Autologous Fat Transfer: Evolving Concepts and Techniques

Chapter Summary

Autologous fat transfer (AFT) is a long established means of facial volume restoration in cosmetic rejuvenation, where it is not only a corrective technique for soft tissue defects and rhytids but also for facial atrophy due to the aging process.
Because of an improved understanding of the process of neovascularization and fat as a living graft, the emphasis has shifted from overcorrection to transfer of small volumes of fat.
Autologous fat is usually harvested by gentle syringe aspiration and concentrated by centrifugation prior to reinjection into subcutaneous fat or muscle.
Fat autograft muscle injection (FAMI) follows the patient's anatomic landmarks by placing fat within or adjacent to facial muscles.
Potential complications of all fat transfer techniques include nodule formation due to overcorrection, fat necrosis, infection, and vascular occlusion, most of which can be avoided by careful, sterile technique.
Data on long-term outcomes are scarce and largely based on two-dimensional photography. Further research on outcomes and factors affecting survival of adipocytes is needed.

Introduction

Fat augmentation is a popular and effective method for restoring volume to facial and body defects utilizing a variety of techniques. In many regards, fat fulfills the criteria as the ideal filling substance. It is readily available in most patients, inexpensive, non-allergenic, has no potential for infectious disease transmission, and has high patient acceptance. How well fat fulfills other key criteria of an ideal filler, such as predictability and persistence of correction over time, is controversial. This chapter will examine evolving concepts in fat transplantation and ongoing debates regarding the optimal techniques for achieving long-term results.

Historical Vignette

Fat transfer dates back to 1893, in an oft-quoted report by Neuber involving transfer of 1 cm pieces of fat from the arm to facial depressions caused by tuberculosis. Bruning was the first to report injecting fat through a needle in 1919, but fat was still extracted by excision. Fat grafting was still an open or semi-open procedure until Fournier's discovery in 1985 that fat could be extracted with a syringe and needle. The popularity of fat transfer subsequently grew and provoked further inquiry into optimal techniques for harvesting, processing, and injection of fat for achieving adipocyte survival and longevity of results. The literature of the 1980s abounds with anecdotal and empirical reports regarding fat cell viability but few, if any, controlled studies.

The 1990s brought a second, even more explosive surge of interest in liposuction, with an eight-fold rise in the number of procedures performed in the USA from 1990 to 1999. This growth was due in large part to Klein's introduction of the tumescent technique, allowing liposuction to be performed less invasively under local anesthesia with minimal postoperative downtime and unparalleled patient safety. The increase in liposuction procedures fueled an increased interest in using fat for correction of soft tissue defects and furrows. The 1990s also gave rise to an aging “baby boomer” population with an increased demand for non-surgical rejuvenating procedures.

With the turn of the century, new synthetic fillers have become available, which can be injected in a less invasive office visit with minimal downtime. These have become so popular that in 2012, according to a member survey of the American Society of Plastic Surgeons, 1 988 767 filler procedures were performed compared with 63 000 AFT procedures. These synthetic fillers may well overtake fat as the preferred volumizer, but autologous fat, a safe and accepted procedure for over a century, will likely remain a valid option, albeit a more invasive one.

New Trends

Concepts and techniques regarding AFT have changed over time. One of the most significant changes in technique has been a shift from overcorrecting with a bolus of fat to transferring small volumes of fat with minimal overcorrection. This reflects a transition in the concept of fat as a temporary reabsorbed filler to fat as a living graft. In the 1980s and early 1990s, it was not uncommon for large volumes of fat to be placed with deforming overcorrection of 50% or more. It was reasoned that all the fat was absorbed and that overcorrection would result in more fibrosis. The rate of resorption of these large volumes was often variable, unpredictable, and asymmetric.

The theory of fat grafting postulates that following transfer to the recipient site, the transplanted fat becomes ischemic. Some cells die and others survive as intact adipocytes or preadipocytes until a blood supply is established from the periphery. In the late 1980s, Coleman championed the survival theory of fat grafting and developed a method he called Lipostructure™. He advocated placing small parcels of fat with repetitive passes into multiple tissue planes, reasoning that a blood supply was more easily established. Gentle atraumatic handling of the fat cells was required for survival of the cells. In 1993, Carpaneda and Ribeiro validated these empiric findings when they compared viability of fat cylinders of different diameters. They found that smaller injected volumes, less than 3 mm in diameter, had optimal viability. At 2 months, viable fat cells were noted only in the peripheral zone of larger grafts having diameters of 3.5 mm or more. The core of larger grafts had undergone necrosis due to lack of vascularization. Indeed, small-volume transfer is a common denominator in studies reporting good longevity of fat.

