Introduction

Autologous fat grafting is a well-established technique that is practiced by many plastic surgeons. Fat cell abundance and ease of harvesting make fat grafting a logical choice for soft tissue defect restoration and augmentation. The technique of fat grafting varies from surgeon to surgeon, and there are no standardized harvesting, preparation and injection techniques.

The current popularity of fat grafting, in many ways, is because of the work done by Dr. Sydney Coleman. He popularized the technique for harvesting the fat using a handheld syringe and centrifuging for compaction.¹

The need for large volume fat harvesting and injection could not be met by the current techniques due to the length of time needed to harvest fat and centrifuge the fat. The average time for harvesting, processing and injecting fat by the Coleman technique is 100 cm³ of fat in 1 hour.²

History of Fat Grafting

The history of fat grafting goes back to 1893 when Neuber used it for facial defects.³ In 1895, Czerney used fat grafting for chest wall deformity post mastectomy.⁴ The early experimentation with fat grafting was not popular because, at a time when little was known about tumescent liposuction, most fat harvesting was performed by excision. The use of tumescent liposuction has given us the ability to harvest large amounts of fat with minimal donor site morbidity.

In 1987, Mel Bircoll published his work on fat grafting to the breast.^5,6 The shortcomings of his work were poor long-term follow-up and a lack of mammographic studies as indicated by letters to the editor from 1987.⁷ American Society of Plastic Surgeons (ASPS) published a position paper in 1987 “Deploring the use of fat injection in breast augmentation” due to the fear of interference with breast cancer detection.⁸ The main concern at that time was that calcification from necrotic fat would cause interference with breast tissue evaluation by mammogram. At the same time published papers stated that surgical procedures such as breast reduction,^9,10 augmentation^11,12 and any breast procedure can also cause calcification. Further studies indicated that calcification from fat necrosis is easily distinguished from breast cancer calcification.^13–20

There was a long gap before any work was published on fat grafting to the breast. Dr. Coleman published his work on fat grafting to the breasts in 2007. His results were remarkable and showed long-term survival of the injected fat.²

In 2007, ASPS and The American Society for Aesthetic plastic surgery (ASAPS) jointly and strongly supported the ongoing research efforts that would improve the safety and efficacy of the procedure²¹ but also cautioned against fat grafting for breast augmentation.

The future of fat grafting depends on the establishment of a standardized harvesting, processing, injection technique, long-term follow up for safety and efficacy, and also establishment of a data base for all the fat grafting patients.

Principle of Low Pressure Fat Harvesting

Handheld syringe aspiration is accepted as a gentler technique for fat harvesting. There are no published data to support this claim. We at LSU division of Plastic and Reconstructive Surgery undertook the study to find out the negative pressure that is generated by handheld syringes and liposuction machines. The graph in Fig. 7.1 shows the in-situ maximum pressure within the 1, 3, 5, 10, 30 and 60 cc syringes. Negative pressures were measured in vitro and in situ with 1, 2, 3, and 10  cc pull on a 10 cc Luer-Lock syringe as well as a conventional liposuction machine at 254 mmHg, 381 mmHg, and 762 mmHg (Figs 7.1, 7.2, and 7.3).

FIG. 7.1 The graph shows the in-situ maximum pressure within the 1, 3, 5, 10, 30, and 60 cm³ syringes.

FIG. 7.2 The graph shows the negative pressure produced in a 10  cm³ syringe to be as high as 660 mmHg with full pull and 280 mmHg with only 1  cm³ pull on the 10  cm³ syringe.

FIG. 7.3 Negative pressure measurements for liposuction machine at different setting in situ.

The graph in Fig. 7.2 shows the negative pressure produced in a 10 cc syringe to be as high as 660 mmHg with full pull and 280 mmHg with only 1 cc pull on the 10 cc syringe.

The constant negative pressure at the low setting (254 mmHg) by a liposuction machine is 220 mmHg. This is less than the negative pressure in a 10 cc syringe only pulled back 1 cm³. Most liposuction machines have a control for adjusting the negative pressure.

In order to evaluate the extent of damage to fat cell caused by all harvesting techniques, lipoaspirant samples were analyzed using lactate dehydrogenase (LDH) and triglyceride levels (Fig. 7.4). Glucose-3-phosphodiesterase (G3PD) assay was used to measure cell viability (Fig. 7.5). LDH and triglyceride are intracellular components and their presence in the aspiration fluid indicates cell damage and cell wall disruption. The results suggests that the samples harvested with the low negative pressure liposuction machine were lower in LDH and triglycerides. The G3PD assay suggests cell viabilities were high in samples from the low-pressure liposuction machine in comparison to the handheld syringe, which indicates more viable cells by the low pressure technique.

