Keywords

1 Introduction

Fat grafting is a versatile aesthetic procedure that has significantly evolved since its advent nearly hundred years ago and is a growing trend in facial aesthetic surgery. In 1912, Eugene Hollander published photographic documentation of natural appearing changes after infiltration of fat in two patients with lipoatrophy of the face. In 1926, Charles Conrad Miller wrote about his experiences with infiltration of fatty tissue through cannulas. He described 36 cases of correcting cicatricial contraction on the face and neck with only “moderate shrinking of the fat.” He observed that the shape of the nose improved over months after fat implantation. Neuber historically investigated the particle size related to the fat grafting as he harvested pieces of fat from the upper arm, cut into pieces the size of bean or almond, and transferred it to the face. It was noticed that such large amount of fat transferring to the recipient site causes scar formation and oil cysts due to lack of vascularity to the fat. According to Peer, 45–79% of fat was lost at the end of 14 months supporting that the size of particles has a direct clinical impact on graft survival. The evolution of these grafts has changed since the advent of liposuction and the later standardization of atraumatic structural fat grafting in the late 1990s. In 2005, Coleman used a harvesting cannula and a 10 mL leur-lock syringe to harvest the fat which was centrifuged at 3000 rpm for 3 min for separating the densities. After the standardization of the technique described by Coleman, a great many clinical applications have been reported to increase volume and to improve the quality of the tissue. Most common complications with this were infection, placement of too little or too much of fat, presence of irregularities, overgrowth of fat, etc. Also, absorption of tissue with time makes patients undergo multiple costly procedures which prevents the widespread clinical application of lipofilling, but at the same time, fat grafting offers many advantages as dermal fillers. It is an autologous material that is nontoxic, biocompatible, nonimmunogenic, and nonirritant and does not migrate. It has similar features to the tissue in which it is to be implanted and is also relatively inexpensive. Another advantage to consider when using it as a filler is its inherent capacity to improve the quality of the tissues and the skin, rejuvenating the area into which it has been injected. Approximately 30% of aspirated fat cells are mature adipocytes. The remaining two-thirds are formed by a very diverse cell population, also known as the stromal vascular fraction (SVF), which mainly comprises fibroblasts, connective tissue fibers, endothelial cells and their progenitors, immunomodulatory cells (e.g., macrophages, lymphocytes), and adipose-derived stem cells (ADSCs). However, the disadvantage of fat is that it is a partially absorbable material.

As a graft that obtains nutrients through plasmatic diffusion from the start of the procedure until vascularization is restored, some of its cells will undergo apoptosis. This issue has been studied in depth by Eto et al. and Kato et al. These authors described three zones in each of the “cylinder” of fat injected: the outermost part, which is in direct contact with the receiving area and is called the surviving zone; an intermediate area called the regenerating zone; and the innermost part called the necrotic zone. In the surviving zone, both adipocytes and ADSCs survive. In the regenerating zone, the adipocytes undergo apoptosis, but the ADSCs survive because they are more resistant to situations of hypoxia. The adipocyte apoptosis generates a series of signals to the ADSCs to initiate differentiation and proliferation to become preadipocytes and later mature adipocytes. However, in the necrotic zone, both adipocytes and ADSCs die; there is no cell replacement, and scar tissue cysts or oily cysts are formed. Precisely in order to increase the retention of the injected volume and survival of the fat, many surgeons have tried to enrich the fat with SVF cells and ADSCs or by using other prosurvival strategies such as platelet-rich plasma (PRP), improving the conditions in the receiving area or studying each of the stages of its preparation.

2 Preoperative Preparations

2.1 Medical Optimization

As with all procedures, a thorough medical history and physical examination is necessary and should focus on major medical conditions, bleeding disorders, and history of drug use. The patient must be able to undergo general anesthesia, particularly in cases of larger fat grafting. Aspirin and other nonsteroidal anti-inflammatory drugs should be withheld 2 weeks before surgery, as should smoking, which may adversely affect graft survival. Vitamin E and select herbal products that interfere with bleeding should also be discontinued preoperatively. Patient expectations must be clearly elucidated and managed. In some extremely lean patients, such as professional athletes, fat reservoirs can be inadequate. Preoperative weight gain or treatment plan modification might be necessary. If the patient is able to gain weight, he or she must be willing and able to maintain this weight after the procedure.