During the 1990s and into the twenty-first century, we have also seen a change in the goals of AFT from correcting rhytides and furrows to replacement of volume loss for the full face. Aesthetic surgeons began to challenge the traditional concepts of rejuvenation, recognizing that the taut skin achieved through rhytidectomy may not equate with a youthful appearance. Correction of the cause of the aged appearance, namely volume replacement for atrophy of hard and soft tissues, is needed to achieve a truly rejuvenated and natural appearance ( Fig. 29.1 ). It has also been acknowledged that rhytidectomy may cause soft tissues to thin out even more, resulting in accelerated aging and a skeletonized appearance.

FIGURE 29.1, A 30-year facial volume loss.

Supporting these views are several studies examining the structured anatomy of aging. Rohrich and Pessa have demonstrated multiple discrete fat compartments of the face that atrophy and then shear and slide over time, resulting in sagging of the face.

In addition, atrophy of the bone and remodeling of the craniofacial skeleton is now recognized to occur throughout life and impart further changes to the overlying soft tissue. These concepts of aging diverge from the traditional view, that facial aging is a result of gravity-induced ptosis. Restoring volume to the aged face is now becoming an integral part of facial rejuvenation in addition to – or in some cases instead of – more conventional methods. In order to restore full facial volume, larger quantities in the range of 20–100 mL or more may be required. Such quantities are not currently feasible with synthetic fillers primarily due to expense of numerous syringes and the temporary nature of most synthetic fillers. AFT is the natural choice for volume correction of this degree.

Other indications for fat augmentation

AFT is not only indicated for correction of facial rhytides, defects and volume loss, but also in non-facial areas. Body areas, which are sometimes augmented with fat, are the buttocks, biceps, calf, and breast. Fat augmentation of the breast is a controversial area given that calcifications may develop postoperatively. Although these calcifications have been shown to differ radiographically from those caused by breast cancer, the areas could require biopsy, causing undue morbidity for the patient. Rejuvenation of the dorsum of the hands is another indication for AFT. Generally, 10 mL or less is placed in each hand, although Coleman recommends 20–30 mL per hand. Other common indications for AFT are defects from disease or trauma, for example acne scars, linear morphea, lupus profundus or erythematosus, depressed full thickness skin graft, lipodystrophy and post-liposuction defects, glucocorticoid lipodystrophy, and cellulite.

Controversies in performing the procedure

AFT is a multistep procedure with each step potentially critical in achieving optimal longevity of the transplanted cells. A review of the literature reveals that the proper method of performing every step of the procedure has been the subject of debate. At issue is the survival of the adipocyte and what factors have a positive or negative impact on survival ( Box 29.1 ).

Box 29.1

Controversial factors in fat cell survival

Choice of harvesting site
Degree of negative pressure during harvesting
Diameter and type of harvesting cannula
Exposure of fat cells to air, blood, or lidocaine
Centrifugation of the fat
Rinsing the fat
Vascularity and mobility of the recipient site
Diameter and type of injecting cannula or needle
Freezing fat for later use

Each of these factors has been examined to some degree but definitive answers are lacking. Although the literature is replete with anecdotal reports, there are few objective studies. The difficulty in establishing consensus is a reflection of the difficulty in measuring outcome. There is no practical method to objectively document results. Transferred fat cannot be labeled or distinguished from recipient site fat cells with a distinct histologic marker. Successive imaging with magnetic resonance or ultrasonography is expensive and exposes the patient to unnecessary radiation. Measuring outcome is further complicated by variable rates of aging over time and changes in body weight over time. Newer three-dimensional imaging systems are now available and may provide more insights as their use becomes more common.

Technical Aspects

Harvesting

Donor site

The optimal donor site has not been unequivocally established. Many choose the outer thigh as the ideal site, due to its non-fibrous nature and relative avascularity. The rationale is that the least vascularized tissue will best survive the initial hypoxic period after transfer. Ullman and colleagues injected fat from various sites into nude mice and found the outer thigh fat to have the lowest resorption rate. However, Rohrich and Pessa more recently found no difference among four different body sites (thigh, flank, abdomen, and knee) in measuring adipocyte viability in vitro with colorimetric assays. In any given patient, availability of fat is certainly a factor. Indeed, many patients desiring improvement of a gaunt facial appearance have very little body fat and one must obtain fat wherever possible.

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