Facial Fat Grafting

Although the popularity of fat transplantation is a relatively recent development in plastic surgery, the concept of fat transfer is not new. As early as 1893, free fat autografts were used to fill a soft tissue defect. The use of autogenous abdominal fat to correct deficits in the malar area and chin was reported in 1909. Throughout the early part of the 20th century, attempts were made to correct other conditions, including hemifacial atrophy and breast defects, but modern fat grafting did not develop until the early 1980s with the popularity of liposuction.

Illouz reported the transfer of liposuction aspirate fat in 1984.[1] In 1986, Ellenbogen reported the use of free pearl fat autografts in a variety of atrophic and posttraumatic facial deficits.[2] With refinements in technique, fat grafting has become the procedure of choice for an array of problems, including facial scarring, lip augmentation, and facial rhytids (such as several otherwise difficult-to-address areas, including the nasolabial fold and glabellar furrows).[3]

Methods of addressing rhytids range from excision and re-draping of excess skin to methods of skin resurfacing including dermabrasion, laser ablation, and chemical peels. Each of these modalities has limitations.

Implantation of a filler substance into a deficient area is another solution. Whereas facial resurfacing can be thought of as leveling the mountains, use of an implantable substance fills in the valleys.[4] Many materials have been tried for the correction of soft tissue defects and deficits. However, the use of most of these substances has met with difficulties, including impermanence, foreign body reaction, unnatural texture, and possible disease transmission. In addition, most of the products currently available remain relatively expensive.

Collagen has been used to address rhytids. Available collagen consists of purified bovine collagen. Zyderm is 95% type I collagen and 5% type III collagen. The addition of glutaraldehyde cross-linking (Zyplast) slows resorption; however, the substance nonetheless eventually is degraded by the host. While collagen works well for the correction of fine lines, results for deeper furrows are less impressive. The major drawback to the use of collagen is the short duration of the response. Within 3-6 months, the collagen is resorbed completely and the improvement is lost. In addition, because the collagen is bovine-derived, pretesting for an allergic response is required. The test spot should be observed for 1 full month prior to treatment.

The Food and Drug Administration (FDA) approved Gore-Tex (solid polytetrafluoroethylene) for facial plastic surgery in 1993. The result is generally predictable because the substance is nonreactive, but the resulting feel of the tissue is somewhat unnatural. The substance is rigid and is not available in an injectable form. In addition, infection remains a potential problem because the substance is a foreign body. Because this substance does not become integrated into the host tissue, it is generally easy to remove.

Newer substances are being marketed. Sheets of human dermis (AlloDerm) are also available and produce a more natural result. Again, the form of this substance limits its use. Although it is derived from a human source and becomes revascularized by the host, it is not autogenous. Concerns about possible disease transmission have been expressed, although processing appears to control for this. A micronized form of human dermis has been available since 2000. While the semiliquid form of the substance gives it the versatility of collagen, the substance does not have the longevity of the sheet form. The major impediments to use of this substance remain the high cost and, although initially touted as a permanent solution, the substance is eventually degraded by the host.

Use of injectable poly-L-lactic acid (PLLA) has gained widespread popularity in Europe since its approval for cosmetic correction in 1999. PLLA is a synthetic polymer of lactic acid that is biodegradable, resorbable, and biocompatible. The large particle size of PLLA (40-63 µm) prevents it from being phagocytosed by macrophages, but it can still be used in needles as fine as 26–gauge (ga). The outcome in patients with a loss of facial volume and contours appears to be very good as judged by physicians and patients, with satisfaction rates reaching as high as 70% and 75%, respectively. One multicenter trial conducted by Laglenne and colleagues involving 110 patients reported minor adverse effects, with only 10% of patients experiencing nonspecific ecchymoses and no patients experiencing allergic reactions.[5] However, others have reported many cases of granulomas and inflammatory reactions, which are difficult to treat.

