Fat grafting by injection is an ever expanding technique in plastic surgery. But it remains far from a perfect method because so little of the science of fat transplantation is well understood. What happens to the fat cells that are injected, do stem cells really survive and convert to fat cells after injection and what is the best method for ensuring survival of both fat and stem cells? These are the major clinical issues of interest. In lieu of not yet understanding the science, the most practiced technique is to overfill…knowing that some percentage of the transplanted fat will not survive and be resorbed.

While fat grafting has few complications, other than an occasional infection, the variability of take remains a vexing one. For some problems, injecting fat is done because it is simpler than other volumetric methods and because it is natural and not an implant. It is generally agreed, whether it is on the face or the body, that small volumes of injected fat survive better than larger volumes. This is believed to be so because the fat is closer to a blood supply to re-establish nourishment sooner but also because it is being asked to do less. Larger injected volumes presumably resorb more because many of the cells are more distant from a blood supply and have a longer period of oxygen deprivation.

A simple technique to one element of the hypoxia problem is to have the shortest time between harvest and injection with the shorter the better. Get the fat and stem cells back into normal body temperature near a blood supply as soon as possible. If fat can be harvested and injected in less than 30 minutes, it would be logical that there is a greater potential for more volume survival.

There are considerable biologic differences between the face and body recipient sites for fat grafting. The face is considerably more vascular and the injected volumes are comparatively smaller. But much of the face has considerable movement and this does not appear to have a favorable effect.

By and large, larger volumes of injected fat are limited to the breast and buttocks and are well known to have significant volume survival issues. But these two body sites are significantly different. Breast injections are done into breast tissue only while buttock injections are also placed into gluteal muscle as well as subcutaneous fat. This is why fat injection breast augmentation has been shown to work best with pre-expansion of the breast tissue prior to fat injections. Using an external vacuum that pulls on the breast tissue, it prepares the recipient bed tissues. This appears to have a stimulatory cellular effect through fibroblast growth and neovascularization. This is useful because fat does not work well to significantly ‘push’ tissues outward or expand them. It does not act like a synthetic implant. Compression on fat grafts induces resorption and cell death.

The buttocks, therefore, poses a conundrum. There is no known method of pre-expansion of the buttock tissues and patients usually have to immediately sit on them afterwards compressing the injectate. The saving grace may be that some of what is injected is placed intramuscular which has the best chance of rapid revascularization. But buttock augmentation by fat remains the one area where overfilling is not just advised but routinuely done.

Over the past ten years, a considerable amount of laboratory and clinical research has been done by plastic surgeons in many aspects of fat grafting. From techniques in harvesting, purification and injection to the assessment of potential recipient sites, some basic biologic behaviors have been revealed. Fat is not like food as leftovers is not appealing. Freshly harvested fat has been shown to survive much better than frozen fat. While it is tempting to save and refrigerate for later use with large volume extractions, it simply doesn’t do well. Fat grafting also appears to work better in younger than older patients. At what age fat survival is adversely affected is not clear but suffice it to say there would be an expected difference between a teenager and a 70 year-old. An overfilling technique should be more reserved for older patients.

Dr. Barry Eppley

Indianapolis, Indiana   

Injectable fat grafting is one of the newer plastic surgery techniques. While it was first done in humans as early as the 1950s, it has gained tremendous popularity in this decade for  a variety of face and body procedures. Liposuction certainly accounts for one of the reasons fat grafting has become popular as we have looked at and discarded suctioned fat for decades. While it is a natural filling material to use, much of the science as to what happens after its transplantation is not fully known. There remain many purported claims as to its benefits, some of which are certainly true. But it is far from a perfected technique and many questions about it remain to be answered.

Patients have many questions about fat grafting and here are some of the most common that I hear in my Indianapolis plastic surgery practice and from the internet.

Where can fat grafting be performed in the body?

The beauty of injectable fat grafting is that it can easily be placed anywhere and is the safest implantable ‘material’ that we know. Therefore, any body area that needs more volume or tissue fill can be injected providing the recipient is healthy tissue with a normal blood supply.

Where do you get the fat to inject?

Fat can be harvested by liposuction anywhere there is an undesired amount. The site chosen must have enough fat for the area to be injected. In general, the amount of fat needed for the face is usually small while that for the body (buttocks) is fairly large. Therefore the abdomen is a universal site for any application. The only area that would be excluded from harvesting is previous liposuction-treated areas which would be scarred with poor quality fat.

One area of active research is to determine if certain body sites have better quality fat for grafting. (i.e., Will some types of fat survive better after being injected/) There is no solid scientific evidence to date that one harvest site is better than another.  

 Does fat grafting work well for any area and how much fat can be expected to survive?

