Adrien Aiache MD Plastic and reconstructive surgery

ABSTRACT

Dermatocutaneous fat grafts, fat flaps and isolated fat grafts have been used with limited applications and successes. Fat transfer has been used successfully to fill defects and for esthetic purposes. The liposuction technique allows a large amount of fat to be harvested and to be reimplanted as a filler.There is discussion of donor sites, amount of fat to be injected, instruments to be used and possible complications. When there is fat resorption, fat injection is something performed after freezing excess fat and storing it by using a new donor area.The process of fat reinjection has given acceptable results in cases where other treatment was available.

Treatment of Cutaneous Surface Defects by Fat Injections

Since the advent of liposuction, the interest in fat as a tissue filler for contour defects has emerged. In the past, only limited applications have been found for using the properties of fat as a “filler”. Dermatocutaneous fat grafts, fat flaps and isolated fat grafts have been used with limited applications and successes.

The liposuction technique allows a large amount of fat to be harvested and to be reimplanted as a filler for areas where defects are present (Table 24-1)

Table 24-1. Body contour defects

  • Steroid injection sites
  • Liposuction depressions
  • Abdominal inverted scars
  • Young-age or old-age cellulite
  • Post-traumatic fat necrosis
  • Thin ankles
  • Depressed cheeks
  • Senile hands

Some attempts have been made to use autologous fat for breast implantation but this technique has been condemned by the American Society of Plastic Surgery since the necrotic fat could become calcified and mimic cancer on mammograms.

Originally the procedure was started by reinjecting fat in cases where during a liposuction a defect was inadvertently created. Then the immediate reinjection of the aspirated fat was performed in the hope of preventing a depression from becoming permanent and the irregularities from being noticed. Furthermore, in cases where the depression was noted after the initial stage of postoperative swelling and edema, correction by injection of fat can be done either from frozen fat or from a new area as a donor (Figure 24-1).

Indications for this technique have enlarged to zones of contour defects either congenital or traumatic such as cases of fat depression due to accidents where the fat necrosis is a result of a deep contusion and destruction of fat (Figures 24-1 to 24-4).

Other areas for fat implants are the deep furrows present in aging faces: the frown lines, the nasolabial folds, the peribuccal and even some deep lip furrows are improved by injecting the fat.

Donor Sites

The location of fat harvesting is elected ( Table 24-2). The iliac crest area the flank, the knees, the lower buttocks and the inner thighs are often used as well as the abdomen; however, it is important not to create depressions or defects during the harvesting as it can be found in the abdomen.

Table 24-2 Fat injection donor sites

Knees Often bruises, tender

Iliac crests Less deforming, less painful, inconspicuous

Abdomen Possible dents and depressions

Saddlebags Often difficult to obtain the right amount of fat without depressions or irregularities since the fat is deep

Arms Objectionable bruising

Waist Ideal on thin people, especially on men

Chin Sometime useful for immediate reinjection when there is a large amount

Inner thighs Excellent, soft fat

FIGURES 24-1A AND B

(A) Preoperative slight dent and depression in the left upper thigh secondary to an excessive liposuction in that zone;

(B) The area to be corrected is marked-out with ink. The fat has been reinjected without undue tension. Often it is surrounded by areas of fatty excess and the challenge is to equalize the surface properly with a combination of liposuction and autologous fat injection.

FIGURE 24-2

Different means have been devised to collect while the liposuction process goes on.In this case, the fat is filtered and separated from the blood and is going in a sterile catch basin to be reinjected

FIGURES 24-3A TO C

Different injection guns are available allowing the fat to be injected with power since this has been aspirated with a larger cannula. The fat is otherwise sometimes engulfed in connective tissue and exits the syringe only with a powerful force especially when it has been taken with larger gauge cannula. (A) Chajchir reinjection system; (B) Levine autolipoplasty syringe assist device developed for high pressure injection;. (C) Byron microinjector for pressure injections

FIGURE 24-4

A trap syringe devised to catch the fat that is aspirated and separated from the blood and the connective tissue

An area surrounding a depression can be liposuctioned and the fat can be used for injecting into the depressed area itself.

Instruments

Cannulas (#4 and #3) are used in the routine liposuction technique and a catch basin collects the fat. The fat is taken in a sterile manner then is cleansed at the time of its implantation either by passing it through a large grill where the large, irregular, thick particles are discarded or by washing it with saline solution. Areas of previous suction are the least satisfactory for donor sites since the fat lobules are connected to multiple strands of connective and scar tissue and are difficult to reinject. It is often better to find a new area to obtain smoother fat (Figures 24-2 to 24-5).

FIGURE 24-5

Different small size cannulas developed for manual syringe aspiration of fat.

Technique

The donor sites are infiltrated with an anesthetic solution using, in independent cases, a 10 cc syringe. Anesthesia is given using a 25 or 27 gauge needle. The aspiration technique is started by using the syringe connected to a 14 or 16 gauge needle. Once the needle is introduced under the skin, negative pressure is created manually by pulling back the piston and holding it, and a back and forth motion is performed until the fat slowly accumulates in the syringe. Two to three punctures are sometimes necessary to obtain a good amount of fat from different spots (Figures 24-6 and 24-7). The facial area to be injected is anesthetized. The anesthesia can be similar to dental anesthesia using a solution of xylocaine with epinephrine and infiltrating the supraorbital nerve or the infraorbital nerve and mental nerve from the oral commissure. Then the local anesthesia itself is injected.