Hyaluronic acid (HA) is a carbohydrate polymer and one of the major components of the extracellular matrix. It is found extensively in neural, connective, and epithelial tissues. Although pure HA is not biocompatible with dermal tissues, the cross-linked form is biocompatible. HA was initially extracted from cock combs, but possible allergic reactions limited its use.[6] This problem was overcome by the compound Restylane, which is produced from nonanimal cells through a process of fermentation and filtration.[7] A study conducted at 6 medical centers in the United States showed similar outcomes to Zyplast as a filler in wrinkles.[8] The FDA approved its use in 2003. Complications are usually related to local inflammatory responses.[8] According to the American Society for Aesthetic Plastic Surgery 2012 Statistics, HA was the second most commonly performed nonsurgical cosmetic procedure, with botulinum toxin A the most commonly performed.[9]

An ideal substance would be readily available, inexpensive, long-lasting, natural-feeling, and would not cause adverse immunologic reactions. Autologous tissue meets these requirements.[10] Several types of tissue can be transferred. Fascia and dermis require longer scars for harvesting. Ideally, dermis can be harvested from the area of a previous incision, such as a Cesarean delivery or abdominal scar, to avoid a new donor site defect. Strips of these tissues can be useful for larger areas and deeper defects but do not have the flexibility of a liquid or semiliquid substance. Fat can be harvested through inconspicuous access incisions. The harvesting does not leave a defect, and the removal of fat is often desirable. Fat tissue is soft and feels natural. It can be introduced to correct various deficiencies, is not immunogenic, and is readily available and inexpensive.

Autologous fat transfer has been used for correction of facial scarring, including acne scars. Enhancement of facial volume also can be achieved for disease processes such as hemifacial atrophy and for patients with aesthetic concerns, such as those who request lip augmentation. Signs of facial aging can be improved.[11] Rhytides that are too deep to be addressed by resurfacing modalities and areas poorly addressed by traditional lifting procedures (eg, nasolabial folds, glabellar creases, tear troughs) can also be treated with grafted fat.

Aging skin is characterized by decreased thickness, elasticity, and adherence to underlying tissue. In the epidermis, the number of melanocytes and Langerhans cells decreases. The rete pegs interconnecting the epidermis and dermis flatten, causing increased susceptibility to shear forces. The dermis atrophies as loss of ground substance, elastic fibers, and collagen occurs. Sun exposure leads to distinct damage to the skin. Elastosis (ie, deposition of thickened, irregular, partially degraded elastic fibers in the dermis) is characteristic of sun damage.

Cigarette smoking also is associated with changes in the skin. Post-traumatic scarring, acne, and the repetitive action of underlying muscle result in predictable histologic changes. Repeated weight fluctuations can contribute to wrinkling. Failure to properly evert skin edges during wound closure can result in a depressed scar. A genetic contribution also is present.

Older patients may present for correction of specific areas or for overall facial rejuvenation. The anatomic areas not addressed by traditional rhytidectomy, auxiliary suspensory procedures, or facial resurfacing often are ideal for fat grafting. Patients of all ages may present for facial enhancement; lip augmentation is the most common request. Often patients have obtained information from friends or media sources such as the Internet. Patient education and understanding are crucial to obtain optimal results. For information on aesthetic procedures, including news and CME activities, see Medscape’s Aesthetic Medicine Resource Center.

This procedure can be performed on an outpatient basis with local anesthesia. The preoperative consultation is crucial. By far, the most important part of the preoperative workup is an extensive discussion identifying areas to be treated. In addition, details of the procedure, postoperative care, expectations, and possible adverse outcomes should be discussed.

Photographic documentation is critical to planning and evaluation of this surgery. Lighting, angle, and expression should be standardized to allow for accurate delineation of detail and adequate comparison of preoperative and postoperative views. The patient should not wear makeup for preoperative or postoperative photographic documentation. Digital photography is useful for the patient to indicate areas of concern during the consultation. Photographs are also useful for postoperative comparisons.

