Chapter 4 Fat Grafting
Chapter 4: Fat Grafting
Kenneth B. Hughes, M.D.
Division of Plastic and Reconstructive Surgery
Beth Israel Deaconess Medical Center
Harvard Medical School
Structural fat grafting is used to enhance contour in virtually any area amenable to grafting and the indications are continually expanding. The first and most common indication for structural fat grafting is breast reconstruction defects. With the increased popularity of fillers for facial augmentation, fat grafting for facial augmentation has been due to plentiful nature of filler material available and decreased cost, particularly for larger volume needs or as an adjunctive measure in facelifts.
Other common indications include fat grafting for buttock augmentation, breast augmentation, and hand rejuvenation. It has been also received recent attention for volume restoration in acquired or congenital conditions such as HIV lipodystrophy, Parry-Romberg syndrome, and craniofacial microsomia.
As with many liposuction procedures, the choice for anesthesia is largely dictated by amount of tissue to be harvested, number of harvest sites, as well as the number of areas to be augmented and the volume to be instilled. Some minor revisions can be performed under local anesthesia alone. Tumescent anesthesia may allow donor site surface area to be increased. However, there is a theoretical concern of disruption of fatty tissue and concomitant decreased survival with these methods.
In addition, the manner of liposuction and technique utilized should be considered. Removal through smaller volume Luer-Lok syringes is theoretically less traumatic to the fat and less painful to the patient as compared to fat harvest through traditional suction cannulae with much greater suction pressures.
Details of Procedure
Typical donor sites for fat grafting include the abdomen and thighs. They are convenient access points in the supine position as breast reconstruction defects and facial augmentation are the most common indications. This also permits a two team approach in which one can harvest, while another can inject. However, almost any site with readily accessible fat will serve as an adequate donor site.
Incisions for access should be placed in relaxed skin tension lines, skin creases, previous scars, striae, or hirsute areas. Although, creating the most optimal contour in donor areas, particularly in large volume aspiration, should be the guiding principle. Avoidance of contour deformities should trump the concern over the addition of small incisions.
A common approach to fat harvesting utilizes blunt-tipped Coleman cannulae applied to Luer-Lok syringes. Some surgeons prefer 10 ml syringes (Coleman), but others opt for larger syringes due to faster harvest times. Once the fat is harvested, the specimen is centrifuged and separated to create the fat sample to be injected for augmentation. 10 ml syringes centrifuged at 3000 RPM for 3 minutes is a typical protocol observed by Coleman. After separation by centrifugation, the top layer contains oil, the middle layer contains viable fat, and the bottom layer contains other more dense liquid materials, primarily the local infiltrate. Decanting after gravity sedimentation is another variant for creation of an appropriate specimen for injection.
Once the harvested fast is prepared, fat injection can be performed with 1 ml syringes for face and hand injections due to need for precision. 3 ml syringes may be more appropriate for breast reconstruction defects or buttock augmentation.
However, the volume to be injected into an area should be the guide. An HIV lipodystrophy patient who may require 40 ml of fat augmentation to one side of his face may be more efficiently augmented with 3ml syringes initially followed by 1 ml syringes for final refinements. More important, large volumetric amounts injected in a single pass should be discouraged as this leads to greater fat necrosis, greater potential for infection, and poorer graft survival. The gauge of the cannulae to be introduced for fat grafting in the face should be in the 18 gauge range, though eyelids may require smaller bore cannulae.
The principles of placement as articulated by Coleman center around the concept that harvested fat must be positioned so that the greatest surface area of contact between it and host tissue is created. This is done to encourage as much diffusion, oxygen exchange, and nutrient exchange as can be obtained.
Blunt tip cannulae are usually used and fat is injected upon withdrawal. Coleman recommends 0.1 ml maximum volume per pass to minimize potential for irregularities and maximize surface contact with host tissue.
Fat is much harder to shape with digital manipulation than many of the filler agents. As such, precise placement is recommended.
These procedures can produce a considerable recovery period of 1 to 2 weeks, which may be longer than most patients expect. The persistent swelling associated with these injections is greater than that associated with Botox or conventional filler treatments to which many patients are accustomed. As such, patients should be educated about convalescence time.
Most common complications include surface irregularities due to errors in technique, migration, and patient healing characteristics.
Fat necrosis, infection and abscess formation are more prevalent in single, large volume fat injections.
Microcalcifications after fat grafting for breast augmentation may lead to greater numbers of biopsies and unnecessary surgical procedures due to difficulties in mammographic interpretation.
Fat embolus may be avoided by epinephrine injection into the area to be augmented as well as the use of the use of blunt cannulae.
Sharper cannulae may be more appropriate for freeing adhesions and augmenting scarred or fibrous beds, but these cannulae still carry greater inherent risk to surrounding structures.
Most important in structural fat grafting is Coleman’s principle that fat must be positioned so as to ensure the greatest surface area of contact between it and host tissue. Small volumes injected upon cannula withdrawal through multiple passes minimize the potential for irregularities and complications and maximize graft survival.
Click on the links below to view a few of the chapters written by Dr. Hughes
Chapter 2: Photography in Plastic Surgery
Chapter 3: Facelift
Chapter 4: Fat Grafting
Chapter 5: Fillers
Chapter 6: The Role of Dermal Matrices in Breast Augmentation
Chapter 7: Scar Revision in Plastic Surgery