Despite the many off-the-shelf injectable fillers which currently exist, none of them can promise permanent results or complete biocompatibility and lack of any type of foreign-body reaction in everyone. Only one’s own fat, when done as an injection, can potentially fulfill those promises. But fat has another problem…..its survival after injection is unpredictable and it can not be injected very easily into small places or directly into the skin due to its irregular thick flow and the need for a large-bore needle from which it is introduced. But despite these drawbacks, the allure of fat as a filler material continues and its ample donor source (for most patients) perpetuates the mystique of a simple transfer from someplace undesired to a more desireable one.
There is no getting around the fact that fat injections are unpredictable. While there are some that blame a surgeon’s outcomes on their methods, an honest assessment of results will show that, even in the best of hands, the fate of fat transfer is not technique dependent alone. There is still much about fat biology that we do not know or understand. Many factors other than method of harvest and preparation influences its transplantation outcome including source, patient age, and the recipient site. It is naive to think that the important but relatively simple step of concentration after harvest is the dominant step that controls how much fat survives later. It is important for sure but it can be only one of the contributing factors. Much active research work is going on right now to study many of these other factors including how fat differs between donor sites and what other factors may be added to fat to improve its survival after injection.
The face is a fortunate site for fat injections in that the relatively small volumes needed have a better chance of survival. The smaller volume to surface area caused by linear injection patterns favors a quicker ingrowth of blood vessels which provides nourishment to traumatized and starving fat cells. As a result, fat does better in the face than any other bodily area. I currently strain all harvested fat and/or do a few minutes of centrifugation to get out most of the liquid debris and pack presumably good fat material into a syringe. Using 1cc syringes and a 16 gauge needle provides a relatively smooth outflow of fat into the desired facial areas.
One biologic approach that I am currently looking at is the addition of PRP or platelet-rich plasma to a fat graft concentrate. PRP is derived from the patient’s blood and is a spin down of concentrated platelets which can be easily added to any fat graft mixture. The dosing (amount of PRP) per fat graft that is necessary is unknown and must be studied further, but I am empirically using 1cc of PRP per 10cc of fat. Early results, particularly in the lips which can be easily followed and assessed, are promising.At the least, PRP is not harmful in any way as it is derived from each individual patient.
The conceptual allure and simplicity of the fat injection makes it a useful facial augmentation technique. It may not have guaranteed survival and is ideally a procedure best done in the operating room at the time of other more major interventions. The future will undoubtably make its use more widespread as a better understanding of fat biology is realized.
Dr. Barry Eppley
Indianapolis, Indiana