> Structural Fat Grafting

 

Lipostructure

 

 

 


Aging skin is characterized by decreased thickness, elasticity, and adherence to underlying tissue.

The dermis atrophies as loss of ground substance, elastic fibers, and collagen occurs. Sun exposure leads to distinct damage to the skin. Elastosis (ie, deposition of thickened, irregular, partially degraded elastic fibers in the dermis) is characteristic of sun damage.

Cigarette smoking, Posttraumatic scarring, acne, are other contributing factors. Repeated weight fluctuations can contribute to wrinkling. Genetics also play a role.


Older patients may present for correction of specific areas or for overall facial rejuvenation. The anatomic areas not addressed by traditional rhytidectomy, or facial resurfacing often are ideal for fat grafting. Patients of all ages may present for facial enhancement; lip augmentation is the most common request.

Although the popularity of fat transplantation is a relatively recent development in plastic surgery, the concept of fat transfer is not new. As early as 1893, free fat autografts were used to fill a soft tissue defect. The use of autogenous abdominal fat to correct deficits in the malar area and chin was reported in 1909. Throughout the early part of the 20th century, attempts were made to correct other conditions, including hemifacial atrophy and breast defects, but modern fat grafting did not develop until the early 1980s with the popularity of liposuction.

Illouz reported the transfer of liposuction aspirate fat in 1984. In 1986, Ellenbogen reported the use of free pearl fat autografts in a variety of atrophic and posttraumatic facial deficits. With refinements in technique, fat grafting has become the procedure of choice for an array of problems, including facial scarring, lip augmentation, and facial rhytides (such as several otherwise difficult-to-address areas such as the nasolabial fold and glabellar furrows).

Methods of addressing wrinkles and lines range from excision and redraping of excess skin to methods of skin resurfacing including dermabrasion, laser ablation, and chemical peels. Each of these modalities has limitations. Implantation of a filler substance into a deficient area is another solution. Whereas facial resurfacing can be thought of as razing the mountains, use of an implantable substance fills in the valleys. Many materials have been tried for the correction of soft tissue defects and deficits. However, the use of most of these substances has met with difficulties, including impermanence, foreign body reaction, unnatural texture, and possible disease transmission. In addition, most of the products currently available remain relatively expensive.

1. Silicone, has unfortunately resulted in spectacular failures. Small volumes of liquid silicone formerly were used as free injections. Defects intentionally were undercorrected, since the ongoing soft tissue reaction created additional volume. However, the reaction of the host tissue led to late complications including chronic edema, lymphadenopathy, scarring, skin ulceration, skin thinning and discoloration, and siliconomas.

2. Collagen currently is used widely. Available collagen consists of purified bovine collagen. Zyderm is 95% type I collagen and 5% type III collagen. The addition of glutaraldehyde cross-linking (Zyplast) slows resorption; however, the substance nonetheless eventually is degraded by the host. While collagen works well for the correction of fine lines, results for deeper furrows are less impressive. The major drawback to the use of collagen is the short duration of the response. Within 3-6 months the collagen is resorbed completely, and the improvement is lost. Also, because the collagen is bovine-derived, pretesting for an allergic response is required. The test spot should be observed for 1 full month prior to treatment.

3. Gore-Tex
(solid polytetrafluoroethylene) for facial plastic surgery was used in 1993. The result is generally predictable because the substance is nonreactive, but the resulting feel of the tissue is somewhat unnatural. The substance is rigid and is not available in an injectable form. In addition, infection remains a potential problem because the substance is a foreign body. Because this substance does not become integrated into the host tissue, it is generally easy to remove.

4. Sheets of human dermis (AlloDerm) are also available and produce a more natural result. Again, the form of this substance limits its use. Although it is derived from a human source and becomes revascularized by the host, it is not autogenous. Concerns about possible disease transmission have been expressed, although processing appears to control for this. A micronized form of human dermis has been available since 2000. While the semiliquid form of the substance gives it the versatility of collagen, the substance does not have the longevity of the sheet form. The major impediments to use of this substance remain the high cost and, although initially touted as a permanent solution, the substance is eventually degraded by the host.

