How Is Injection Fat Grafting Done And How Long Does It Last?
Q: Dr. Eppley, I am a freelance writer working on an assignment for a medical aesthetics magazine and I could use your input. The topic is fat transfer procedures; specifically, techniques and longevity. Here are the questions I’d like to ask:
 In general, how is fat harvested? What type of equipment is used?
 How is fat then prepared for injection? Which components of it are used? What type of equipment is used?
 What specific injection techniques are used? Do any of the techniques pose greater risks to the patient? Do any of them generally produce better results?
 How long can patients expect the results to last? Does that vary by patient? By technique used?
 Are certain patients more likely to experience bad results? Are some patients riskier than others? How important is patient selection in ensuring best results and least risk?
 Any other comments?
A: Injectable fat grafting is both a reconstructive and cosmetic technique in plastic surgery that is undergoing widespread acceptance and use. While fat grafting has been around for 75 years, the ability to place it with an injectable approach and the generous amounts that most people have and its easy accessibility has made it into a standard modern-day plastic surgery technique. Just because fat is natural and most everyone would love to give some up, however, does not necessarily make injectable fat grafting a completely reliable treatment method. It is important to understand that the biologic behavior of fat cells and the concomitant stem cells that accompany them is not well understood. Fat grafting is equal art as science in current practice and that should be borne in mind when its techniques are discussed. They are based on what we know today…that will likely change significantly a decade from now.
- Fat is harvested using liposuction techniques. Most believe that low pressure vacuum extraction preserves fat cell structures and improves their viability after transfer. Whether this is syringe extraction or a traditional machine that generates less than -20cc of water pressure depends on how much fat is needed.
- The preparation of lipoaspirated-fat grafts has seen the greatest number of techniques currently used, all of which strive to separate the liquid fractions (blood, free lipids, injectate) from the cellular component. This include straining and washing, free-standing decanting, machine centrifugation, hand-held separation using centripetal force and low pressure forced straining using low micron filters. Much debate surrounds which, if any, of these offers a superior number of viable fat cells for transfer.
- Fat grafts are injected using small-bore blunt cannulas ranging in size from 16 gauge to 26 gauge size (comparative injection needle sizes) connected to luer-lok syringes of 1 to 3cc sizes for the face and 10cc to 60cc size for body areas. Placing the fat grafts in small aliquots (0.1cc for the face and .5cc to 2ccs for the body) is well shown to allow their best survival. Retention is all about how quickly the fat cells can be nourished by blood vessel ingrowth and the delivery of oxygen. Big globs of fat are hard to get perfused while small droplets interspersed about the tissues allows the best opportunity for nutrient perfusion.
- The retention of fat grafts, both short and long-term, is not a completely well-known issue. It is believed and considerable experience shows that what survives by three months after injection treatment is what will be ‘permanent’. (retained) Whether this same fat survives 5 or 10 years later is not precisely known and depends on what specific condition is being treated. Aging-related treatments are believed to be less permanent than those of structural rebuilding.
- All other factors being equal, there are no ‘bad’ patients for fat injections. Some of the historic predisposing factors for plastic surgery treatments that bode poorly for healing, such as radiation and even diabetes, are exactly what some of the indications are for fat imjections. Age is an interesting potential issue because one would assume that older fat cells are less hardy, survive the transfer process with less viability and would take after transfer more poorly. This assumption, however, has yet to be shown to be true. This may more of a reflection that older patients (> 65 years old) make up a minority of the fat injected population.
- What was once thought to be a useless and unwanted tissue has ironically turned out to be a depot of regenerative material. Plastic surgery has just scratched the surface of what injection fat grafting has to offer and a whole new generation of research and clinical experience will take us much further than what we know today.
Dr. Barry Eppley