2.2 Photography

Standard preoperative photographs serve two useful functions. First, they assist with patient communication, particularly when determining patient expectations and helping to explain procedural risks and benefits. Second, photographs can detect and document donor site deformities and asymmetries that are neglected in the initial preoperative interviews and physical examination, despite the surgeon’s best efforts. The author uses the Canon EOS 700D.

2.3 Anesthesia

Anesthesia preference selection is very personal and depends on the patient, the surgeon, or both. To control pain, we can use four methods: lidocaine 10.56% cream alone, local infiltration with lidocaine HCI 2% and epinephrine 1:100,000, sedation, or general anesthesia. For nanofat, small augmentation or procedures can proceed with anesthesia cream, nerve blocks, sedation, or a combination of different methods. In big cases with several areas to fill, it is more recommendable to go for sedation or general anesthesia.

2.4 Donor Site Assessment and Selection

Ease and safety of access are not the only criteria to bear in mind in the choice of the donor site; the enhancement of the patient’s contour should also be considered. Preoperatively, potential donor sites are identified which included lower abdomen, hips, flanks, and thighs. Some investigators think that fat is best obtained from reservoirs that are resistant to diets. Others think the medial knee has the least amount of elastin fibers and provides the best quality of harvested fat. However, this has not been shown to provide statistically different results, and recent well-designed studies clearly show that there is no difference in harvested fat quality from various donor areas of the body. Incisions should be placed wherever possible in previous scars or natural skin folds or in areas that are covered by clothing (preferably those covered by underwear). In general, we try to use areas in which any small irregularity or sequel after liposuction would not be noticeable to the patient. The internal sides of the knees and thighs are locations where thin or athletic young women tend to have higher amounts of fat.

2.5 Instrumentation and Materials

Multiple cannulas are available with a variety of diameters with one or more orifices having either blunt or cutting surfaces through which the fat is aspirated. In general, most of them have a blunt tip in order to keep trauma to a minimum. Currently, the author uses the system from Tulip Medical™ (Tulip Medical Products, San Diego, CA). Another brand popular for the same is Wells Johnson (Tucson, AZ). The patented Tulip Medical™ (Tulip Medical Products, San Diego, CA) is a great organized system to harvest and process the fat. The needed sets for the procedure are Tulip Gold Standard Facial Set™ and Tulip Nanotransfer Reusable Starter Set™. Other materials needed are standard leur-lock syringes of 1 cm3, 10 cm3, 20 cm3, 11 no. Bard Parker blade, betadine solution, modified Klein’s tumescent solution (saline, adrenaline, lidocaine), sterile gauzes, lidocaine cream 10.56% lidocaine, and needles (18 G, 23 G, 27 G, 33 G).

2.6 Tumescent Solution

Fat grafting can be performed under general, epidural, or local anesthesia with or without sedation. When surgery is performed under local anesthesia, tumescent solution is infiltrated in all the regions where the cannula is going to be passed. We have two methods of infiltration: (1) wet method and (2) dry method. Dry method or dry technique involves liposuction without injecting the tumescent solution. In wet method, a modified Klein’s tumescent solution is infiltrated which contains 500 mL NaCl 0.9% solution, 1 mg/mL adrenalin (1:10,000), and 25 mL of lidocaine (20 mg/mL). When the procedure is performed under general anesthesia, the tumescence can be infiltrated with a vasoconstrictor alone diluted in saline solution or by adding low concentrations of local anesthetic. Infiltration should be performed slowly, avoiding sudden movements to ensure maximum patient comfort, especially when general anesthesia and sedation are not used. In general, the infiltrated volume is usually about the same as the volume of aspirated fat (1:1 ratio). After waiting about 10–15 min for the tumescence to take effect, the liposuction is initiated.

2.7 Preparation of Lipoaspiration Sites

It is considered important to follow a standard aseptic protocol for both harvesting and injecting. Patients should be marked in an upright or standing position to effectively mark the area. After marking the site, betadine painting is carried out, and the procedure for harvesting is begun.