5. Poly-L-lactic acid (PLLA) injectable has gained widespread popularity in Europe since its approval for cosmetic correction in 1999. PLLA is a synthetic polymer of lactic acid that is biodegradable, resorbable, and biocompatible. The large particle size of PLLA (40-63 µm) prevents it from being phagocytosed by macrophages, but it can still be used in needles as fine as 26–gauge (ga). The outcome in patients with a loss of facial volume and contours appears to be very good as judged by physicians and patients, with satisfaction rates reaching as high as 70% and 75%, respectively. One multicenter trial conducted by Laglenne and colleagues involving 110 patients reported minor adverse effects, with only 10% of patients experiencing nonspecific ecchymoses and no patients experiencing allergic reactions.However, others have reported many cases of granulomas and inflammatory reactions, which are difficult to treat.

6. Hyaluronic acid (HA) is a carbohydrate polymer and one of the major components of the extracellular matrix. It is found extensively in neural, connective and epithelial tissues. Although pure HA is not biocompatible with dermal tissues, the cross-linked form is biocompatible. Presentlyy no animal HA (Restylane), is commonly used.

Autologous Tissue
An ideal substance would be readily available, inexpensive, long-lasting, natural-feeling, and would not cause adverse immunologic reactions.

Several types of tissue can be transferred such as Fascia and dermis. Ideally, dermis can be harvested from the area of a previous incision, such as a cesarean delivery or abdominal scar, to avoid a new donor site defect. Strips of these tissues can be useful for larger areas and deeper defects but do not have the flexibility of a liquid or semiliquid substance.

Fat can be harvested through inconspicuous stab incisions. The harvesting does not leave a defect, and the removal of fat is often desirable. Fat tissue is soft and feels natural. It can be introduced to correct various deficiencies, it is not immunogenic, and it is readily available and inexpensive. Despite early views that fat is a relatively inert and isolated tissue, fat has been demonstrated to be a well-vascularized tissue with high metabolic activity. In addition to its structural role, fat tissue serves as a reservoir for energy storage. The number of fat cells generally is assumed to be stable after the completion of adolescent growth. Changes in the volume of fatty tissue relate to the size of the cells and their overall lipid content. Cells removed by liposuction or other surgical procedures do not regenerate. Cells shrink with overall weight loss and, in fact, may dedifferentiate. However, subsequent weight gain causes redifferentiation of the cells with an increase in volume.
 

Autologous fat transfer has been used for correction of

1. Facial scarring, postsurgical including acne scars.
2. Enhancement of facial volume also can be achieved for disease processes such as hemifacial atrophy.
3. Lip augmentation.
4. Signs of facial aging also can be improved. Rhytides that are too deep to be addressed by resurfacing modalities and areas poorly addressed by traditional lifting procedures (eg, nasolabial folds, glabellar creases, tear troughs) can be treated with grafted fat.


Primary Consultation
This procedure is performed in a hospital or well equipped centre under local or general anaethesia. An important part of the preoperative workup is an extensive discussion identifying areas to be treated. In addition, details of the procedure, postoperative care, expectations, and possible adverse outcomes will be discussed.

Photographic documentation is critical to planning and evaluation of this surgery. The patient should not wear makeup for preoperative or postoperative photographic documentation.

Contraindications for Fat Grafting
1. Poor wound healing and poor overall health status of the individual.
2. Contour abnormalities resulting from breast biopsy or for breast augmentation. The grafted fat can cause both palpable nodules and calcifications, situations that may hinder a diagnosis of breast cancer or cause unnecessary intervention.

The Operation
Almost any site can be used for harvesting; however, the abdomen is easily accessible, and stab incisions can be hidden within the umbilicus or in the hair-bearing skin of the pubic area.

First, carefully mark the recipient site with the patient's agreement while he or she is in the upright position.

The most important principle in the surgical management is the atraumatic transfer of fat. Trauma to fat in the process of harvesting or placing fat affects the survival of the graft. While a nonviable graft initially may appear to have corrected the problem, eventual resorption of the tissue negates the result. Any blood that remains in the harvested fat also facilitates rapid degradation of the transplanted lipograft. Sterilely prepare and drape both the harvest site and the recipient site.


Harvest
The technique is designed to harvest the fat in parcels of readily transferable size. Common donor sites include periumbilical, lumbar, and trochanteric areas; the thigh; and medial sites of the knee and arm.

