Chapter 2 Microfat Grafting

10.1055/b-0038-149621

Chapter 2 Microfat Grafting

Patrick L. Tonnard • Alexis M. Verpaele

I keep on making what I can′t do yet in order to learn to be able to do it.

V G

Fat grafting is not new. In 1893 Neuber1 published the first clinical report on autologous fat transplantation.

Since then the popularity of fat grafting has fluctuated between wild enthusiasm and complete demonization. It was only with the pioneering work of Coleman2 in 1995 that “lipostructure” became predictable and reproducible.

Nevertheless, difficulties and problems arose in specific cases. In particular, grafting the lower eyelids sometimes resulted in palpable or even visible irregularities or lumpiness. Downtime was also excessive, with pronounced and lengthy swelling of the face.

From discussions with colleagues such as Thomas Roberts III, Frank Trepsat, and J. William Little, we realized that a reduction in grafted particle size may resolve many of these problems.

Geometry teaches that the surface area of a spherical particle is inversely proportional to its radius (Fig. 2-1). Thus given a certain volume of fat particles, reducing the particles to half their size will double the total contact surface area. Because a fat particle is dependent on the diffusion of nutrients during its initial embedding phase before revascularization, the likelihood of particle survival is increased. Moreover, as Yoshimura et al3 showed in their 2011 research, grafted fat particles larger than 2 mm in diameter will develop central fat necrosis.

**Fig. 2-1** The principle on which microfat grafting relies: Reducing the diameter of a sphere proportionally increases its contact surface.

According to Yoshimura, a fat particle exceeding 2 mm in diameter will show three zones of behavior after transplantation: (1) the external “surviving zone” of 100 to 300 µm, (2) a “regenerating zone” of 600 to 1200 µm, and (3) a central “necrosis zone” of all the fat tissue deeper than 1 mm in the particle. This means that any fat particle exceeding 2 mm in diameter will have a central necrosis zone.

Because fat graft survival becomes more predictable with the use of smaller fat particles, overcorrection is less necessary. Better fat survival also results in less fat necrosis and thus reduces inflammation and possible prolonged edema. This in turn reduces downtime and the risks of visible and palpable lumps, especially under the thin lower eyelid skin (Box 2-1).

Box 2-1 Benefits of Smaller Fat Graft Particles

Better survival

Less need for overcorrection

Reduced downtime

Less risk of visible and palpable lumps

Presently we harvest all fat with small 2 to 3 mm diameter cannulas with multiple sharpened 1 mm diameter holes. A direct relationship exists between the size of the holes in the cannula and the size of the harvested fat particles. For example, 1 mm holes will produce fat particles with a maximum diameter of 1 mm. The sharp edges of the holes enhance the harvesting yield by cutting any small particle, which is suctioned into the cannula. Without these sharpened holes, the aspirated material contains more liquid than fat. With the sharp holes the fat is literally grated out of the subcutaneous tissue. These cannulas are known as grater-type cannulas (Fig. 2-2).

**Fig. 2-2** Sharp “grater” or “Tonnard” cannula. The harvesting cannula consists of a sharp, multiport cannula that is 2.4 mm in diameter, with holes 1 mm in diameter. Note the sharp edges of the holes, which transform the cannula into a rasp, augmenting the harvesting yield of this small-holed cannula. (Courtesy Tulip Medical Products, San Diego, CA.)

Several companies produce liposuction cannulas with finer holes for harvesting smaller-diameter fat particles. Tulip Medical Products offers a Luer-Lok cannula that can be mounted on a Luer-Lok syringe (smaller-diameter cannulas) or a liposuction machine (larger-diameter cannulas).

These cannulas have sharpened edges on the small holes, so they act like a grater, augmenting the harvesting yield through the fine holes. We prefer 2 to 3 mm diameter cannulas with 1 mm diameter holes for fine fat particle harvesting. For larger-volume harvesting, a larger-diameter (3 mm) cannula can be chosen with the same multiple sharpened 1 mm holes at the tip.

Because more liquid is aspirated with fine, multihole cannulas than with larger holes, a total aspirated volume of about five times the estimated fat volume for injection into the facial areas should be obtained. With this method of harvesting, which resulted in smaller fat particles, we began to use smaller-diameter injection cannulas. Today we exclusively inject microfat through 0.7 to 0.9 mm diameter blunt-tipped cannulas.

These injection cannulas can only be used with fine fat harvested with the harvesting cannulas previously described, because larger particles will be difficult to pass through. Exerting too much force on the plunger of the syringe will produce accidental large blebs that will be delivered under the skin.

PATIENT EVALUATION AND SELECTION

Every aging face undergoes a degree of deflation. The individual′s aging pattern is analyzed by comparing the present appearance with photos taken between 20 and 35 years of age. The areas most commonly involved are the periorbital area (upper and lower eyelids, temples, and malar area) and the perioral area (nasolabial fold, upper and lower lips, and marionette groove). These subjects are covered in detail in Chapters 3 and 4.

INDICATIONS AND CONTRAINDICATIONS

Microfat grafting is now used in 95% of all facial rejuvenation treatments. We routinely use microfat grafting separately or in combination with surgical lifting procedures. Contraindications are the use of anticoagulant medication, smokers, cachectic patients, and all catabolic states.

PREOPERATIVE PLANNING AND PATIENT PREPARATION

Microfat grafting does not substantially prolong the morbidity and downtime of associated facial aesthetic procedures. Downtime after fat grafting is largely caused by an unnatural appearance resulting from overcorrection. The microfat system, however, results in very little graft resorption because of the better take of small particles. Therefore overcorrection is rarely indicated. This considerably reduces downtime after fat grafting compared with other methods. However, if the patient considers the result insufficient after the grafting has stabilized (approximately 4 months), a refill procedure can be proposed to the patient, which is performed using local anesthesia. In our practice this occurs in about 10% of facial fat grafting cases.

For 2 to 3 weeks after surgery, the face will look and feel unnatural. The patient may experience a tense feeling, especially in the malar areas and the lips, which will be less mobile. The surgeon must explain that these side effects are temporary and that patience is essential. Before surgery patients can be reassured by showing them clinical photographs reflecting the gradual resolution of the swelling and disfigurement.

Areas that will be grafted and donor sites are identified and explained to the patient. We usually select the infraumbilical region, the inner thighs, or the knee areas as donor sites, because these areas are easily accessible with the patient in the supine position. In very thin patients with no significant fat in these donor sites, the anterior thigh is a useful option. Considering that the surface of the palm of the hand is about 200 cm2, aspiration of a 1 mm layer of fat from this surface yields 20 cc of fat. From an average anterior thigh, a surgeon can easily harvest at least 60 to 100 cc per side.

MICROFAT TECHNIQUE

Anesthesia

The donor areas are infiltrated with a tumescent Klein solution containing 0.8% lidocaine and 1:1,000,000 epinephrine.

In the acceptor areas the anesthetic solution (Box 2-2) is the same as that used for minimal access cranial suspension (MACS) lift procedures; a diluted 0.3% lidocaine solution is used along with 1:650,000 epinephrine and 0.15% ropivacaine, which is a long-acting local anesthetic with very low cardiotoxicity. The epinephrine concentration of 1:650,000 produces effective local vasoconstriction without any systemic side effects, such as palpitations or hypertension. Adding 2 ml of 8.4% sodium bicarbonate increases the solution′s pH so that the infiltration is less painful and the acidity of the lidocaine is buffered. An acidic pH is suspected to increase adipocyte apoptosis. In contrast to the MACS lift solution, we do not add triamcinolone to prevent any negative effect on adipocyte survival.