**4. Under correction**

Under correction occurs when an area of fat is not adequately removed. In almost all instances, this contour deformity is entirely technique-based. The most common areas are the arms, flanks, the periumbilical region and above the knee [16].

The primary cause of under-correction is patient discomfort. Inadequate tumescent volume, poor deep tumescence and incorrect lidocaine concentrations lead to intraoperative pain or systemic side effects. As discussed above, care should be taken to tumesce deeper layers adequately and then suction should be started in these layers first. Pitman et al. recommend the total fluid administered should be approximately double the volume of expected aspirate, meaning an approximate 1:1 ratio of tumescence to fat if all tumescence was aspirated [17]. This is a reasonable rule of thumb keeping in mind the maximum dose of 55 mg/ kg lidocaine. Typically, 21–22% of injected fluid is not absorbed, making the ratio of fat removed to fluid absorbed 11:1. Matarasso recommended that this should be kept in mind during longer or more complicated large volume procedures when calculating fluid replacement and to achieve "consistency in reporting" authors should standardize comments on volumes of injectate, aspirate, and infranatant fluid fractionation [18].

More fibrous areas, such as the male chest, the outer hip or the submentum may require a higher concentration of lidocaine in the tumescent fluid. In the authors' opinion, the 1:1 recommendation still applies. Taking too long to perform the procedure can lead to patient discomfort and incomplete liposuction. Smaller cases should be selected first until the technique is comfortable and familiar.

Under corrected areas can typically be corrected with repeat liposuction. There is no consensus as to when second liposuction can be performed. It is inadvisable to perform a second procedure during the healing process when inflammation, edema and fluid retention are still present. Most physicians are comfortable waiting 3–4 weeks if the intent is in correct volume. Tissue laxity and lymphedema must be excluded as causes. Pinch testing and sweep testing, as described by Toledo and Mauad, help to identify residual fat deposits [19].

When the volume to be corrected is relatively small, cryolipolysis may be a reasonable consideration. Coolsculpting has been Food and Drug Administration (FDA) approved for fat reduction of the chin, abdomen, thighs, flanks, bra fat and buttocks. The results have been reviewed in several publications. Submental fat reduction can be as much as 2 mm, with 83% satisfaction [20]. Fat reduction in the abdomen was as much as 27%, the bra area 20%, the flanks 25%, the inner thigh 20% and the outer hip 29% [21]. The technique remains safe, and erythema occurs in almost all patients. The incidence of post-treatment sensitivity treatment ranged dramatically from 0.6% in one study to 73% in another, with gradual improvement over 2 months. 29–96% of patients reported at least mild pain during the procedure, but this resolved and 1 week later only 2.5% reported pain [22].

External ultrasound devices can also be used to decrease small areas under correction. Several devices exist. External ultrasound devices heat fat via a photoacoustic effect. Specific frequencies heat fat faster and more selectively. Free lipids can be detected in lymphatic fluid post-treatment, verifying cell membrane permeability and/or cell death [23]. There is no consensus on the best intensity settings, frequency of ultrasound, or frequency of treatment. A few reviews of larger patient populations do exist, indicating improvement in volume [24]. High-intensity focused ultrasound (HIFU) focused at a depth of 1.1–1.6 cm, results in almost immediate adipocyte death primary via acoustic cavitation and heating. Apoptosis may also play a role. An excellent review by Atiyeh and Chahine of several studies

reported a mean waist circumference reduction of 2–5 cm. Overall, HIFU resulted in a "modest" reduction in fat, but most studies had inaccurate and inconsistent measuring tools. These authors recommended HIFU for non-obese patients seeking a minimal reduction in volume [25]. This makes HIFU reasonable for small areas remaining after liposuction. Anecdotally, our clinic uses HIFU for exactly this purpose, often combined with radiofrequency to promote dermal heating and subsequent tightening.

