Mr Anthony Macquillian provides an introduction to fat grafting for facial augmentation
Fat grafting to the face has often been limited to lipodermal structural grafts and in the past has perhaps been used as more of a reconstructive procedure rather than an aesthetic one.1
There has been an increasingly better understanding of fat harvesting and injection techniques, which has produced a more reliable level of graft take and reduced the risk of lumpiness in the recipient sites, making its use a far more attractive proposition for both patients and practitioners.
Fat grafts are stable, autologous, and part of the normal tissue composition at the recipient site. They appear to have the potential ability (although it is not yet fully understood) to rejuvenate the tissues into which they are injected, through the stem cells contained in the vascular stromal fraction of the lipoaspirate.2
Although the treatment is unlikely to replace hyaluronic acid dermal fillers as the mainstay product for soft tissue remodelling, as the modality requires a degree of surgical training, it presents a compelling alternative to those able to offer the technique to their patients. It is also beneficial that practitioners who are not qualified to conduct these treatments understand the treatment process so that they are able to explain it to their patients should they ask. This article will outline the basics of fat harvest and transfer for the face as well as provide an overview of indications and contraindications.
Fat grafts are stable, autologous, and part of the
normal tissue composition at the recipient site
Fat grafting or fat transfer is, as the name suggests, the movement of fat cells (adipocytes) from one part of the body (the donor area) to another. The technique of grafting a tissue involves removing it from its blood supply entirely and then relying on the ingrowth of a new capillary network to support the transferred cells once they are at the recipient site.3
It is the establishment of this new blood supply that is crucial to the survival of the transferred tissue. If this fails, it will result in graft loss; in the case of adipocytes, necrosis of the cells, with resorption of their lipid content (and loss of volume at the recipient site).4
Due to the fact that capillary ingrowth takes a few days following graft placement, the cells have to rely on diffusion of oxygen and nutrients from surrounding tissue fluid. This means that only cells near the surface of the block of tissue will be nourished and survive. If the fat particles are very small and have a large surface-to-volume ratio then the whole particle will survive.
Large particle size, however, means that the inner cells will not achieve re-establishment of blood flow in time to prevent cellular death. This is why small particle grafting is essential. Fat graft systems that are able to produce small graft particle size will therefore have better rates of graft take.5
Fat grafting is increasingly being used for rejuvenation or augmentation of several areas of the body, the most common being the breast,6 hands7 and face.8,9 It has the benefit of being fully autologous (no risk of hypersensitivity reactions), and once vascularised (capillary ingrowth has been completed) there is an extremely low risk for infection.
It responds to touch exactly like normal tissue and can be used as a bed into which further fat can be injected if desired in the future. In my opinion, this has the makings of the ultimate injectable revolumising material.
Several forms of fat graft application to the face have been described, such as lipodermal grafts, micro grafts and nano fat transfer. Recently the introduction of micro-straining techniques to filter, purify and reduce particle size (one of the original descriptions being emulsification) has resulted in the development of ‘nano fat’.2 Nano fat grafting is the use of very small particles, or almost liquidised fat, which has been used for correction of very fine wrinkles and for its direct rejuvenation properties.
Although the exact mechanism of action is unclear, nano fat is thought to work by the action of stem cells and growth factors up-regulating collagen and elastin production.2 Indications for the use of nano fat include intradermal injection for the correction of fine wrinkles, intra and subdermal injection for the correction of sun damage and intra and subdermal injection for the correction of skin discolouration (for example in the lower eyelid).2
Harvesting of fat cells for transfer is carried out by liposuction. Unlike liposuction performed for body contouring, the fat that is aspirated has to be collected in specialised systems that usually filter the aspirate and separate living cells from non-viable adipocytes and lipid (to a greater or lesser extent). The idea behind this is to only inject viable tissue that will not be resorbed – hence maximise volume preservation. This leaves the practitioner with a viable population of fat cells that can be injected into the recipient site.
For large volume fat harvest (such as for breast or buttock augmentation) several dedicated systems are available for efficient harvest of large quantities of lipoaspirate.10,11,12 However, where smaller volumes are required, many practitioners use a fine liposuction cannula mounted on to a syringe.
Handling of the fat graft is different from that of normal fillers such as hyaluronic acid, as the cells are sensitive to pressure, which must be kept in mind when injecting, and the liquidity of the fat differs depending on the site of injection.
In the malar and temporal regions ‘dry’ graft (non-diluted) is generally the preferred choice by practitioners, but in the periorbital area a more liquid form of graft is utilised (with some practitioners reporting mixing the graft with saline in a 70:30 ratio).13,14 In my experience using a liquid graft in the periorbital region has less likelihood of getting lumps developing under the thin skin of the lids.
