Fat tissue grafting is not a novelty. As far back as over 100 years ago (1892), German surgeon Neuber introduced a method of filling facial soft tissues (volumetric reconstruction) by transfer of adipose tissue blocks of approx. 1 cm in diameter, harvested from the subcutaneous tissue of the arm.

Such procedure yielded various results, in most cases resulted in ischemia and necrosis of the central part of the graft, which entailed a significant loss of its volume within a few months. Such results were consistent with later research by Peer (1950) who stated that after a year about 50% of the initial volume of transferred fat blocks is maintained.

Injectable fat tissue transfers were introduced in 1911 by Bruning. He used to place a small portion of harvested body fat into a syringe with a large needle and to inject it into a recipient site, thereby avoiding surgical incision. However, the procedure did not gain a widespread popularity.

Injections of synthetic materials, such as paraffin or liquid silicone, introduced in the years 1950 – 1970, seemed to be more advantageous in terms of durability of the effect. Yet, in subsequent years, data collected on numerous postoperative complications resulted in discontinuance of the method.

In the 1980's with the introduction of a new method of liposculpture by vacuum suction - liposuction (Fischer, Fisher, Illouz, Kesselring), many surgeons (Illouz, Chaichir, Bezaquen, Fournier, Coleman) initiated the aspirated tissue grafting in various pathological conditions. Many variants of this procedure, differing in terms of technical details, are used until now. There is no consensus as to the durability of the reconstruction effect. Nevertheless, the method of fat grafting still arouses considerable interest among many dermatologists and surgeons. Fat grafting is subject to a continuous process of improvement and new indications for its use are being developed.

Indications for fat transfer include contour defects of subcutaneous tissue (volumetric reconstruction), e.g. atrophy of tissues associated with Parry–Romberg syndrome, scleroderma, injuries, excessive liposuction, as well as cosmetic correction of body contours (augmentation of cheeks, chin, lips, ankles, buttocks, breasts).

It is important to transfer fat tissue in a way which facilitate minimum damage to fat cells and provide optimum conditions for the healing process.

A generally accepted rule of fat grafting is to use a gentle, atraumatic surgical technique and to comply with the principles of aseptic. As for the technical details of the different fat transfer stages, many authors have proposed their own modifications of the procedure. Variations apply to all stages of the proceedings: the choice of the harvest site, the form of anaesthesia, techniques used for harvesting, graft preparation (sedimentation and thickening) and the injection technique. The most prominent approaches are described below.

Anaesthesia. Since the 1990s, when a specific form of local anaesthesia using dilute neutralized anaesthetics (tumescent anaesthesia) has been popularised, this form of anaesthesia is considered the method of choice by many surgeons, as it is fast, straightforward, safe and helps to reduce the bleeding.

Location of the harvest site. Many authors claim that thighs constitute a better harvest site than the buttocks and abdomen, due to less pain, a larger size of fat cells and their greater lipogenic activity. There is also an approach that advocates the selection of the harvest site on the basis of medical interview, bearing in mind, however, that it is most reasonable to chose a site least susceptible to weight loss.

Harvesting fat tissue for transfer. It is now recommended to harvest fat by means of syringes (10 - 60 cm3) with a needle of 2 - 2.5 mm in diameter or a cannula of 2 - 4 mm in diameter. Fat particles obtained this way have a diameter of about 2 mm (Fournier, Coleman, Pinski, Roenigk, Sattler).

Fat graft preparation. Pinski and Renigk recommended to set the syringes aside to stand for 10 minutes to let the liquid fraction (blood and anaesthetic solution) accumulate at the bottom and then expel it by pushing the plunger. At the top of the proper fat layer, a thin layer of fatty acids forms; it should be poured off after the plunger is removed.

According to Sattler’s method, syringes are put in a vessel where the excess fluid seeps into the absorbent gauze swabs (tampon gauze), then thick connective tissue fibres are removed mechanically and subsequently the dense fraction is poured into syringes of 1 ml (for immediate injection) or 5 ml  (to freeze for the follow-up supplementary injections). Many authors (Fournier, Sattler) postulate freezing adipose tissue for a single or repeated follow up injections in several weeks to a year after the procedure. It has been proven that slow freezing to a temperature of - 20 ° C immediately after harvesting has no negative effect on cell survival, whereas rapid freezing (such as by immersion in liquid nitrogen) causes cell destruction. It has been demonstrated that frozen fat cells can survive even a few years. Nonetheless, most authors do not recommend storing adipose tissue longer than 6 -12 months.