Aging and scarring result in loss of subcutaneous tissue, which is amenable to replacement by fat grafting. Indications for fat grafting include correction of atrophy due to aging or scarring and enhancement of facial elements (eg, to correct glabellar frown lines or to provide a fuller, more voluptuous lip-). Areas of the face not addressed by procedures such as rhytidectomy include nasolabial folds, glabellar creases, and tear troughs. Lip augmentation may improve the appearance of fine perioral lines and increase the amount of vermilion show.

Despite early views that fat is a relatively inert and isolated tissue, fat has been demonstrated to be a well-vascularized tissue with high metabolic activity. In addition to its structural role, fat tissue serves as a reservoir for energy storage. The number of fat cells generally is assumed to be stable after the completion of adolescent growth. Changes in the volume of fatty tissue relate to the size of the cells and their overall lipid content. Cells removed by liposuction or other surgical procedures do not regenerate. Cells shrink with overall weight loss and, in fact, may dedifferentiate. However, subsequent weight gain causes re-differentiation of the cells with an increase in volume.

Fat tissue consists of fat cells, which have thin cell membranes enmeshed in a fibrous network. Without the supporting fibers, the cells tend to collapse. An additional supporting network of connective tissue structure creates the lobules of fat, which can be observed grossly. Harvesting fat while maintaining as much supporting structure as possible preserves structural integrity of the tissue and helps the tissue retain bulk in the transplanted site. Almost any site can be used for harvesting; however, the abdomen is easily accessible, and access incisions can be hidden within the umbilicus or in the hair-bearing skin of the pubic area.

Contraindications to fat grafting include the presence of any disease processes that adversely affect wound healing and of poor overall health status of the individual.

The use of free fat grafting for the treatment of contour abnormalities resulting from breast biopsy or for breast augmentation is generally contraindicated. The grafted fat can cause both palpable nodules and calcifications, situations that may hinder a diagnosis of breast cancer or cause unnecessary intervention.

Almost all candidates have some fat for harvesting; however, some individuals are unwilling to have a procedure performed at a distant site.

See the list below:

• No specific laboratory studies need to be ordered for patients undergoing this procedure unless clinically indicated (ie, patients with history of easy bleeding or bruising should have coagulation parameters and platelets checked).

See the list below:

• No specific imaging studies are required for this procedure. However, if concern exists as to the presence of an abdominal hernia, obtaining an ultrasound to exclude this diagnosis is prudent to avoid a potentially devastating bowel injury.

Skin care regimens such as glycolic acid peels (mini-peels) and at-home products such as glycolic acid lotions and Retin-A–type products are useful adjuncts for the treatment of facial aging. Other management options for the treatment of rhytids include traditional lifting procedures such as facelifts and brow lifts as well as chemical peels, laser resurfacing, and dermabrasion.[12] Often these modalities can be used in conjunction with fat grafting.

The most important principle in the surgical management is the atraumatic transfer of fat. Trauma to fat in the process of harvesting or placing fat affects the survival of the graft. While a nonviable graft initially may appear to have corrected the problem, eventual resorption of the tissue negates the result. Any blood that remains in the harvested fat also facilitates rapid degradation of the transplanted lipograft. The 3 parts of the surgery are harvesting the graft, transferring the graft, and placing the graft.

First, carefully mark the recipient site(s) with the patient's agreement while he or she is in the upright position. Sterilely prepare and drape both the harvest site and the recipient site.

Harvest

The technique is designed to harvest the fat in parcels of readily transferable size. Common donor sites include periumbilical, lumbar, and trochanteric areas; the thigh; and medial sites of the knee and arm.

Use local anesthesia to anesthetize the site for a small access incision. Through this incision, use a long syringe to introduce tumescent fluid for anesthesia of the region. The same site serves as the access for harvesting.

The choice of tumescent fluid varies. A standard solution consists of 1 mg of epinephrine, 200 mg of lidocaine, and 5 mEq of sodium bicarbonate in 1 L of normal saline. Dosages of lidocaine up to 35 mg/kg can be used for the tumescent technique, although substantially less is required for simple fat harvesting.