2.8 Fat Harvesting

After skin preparation and draping, we infiltrate with modified Klein’s tumescence having 500 mL NaCl 0.9% solution, 1 mg/mL adrenalin (1:10,000), and 25 mL of lidocaine (20 mg/mL). We use the “wet” technique for infiltration. Modified Klein’s solution was infiltrated with tumescent infiltrator of 2.1 mm × 20 cm through a small 1–2 mm incision using a number 11 blade in the donor area. These cannulas having holes of 1 mm are considered optimum for microfat harvesting, whereas using cannulas larger than 2 mm holes are considered optimum for harvesting macrofat. During inward and outward strokes of the infiltrating cannula, very slow injection of the tumescent local anesthesia fluid was injected evenly in layers. The importance of avoiding pooling of solution is that evenly distributing liquids improves the efficiency of harvest due to the need to provide a suspensory fluid carrier for the adipose graft tissues as well as excellent patient comfort. Upon completion of even distribution of tumescent fluid within the proposed donor area, it is recommended that re-passage of the infiltrating cannula is done throughout the donor area (termed “pre-tunneling”) multiple times which is important and very helpful to attain an even and high quality graft. This more thoroughly distributes local anesthetic fluid for patient comfort and also provides the needed “carrier fluid” to suspend the adipose tissues prior to harvesting with low pressure and minimal bleeding. After 20 min, liposuction was performed manually using the Tonnard harvester 2.4 mm × 20 cm having sharp side holes of 1 mm in diameter to harvest the microfat in a 10 mL leur-lock syringe that is pulled back gently to create a light negative pressure to create suction (low vacuum suction (<180 Hg) = syringe 10 cm3 to half). This cannula is passed in a horizontal fashion within subcutaneous donor fat deposit, above the muscular layer in a “spokes-of-a-wheel” pattern and in a forward and back series of passages. Pinching the skin-fat tissues may help in passing the cannula. The harvested fat mixed with tumescent solution from the subdermal fat plane of the donor site is now ready for processing.

2.9 Processing

Fat grafting techniques are usually divided into three stages: fat harvesting, fat processing, and fat transfer. The three most common methods to achieve these stages include centrifuge, washing and filtering, and sedimentation. Though there is no consensus on the most effective approach, current literature shows that meticulous conservative handling of adipocytes with strict attention to known techniques will provide predictable results. Processing techniques are intended to isolate the adipose tissue aspirated from the oil, blood, debris, and other unwanted components of the tumescent solution. This is important because these elements may adversely affect the viability and retention of the fat graft. According to the literature, the processing techniques for fat grafts are centrifugation, washing and filtration, sedimentation, and Telfa rolling. When all the data are evaluated, no one technique emerges as clearly superior to the others. There is still a high degree of discordance because of the inconsistent results from animal and human studies.

2.9.1 Centrifuge

Benefits of the centrifuge modality include processing relatively pure fat for grafting and providing an easily predictable volume for grafting without excess oil or wetting solution. Drawbacks of centrifugation include potential harm to adipocytes. Coleman has suggested that a relative centrifugal force of 1280 g is ideal for adequately separating fat from its wetting solution and oils. After 1–3 min of centrifugation, three distinct layers should be visible in the syringes. The lower one contains blood, debris, water, and components of the tumescence solution; the middle layer consists of the fat to be injected; and the top layer is formed by the oil resulting from the broken down fatty acids. To separate the hematic level, the bottom plug is opened, and the blood is allowed to flow out onto a tray. The broken down fatty acids in the top level can be removed by decantation, and if necessary, the oil can be removed with the aid of a small lined gauze/Telfa rolling. Lately, it has been found that centrifugation destroys the adipocytes, and thus this step can be avoided, and directly the harvested fat can be kept in the stands for sedimentation and filtration.

2.9.2 Sedimentation

This technique relies on gravity to differentially affect the various components of harvested material. The 10 mL filled syringe’s end is capped and placed in a vertical position in a decanting stand to allow gravity to separate the layers within the syringe. Decantation for about 5 min is carried out. The yellow adipose grafts will quickly separate according to their densities from the underlying (infranatant fluid), resulting in the graft floating in the middle on top of which is the lipid layer within the syringe system. A yield of 1.5 mL of fat graft per 5 mL of aspirate can be expected. Following this, we expelled the unwanted liquid layer on which the fat graft floats into sterile containers for disposal. Oil layer (clear yellow liquid above the harvested graft) should not be aspirated in the syringe to prepare the final fat graft. This layer is irritating and causes oil cysts and prolongs the healing of the graft tissues, and thus it must be removed.