Radiofrequency non-invasive body contouring may also be of some benefit for contour irregularities. Radiofrequency heats fat indirectly by orienting water molecules in an electric field. Subsequent spinning results in heat and eventually adipocyte death. The frequency of devices ranges from 3 kHz to 24 GHz and may be unipolar, monopolar, or bipolar. These treatments typically involve heating the skin above 42°C for a 15–45 min period. Higher intensities may destroy fat more quickly but are typically not tolerated by the patient. Most studies demonstrate improvement in skin tightening but a few studies demonstrate volume reduction as high as 20% [26]. Radiofrequency is safe to use for small areas but should be avoided directly over bony structures, in patients with metal implants or defibrillators or those with metallic intrauterine devices.

Diode lasers emitting 1060 nm infrared light have recently been introduced. With these devices, abdominal fat may be reduced by as much as 19% and submental fat by 26.4% after a single treatment. The devices are relatively new, and we await larger studies [27]. Likewise, low-level laser light therapy (LLLT) devices may have some effect on localized adiposity. However, these devices vary wildly in efficacy, treatment intensity, treatment time and treatment endpoint. Typically, these results are experienced more slowly and maybe less than ideal for correcting contour deformities post-liposuction. Some evidence exists demonstrating LLLT plus liposuction may be beneficial, but that LLLT as a stand-alone procedure is not sufficiently effective [28–30].

In the last 2–3 years high-intensity focused electromagnetic (HIFEM) field treatment has shown efficacy in inducing muscle hypertrophy and fat reduction [31]. Katz et al. demonstrated an average reduction in abdominal fat of 19% from 1 month after treatment and 23.3% from 3 months after treatment using HIFEM in patients BMI 20–30 kg/m<sup>2</sup> . Each patient received for 30-minute treatment spaced 2 days apart over 2 weeks. The treatments were highly tolerated. Cellular controlled apoptosis appears to be the predominant mechanism [31]. The procedure is also an option for treatment of other sites, such as the calves or arms [32].

Finally, liposhifting may be appropriate for small under corrected areas. This technique involves anesthetizing the area, then gently loosening fat with a cannula (without suction). The loosened fat is gently rolled out to the desired contour and a garment placed to fix the tissue in place. Several patients in our practice have had excellent results with this technique [33].

## **5. Overcorrection**

In the case of overcorrection, excess fat has been removed from the subject such that the desired contour is depressed. These occur in every possible anatomic site but are most evident where the esthetic result is visible ventrally. The abdomen is the most common site, primarily because of the larger area, although it is the least technically difficult. However, more technically difficult sites include the outer and inner thighs and the posterior upper leg [16]. Treatments for overcorrection include reinjection of aspirated and prepared fat (see below), the release of fibrous bands using either mechanical or enzymatic release (e.g. as seen in areas of bound down skin or cellulite), and various fillers, specifically poly-l-lactic acid (PLLA).

#### *Complications and Solutions for Post-Operative Liposuction Deformities DOI: http://dx.doi.org/10.5772/intechopen.101284*

It can be very helpful to annotate the expected amounts of aspirate on a photograph or body map. Then during the procedure documentation can be made as to actual volumes extracted. Toledo and Mauad recommend collecting several syringes of fat initially so that overcorrected areas can be grafted immediately [19]. We find it helpful to have the patient stand at the end of the procedure so that contour irregularities can be assessed. In a supine patient, contour irregularities can be observed by stretching the skin and looking for subtle changes in contour. These areas can then be further assessed with a pinch test. Care must be taken not to overcorrect and undercorrected area causing the provider to go back and forth between sites. While it is often helpful to blend the hills surrounding under corrected sites into the normal contour, this can be an easy pitfall and reinjection may be a better option. Overcorrection can also occur in what Klein refers to as a "spoke and wheel deformity". This occurs when suctioning occurs repeatedly at the base of a fanning pattern where more passes occur. Avoid this by stopping suction on entry and exit and during changes in direction.

Overcorrection also occurs in the mons pubis, where vulvar edema can be problematic. This area should be approached very conservatively. Even a mons pubis that appears to have significant volume may be deceptive because the fibrous borders of this area make small amounts of fat seem larger. Overcorrection of this area can result in painful intercourse.