Following infiltration of the region to be harvested, use an aspiration cannula (eg, Mercedes) connected to a syringe. Alternatively, a 14-ga needle can be used, as this causes no reduction in survival of fat harvested. Suction by hand or with a mechanical vacuum. Use a gentle passing motion for aspiration. Small syringes are recommended to avoid creation of negative pressures greater than 1 atm. Increasing the power suction from -0.5 atm to -0.95 atm has been experimentally demonstrated to result in the breakage and vaporization of fat cells, destroying their ability to be successfully transplanted.[13]

For visible tarsal plates and tear-trough or nasojugal fold improvements, a combination of pearl fat grafting and sparse fat injection may provide optimal results. Pioneered by Ellenbogen, this technique employs small pearls (5-8 mm in diameter) excised from fat and placed in saline. These pearls are then stacked on top of each other through an incision in the depressed area.[2] This technique is not useful for nasolabial folds, labiomandibular folds, or chin augmentation.

Transfer and purification

Once harvesting is complete, the aspirate then is transferred sterilely through multiple syringes using the tulip connections to 1-mL tuberculin syringes. The liquid fraction of the graft is gently washed free of oil, lidocaine, and blood with this transfer.

An alternative to gentle hand tipping is use of the centrifuge. Although Chajchir found that use of the centrifuge machine at high or low speed completely destroyed the adipose cells,[14, 15] other groups have reported good results with use of the centrifuge. The aspirate divides into 3 layers. The top layer is free oil from ruptured fat cells. This layer is decanted or blotted gently. The bottom layer contains variable amounts of tumescent fluid and blood and is drained. The middle layer consists of fat cells for grafting. More vigorous washing or straining may damage the fragile cells and decrease the viability of the graft.

A literature review by Langridge et al indicated that with regard to processing techniques for autologous fat grafting in the head and neck, volume retention is greater when the graft is treated with adipose-derived stem/stromal cell enrichment methods (64.8-95%) or is processed in commercial devices (41.2%) than when it undergoes centrifugation (31.8-76%).[16]

A study by Gerth et al indicated that in autologous facial fat grafting, the long-term retention of fat processed via closed-membrane filtration is significantly greater than that for centrifuge-processed fat. The study, which included 26 patients who underwent grafting with closed-membrane filtration fat, found that at a mean follow-up period of 17 months, the mean retention rate for these patients was over 41%, compared with 31.8% for patients who had undergone grafting with centrifuge-processed fat.[17]

Inspired by a yogurt concentration method used in Anatolia, Kuran had recent success transferring aspirated fat to a sterile cup dressed with gauze.[18] Five washes of lactated Ringer solution rinses local anesthetic solution and blood from the fat. The aspirate is left to dry and the concentrated product is transferred to small syringes. Most groups favor a closed technique for sterility issues, but no published data exist for higher risk of infections in open procedures. The advantage of open technique is the option that allows the surgeon to manipulate fat to produce a graft that is easier to inject.

The choice of fluid for fat suspension is controversial. Most commonly, normal saline or lactated Ringer solution is used. Serum free culture medium is also available, although it is more expensive. Some groups advocate additives such as heparin, insulin, vitamin E, and nonsteroidal anabolic hormones. The contribution of lidocaine is also debatable.

In anticipation of future lipografts, adipocytes may be frozen to -30°C and reused. A high number of viable cells exist even after defrosting. Slow freezing and thawing is the method of choice to retain the maximal number of live cells.

Placement

Regional nerve blocks are the most useful because adequate anesthesia can be provided without obscuring the defect to be treated.

The goal with any grafting procedure is to gently apply the graft to a well-vascularized bed to maximize graft take. Every part of the graft should be within 1.5 mm of living, vascularized tissue. If a large area is grafted, the central area, which is most removed from the blood supply, may not survive. Still, some clinical evidence shows good lipografting survival in some tissues that are not well-vascularized (ie, hemifacial hemiatrophy and posttraumatic scars).

Creating small tracks for the grafts helps keep the grafted fat adherent to the recipient site. Keeping the tracks independent prevents the fat from leaking out of the tunnel. Also take care to avoid overfilling the track. Overfilling can adversely affect graft survival and graft location.

