palpate the patient's own muscular boundaries and aim to only enhance the muscle borders rather than to artificially enforce muscles on the soft tissues to avoid odd-appearing contours, especially with movement and muscle activation.

Several principles can help surgeons avoid irregularities, in addition to staying in the deep adipose layer. We advocate using a small cannula (3 mm). A curved cannula is optimal for reach in cylindrical regions such as the arms (and medial thighs) and can help to enhance the smooth curvature of muscle boundaries where needed. We have a low threshold for performing fat equalization following aspiration as in the SAFE technique [30] with either a power-assisted or handheld basket cannula (off suction) if any irregularities are noted. When using energy-based devices (VASER or RF skin tightening), excessive heat application can result in fibrosis and uneven adhesions. As covered below, the key to any energy application is to protect the entry site, avoid end-hits and tenting up the device tip against dermis, and keeping the handpiece in constant motion to avoid such adverse outcomes.

### **9.3 Excess skin**

We have found that energy devices provide a treatment gap for patients with mild to moderate skin laxity (with or without associated lipodystrophy) and those who are scar intolerant. We advise every patient that, while significant improvement in skin laxity and quality can be achieved with energy-devices, no alternative treatment is equivalent to lax tissue excision with surgery. There is also variability in individual response to skin tightening treatments, and multiple treatments, or even possible skin excision, may be indicated in the future.

The best candidates for energy-based minimally invasive skin tightening are those with mild to moderate skin laxity. PDWL patients and even those with significant striae typically have an irreversibly damaged dermis and are better suited for excision surgery. This does not mean that skin tightening with RF cannot be incorporated into their treatment journey to provide advantageous results. We often discuss and offer a staged approach to treatment of these patients beginning with VASER liposuction of the deep layer to debulk the arm and RF treatment of the subdermis. At the second stage, brachioplasty is performed. With this two-stage approach, some improvement in the skin laxity is achieved by recruiting the patient's own skin tightening and the length of the excisional scar is more shortened, particularly at the elbow, axilla, and the lateral chest wall. In some cases, additional treatments with subdermal RF may also be performed.

#### **9.4 Burns and tissue necrosis**

All energy-based devices, whether utilizing ultrasound, RF, or laser, generate heat that results in soft tissue skin tightening as a primary or secondary treatment goal. Skin burns and tissue necrosis, however, can result from too much energy and heat application. In order to avoid excess energy accumulation in any treatment area, the device is kept in smooth motion, end-hits are avoided, tissues are well-hydrated, and the incision and immediate surrounding skin are protected with use of a port and energy application is avoided in a 2-5 cm radius around the entry site.

Along with more skilled application of technology, energy-based devices themselves have evolved to provide more tissue protection and safety. The earlier generations of UAL devices generated high levels of ultrasound energy, thought to underlie most UAL complications such as burns and seroma formation. The current generation of VASER device delivers notably lower amounts of ultrasound energy to the soft tissues, especially when using the pulsed (VASER) mode, while still efficiently and effectively emulsifying fat and supporting skin tightening [5].

RF devices have undergone improvement as well. As described earlier, bipolar devices have developed to better manage direction of heat and energy application than monopolar devices. Bodytite incorporates internal and external temperature monitors with safety shut-offs if the tissue heats beyond temperature boundaries set by the surgeon. Perfusion imaging assessment using indocyanine green imaging and optical coherence tomography demonstrated no compromise of subdermal perfusion following treatment with a bipolar RF device [12].

We use Renuvion as our preferred subdermal RF device in the arm for its efficacy and safety features. Renuvion generates a low-current RF energy, the depth of heating is minimal, and overheating of the tissues with multiple passes is less likely. As tissues are treated, the fibroseptal bands coagulate, contract, and increase in impedance. The plasma beam thereby quickly alternates to target different tissues adjacent to the device tip in a 360° fashion, as untreated tissues present lower impedance. Surrounding untreated tissue remains cool, allowing for heat to dissipate quickly post treatment by heat conduction. Energy flow is thereby fractional resulting in effective FSN contraction without excessive heating of the tissue field and, in particular, the dermis. The difference in subdermal and skin surface temperatures is much larger with Renuvion, allowing for safe skin temperatures to be maintained without the need for temperature monitoring. With subsequent passes in the same region, the energy continues to follow the path of least resistance (lower impedance) and therefore preferentially treats previously untreated tissue. With multiple passes, untreated tissues are optimally targeted, and over-treatment of any single area is avoided [14].

Regardless of the device used, the risk of burn is not entirely eliminated. Should there be any concern about too much heat application and burn potential, the area should be cooled with a cold moist dressing immediately. We apply topical dimethyl sulfoxide (DMSO) for any areas of potential skin compromise beginning immediately postoperatively and continued at home by the patient as long as required.

DMSO is a topical anti-inflammatory agent that has been shown to be beneficial to wound healing and analgesia [31]. Any areas of skin or tissue necrosis must be cared for in accordance with principles of burn and wound healing.
