What is fat grafting (or fat transfer)?
Fat grafting is a process by where fat is taken from one part of the body and transferred to another part. An example is fat grafting is seen in facial rejuvenation or buttock augmentation.
Where is the fat taken from?
The removal of fat is called harvesting. The site where the fat is harvested is called the donor site. While fat is distributed all over the body, there are certain areas that are probably better donor sites than others. The love handles and abdomen are generally the sites most often used. Fat here appears to be in abundance, even in men and women who are thin. The fat in this area tends to be the hardiest, and it is thought that “tough” fat in this area may translate into better incorporation and longevity.
How is the fat taken (harvested)?
Fat is aspirated through a very small incision placed in an area that is hidden easily such as the hip or inside the belly button. From this incision, a small cannula is tunneled under the skin and moved back and forth. The cannula breaks up the fat. Attached to the end of the cannula is a syringe that serves as a collection tube. The syringe generates negative pressure and acts like a mini vacuum.
Does taking fat leave a dent or divot?
For facial fat grafting and other low volume areas it shouldn’t. The amount of fat needed for transfer is relatively small. Considering that liposuction of the love handles can range up to 600 cc of fat, the 30 to 80 cc of fat harvested for grafting is almost inconsequential when it comes to leaving an impression. That is, the fat that is harvested for grafting and transfer won’t be enough to make a visible difference at the donor site. When we graft areas like the buttock or breast, we take fat from multiple sites and in high volumes as part of a liposuction procedure. Thus, in those cases we expect (and want) there to be visible fat depletion at donor sites.
How much fat is harvested for grafting?
The amount of fat harvested ultimately depends on how much fat is needed. How much fat one needs to correct an area of deficiency, of course, depends on the area one is correcting. Grafting can range from a few cc’s to hundreds off cc’s. As a rule, the face will often receive between 20 cc and 80 cc of fat. The buttock for augmentation (Brazillian Butt Lift) generally receives anywhere between 100 and 500 cc of fat. The breast may receive anywhere between 10 cc to correct rippling to several hundred cc for augmentation.
How much fat survives the transfer process?
It depends. Unfortunately, there is no hard and fast set number that any one doctor can quote. There are so many variables at play, so the best one can do is come up with a range. The amount of fat that is retained after fat grafting generally ranges from 20 percent to 60 percent.
What factors determine fat “take” and survivability?
From harvest to injection, fat cells are vulnerable to death. For fat cells to survive a transfer, they must be collected and injected properly. The amount of pressure generated to aspirate fat must be great enough to collect the fat, but not so great it damages the integrity of the cells. Collecting 100 cc of dead fat won’t help anyone. Thus, technique is an important component of fat grafting “take”. Once fat is collected, it can be processed or not processed. Processing can ranges from centrifuge to adding growth factors and stem cells to simply allowing the fat to be strained. All of these may offer some advantages (and disadvantages). And again, adding growth factors of stem cells to fat that was collected improperly doesn’t make a lot of sense. Not processing fat refers to taking the fat that was harvested and injecting this right from the harvest syringe into a donor site.
Once fat is collected, it must be injected relatively soon. If fat is collected in the beginning of a liposuction case and injected into the buttock at the end of the liposuction case, there may be some fat cell death depending on the time interval between harvest and injection. In addition, if the fat is going to sit around after a harvest, how is it preserved? Cooling fat offers some advantages to cell viability over room temperature.
How is the fat injected? The size of the injection cannula, syringe, and location of fat donor site all play roles in fat survivability. If the cannula is too small the trauma from fat injection through a small opening can damage cells. If the cannula opening is too large then too much fat may be injected into any one area resulting in fat cell crowding. Since every single fat cell needs its own blood supply, crowded injections will result in cell death.
Thus, there are so many variables when it comes to fat grafting that it is impossible to give straight percentages when it comes to fat “take”. The last factor one must consider is donor site. Areas that already have native fat (cheeks, breasts, buttocks) will inevitably have a higher fat grafting survivability than areas that don’t have much native fat (lips, temples). In areas that have little to no native fat, often overcorrection is the rule. When one “overcorrects”, more fat is preferentially placed anticipating a larger percentage of cell death.
What are risks of fat grafting?
Harvest site risks include bruising, pain, contour deformity, and infection. Contour deformity is rare because the fat collected for grafting is from deep layers of fat. In thin people, more than one donor site is often used to reduce or eliminate a contour irregularity. Infection at donor site is exceptionally rare.
Risks associated with the recipient site include bruising, swelling, and infection. Infections of the face from fat grafting are exceptionally rare as the face is very vascular. Breast and buttock infections are also rare, but more common than face infections. Contour irregularities and “hard lumps and bumps” in experienced hands are very uncommon. If fat is injected in proper cannulas at appropriate depth, the risk of any visible irregularities is very, very rare. If they do occur, they are often correctible in experienced hands.
Does adding stem cells or growth factors help “take”?
More important than the addition of stem cells and growth factors is technique of harvest and injection. Theoretically, it would make sense that the addition of growth factors (PRP) or stem cells would offer an advantage to survivability and longevity of results. However, there really isn’t any good evidence to support this idea. Stem cell addition and PRP might add time to the procedure (and cost) but at probably no added benefit to results. Until more science is collected, stem cell addition to fat grafting mainly offers only theoretical advantages assuming that the extra steps don’t interfere with cell viability given the delicate nature of fat cells.
How long does fat grafting last?
Forever and never. Because not all cells live, the “take” varies. However, of the fat that does survive, it will last up to forever. If the fat cells integrate and become part of one’s body as is the goal of fat transfer, then the results are permanent for those cells.
What is downtime for fat grafting?
Downtime for fat grafting is generally cosmetic in nature. It’s a surface operation. Fat is injected in the tissues below skin and above any major organ or vessel. Thus, the time needed off work is strictly related to how one feels about the swelling and bruising.
For face: Large amount of swelling and possible bruising for 7 days. Residual mild swelling for another week or two.
For breasts and buttock: Mild to moderate swelling for up to 7 days.