2.9.3 Telfa Rolling

This procedure consists of pouring the aspirated fat onto large pieces of Telfa non-adherent dressings. The fat is gently rolled and kneaded around the gauze and then transferred back again into the syringes.

2.9.4 Washing

The harvested fat graft can be washed with ringer lactate to remove extra material such as oil, blood, and local anesthetics. The benefits of this method include minimal damage to adipocytes; however, some investigators think that washing of the graft removes fibrin, which is essential for fat cell adherence to recipient tissues. We favor the use of a closed circuit. 5 mL of isolated fat after decanting is mixed with 5 mL of Ringer lactate in the same syringe to decant again and wash the fats and remove the supernatant or traces of lidocaine that the fat could still have. After washing the fat, sedimentation process is done again. Semisolid purified fat in this stage is then transferred to 10 mL leur-lock syringes. By using a connector, 10 mL syringes are easily transferred to 1 mL syringes and prepared for final grafting.

2.10 Donor Area Post-lipoaspiration

When the desired volume is obtained and lipoaspiration is completed, the donor area is massaged, and tumescent solution is drained out the incised opening. Then, it is sutured with 6/0 nylon and covered with sterile gauze dressing to absorb any excess residual fluids, and an external compression is used to eliminate or minimize post-harvest bruising of the donor area. Some surgeons do not suture to leave it to drain the remnant tumescent solution; we consider that suturing after a good massage is sufficient to have finer scar in the incision line.

2.11 Fat Grafting

For some authors, the moment of injection is the most important part of the process. In general, when there is no fibrosis, the fat should be injected with blunt cannulas. However, when there are scar retractions or fibrosis, sharp needles can be used to release them before injection of the fat in order to avoid damaging nerves, vessels, or other anatomic structures. In cases in which fat needs to be injected into more superficial subdermal planes, direct injection with a needle can also be useful. Various types of fat are used for grafting: Macrofat, Microfat, SNIF, SNIE, and nanofat. Macrofat grafting was done earlier but is no longer done for facial region and has been associated with complications when grafted fat does not survive forming oil cyst and, thus, was abandoned for facial grafting.

2.11.1 Microfat

Microfat is injected for filling purposes in any area in the face in the deep dermal level (subcutaneously). These grafts should deposit small amounts of fat in each pass, thereby enhancing graft survival and the integration of the adipose tissue implanted into the recipient site. First we introduce the cannula and then infiltrate microfat as we withdraw it. Usually in Microfat and SNIF we infiltrate 0.1 mL in every 0.5 cm area. This creates an effect like beads on a necklace, generating several levels of injection. The procedure must be repeated several times at different levels. It is also very important to introduce the fat into different areas to create a mesh or crisscross pattern and to make tunnels at all levels so as to prevent the accumulation of fat. The quantity of fat that needs to me injected depends so much on the volume needed to augment. In fillers it is easier to calculate the quantity needed since correction is 1:1. Whereas in Microfat, it is more related to experience, technique, and survival rate. To make things easier, as an average for defects ranging from average to deep defects, author uses in temples around 5–10 mL, posterior cheeks 5–10 mL, anterior cheeks 2–4 mL, posterior jaw 5–10 mL, anterior jaw 2–4 mL, marionette folds 2–4 mL, nasolabial folds 2–4 mL, chin advancement 2–3 mL, frontal bossing 3–5 mL, parotid area deficiency 4–5 mL, buccal area 2–4 mL, tear trough 0.5–1 mL, tear valley 0.5–1 mL, peri-orbital area 1–2 mL, upper eyelid hollowness 1–2 mL, and upper lips or lower lips 1–2 mL. All these areas are injected with the Tulip Micro Injector super leur-lock. Lip contouring can be done with cannula but with other microcannulas of 27 G or 25 G × 38 mm, and around 0.5 mL in the upper or lower can be injected. Figure 30.1 shows volume augmentation with microfat.

Fig. 30.1
figure 1

28 years old female patient with cheek, jaw, and chin volume deficiency who seeks facial fat grafting to volumize her face. Microfat injection 5 cm3 in the posterior tail of the left cheek, 5 cm3 in the posterior tail of the right cheek, 2 cm3 in the anterior right cheek, 2 cm3 in in the anterior left cheek, 6 cm3 in the posterior left jaw angle, 6 cm3 in the posterior right jaw angle, 1 cm3 in the anterior right jaw depression, 1 cm3 in the anterior left jaw depression, 2 cm3 in chin augmentation, 2 cm3 in the right nasolabial fold, 2 cm3 in the left nasolabial fold, 2 cm3 in the left marionette fold, and 2 cm3 in the right marionette fold. Results shown here are post 1-year follow-up

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The following are according to the current literature:

  • Injections may be done in multiple passes, in multiple tissue planes, and in multiple directions, injecting small volumes in each pass.

