Everything You Need to Know About Fat Transfer Procedures

I personally do not do many small volume fat transfers as in my opinion for small volumes the hyaluronic acid fillers do the job so much better. However, if needed, small volumes of fat can be injected into areas such as the face and the back of the hands.

What is so good about fat transfers?

There are several benefits of large volume fat transfers when compared to prosthetic (silicone) implant procedures such as breast augmentation or buttocks enhancement (the so-called “Brazilian butt lift”).

1. The recovery time is much faster: Fat transfer is done by injection so no large cuts are needed in the recipient area. 
2. It feels natural: Breast or buttock augmentation with prosthesis needs getting used to. Some patients can take months, or even years, to get used to the sensation of the implants. If there is not enough fat over the implants, they will also feel like an implant! 
3. It looks natural: Prosthetic breast augmentation or buttock implants can often look unnatural. 
4. It does not need to be replaced: Prosthetic breast implants often need to be replaced after a period of time.
5. There is no risk of hardening: Prosthetic breast implants can become encapsulated with scar tissue forming around the implant which makes them feel very hard and they will need to be replaced. 
6. There is no risk of rupture: Prosthetic breast implants can in rare cases rupture if there is a weakness in the product. The hard impact such as during a car accident can also cause prosthetic breast implants to rupture. 
7. Minimal or undetectable scars: As fat transfers do not require big cuts there is usually no visible scar in the recipient areas. 
8. Safer: Fat transfer procedures can be done under local anaesthetic so the inherent dangers associated with general anaesthetic can be avoided. 
9. Breastfeeding: There is a risk that breast surgery and the use of prosthetic implants can impact the ability and success of breastfeeding post-procedure, depending on the exact surgical techniques used, as far as I know, there is no study about the impact on breastfeeding following fat transfer to the area.

The second biggest problem with fat transfers is that the final results cannot be guaranteed. Not all the fat that is transferred will survive the procedure, and some will just be reabsorbed by the body.

From my own experience, this can vary from about 15% to 85% survival rate.

The average is about 60% to 70% fat survival rate. Therefore to compensate for this, I tend to overfill the area, knowing that the final result will be smaller. The fat cells that survive the transfer should last a lifetime.

In fact, over the years after the procedure, as the patient puts on weight, the volume in the recipient’s areas will get larger too.

Other potential downsides to fat transfer include infection, fat embolism, asymmetry and fat cyst formation. The risk of infection can be mitigated by using sterile or clean techniques and antibiotics prophylaxis.

Using blunt cannulas instead of sharp needles for the fat injection will almost eliminate the risk of fat embolism. Asymmetry is not common in large volume fat transfers.

However, if this does happen it can be corrected by further fat transfers. If fat cysts happen to form they will need to be drained.

In my opinion, for the best survival of the fat, the following are some principles that might help:

1. Use liposuction methods that cause the least trauma to the extracted fat cells: Laser-assisted liposuction and ultrasound-assisted liposuction methods might be too traumatic for the fat cells. Pure Tumescent Liposuction in my opinion causes the least trauma to the fat cells. Using low suction power will also cause less damage to the fat cells.
2. Avoid overprocessing the fat: Centrifugation with a high setting will kill the fat cells (5).
3. Transfer the fat as soon as possible: Avoid doing unnecessary large liposuction procedures if the main purpose is for fat transfer. The longer the fat is out of the body the more likely it will not survive. 
4. Inject the fat in multiple layers (into fat and muscles) and in tunnels: Injecting the fat in one area and creating a pool of fat will make it harder for the fat cells to establish a blood supply and can cause fat necrosis (cell death) and fat cysts. 
5. Advise the patient to avoid putting pressure on the recipient areas for about 3 weeks: High pressure might kill the fat cells. Avoid tight brassieres after fat transfer to the breasts and avoid sitting down after fat transfer to the buttocks. 

Summary

In my opinion fat transfer or fat grafting is a safe and effective way to create a large volume of fat in areas that need it. However, more studies are needed to establish the best practice to get the best results for the patients.

^{References:
1. Asilian A, Siadat AH, Iraji R. Comparison of fat maintenance in the face with centrifuge versus filtered and washed fat. J Res Med Sci. 2014 Jun;19(6):556-61.
2. Davis K, Rasko Y, Oni G, Bills J, Geissler P, Kenkel JM. Comparison of adipocyte viability and fat graft survival in an animal model using a new tissue liquefaction liposuction device vs standard Coleman method for harvesting. Aesthet Surg J. 2013 Nov 1;33(8):1175-85
3.  Smith P, Adams WP Jr, Lipschitz AH, Chau B, Sorokin E, et al. Autologous human fat grafting: effect of harvesting and preparation techniques on adipocyte graft survival. Plast Reconstr Surg. 2006 May;117(6): 1836-44.
4. Gupta R, Brace M, Taylor SM, Bezuhly M, Hong P. In search of the optimal processing for fat grafting. J Craniofac Surg. 2015 Jan;26(1):94-9.
5. Gerth DJ, King B, Rabach L, Glasgold RA, Glasgold MJ. Long-term volumetric retention of autologous fat grafting processed with closed-membrane filtration. Aesthet Surg J. 2014 Sept:34(7):985-94}