These two questions from any patient’s standpoint are the most important. We do know that not all body areas respond as well to fat grafting as others. On the face, the lips and laugh lines respond the poorest and often may eventually lose all injected volume. The rest of the face will usually have fat that will take at least 50%. The buttocks is the only body site currently where large fat volumes are placed.  Ultimate survival can be anywhere from 30% to 80%. Complete survival of all injected volume does not usually occur anywhere.

Can I have my fat frozen and used later for additional sessions?

No. While fat storage and thawing reuse can be done, it has been shown that it will completely reabsorb after grafting. In addition, the chance of infection is increased.

Can I use a friend’s or relatives fat for injection?

Fat like all of our body’s tissues are very specific for each person. Your body will reject it and get infected if anyone else’s fat is used. Tissue matching is not an option for fat grafting currently.

How does the fat survive after it is transplanted?

Fat cells are very delicate and fragile and only loosely connected to their blood supply. The cells are harvested, prepared, and then injected into the treatment site in many small criss-crossed tunnels. The fat cells survive and keep their volume if and when the new blood vessels grow in to feed them. It is a race between having them get hooked back up to a nourishing blood supply and the cells dying due to lack of nutrition. 

What special methods are used to prepare the fat?

Fat grafting remains a bit of an alchemy approach. But the one consistent preparation step is the concentration of the fat and removal as much as possible of any extraneous fluids. What it is mixed with after varies by surgeon preference. Most will not mix it with anything else and put it directly into syringes for injection. Others may use antibiotics or even insulin. In some cases, I will use PRP (platelet-rich plasma) as a natural ‘supercharging’ treatment as it is loaded with high concentrations of growth factors which may be helpful in nourishing the fat cells and getting them an early ingrowth of blood vessels.

How is the fat injected?

Fat is injected and transplanted using the micro-grafting technique. This means using very small cannulas. This is so very thin tunnels will be created with fat filling these tunnels. The fat tunnels are at different levels, and cross through the area to be augmented. Together, these will allow the best opportunity to have the new blood supply grow in.

How long does fat grafting take to perform?

Depending on the areas to harvest and to graft, it can be as little as 1 hour for the face. If it is a larger area like the buttocks with liposuction the procedure usually takes 2 to 3 hours.

What is the recovery time for fat grafting?

It depends on the areas and the size to be treated and where the fat is harvested. In face grafting you feel fine right away, just look very swollen for days to weeks. For buttock grafting, after about 2 days most patients feel good enough to walk around and slowly get back to their normal activities. There is not much swelling. I do not restrict patients from sitting afterwards

Dr. Barry Eppley

http://www.eppleyplasticsurgery.com

http://www.ologyspa.com

Clarian North Medical Center, Carmel, Indiana

Clarian West Medical Center, Avon, Indiana

Indianapolis

A smaller lower face has been shown to be more attractive and youthful looking. Recent research (at the University of Texas - Southwestern and published in Plastic and Reconstructive Surgery 2008 by Dr. Joel Pessa) has shown that, as we age, the lower jaw continues to grow more so than the rest of the face. Therefore, there is a change in the shape of the face as we get older that in some patients makes it less attractive. These bony changes combined with the loss of facial fat as one ages accentuates the appearance of age. A youthful face is full which is lost as we age, particularly around the eyes and cheeks. These bone and fat changes make the cheeks more sallow and give the impression, with the development of jowling, that the chin is bigger.

 
Understanding these aging changes provides direction as to how to approach facial rejuvenation surgery in the aging patient. While you can’t make the jaw smaller, you can make it appear smaller by augmentation of the cheek and midface areas. This can be done with either fat grafts or cheek implants. Which one is best must be individualized for each patient. Cheek implants or submalar (under the cheek) implants can help lift a sagging midface as well as provide better cheek projection. If malar crescents (sagging skin from the lower eyelid hanging on the cheek) are significant, then a midface lift may also be done with a lower blepharoplasty to work out the excess skin as well.

 
The lower face and jowling still relies on the ‘traditional’ facelift approach with the objective of eliminating the jowling and tightening up loose neck skin. This effect, combined with cheek volume restoration, helps make the face look younger by changing the disproportions caused by aging.
In the younger patient with early signs of facial aging, injectable facial fillers can be an effective non-surgical approach in the cheek area. When these fillers become more long lasting or even permanent, we will see more of these patients seeking these treatments earlier before the negative facial effects of aging become too noticeable.

 
Dr. Barry Eppley
http://www.eppleyplasticsurgery.com
http://www.ologyspa.com
Clarian North Medical Center, Carmel, Indiana
Clarian West Medical Center, Avon, Indiana
Indianapolis

Enhancement of the buttocks is most consistently done with a gluteal implant. Despite its predictable improvement in the size and shape of the buttocks, buttock implants are not without complications. Intramuscular implant placement makes recovery more uncomfortable and having to sit on the implant predisposes it to positional shifting and the formation of fluid collections and possible infection.