  • At present, overcorrection to obtain better graft survival seems to lack scientific support.

  • Compressive bandages or massages on the grafted area should be avoided in case of Microfat and SNIF.

2.11.2 SNIF

SNIF is injected for filling purposes as microfat but with a 23 G needle in the deep dermal level. Usually, it is used for areas where cannulas could be more difficult to handle, for contouring, or for elevation of a specific area like a depressed scar. A great indication is for deep scars (Fig. 30.2) or wrinkles that need filling like neck wrinkles.

Fig. 30.2
figure 2

28 years old male patient with acne scars. Microfat, SNIF, SNIE, and nanofat injection for two sessions: 1 cm3 of Microfat to restore volume deficiency, SNIF 2 cm3, SNIE 2 cm3, 4 cm3 nanofat. Post fat grafting patient underwent controlled depth peel TCA 30% (ZO Skin Health); then he underwent 2 cm3 nanofat injection post 6 months peel. Result shown after 1 year

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2.11.3 SNIE

SNIE is injected for superficial filling purposes with a 25 G needle in the superficial dermal level. These grafts should deposit like a liquid mesh release. Usually, it is used as levelization of very superficial wrinkles or area and also very useful in very superficial scars (Fig. 30.3). Also SNIE could be used for filling of little depth tear trough by cannulas of 25 G.

Fig. 30.3
figure 3

26 years old male patient with acne scars. SNIE and nanofat injection. 2 cm3 SNIE in all scars bilaterally and 2 cm3 of nanofat. Result shown after 1 session at 6 months

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2.11.4 Nanofat

Nanofat is injected for skin quality improvement using needles 27G–33G (Fig. 30.4). Also, it is used to improve dark circles (Fig. 30.5) which are related to skin thickness, hair loss (Fig. 30.6), burns, and scar quality improvement. Nanofat is injected intradermally forming small papules like bumps over the entire face. The endpoint of injection is reached with the appearance of yellowish discoloration of the skin during the injection process leaving about 1–2 mm of bumps. This slight yellowish overcorrection is advised as it will normalize within a few hours after resorption of the interstitial fluid, but the bumps will stay for several weeks. A video demonstrating the technique is available in this link: www.youtube.com/watch?v=2-0exTbHlto&t=470s

Fig. 30.4
figure 4

33 years old female patient who seeks facial prejuvenation with adipose-derived stem cells. 35 cm3 of nanofat injection. Result shown after 1 month

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Fig. 30.5
figure 5

36 years old female patient who seeks improvement of hollow eyes and dark circles. 1 cm3 of Microfat and 4 cm3 of nanofat Injection. Result shown after 6 month

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Fig. 30.6
figure 6

28 years old male patient with hair loss. Three sessions of nanofat, PRP, and vitamin injection. Result shown after 4 months

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This video demonstrates the preparation of Microfat, the emulsification process to convert it to SNIE, preparation of the nanofat, and injection as mesotherapy for facial skin rejuvenation.

2.12 Preparation of Types of Fat Grafting

2.12.1 Preparation of Microfat

The fat left processing will be denominated as Microfat when it is injected with Tulip Micro Injector super leur-lock of less than 1.2 mm size (three available types: 1.2 mm × 7 cm, or 0.9 mm × 5 cm, or 0.7 mm × 4 cm). Every cannula has a length and a diameter that adapts to the area of treatment; smaller cannulas are used for tear trough or lips, whereas longer cannulas are used for cheeks and jaw line filling. Microfat is injected in deep dermal layer in the fat tissue plane. Microfat could be used for any area that requires filling to give volume to a certain area.

2.12.2 Preparation of SNIF (Sharp Needle Intradermal Fat Grafting)

Tonnard et al. described the SNIF in his article. It is identical to Microfat but injected with a sharp needle of 23 G instead of micro injector cannulas. It is injected in the deep dermal plane using a needle.