Insert the cannula either over a bevel-tipped needle or through a 1-2–mm access incision made by a No. 11 blade scalpel. Guide the needle or cannula superficially under the rhytid or scar and inject fat in a controlled method gently upon withdrawal. Slight overcorrection is important because some absorption of the liquid carrier occurs. Some groups recommend a 30% overcorrection.

The level of fat grafting varies with the structure being augmented. Fat is grafted from the deep layer to the superficial layer.

Kuran's technique calls for injection in parallel and crossing directions and at subcutaneous, intramuscular, and supraperiosteal levels for malar, buccal, and mental areas. Injections are only made parallel to the line for correction of rhytids and prominent nasolabial folds.[18]

With lip augmentation, grafting near the mucosa increases the amount of vermilion show. Grafting near the white roll tightens perioral rhytids. Gatti describes injection of 3 mL into the upper lip and 4 mL into the lower lip, although much larger amounts have been reported.[19]

Serial injection may be performed at 3-month intervals. Generally, 3 procedures should be anticipated. Even distribution of the injection is crucial. Excess bulk in a particular area may isolate the fat in the central region from the new blood supply.

A study by Lin et al indicated that microautologous fat transplantation (MAFT) is an effective means of accurately grafting small fat parcels. The study involved 168 patients who underwent the procedure for sunken upper eyelids, with satisfactory results obtained, suggesting that MAFT can be used to reduce the potential complications of fat grafting.[20]

Discourage massage and excessive facial animation immediately following fat grafting. These restrictions are to prevent migration of fat away from the desired areas of treatment.

Compression dressings to prevent migration have been described; however, they are often difficult to maintain and probably add little to the final result. If the fat has been placed in an appropriate tunnel, minimal concern about migration should exist.

Patients should be seen in the first week postoperatively to check the donor and recipient sites. Some edema and a minimal amount of bruising may be apparent; reassure patients.

An additional follow-up appointment should be made for approximately 6-8 weeks. At this point, most of the edema has subsided, and early results can be assessed.

If a repeat procedure is to be performed, a waiting period of 3 months is prudent to allow the first graft to re-vascularize and to allow any edema to resolve.

A prospective study by Denadai et al indicated that in patients who undergo facial fat grafting, independent risk factors for asymmetry at 12-month follow-up include age, the presence of Parry-Romberg syndrome, and previous bone surgery at the fat-grafting site.[21]

The major complications of fat grafting are undercorrection and overcorrection. Undercorrection can be the result of the placement of less than the required amount of fat or from the resorption of some of the graft.

Although placing too little fat obviously fails to correct the defect, increasing the amount of injected fat does not always prevent problems. Placing too much fat in a particular area can contribute to failure of revascularization of the graft. Graft necrosis may cause palpable irregularities and eventual disappearance of the grafted material. Graft migration is usually caused by infiltrating too much fat into a particular site. The graft either is forced into an undesirable area or succumbs to pressure and lack of blood supply.[22]

When grafting scarred areas, the graft tends to move to the areas of least tension. Clumping of the graft also may occur. This may be a particular problem under thin skin. After 1 month, if clumping is still a problem, instruct the patient on how to perform scar massage.

Undercorrection is generally easier to treat than overcorrection. Additional fat may be grafted at a separate sitting to complete the correction. Removing excess graft is more difficult as the host tissue infiltrates into the graft.

Damage to underlying structures, particularly around the eye, is possible and generally is prevented using the blunt needle for infiltration. Coleman reported a case of parotid injury when grafting a scar adherent to the parotid. Sharp needles were used. Niechajev and Sevcuk reviewed complications and discovered 4 cases of unilateral blindness and 1 case of severe damage to the CNS.[13] All of these cases involved treating glabellar frown lines with probable resultant fat embolism. Careful control of the injection to keep the fat in superficial areas as well as use of the blunt cannula should prevent these complications.

Edema usually is evident for 2 weeks after the procedure; however, as with any procedure, prolonged edema is possible and troubling to the patient.