Injection of fat grafts. Fat grafts may be placed in the following locations: a) in the dermis (rarely, due to technical difficulties and unsatisfying results); b) at the border of the skin and subcutaneous tissue; c) in the subcutaneous tissue; d) multi plane (in the subcutaneous tissue, muscle and fascias); e) perimuscular  (within the muscles and surrounding tissues). In order to perform an aesthetic correction, fat grafts can be injected only directly under a targeted defect (punctuated or linear application) or over a larger area (planar application), especially on the face, and less frequently in other areas. Examples of  planar face filling techniques include: total face lipofilling (Donofrio) and fat autograft muscle injection (Butterwick, Amar).

In order to inject the fat graft under the skin, it is recommended to use power syringes or standard syringes of small capacity (1-2 cm3) with 1.5 to 2 mm  injection needles (no. 12) or, preferably, blunt needles or special cannulae. Dermal injections are made with fine needles (no. 0.6 - 0.7).

Fat graft is injected into different layers, depending on the nature of the defect. Most commonly, grafts are placed only in the subcutaneous layer, including the area directly beneath the dermis. Less frequently recommended is multi-plane grafting (in the subcutaneous, fascial and muscular layer) facilitating the most substantial filling (Chaichir). A relatively new approach, associated with an increased perioperative risk and thus not recommended for beginners, is intra- and peri-muscular injection (Butterwick, Amar).

Assuming quick partial absorption of the graft, most authors recommend injections of volume 30-50% larger than desired  (Chaichir), while others prefer gradual correction in order to avoid hypercorrection and temporary deformation, which could be problematic especially on the face (Moscona).

Fat grafts stability. Many authors emphasize that differences in the reconstruction outcomes depend on the location, even though their assessment in this regard is mixed. Satisfactory outcomes were obtained mostly in the following body areas: glabella, forehead, zygomatic bone, cheeks, chin, legs, dorsal hands (Fournier), buttocks (De Perdosa), orbital (upper eyelid) (Barman), the border of the lower eyelids and cheeks (Sattler - liporecycling), naso-labial folds and marionette lines (Eremia).Moderate results were obtained in the thoracic region (Fournier) and lips (Eremia). Unsatisfactory (short-term) outcomes were reported on the lips (Fournier) and glabella (Eremia). It is believed that more permanent results are obtained in the subcutaneous tissue reconstruction, whereas the treatment of superficial defects, e.g. acne scars, yields worse outcomes (Ersek).

There is a common belief that due to the partial absorption of the graft it is necessary to repeat the procedure. Nevertheless, a long-lasting (permanent) stability of fat grafts is observed in numerous cases.

Postoperative care. It is recommended to use antibiotics, anti-inflammatory drugs, analgesics and a gentle massage of the site to facilitate even distribution of fat. Adits are covered with dressings (usually in the first day) or left open to heal. Follow-up clinical checkups are necessary.

Discussion: Fat grafting has many advantages: it is simple, well-tolerated by patients, and may be performed in the outpatient surgical unit. A minor drawback is a downtime period of about 3 days caused by tissue swelling. Typically, injection of marketed fillers provide a more comfortable procedure followed by less intense and shorter-lasting swelling. Thus, before deciding on a fat transfer, a patient must be warned about the potential adverse events.

The shortcoming of the procedure is the inability to predict its effectiveness. There is a significant disparity in  the degree of healing and survival rate of fat grafts in patients. According to many authors, beneficial effect lasts on average for about a year, which in terms of durability equals the marketed absorbable fillers, mainly the commonly used preparations of hyaluronic acid and collagen (Fredricks).

Today, fat grafts are preferred for sites where a larger amount of filler is required, such as deep nasolabial folds also with coexisting cheek atrophy, deep wrinkles in the glabella region or dorsal hands. The possibility of using fairly larger amount of fat compared to the conventionally used fillers (also in terms of their high price) speaks in favour of fat grafts. However, there are some cases and some areas of the body where dermal fillers are still the material of choice (e.g. in mouth area or in patients who cannot accept a downtime period).

Fat transfer is a very safe procedure. The adverse events and complications are rare and usually minor. These include bruising, swelling and infection.

Currently there is an upward trend towards using non-absorbable injectable fillers. In our clinic, however, we take a cautious approach to such fillers and use them only exceptionally. Firstly, we believe that despite the most precise technique it is not always possible to achieve a perfect distribution of the filler. Therefore, permanent fillers may cause permanent problems. Secondly, the skin is getting thinner with time and thus, an unaesthetic display of permanent implants placed under the skin may occur. This phenomenon is referred to as a snow-melting-effect. When snow gradually melts, the thick, even surface gets thinner, revealing the rocks underneath and that’s how your skin with permanent fillers may look like in time.