2.12.3 Preparation of SNIE (Sharp Needle Intradermal Emulsified) Fat Grafting

After decantation, the cleaned microfat is loaded in 20 cm3 syringes and is ready for emulsification. Microfat is mechanically emulsified by shifting the contents 30 times back and forth between two 20 cm3 syringes connected to each other by the 2.4 mm Tulip transfer and then 30 times back and forth with 1.4 mm Tulip transfer, and we finish with 30 times back and forth with 1.2 mm Tulip transfer until the fat became liquefied and acquired a whitish appearance which is termed as SNIE. After emulsification, it is transferred to syringes of 1 cm3 via a three-way stopcock. It is injected with a 25 G needle as mesotherapy treatment, but it can also be injected with cannula for tear trough area for example. SNIE is injected in the subcutaneous plane or more superficially (intradermally). The cell counter indicates that the emulsion has a similar number of stromal vascular fraction cells as the nanofat.

2.12.4 Preparation of Nanofat

To create nanofat as described by Tonnard et al., the emulsified fat is then passed once through a nanotransfer block that contains two meshes 400–600 μm single use cartridge net (Tulip Medical Products, San Diego, CA) into a 20 cm3 syringe. When the emulsified fat is transferred through the nanotransfer, the filling effect is lost, and it then only has ADSC. Thus, nanofat is only used intradermally and not for filling purpose. This nanofat is then transferred via a three-way stopcock into to a 1 mL leur-lock syringe; it is then connected to a 27 G till 33 G needle and injected. Post nanofat injections, improved elasticity was seen which can be attributed to increase collagen and elastin synthesis and remodeling which are triggered by stem cells. This liquid preparation is very useful for improving the color of the region beneath the eyes wherein it is injected with microcannula of 27 G or 25 G × 38 mm or by a needle as mesotherapy in case of facial rejuvenation.

2.13 Important Points in Fat Grafting

2.13.1 Wet Verus Dry Approach

Dry approach to fat harvesting is frequently reported to be effective. Blood has the potential to cause donor site morbidity and can negate the method’s advantages. Agostini et al. had demonstrated that these techniques yielded similar morphometric and viability results for adipocytes. We performed the wet technique because the dry technique poses greater risks of blood loss and hematic contamination and involves more challenging washing procedures.

2.13.2 Lidocaine in the Fat Graft

Keck et al. suggested that lidocaine adversely affects adipocytes and interferes with preadipocytes and their differentiation into adipocytes. Conversely, Moore et al. and Shoshani et al. found that local anesthetics had no detrimental effects on adipocytes. Cuchianni et al. demonstrated that exposure to concentrated lidocaine (1 U lidocaine per 9 U fat) substantially reduced adipocyte viability. The application of diluted lidocaine before fat harvesting is likely to have a milder adverse effect, but this effect remains to be quantified in patients. Studies showed that levels above 1.6 mg/cm3 can decrease 50% in viability.

2.13.3 Epinephrine in Fat Graft

Epinephrine provides vasoconstriction at the donor site during graft harvest and can be transferred to the fat. This has potential to endanger vital adipocytes by inhibiting diffusion from adjacent vascular tissue at the recipient sites. Precise processing of harvested fat should remove almost all epinephrine from the graft. Some investigators think that syringes containing the first harvest material have proportionately more epinephrine than material harvested later. Thus, syringes should be marked by their harvest order, and the most recently harvested should be used in critical recipient areas.

2.13.4 Pressure

Cuchianni et al. determined vacuum pressures for various syringe sizes and plunger positions. A similar analysis was conducted previously with the same results (J. Robles, personal communication, July 1995). Cuchianni et al. found a direct relationship between vacuum pressure and adipocyte damage. This relationship was corroborated by direct microscopic observation of destroyed structural fat cells. The results of other studies have indicated that adipocytes are highly resistant to negative vacuum (harvest) and positive pressure (reinjection); however, he found that high vacuum pressure reduces viability. In a closed-suction system, low tension may be applied by adjusting the suction machine, but shear stress over adipocytes may endanger viability of the graft despite a low setting. It is more recommendable to harvest with syringe-assisted harvesting. In syringe-assisted harvesting, it is recommended to pull back the plunger at low vacuum (<180 Hg) for a maximum to half the syringe of 10 mL while the cannula is inserted into the donor tissue. Studies showed reduction in viability between 30 and 50% if vacuum pressure is more than 200 Hg.