Bleeding complications usually are limited to transient mild ecchymosis and are associated with the use of sharp needles for fat injection. Superficial ecchymosis tends to resorb rapidly. Small hematomas are more unusual and are associated with the use of sharp needles for graft placement.

A literature review by Wang et al of severe vascular complications resulting from autologous facial fat grafting reported the glabella and temple to be the most common sites of such complications. The investigators found that the number of severe vascular complications, as determined annually, has risen over time, with increases having been particularly significant since 2010.[23]

Although rare, infections can occur wherever the skin envelope is violated. The most common source of infection is the oral mucosa.

Additionally, donor site scarring is a potential concern. Contour irregularities can result from overly aggressive harvesting in a small area.

 

The major questions regarding fat grafting are how much of the graft survives and for how long. Many groups have reported on the fate of grafted fat; however, solid quantitative results have been difficult to establish. In addition to the variations in technique of fat grafting, quantifying the results objectively has been nearly impossible. Biopsy of the areas has been performed but is not a palatable option in the cosmetic patient. Further, while histology may demonstrate the integration of the graft, the relative volume retained remains unknown.[24]

Imaging studies, such as MRI, may yield information in a noninvasive manner; however, such studies are quite expensive and inconvenient for the patient. Also, many of these patients undergo additional procedures either simultaneously or at a later date, which may confound the results. Individual variation in aging is another uncontrollable factor, although many studies reporting poor long-term results have been published. Surgeons who routinely perform fat grafting counter that failure to maintain meticulous technique accounts for the shortcomings.

Two major theories describe the survival of grafted fat. Peer proposed the host cell replacement theory.[25] Histiocytes phagocytize free fat and become adipocytes. This idea largely has been replaced by the cell survival theory. Circulation is restored to the grafted fat cells in a manner similar to the revascularization of a skin graft. In the first 4 days, host cells, such as polymorphonuclear leukocytes (PMNs), plasma cells, lymphocytes, and eosinophils, infiltrate the graft. Within the vessels of the graft, red and white blood cells are clumped. On or about the fourth day, neovascularization is evident. Histiocytes act only to remove fat from broken down, nonsurviving, or disrupted cells.

Chajchir et al performed biopsies on the sites of grafted fat at intervals. Three months after transfer, zones of cytosteatonecrosis, lipophagic granulomas, lymphocytes, adipocytes, giant multinucleated cells, and new vessels were found. At 6-8 months, the specimens were infiltrated heavily by PMNs in a fibrotic matrix, and, at 1 year, a large amount of connective tissue and fibrotic reaction was present. Some fat was still present, but the authors felt that the inflammatory reaction may contribute more to the long-term result.

The key points of the theory of fat survival are (1) fat is a dynamic tissue and (2) cells that suffer trauma lose more volume. Therefore, careful handling of the graft is critical. Scarring and the added bulk of reactive tissue may contribute to the anticipated result.

A study by Cohen et al found evidence supporting another existing theory, that immediately after fat grafting the transplanted adipose tissue dies, with subsequent replacement by adipose-derived stem or progenitor cells. In patients who underwent facelift incorporating fat grafting, the average facial volume at 1- to 2-month follow-up was about half the volume of the initial fat injection, while at 18- to 24-month follow-up, the average facial volume was only 26.36% less than the injection volume.[26]

Moore et al reported on the effects of mechanical damage to fat cells harvested with syringe suction lipectomy versus excision with local anesthetics.[27] The mechanical damage to tissue aspirated versus tissue that was excised was unchanged. Lidocaine inhibited the glucose metabolism and lipolysis of adipocytes in culture. The effect was maintained only for as long as the lidocaine was present.

Also, as Smahel reported, fat grafts, like other grafts, must be small enough to be revascularized but large enough to maintain structural integrity and some native blood vessels.[28] When part of the graft is not revascularized, the fat becomes necrotic and is not simply resorbed but is broken up and removed by the cellular elements.

Outcomes of early studies yielded disappointing results.