By collecting several syringes at the beginning of the procedure fat can be saved for same-day reinjection. Fat graft survival is based on several factors. Larger cannulas decrease the sheer force of adipocytes against the cannula wall. Adipocytes exposed to higher vacuums can also suffer damage. Larger and shorter cannulas have better adipocyte viability based on Poiseuille's law because pressure drop is directly related to the length of the cannula and inversely related to the 4th power of the radius. A larger bore dramatically decreases the change in pressure an adipocyte must undergo. Fat should be cleaned of blood and tumescent fluid, but centrifuging may be damaging [34]. There is a 1470 diode laser powered to disrupt septa but not destroy adipocytes. This works because water-containing septae preferentially absorb 1470 nm infrared energy over adipocytes. Adipocytes are then collected in a mesh basket within the container and excess tumescence, blood and oil are suctioned out in a two-step process. This fat is reported to be over 90% viable [35]. The addition of platelet-rich plasma may nearly double fat graft survival (55–89%) [36]. Platelet-rich fibrin may be beneficial as well, as it releases growth factors more quickly to adipocytes at risk of death (greater than 300 μm away from the periphery of the transfer) [37]. Reinjection should be performed in small aliquots using only gentle pressure. Distribute it in a fanning pattern to increase vascular exposure. Depending on the method of collection and fat preparation, the problematic area should be injected with an additional 50–100% over baseline to allow for resorption. Liposhiftng is beneficial if the over-corrected area is adjacent to a larger volume of fat.

Cellulite and scar depressions can be released using a forked cannula. These release fibrous bands in a technique called subsicion [38]. After release, cellulite and scars may be fully corrected and no further treatment is needed, otherwise fat grafting or poly-l-lactic acid may also be used.

Collagenase may be an additional off-label consideration to improve bounddown scarring or cellulite. Collagenase derived from *Clostridium histolyticum* has recently been FDA approved for treating cellulite and has been used for Dupuytren's contracture and Peyronie's disease as early as 2013 [39]. The most common side effects have been ecchymosis and pain at the injection site but reports of edema and hematoma exist [40].

Poly-l-lactic acid (PLLA) is a deep dermal filler that stimulates collagen formation by activating fibroblasts. Volume correction can persist for 2 years or more. Results may not be seen for 4–8 weeks, and injections typically are placed 4–6 weeks apart. Correction of depressed areas is temporary, and results may not be visible for several weeks after injection. Unlike autologous fat transfer, overcorrection is not recommended here. Several sessions are needed. The technique can be cost-prohibitive for larger areas. Each syringe provides only 5–12 ml of fluid depending on dilution. Fillers should not be used on the day of liposuction. Time should be allowed for swelling and edema to subside. Also, 1% lidocaine with epinephrine is often used in reconstituting ploy-l-lactic acid and this complicates calculations of maximum lidocaine dose after tumescence when numerous syringes are used. We have had success with the correction of gluteal cellulite and volume using PLLA (**Figure 2**) but found no case reports using PLLA specifically for overcorrection.

Recently allograft adipose matrix (AAM) has been introduced for volume correction. An AAM was developed by the processing of recovered adipose tissue as a human cell and tissue products (HCT/P) allograft [41]. It is stored at room temperature and as such can quickly be reconstituted if overcorrection is observed. Injection of an adipose-specific matrix promotes adipocyte differentiation, proliferation, and neovascularization. Patients generally tolerate injection very well. Biopsy of treated temporal tissue revealed an increase in adipocytes and blood vessels at 8 weeks. Gold et al. observed that AAM generally appears to follow the same trend as autologous fat grafting and may reach final volume more quickly. Thus, the underlying mechanisms of fat grafting and AAM may be similar [42]. More experience is needed with this product, but it seems to have great potential.

Millifat (2–2.5 mm "parcels" of fat) may be an alternative solution to mild superficial contour deformities, probably by the same mechanisms as AAM and grafting. Nanofat (500 μm particles) can similarly be used to improve skin texture and assist in volume support [43]. This is typically introduced via microneedling or a 25 gauge cannula.

**Figure 2.** *Correction of cellulite and volume using PLLA. Photo courtesy: Jamie Wilson PA-C.*
