Keywords

1 Definition

Fat grafting is defined as the improvement of body contour by a multistep low-invasive procedure consisting of harvesting, preparation, and final application of refined fat tissue into a recipient site inducing regenerative processes [1, 2].

2 Indications and Contraindications

Autologous fat transfer has become widely accepted for an increasing number of indications. Fat grafts are primarily applied as a biocompatible filling substance for soft-tissue deficiency resulting from trauma, illness (e.g., breast cancer), or senescence as a secondary reconstructive measure [3].

Lipofilling has become a pivotal adjunctive therapeutic measure in breast reconstruction. Asymmetries or contour irregularities after the initial surgery (e.g., pedicled or free microvascular flaps, breast implants or expanders) can be corrected [4, 5]. Patients suffering from radiation injury with indurations and irregularities of the breast envelope are treated with fat grafts to smooth the skin surface and reduce adhesions [6]. In fact, in critically ill patients, complete breast reconstruction via fat mammoplasty can be considered to avoid the perioperative risks and comorbidities associated with more extensive surgeries such as free tissue transfer (e.g., in the palliative setting) [1].

According to the recently published consensus statement of the German society of plastic surgeons (DGPRAEC—Deutsche Gesellschaft für Plastische, Rekonstruktive und Ästhetische Chirurgie), the operative indication for fat grafting after lumpectomy in marked contrast to complete breast ablation should be strictly handled. After segmental mastectomy of ductal carcinoma in situ (DCIS) , at least 2 years of absence of cancer recurrence is recommended before the procedure may be evaluated [1].

Likewise, patients with a hereditary predisposition for breast cancer (e.g., carriers of BRCA-1/-2 mutation, positive family history) should be treated with extreme caution only (e.g., in a controlled study setting) [6]. Postoperatively, the radiographic adjudication may be aggravated [7,8,9]. With regard to its oncologic safety, a recent study has shown no overall increase in locoregional or systemic cancer recurrence after fat grafting in patients with segmental or total mastectomy followed by reconstruction compared to an analogous control group treated without lipofilling . However, further analysis of this data unveiled that a specific subgroup consisting of patients treated with hormonal therapy had an increased risk of locoregional recurrence of 1.4% following lipofilling versus 0.5% without lipofilling (p = 0.038) [10]. Nevertheless, based on current scientific knowledge, the recurrence rate can still be considered low. Investigations in the closer future will hopefully determine the clinical significance of this increase.

Informed consent , close follow-up, and personalized breast cancer-screening regimes in accordance with the latest breast cancer guidelines (e.g., http://www.ago-online.de/en/guidelines-mamma/march-2016/) are inevitable for patients under hormonal therapy, segmental resection of DCIS, and hereditary breast cancer predisposition.

Aside from its application in oncologic breast reconstruction , micromastia, Poland syndrome, or tuberous breasts have been considered as indications for fat grafting as primary reconstructive measure (Fig. 12.1) [5, 6]. In comparison to conventional breast augmentation, implant related complications such as foreign body reaction including capsular contracture or implant rupture necessitating removal or replacement surgeries can be avoided. The unpredictability of fat volume retention and related aesthetic outcome, however, remains a challenge in autologous fat transfer procedures. As much as 40–60% of the transplanted fat grafts are typically retained [11]. In contrast, overcorrection increases the risk of fat necrosis and should be avoided [12]. Adequate volume gain along with a satisfying cosmetic result is usually achieved by serial interventions. Most authors recommend a refractory phase of 3 months minimum in between two sessions [2].

Fig. 12.1
figure 1

Patient with congenital breast asymmetry before (first row) and after three sessions of autologous fat grafting (second row) with a considerable impact on breast volume, 1 year postoperatively (third row), and late results 4 years after the procedure (fourth row)

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Despite this variable degree of fat intake, fat grafting is generally well accepted by the great majority of patients due to its low morbidity, tolerable downtime, and natural results.

Furthermore, autologous fat transfer has become an appreciated adjunct procedure for the low-invasive correction of residual contour deformities occurring after breast reduction or augmentation [5, 6, 13].

Aside from the breast, fat grafting has been used in multiple other body regions. The aim of volume and contour improvement has been successfully achieved in facial, gluteal, and penile volume deficiencies [6, 14,15,16,17,18,19,20,21,22,23]. HIV seropositive patients suffering from facial lipodystrophy under antiretroviral therapy were successfully treated with facial fat auto-grafting leading to aesthetic and social benefits [24].

Skin rejuvenation by placement of fat grafts and restoring fullness to atrophic subcutaneous tissue in the face or on the dorsum of the hand showed promising results (Fig. 12.2) [22, 25, 26].

Fig. 12.2
figure 2

Patient suffering from soft tissue deficiency in the right superior orbital compartment before (top) and 3 months after the lipofilling procedure (bottom)

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Contraindications to autologous fat transfer include general limitations to surgery such as unrealistic expectations or body dysmorphic disorder, active malignancy or infection in the donor or recipient site, hematologic abnormalities or anticoagulation, as well as pregnancy and breastfeeding. In severe chronic disease states, operability might be assessed with caution [1, 27].

