Review: Proposed Methods to Improve the Survival of Adipose Tissue in Autologous Fat Grafting
In 2009, the American Society of Plastic Surgeons Task Force on Autologous Fat Grafting (AFG) determined that autologous fat grafting was a relatively safe procedure with a generally low rate of complications. In recent years, fat grafting has been used widely within the field of plastic surgery such as facial rejuvenation, hand rejuvenation, breast reconstruction and volume enhancement, treatment of skin photoaging, and correction of contour deformities.
In this article, we review the basic science of fat grafting, proposed methods offered to improve survival rate, engraftment, and reported outcomes of AFG procedures.
The most problematic and persevering issue in fat grafting is the unpredictable volume of retention of fat grafts after transplant. Over the course, studies have reported a wide range of reabsorption rates after transplantation. Albeit a portion of the variability is no doubt due to inconsistent methods of pre- and post-operative volume assessment used in various clinical studies reported, the absence of predictable volume retention is clearly a characteristic of AFG. A better understanding of the fat graft microenvironment in which engraftment happens is obviously critical to the improvement of clinical outcomes.
Harvest, Handling, and Grafting Technique
Numerous groups have attempted to determine the ideal methods and techniques for harvest, processing, and transplantation, however there is still no general consensus on the most effective technique. This is because AFG actually consists of a multiple individual steps from fat harvest, to graft preparation, to fat injection. Most of the component steps at each stage are likely to substantially affect survival of each small adipose tissue fragment, which constitutes the injected graft, thereby affecting the permanent graft volume.
Nevertheless, there is a significant body of knowledge concerning the factors known to affect graft viability and the engraftment process. These factors fall under:
Fat graft harvest methods
Fat graft processing methods
1) Fat Harvest Methods
In 2013, Fisher et al. investigated and compared fat harvest techniques using either suction-assisted liposuction or ultrasound-assisted liposuction used in AFG. In terms of graft retention and stromal vascular fraction (SVF) content, there was no significant difference between the 2 methods. And in 2014, this was reinforced by Chung et al, who reported no decrease in viability with ultrasound-assisted or suction-assisted liposuction; but when comparing suction-assisted liposuction with laser-assisted liposuction, they noted that laser-assisted liposuction reduced viability of graft material.
Another factor that was proposed as a point of variance in producing lipoaspirate graft material is the location of harvest. Many studies have investigated fat graft characteristics and AFG results based on harvest location but there was no significant effect on adipocyte viability or survival. In general, harvest location has not been determined to not be a significant factor in the outcomes of AFG procedures. This data is beneficial because it allows the surgeon more versatility to harvest based on tissue availability and patient aesthetic preferences without compromising the result.
2) Fat Processing Methods
Fisher et al. also compared 3 common processing techniques: filtration, cotton gauze rolling, and centrifugation. When grafted using the cotton gauze method, it was reported to have the highest volume retention compared with the other methods, with 70% retention. The filtration method retained 58% and the centrifugation method retained only 47%. Fisher et al. suggested that cotton-gauze was the preferred method for cosmetically sensitive parts of the body where less fat is required, but filtration and centrifugation were more practical options for large volumes.
3) Grafting Technique
Based on the literature, there isn’t any recommendation that can be made about the best grafting technique. Multiple individual studies have found different methods to be superior depending on the protocols used in each study.
However, there are common trends and observations reported across many studies. One in particular observed that grafts prepared using simple decantation contained the highest amount of viable adipocytes, but also the highest number of contaminants. Additionally, grafts prepared using centrifugation at a speed above 400 g have decreased viability of adipocytes.
To this date, fat grafting continues to increase in popularity with new indications and different technical modifications frequently reported. AFG helps augment and regenerate deficient, scarred, irradiated and aged subcutaneous soft tissue, and skin in a wide variety of clinical situations with low complication rates and low donor-site morbidity.
In any case, there is still no ideal technique that ensures maximum graft survival and predictability of lasting graft volume. At present, there is no consensus on the optimal AFG technique that produces the most predictable outcome for a given clinical situation.
However, based on the results of cell biology research and the long-term accumulation of objective patient data, we believe that a standard technique of fat grafting for a given clinical scenario will emerge.
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Sept 7-8, 2020
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