Use local anesthesia to anesthetize the site for a small stab incision. Through this incision, use a long syringe to introduce tumescent fluid for anesthesia of the region. The same site serves as the access for harvesting. The choice of tumescent fluid varies. A standard solution consists of 1 mg of epinephrine, 200 mg of lidocaine, and 5 mEq of sodium bicarbonate in 1 L of normal saline. Dosages of lidocaine up to 35 mg/kg can be used for the tumescent technique, although substantially less is required for simple fat harvesting.

Following infiltration of the region to be harvested, an aspiration cannula is connected to a syringe. Alternatively, a 14-ga needle can be used, as this causes no reduction in survival of fat harvested. Suction is done manually. Small syringes are recommended to avoid creation of negative pressures greater than 1 atm.

For visible tarsal plates and tear-trough or nasojugal fold improvements, a combination of pearl fat grafting and sparse fat injection may provide optimal results. This technique uses small pearls (5-8 mm) excised from fat and placed in saline. These pearls are then stacked on top of each other through an incision in the depressed area. This technique is not useful for nasolabial folds, labiomandibular folds, or chin augmentation.

Transfer and purification
Once harvesting is complete, the aspirate then is transferred sterilely through multiple syringes using the tulip connections to 1-mL tuberculin syringes. The liquid fraction of the graft is gently washed free of oil, lidocaine, and blood with this transfer.

An alternative to gentle hand tipping is use of the centrifuge. The aspirate divides into 3 layers. The top layer is free oil from ruptured fat cells. This layer is decanted or blotted gently. The bottom layer contains variable amounts of tumescent fluid and blood and is drained. The middle layer consists of fat cells for grafting.

Five washes of lactated Ringer's solution rinses local anesthetic solution and blood from the fat. The aspirate is left to dry and the concentrated product is transferred to small syringes.

Placement
Regional nerve blocks are the most useful because adequate anesthesia can be provided without obscuring the defect to be treated.

The goal with any grafting procedure is to gently apply the graft to a well-vascularized bed to maximize graft take. Every part of the graft should be within 1.5 mm of living, vascularized tissue. If a large area is grafted, the central area, which is most removed from the blood supply, may not survive.

Creating small tracks for the grafts helps keep the grafted fat adherent to the recipient site.

The fat is injected with a needle or cannula superficially under the rhytid or scar in a controlled method while withdrawing. Slight overcorrection is important because some absorption of the liquid carrier occurs. Fat is grafted from the deep layer to the superficial layer.

Serial injection may be performed at 3-month intervals. Generally, 3 procedures should be anticipated. Even distribution of the injection is crucial. Excess bulk in a particular area may isolate the fat in the central region from the new blood supply.

Post operative Instructions

  • Discourage massage and excessive facial animation immediately following fat grafting. These restrictions are to prevent migration of fat away from the desired areas of treatment.

  • Compression dressings to prevent migration have been described; however, they are often difficult to maintain and probably add little to the final result. If the fat has been placed in an appropriate tunnel, minimal concern about migration should exist.

  • Ice compresses are applied for 24-48 hours to minimize inflammation.

  • Patients should be seen in the first week postoperatively to check the donor and recipient sites. Some edema and a minimal amount of bruising may be apparent.

  • An additional follow-up appointment should be made for approximately 6-8 weeks. At this point, most of the edema has subsided, and early results can be assessed.


If a repeat procedure is to be performed, a waiting period of 3 months is prudent to allow the first graft to revascularize and to allow any edema to resolve.

Risks and Potential Complications

  • The major complications of fat grafting are undercorrection and overcorrection.

  • Graft necrosis may cause palpable irregularities and eventual disappearance of the grafted material.

  • Graft migration is usually caused by infiltrating too much fat into a particular site.

  • When grafting scarred areas, the graft tends to move to the areas of least tension. Clumping of the graft also may occur.

  • Damage to underlying structures, particularly around the eye, is possible.

  • Prolonged edema is possible and troubling to the patient.

  • Superficial ecchymosis

  • Although rare, infections can occur wherever the skin envelope is violated.

  • Donor site scarring is a potential concern.