As mentioned before, careful consideration is indicated in patients with positive family history for breast cancer or genetic predisposition (e.g., including BRCA-1/-2 gene carriers) as well as after lumpectomy of DCIS [1, 6].

2.1 Fat Grafting in Burn Wounds and Scars

Recently, autologous fat transfer has gained attention in the treatment of burn scars and wounds owing to its high plasticity and scarce donor site morbidity. Improvements in scar softness, color, texture, and quality have been attributed to a favorable cytokine and growth factor profile of adipose derived stem cells (ASC) (Figs. 12.3 and 12.4) [28]. The well-known in vitro changes of cytokines, growth factors, and adhesion molecules in different co-culture models with ASC support the clinical observation that ASC have a stabilizing effect when injected into irradiated wounds and scars [29].

Fig. 12.3
figure 3

Patient suffering from burn injury in early childhood before and after three sessions of lipofilling . Reduced redness and less scar tension are reported by the patient

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Fig. 12.4
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Patient with extensive thoracic scalding requiring skin transplantation before and after autologous fat transfer. According to the patient, skin quality improved markedly with reduced tendency of laceration

Table 1
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In a controlled nude mouse model, fat grafting induced dermal hyperplasia due to increased collagen deposition compared to an untreated control site [30].

Further, investigations in chronic burn scars treated with lipofilling showed an increase in neovascularization and improved dermal organization in comparison to untreated areas. Immunohistochemical analysis confirmed a reduction of melanocytes with a corresponding decrease in hyperpigmentation and consecutive color improvement of the scar [31].

Another controlled study found enhanced skin elasticity following autologous fat transfer in cicatrices while no difference could be detected for the control group, which had been injected with saline only. Pre- and postoperative durometer analyses confirmed a significant reduction in skin hardness at 3 months follow-up in fat-grafted areas of mature burn scars [32].

Further, this regenerative effect is not limited to burn injuries. In fact, lower lid ectropion caused by chemical burn was effectively treated with autologous fat transfer. One month postoperatively, the patient presented with a considerably improved esthetic and functional aspect with the absence of xerophthalmia. Remarkably, sustainable results could be documented as long as 5 years after the procedure [33].

A few studies report beneficial effects of fat transfer providing wound coverage in acute burn injury with a potential reduction of inflammation and promotion of vascularization [34,35,36]. However, critical evaluation is indicated as an additional trauma is caused by harvesting fat from a healthy donor site in a critically ill patient.

Overall, studies on fat grafting in burn patients are of small sample size, and large randomized controlled trials are missing requiring further research [35]. We face the same conflict with the increasing application of platelet-rich plasma (PRP) as single therapy or in combination with ASC. Numerous in vitro studies have proved the regenerative aspect of platelets; however, supportive clinical evidence is widely missing [37].

3 Technique

Autologous fat transfer is a highly elective surgery that is performed under sterile conditions by trained health professionals in an outpatient or inpatient setting. Preoperatively, patients need to be instructed in detail about the procedure itself, associated risks and complications, and the postoperative course by the surgeon and provide oral and written informed consent acknowledging their understanding. Photographic documentation of the donor and recipient sites is essential to compare postoperative results with the preoperative status and assess the absorption rate of the transplanted tissue [2].

Fat grafting is a multi-step process including (1) harvesting and (2) preparation of lipoaspirate as well as (3) injection of purified fat.

3.1 Harvesting

Prior to fat aspiration, small incisions of a few millimeters length, ideally hidden in creases or previous scars and placed convenient for access, are created with the tip of a scalpel No. 11. Then the donor site is prepared by infiltration of tumescent solution containing a vasoconstrictor (e.g., epinephrine, 1:200,000) for minimization of bleeding and optionally a local anesthetic for pain relief [38]. Lidocaine and articaine have recently been associated with a reduction in viability of adipocyte precursor cells. Other agents such as ropivacaine might preferably be used for tumescent anesthesia [39, 40].

The donor site is chosen preoperatively according to tissue volume and the patient’s preference. To improve body contour, most commonly liposuction is performed on the abdomen, thighs, and hips.

For tissue extraction, various liposuction methods are in common use, e.g., manual syringe liposuction (“Coleman technique ”), pump-assisted vacuum liposuction , water-assisted liposuction (“WAL”) , ultrasound-assisted liposuction, or liposuction with the aid of harvesting devices such as LipiVage (Genesis Biosystems Inc., Lewisville, TX) [12, 26, 41,42,43,44,45]. No clear evidence for the superiority of any fat aspiration technique has been found to date, and it appears that all available harvesting methods are appropriate for successful autologous fat transfer [2, 46,47,48,49]. Recently adipocyte viability of up to 90% has been reported for water-assisted liposuction [1].

Irrespective of the technique used, blunt harvesting cannulas are recommended to encourage viability of adipocytes. Cannulas with large diameters (>4 mm) may be advantageous, and low suction pressure should be administered [50,51,52,53].