2.13.5 Washing

Cuchianni et al. results indicate that simple decantation yields an adipocyte population with the highest viability, followed successively by washing, cotton gauze concentration, and centrifugation. Like decantation, washing involves minimal cell trauma. However, washing also clears cellular debris and blood remnants, which are stimulators of the inflammatory response that can facilitate degradation of the graft. Moreover, washing extracts growth factors, but stem cells keep adhered to the stroma. He observed that washing and cotton gauze concentration yielded high concentrations of stem cells. Lactated Ringer’s solution is better because it counteracts acidosis in tissues subjected to hypoperfusion.

2.13.6 Transfer

Transfer between syringes decreased viability. As expected, Cuchianni et al. found that transfer between syringes of disparate volumes (60 and 10 mL) decreased viability more than transfer between syringes that are closer in size (20 and 5 mL). This was attributed to trauma caused by transferring fat between syringes that differ substantially in size.

2.13.7 Overcorrection

It is widely thought that grafted fat will lose volume over time; thus surgeons commonly overcorrect for this perceived future resorption. Kaufman and colleagues published a comprehensive national indicating that overcorrection is extremely common in the United States. However, some investigators think that overcorrection is unpleasant for patients and prefer to perform touchups as needed. The literature on overcorrection for expected fat resorption is conflicting, although the investigators recommend a 30% over contouring to accommodate for expected fat volume loss. Overcorrection should be done in different planes and not in the same exact area and avoid depositing more than 0.1 cm3 of fat in the injected area because viability reduces if it is over filled.

2.13.8 Freezing and Storing Fat

Some studies show that adipocytes can survive slow freezing of harvested fat to temperatures of 20 °C and the defrosting process. However, clinical application of these findings is extremely questionable, and freezing fat is not recommended at this time.

2.13.9 Length of the Surgery

Although most processed adipocytes can easily tolerate 4 h from time of harvest until grafting to access recipient site nutrients, it is recommended to plan the procedure in a way such that grafting occurs as soon as possible. This is particularly true when fat grafting is used as an adjunct to other lengthy facial esthetic operations. Additionally, some techniques, such as the sedimentation technique, require additional time for processing before injection and will add to the total procedure time.

2.13.10 Obesity

Fat grafts prepared from obese patients comprise hypertrophic adipocytes (60–150 μm) that are 2–3 times larger in diameter than adipocytes from nonobese patients. Cuchianni et al. found that larger cells were more susceptible to mechanical damage than smaller cells; this was especially true for exposure to high gravitational force. All fat samples from obese patients had reduced cell viability in his study.

2.13.11 Enrich Microfat with Stem Cell

Cuchianni et al. observed a 36% increase in adipocyte viability in the stem cell-enriched group, compared with the non-enriched group, after 1 week of cell culture. Enriched cultures also contained a higher concentration of preadipocytes after 1 week. Because enrichment with high amounts of stem cells has a degenerative effect on the fat graft, optimization of enrichment protocols is needed.

3 Recommendation for a High Viable Graft Technique

  1. 1.

    Harvest fat at a low vacuum pressure (5 mL syringe, plunger pulled to the 5 mL mark; 10 mL syringe, plunger at 2 mL mark; 60 mL syringe, plunger at 10 mL mark).

  2. 2.

    Prepare the fat graft by washing in a closed system without exposure to ambient air.

  3. 3.

    If syringe transfer is necessary, ensure that syringe volumes are similar, and perform transfer in a closed system.

  4. 4.

    Enrich the fat preparation with stem cells.

  5. 5.

    Ensure soft reinjection at the recipient site.

  6. 6.

    Expect graft viability to be reduced for patients with high BMI.

4 Postoperative Care

Bruising, edema, and ecchymosis are common sequelae of facial fat grafting. Patients must be informed about possible downtime. Deep massage may lead to migration of graft and/or damage to fat cells and should not be performed. Donor sites are closed with compressive dressings for the first 48 h. Some investigators advocate herbal supplements such as Arnica Montana, which is effective for controlling postoperative ecchymosis. Cool compression may be helpful in the first 72 h; however, direct use of ice or extreme cold can endanger circulation and is not recommended. Warm compressions that are common in many facial aesthetic surgeries are not recommended in fat grafting procedures. Compressive garments may be worn in the first 2 weeks after grafting, and vigorous activities should be avoided in the first 3 weeks postoperatively.