 
Because of these concerns, the alternative treatment of fat injections or free fat grafting has emerged. Fat grafting to the buttocks has numerous potential advantages such as the elimination of the need for a synthetic implant, the use of a patient’s own body tissues, an easier recovery with few limitations, a simultaneous benefit of cosmetic emhancement of the donor site, and a very low risk of bleeding or infection. All of these advantages of free fat fat grafting is counterbalanced by one significant disadvantage….an unpredictability of after surgery shape and size. How much fat survives and is retained is widely variable. No plastic surgeon can guarantee or predict with 100% accuracy how much fat will survive on a consistent basis. I prefer to inject no more than about 300cc per buttock as I think much volume than that results in greater volume loss.

 
The burning question through the past several decades is…how to make fat grafting work better. The injection technique is, of course, important but is only half of the answer. How the fat is prepared after harvest in the oeprating room is the other half. Everyone agrees that concentration is very important after harvest. This is the mechanical process of removing the liquids from the more solid fat components. Whether this is done by a centrifuge or passing the fat aspirate through a strainer or sieve are two methods of which one has not been proven to be better than the other. Additives to the fat are theoretically appealing but there is no universal magical additive. Currently, I add platelet-rich plasma (PRP) to the concentrated fat prior to injection. Whether this aids fat survival is not proven but since it is a product of the patient, there is no risk in so doing. PRP is a concentrate of a patient’s own blood done at the time of surgery. While there is no standardized amount of PRP to add to fat, I typically use 3cc of PRP per buttock graft site.

 
If a patient opts for buttock augmentation with fat injections, they must accept that the amount of fat that will survive is unpredictable. It may require more than one injection session to obtain the best result. Most fat grafting methods will not achieve the degree of volume enhancement that a gluteal implant will.

 
Dr. Barry Eppley
http://www.eppleyplasticsurgery.com
http://www.ologyspa.com
Clarian North Medical Center, Carmel, Indiana
Clarian West Medical Center, Avon, Indiana
Indianapolis

 Despite the more recent public awareness of fat removal by liposuction and fat injections for volume addition in the past 20 years, the use of fat in plastic surgery has been around for over 50 years. The history of liposuction dates back to the early 20th century with the famous first case of unsuccessful liposuction in a ballerina who subsequently lost her leg. Necessary improvements in liposuction techniques made it an everyday procedure in the United States by the mid-1980s. Fat transfer or transplantation work by the famous plastic surgeon Dr Peer in the 1950s started by establishing that big pieces of fat don’t survive as well as small ones. The important concept of the need for blood vessels to grow into the transplanted fat as fast as possible for survival was established by this first experimental work.

As we sit here today, what do we know about fat transplantation? Certain aspects of fat transfer do work well and have been used for years. The ‘old’ dermal-fat graft, while completely unknown to the public in general, is still a reliable method for correcting small contour problems or acting as an interface to thicken up some areas. Its problem is that it results in a scar from the harvest (must take skin and a thin layer of fat) so this is only good if you already have a scar somewhere or the scar is more ‘tolerable’ if the procedure is being done for reconstructive purposes rather than purely cosmetic. Small whole pieces of fat can work well but you have to again get the ‘chunks’ from somewhere (scars) and you then have to get it in where you need it. (possibly more scars?) So, these whole fat grafting methods can reliably work but their uses are more limited due to scarring.

Fat injections today remain, by far, more widely done than whole fat methods because they cause little if any scarring and their placement can be more precise……even if they do not work as well. Despite what is frequently touted, fat injections are unpredictable in how much actually ‘takes’. That is why overcorrection is always done. Why do they not always work well? The harvest of the fat, through liposuction, dices it into many minute pieces and kills some of the fat cells. Therefore, what is injected is some portion of liquid fat that will simply be resorbed. While we strain the fat obtained by liposuction, and this helps get rid of loose liquid and blood, and makes it more ‘concentrated’,  there still is ‘dead’ fat in the concentrate. What we have not mastered, yet, is how to make those fat cells that survive this hazardous journey grow in their new home, rather than merely survive.

Recent scientific work and interest has been in the awareness that stem cells, which in theory can grow into any type tissue, are in great numbers in fat tissue. Why do these not grow after being injected with fat into more fat? Perhaps we have just not found the right trigger yet….whether it be a drug to mix with it or the type of fat injected.

The beauty of fat injections, despite their unpredictability, is that they are generally safe, easy to do (in the operating room), and the availability is plentiful in most patients. As plastic surgeons, we will continue to work with fat and I am confident one day we will turn it into a more reliable soft tissue filler.

Dr. Barry Eppley

http://www.eppleyplasticsurgery.com

http://www.ologyspa.com

Clarian North Medical Center, Carmel, Indiana

Clarian West Medical Center, Avon, Indiana

Indianapolis