To avoid exposure to the air and potential bacterial contamination, a closed, sterile system from suction device to collection container is favorable (Fig. 12.5) [1].

Fig. 12.5
figure 5

Equipment used for fat grafting. Suction device, collection container, transfer syringe, Luer-lock syringes, and blunt infiltration cannula

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3.2 Preparation

After adequate accumulation of lipoaspirate , the tissue is transferred from the collection container into Luer-lock syringes , stored vertically upside down sitting in a grid for sedimentation for a few minutes (Fig. 12.6a, b) [54]. Under the action of gravity, the aspirate is separated into three phases, an upper oily layer from disrupted fat cells, a middle relatively pure layer containing vital adipocytes, and a lower watery layer consisting of blood and infiltration liquids [6]. The aqueous phase is discarded from the syringe to obtain a proper purified fat graft ready to inject into the recipient site (Fig. 12.6c). It has to be considered that a significant fraction of the obtained lipoaspirate is tumescent solution, erythrocytes, and other contaminants that are eliminated prior to fat injection, relevantly reducing the volume of the graft.

Fig. 12.6
figure 6

(a) Fat transfer into Luer-lock syringes . (b) Syringes stored upside down in a tray for sedimentation. (c) Discarding the aqueous phase

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To separate the different phases, alternatively, the aspirated tissue is processed via filtration or centrifugation [54]. Comparative studies trying to identify the optimal technique of fat graft preparation provided ambiguous results, and to date, none of them can be given a clear preference [25, 47, 55,56,57].

3.3 Injection

For fat placement, blunt infiltration cannulas with a single distal aperture are used. The cannulas are available with different diameters, lengths, and curves as needed for different parts of the body (Fig. 12.7) [1]. For hand and face, usually 1–3 mL Luer-lock syringes are used, for any other region (e.g. breast, gluteal region) 10 mL or even larger syringes seem to be appropriate.

Fig. 12.7
figure 7

Blunt infiltration cannula

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Through the same incisions that were used for infiltration of tumescent solution, the cannula is inserted and a pathway is generated. While the cannula is being withdrawn, the plunger of the syringe is pressed slightly and fat is deposited. Multiple ducts in a V-shaped pattern are produced, and with each pass, about 0.5–1.0 mL of fat is placed to create a homogenously distributed three-dimensional meshwork [58].

3.4 Postoperative Care

A close follow-up with regular wound inspections to recognize complications such as infection promptly is indicated to ensure patient safety [2]. Patients should be prepared for a recovery period of a few days minimum. Initially, analgesic agents may be necessary. Local cooling measures promote a rapid regression of swelling and alleviate pain. Fat graft donor sites are provided with compression garments to reduce the risk of formation of hematoma and seroma [1]. At the recipient site, a slightly shaping dressing can be considered; however, direct pressure on the freshly transplanted lipoaspirate should be avoided rigorously [4, 59].

4 Risks and Complications

Fat grafting is generally considered a low-risk, low-morbidity surgical technique associated with tolerable pain and a short postoperative downtime.

Complications include swelling, hematoma, or seroma of the donor as well as the recipient site, whereas severe bleeding requiring emergency surgery has not been reported so far [60,61,62]. Infections with skin microbes occur occasionally, and rare cases of septic shock were noted [23, 60, 63].

Preoperative assessment of fat-intake rates is challenging. Graft volume loss up to 40–60% due to absorption or fat tissue necrosis is described [11, 19]. Interestingly, fat transplant hypertrophy or overgrowth was seen as an infrequent event [64, 65]. Consequently, patients’ frustration is common if postoperative results do not mirror the expected outcome.

Adiponecrosis , oil cysts, or calcifications of breast tissue may develop after fat transferring [1]. These morphological irregularities may impede interpretation of breast sonogram, mammography, or MRI, thereby potentially interfering with breast cancer detection [7, 13, 60]. No reported case of delay in diagnosis or treatment of malignancy after autologous fat transplantation neither any other clear evidence was found to date; however, that strongly confirms this interference.

Unsatisfactory esthetic outcomes with scarring of stab incisions, surface contour irregularities, or asymmetry are rare [1].

Extensive thinning of the skin with the cannula at the donor and recipient site may lead to skin necrosis or laceration [1]. Nerve injury with sensory reduction or complete loss is another possible complication of fat grafting [1].

The surgeon and anesthetist must be aware of adverse drug reactions, e.g., if tumescent solution includes local anesthetic agents that rarely induce allergic symptoms [1].

According to a recent study, during lipofilling procedures, interstitial pressures are reached that exceed pressure limits defined as hazardous for fat embolism [66]. Complications such as fat embolism, as well as stroke, lipoid meningitis, pneumothorax, or septic shock as potentially life-threatening conditions, however, are depicted as isolated incidents in scientific literature databases [6, 63, 67,68,69]. Severe or lethal events seem to be extremely rare and causation in these singular incidents could not be fully established.

Overall, the complication rate associated with autologous fat transfer is low. Preoperatively, patients should be educated in an appropriate matter about the procedure and its associated risks.