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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