FIGURE 24-6

A 14 gauge or 16 gauge needle is inserted in the medical knee area or the left hip using a manual negative pressure. The fat is then withdrawn using back-and-forth motion

FIGURE 24-7

An excellent donor site consists of the iliac crest which has often an excess of fat and where the depression after aspiration will not be conspicuous as it could be in the abdomen

The syringe containing the harvested fat is tilted, separating it by gravity-the blood from the lighter fat. The blood is expelled and the fat injected using multiple parallel channels along the creases. If the blood is too copious and mixed with the fat and does not seem to separate spontaneously, the syringe is then introduced into a centrifuge. Before centrifugation, the syringe should be covered with a blind cap or with a smaller gauge needle in order to prevent the fat from exiting the syringe under pressure while the blood is allowed to separate out. Once the fat is purified and it is visible that there is no other tissue mixed with it, it can then be reinjected in the different areas that have been elected (Figured 24-8 and 24-9).

This technique of fat harvesting is modified according to each surgeon’s preference. It is logical to utilize the fat that has been extracted by liposuction at the same operative procedure; however, since the discovery of the fat defect is often made at a later stage, the correction by fat injection is sometimes performed by freezing the fat and storing it or by using a new donor area. The preoperative assessment of size of the defect, its relationship to the surrounding tissues and the marking of the deep creases to be created are all done and the deep creases are marked with ink. These marking allow the infiltration with anesthesia and the injection to be done without distortion of the exact line to be repaired (Figures 24-10 to 24-13).

FIGURE 24-8A AND B

The vertical positioning of the syringe allows the fat to float on top and separate from the remaining blood which is then ejected. The blood is liquid and heavier than the fat

FIGURE 24-9

The centrifuge is used for faster separation of the fat from the blood. It can be used only for a few seconds making sure that a smaller needle is connected to the syringe for proper ejection of the blood without fat which is heavier and will not go through the small needle gauge

FIGURE 24-10

Markings are made over each of the deep lines present in a typical case of perioral wrinkling. Five to seven inferior buccal lines are also commonly found and infiltrated. In the upper lip, seven to nine vertical lines can be found

Fat Evaluation

(Figures 24-14 to 24-17)

Over correction is achieved up to a point where it becomes cosmetically unacceptable (Table 24-3). A 16 gauge or 14 gauge needle is used as a dissector to free the dermis from its deeper attachments and to insert a layer of fat in order to prevent the reattachment of the dermis to the deeper tissues. This technique allows the vertical wrinkles of the lip to be somewhat corrected. In the nasolabial correction, the infiltration is started from the lowest point of the crease and is continued upward until it reaches the area below the nostril. It could also be performed from the oral mucosa and the line of injection will be perpendicular to the nasolabial line allowing multiple strands of fat to cross the nasolabial line and helping in the correction of the defect. In thin and flat faces, a disk of fat is injected around the nostrils and lateral to it, in order to restore the maxillary projection. From the same lower injection point, a zone below the lip commissure is infiltrated to correct the peribuccal deep creases. These marionette lines are notorious for not keeping the fat and some over correction and area grafting is necessary to obtain an improvement and to lift the corners of the lips. A test of overfill consists of the sponttaneous regression of fat through each injection site.

No specific postoperative care is necessary. The patient is advised to keep the area as immobile as possible and apply some ice during the first 24 hours. No analgesics or antibiotics are given.

It is felt that a period of two days is crucial in the survival of the fat that has been injected. The first hours are usually allowing the fat to survive by osmolality and by osmosis; however, a new circulation is to develop to assure the survival of the fat cells. This specific finding is important in understanding the poor survival of fat which is sometimes blamed as nonsurvival at all.

Results

Since 1986, the author has performed more than 2000 fat grafts. Of these cases, approximately 50% have received a second injection approximately three month after, and approximately 15% have received a third injection. Only 3-5% of the patients have received more than four injections.

Approximately 50% of the cases were corrected only once. The natural course of the treatments is the following: after an initial period of swelling and bruising, the treated area returns to a natural stage with some swelling and eventually will return to a normal appearance, which will prompt the patient to request a secondary or tertiary injection. A large number of the patient never had more than one or two injections and have been satisfied with the results (Figures 24-18 to 24-21).

Complications

No severe complications were observed. A couple of areas of redness and cellulitis have been noticed in the knee. Approximately 5-10% of the patients will have a hematoma in the donor site, more often in the knee than the hip, and swelling, ecchymosis and distortion will last 2-6 weeks especially in the perioral area since the injection of fat through a large bore needle can sometimes injure the orbicularis vessels, thus creating large hematomas that take quite a while to disappear.

Discussion

The process of fat reinjection has given acceptable results in cases where other treatment was available. This treatment is used in cases of severe wrinkling where the only treatment consisted of collagen or dermologen injections or surgical excision. The technique has multiple advantages. It is simple and can be performed with needles and syringes, thus not requiring any specific equipment or set-up. It can be performed as a treatment room procedure. It allows the correction of multiple areas of the face and can be repeated until the results are satisfactory. In addition, it has afforded a large improvement in the face-lifting procedure which was wanting in areas such as the frown lines, the nasolabial crease and the peribuccal crease. The procedure is recommended since it has brought a high degree of satisfaction.