Injection of the fat into the recipient site can be undertaken by a number of means – all require the use of some form of cannula or needle. Many practitioners use a wide bore needle to introduce the graft material, although most advocate use of fine blunt cannulas for injection, as needles are more likely to puncture a blood vessel, with typical delivery diameters of 0.7mm to 0.9mm.9 My preference is for a blunt tipped 0.9mm cannula.
Handling of the fat graft is different from that of normal fillers such as hyaluronic acid
Most users would advocate injection being undertaken during a controlled withdrawal process, though other techniques such as ‘air brushing’ (multiple passes with extremely fine cannula depositing very small volumes but quite rapidly) have been suggested by some experienced practitioners in the field15 – I would suggest that this is for the experienced clinician only. Areas particularly suited to fat graft treatment are shown in Figure 1.15
As stated above, once vascularised and incorporated into the surrounding tissues, the fat cells are living and will respond to changes in nutritional status like elsewhere on the body. This leads to two considerations – firstly the patients’ weight should be stable prior to undertaking any procedure (or else the result may be unpredictable) and subsequent significant weight gain will have additional effects on the facial appearance.
It is possible, however, to mitigate against these potential problems by choice of fat donor site. Transferred fat retains its stability in relation to nutritional status once embedded in its new location and, therefore, the ideal donor site is one that is relatively unaffected by weight loss or gain.16 In practice this means that for facial fat grafting, the first choice donor site is the inner aspect of the knee (see Figure 2 for my donor site preference order).
The technique is widely applicable, but like all treatments there are certain circumstances where it is contraindicated. Firstly, the patient must have sufficient fat to act as a donor site for the procedure (not usually so much of a problem for facial fat grafting but definitely an issue for larger areas such as the breast).
The practitioner must explain to the patient that although it is a permanent procedure, there is likely to be some resorption of graft material and they may require a repeat procedure or touch up to get the ideal outcome.
In my practice, smoking is an absolute contraindication to treatment due to its interference with graft take.16 It is important to explain to patients that any areas that have pre-existing scarring will require at least two treatments (the first to treat the scar bed and provide a bed of fat into which further graft can be injected with subsequent treatments delivering increases in volume), and those who have had previous surgery to the area will be particularly hard to inject (due to surgical scar formation).
Ideally the patient will have revolumisation done as part of a facial surgery procedure or done prior to subsequent surgery. If a patient has been previously treated with HA dermal filler, it is important to wait until all filler material has been resorbed prior to grafting as filled areas will not be able to provide the graft with vascular ingrowth and the transferred cells will die and resorb.
In the past, a particular area of concern (based on the experience of many surgeons) has been the development of lumpiness within the graft, especially in the perioccular area. With the use of more ‘liquid’ grafting techniques this is now a rare complication, although if it does occur, areas resistant to massage can be treated with the judicious use of dilute steroid injection.17
The most common complication is loss of graft volume. However, as stated above, meticulous harvest and injection techniques helps to reduce the rate of graft loss.18 Infections are rare, but in my practice I always prescribe patients with one week’s worth of antibiotic treatment post operatively as a precaution.
As with all injectables, there is the risk of embolism if the fat is injected directly into a vessel with ophthalmic artery embolism being the foremost concern. The use of a blunt tipped cannula and injecting only when withdrawing the cannula mitigates against such complications,17 but in the event of concern immediate contact with the nearest ophthalmic surgery emergency facility is mandatory. Trauma to the surrounding facial structures (nerves, vessels and the eye itself) resultant from the cannula is possible but careful, gentle technique renders this an unlikely eventuality.
Post operatively it is important that the patient minimises pressure to the grafted areas and keeps the face warm by avoiding cool outside conditions for at least a week. A high carbohydrate intake for four weeks post surgery helps with graft take (thought to be mediated through the actions of insulin-like growth factor).17
It is important to limit patients’ immediate post-operative expectations – it is usual for them to appear swollen and red for two to three weeks following surgery and telling them that they should not expect to see any indication of how they will ultimately look until after the three-week mark is important. Volume changes are normally apparent up four months post procedure, with the final outcome being visible by six months.
In summary, facial fat grafting offers an exciting alternative to traditional filler materials when considering facial rejuvenation. It has the additional benefits of being fully autologous, permanent, and seems to have a direct antiageing effect on the skin and soft tissues. Improvements in graft harvest technique and placement have translated into markedly better rates of graft survival. Although still a comparatively rare technique in the aesthetic field, I believe it is likely to play an increasingly important role for practitioners to treat the signs of facial ageing.