A 1991 report by Ersek revealed a 3-year follow-up period of fat grafting that was disappointing; however, although the fat was harvested atraumatically using a blunt cannula and minimal vacuum, the fat was processed in a traumatic manner using a whisk and strainer.[29] The range of fat resorption was reported at 20-90%. Cortese et al reported resorption of 75-98% of the graft, but some good results were obtained with multiple procedures.[30]

The techniques of grafting fat have changed markedly since these studies were performed. Niechajev and Sevcuk reported long-term results of fat transplantation clinically and histologically.[13] Fat harvested by low-power aspiration was used. Patients were overcorrected by approximately 50% at the time of the initial procedure. Only partial resorption had occurred 1.5-4.5 years postoperatively. The clinical impression was that 40-50% of the result was maintained long-term. Histologic sampling at 7-36 months revealed fat cells in an organized structure. Longer-lived specimens demonstrated more pronounced fibrosis and organized connective tissue. The size of the graft was demonstrated to increase with overall weight gain by the patient.

Bertossi reported on the histology of biopsy specimens from the upper lip of 99 patients.[31] Upon examination, the structure of the transplanted adipocytes was well-preserved. In some areas, connective tissue was dense and organized; in other areas, adipocytes and reactive cells with increased vasculature were in higher abundance.

Coleman reported long-term success when the treated rhytid was compared with a control rhytid.[32] Patients were monitored clinically with careful photographic controls for 6.5 years. However, ongoing aging and choice of control rhytid can affect the interpretation of results.

Koh et al showed that patients who received adipose-derived stem cells and fat grafts had less fat absorption than those who received fat grafts alone.[33] They measured fat absorption and volumetric differences using a 3-dimensional camera and 3-dimensional computed tomography.[33]

Clearly, the results depend on the technique used for the procedure and on the method of measuring results. Advances in digital photography aid in long-term follow-up care and documentation. Presently, clinical impressions and patient satisfaction support the use of fat grafting in many different situations.[31]

Fat grafting has become a popular procedure for facial reconstruction and rejuvenation. The long-term results remain debatable. Standardized digital photography may allow more precise quantification of long-term results in a noninvasive manner.

Fat grafting for breast enhancement remains a controversial issue. Clinical trials assessing the long-term efficacy and safety are currently underway. Concerns include the low survival rates of adipocytes after implantation and the difficulties in differentiating calcifications due to breast cancer from calcifications due to fat transfer.

Preliminary studies have suggested that fat injections may even be clinically effective in patients who experience the adverse effects of radiation and in patients with severe burns.[34, 35, 36] The results are not only aesthetically pleasing but also appear to mimic the texture of skin better. Histologically, biopsy tissue shows neovascularization, increased collagen deposition, and dermal hyperplasia.[35] These effects are thought to be influenced by a population of stem cells, residing in the stromal vascular fraction of lipoaspirate tissue, that are capable of differentiating into multiple tissue types.[37, 38, 39]

A study by Boneti et al indicated that both laser fiber contouring and autologous fat grafting can effectively be used in combination with standard surgical facelifts. The study’s patients received fat injections after laser treatment, with facelift subsequently performed. The investigators reported significant improvement in the perioral, periorbital, and cheek areas; moreover, the temples demonstrated excellent fat retention at 2-year follow-up.[40]

A study by Tringale et al indicated that autologous fat grafting can safely and effectively be used in pediatric patients for the correction of facial asymmetry. The investigators also reported, however, that fat grafts may need to be repeated to obtain adequate results and that in cases of overcorrection, spontaneous resolution in pediatric patients is unlikely.[41]

Investigations regarding the pharmacologic manipulation of fat grafts are underway. Some groups have tested agents such as insulin-like growth factor, basic fibroblast growth factor, and a selective B1 blocker to enhance the survival of lipografts in rats.

In addition, techniques for simplification of harvesting are being developed. The ability to grow cells in culture may allow for multiple grafting procedures with a single harvest. The results seem promising and may one day be used in human facial fat grafting.