FIG. 7.4 Basis of fat grafting – biochemical markers.

FIG. 7.5 Assessment of viability – G3PD activity.

Harvested fat cells were stained with fluorescent dyes for imaging using scanning electron and confocal laser electron microscopes (Fig. 7.6). The slides show the outer cell layers bursting from the negative pressure.

FIG. 7.6 Basis of fat grafting – microscopic analysis.

FIG 7.6 APPEARS ONLINE ONLY

The low-pressure liposuction method removes the human factor and variation of the pull on the syringe and provides consistent negative pressure that helps to decrease operating room time and also prevents the surgeon’s hand fatigue. This technique yields large volumes of fat in a short period of time and minimizes the damage to the fat cells.

Autologous Fat Grafting to the Breast

In June 2008 at Louisiana State University Health Science Center in New Orleans, we started an IRB approved study on fat grafting to the breast. So far we have had more than 276 patients in this study and collection of the data has started for the follow up studies. Currently, fat grafting to the breast is a treatment option in conditions such as micromastia, breast ptosis, post mastectomy breast reconstruction, asymmetric breast, congenital malformation of the breast, and for treatment of complications associated with implant augmentation mammoplasty.

Technique

Harvesting

Local Infiltration

The solution that is used is 20 cm³ of lidocaine 1% with epinephrine, plus 2 cm³ epinephrine 1/1000 in 1 liter of lactated Ringer. The volume of tumescence is 10–20% more than the aspirate. It is imperative to wait 20 min. post infiltration to maximize vasoconstriction and minimize blood loss.

Cannulae

A blunt 5 mm Mercedes tip cannula is used for harvesting the fat. The common belief is that a large cannula will damage the donor site, but our experience with large cannulae has been the opposite. The other belief is that a large cannula will produce large particles of fat, which will make it hard to reinject with a small cannula (11 gauge) but our experience also has been contrary to current belief.

Fat Cell Preparation

The process of centrifugation increases the risk of contamination and cell damage. One advantage of centrifugation is to compact the fat cells. Another advantage of centrifugation is the ability to separate damaged cells from intact cells. Centrifugation at a low speed for a short period (100 g/30 s) will give the same compaction as a higher speed and longer period (1400 g/3 min). Refer to Fig. 7.7. The other observation is the lack of oil on the top of the syringe with low pressure fat harvesting. This observation is consistent with our study showing that the fat cells harvested by low pressure are damaged less, and less oil leaks out.

FIG. 7.7 The picture shows the lack of free oil on the top after centrifugation at 100 g and 1500 g.

The drawback of not centrifuging the fat is overestimation of the amount of actual injected fat. We adjust the actual injected fat by 20% to correct for this if we do not centrifuge the fat before injection.

Fat Injection

After the fat has been decanted, the fluid in the bottom of the jar is discarded and the fat cells transferred to 30 cm³ syringes and then from 30 cm³ to 10 cm³ syringes with a male-to-male connecter. Fat cells are then injected in a multilayer technique while withdrawing. Each 10 cm³ syringe will require at least five to seven passes to finish. The cannula for injection is an 11 gauge blunt tip single-side port cannula. A double-sided port causes trapping of the ligaments and clogging. Injection is started in the submuscular plane, then at the subcutaneous layer and finally, the subglandular planes.

FIG. 7.8 For patients with saline implants the implants are deflated under local anesthesia 2 weeks before the planned surgery to give the tissue time to contract.

Postoperative Care

In our practice the recovery from fat grafting is fast and much less painful than with implant breast augmentation. Most patients complain more about the donor site than the breast pain. There is usually swelling that resolves in a few weeks. The breast volume will finalize at 3 months post injection. Massaging of the breast is discouraged during the first few days to prevent pooling of the fat.

A preoperative mammogram, 3D imaging and photographs are obtained on all patients as well as a postoperative mammogram and 3D imaging a year after the surgery. Patients follow the American Cancer Society guidelines for follow up breast cancer screening.

Our experience with patient satisfaction has centered around long-term volume retention. Most patients are concerned about the loss of volume. The use of 3D imaging, patient education and also consistent photographic documentation is a must. Patients emphasizing the size rather than the quality of the result are not good candidates for fat grafting.