5 Complications

The injection of fat in the facial region is a relatively safe procedure. When performed correctly, the complication rate is low. Although most complications described after fat injection in the facial region refer to aesthetic aspects such as irregularities or asymmetries, several serious complications have been reported. Evidently, surgeons need to be aware of these situations in order to prevent them. Currently, the development of new forms of injection with small diameter cannulas or sharp needles has improved the results and made it possible to correct areas where until recently fat grafting could not be performed. Examples include eyelids and the tear trough, where the skin is very thin. In these areas, in particular, great care is needed with regard to the selection of the correct volume of fat to be injected and the depth of injection, especially when using sharp needles, in order to prevent damage to vessels or other structures.

When needles are used instead of cannulas, the injection should be dermal or subdermal; injections in the deep subcutaneous plane should be avoided. The main complications to consider when performing facial fat grafting are as follows:

5.1 Bruising and Swelling

A certain degree of surface bruising and swelling is normal during the first 2 weeks after surgery. It is important to inform the patient of this, especially in the case of nanofat grafting in the periorbital region, when the bumps usually lasts longer—up to 4 or 6 weeks. Chronic inflammation or swelling in the eyelid has very occasionally been reported in the literature. In these cases, reoperation may be required to extract fat.

5.2 Infection

As with all surgical procedures, it is essential to prevent bacterial contamination of the graft. This is done by using a sterile technique and the preoperative preparation of the donor and recipient areas. There do not appear to be any great differences between the uses of open or closed methods for the processing of the fat graft when it is performed in the operating room using a sterile technique.

5.3 Accumulations or Cysts

Distributing the fat in multiple planes during the injection and taking care not to inject all the fat in one place avoid irregularities and the formation of oil cysts in the injected area. In the area of the eyelids and tear trough, where the dermal component is practically non-existent, the formation of irregularities visible to the naked eye is common if fine microfat grafting cannulas are not used.

In this area especially, great care must be taken to inject only a small amount of fat and also to place it below the orbicularis muscle. If irregularities appear after the injection of fat, the area should be massaged until they disappear.

5.4 Asymmetries

Prior to surgery, the vast majority of patients present small asymmetries between the two sides of the face. The surgeon must identify them during the preoperative evaluation and mention their existence to the patient. During the intraoperative phase, it helps to divide the face into different compartments or areas and to count the amount of fat that is injected into each of the areas on both sides. The symmetry should also be assessed as the fat is injected.

5.5 Resorption

Inevitably, some of the fat is reabsorbed. Although we believe that the degree of resorption depends on the technique and also the surgeon’s experience, changes in the weight of the patient may play an important role. In reviewing the literature, whether or not prosurvival strategies such as the fat-enriched stromal vascular fraction, platelet-rich plasma, or second-generation platelet-rich fibrin (PRF) are used, reabsorption of around 40–80% of the injected volume has been reported.

5.6 Hypo- or Hypercorrection

Regarding this, the surgeon’s experience with the technique is particularly relevant. According to us, especially early in the surgeon’s career, hypocorrection is preferable because there will always be time to carry out any necessary retouches.

5.7 Fat Embolism

Although it is a rare complication, some cases of blindness have been reported, probably related to retinal ischemia caused by embolization of the ophthalmic and central arteries and also occasional cases of cerebral infarction after facial fat grafting. To avoid this complication, it is important to use blunt cannulas, to inject the fat while withdrawing, and always to aspirate before injecting. When sharp needles are used, the injection must always be superficial. In our opinion, although needle techniques are useful in some cases, they should never be used in deep planes, and great care must be taken when injecting into the periorbital, temporal, glabellar regions and the nasolabial fold so as not to damage the vascular structures.

5.8 Damage to Anatomic Structures (Nerves, Arteries, Muscle, Parotid, or Other Glands)

Complications can occur, especially in cases of reconstructive surgery in which fibrous attachments are released using sharp needles. Permanent damage of nerves and other structures is rare. That is the reason why for injection in deeper tissues, cannulas are used instead of needles.

5.9 Irregularities in the Donor Area

Although more common in the case of aggressive liposuction in which large amounts of fat are obtained, irregularities may occur in cases of facial fat grafting even though the volume required is usually small. It is useful to regularize the donor area with a flat cannula so as to minimize these irregularities.