Current Fat Grafting Practices and Preferences: A Survey from Members of ISPRES

Background:

Fat grafting has established its niche in a wide spectrum of aesthetic and reconstructive procedures. A consensus-based method of harvest, processing, enrichment, injection, and assessment is lacking, despite the rising trends in its application. We conducted a survey among plastic surgeons to evaluate and identify trends of fat grafting practices.

Methods:

We conducted an electronic survey with a 30-item questionnaire of 62 members of the International Society of Plastic Regenerative Surgeons. We collected demographic information, techniques, and experiences related to large volume (100–200 ml) and small-volume (<100 ml) fat grafting.

Results:

The majority of the respondents worked predominantly as aesthetic surgeons. The donor area selection was based on the patient’s fat availability (59.7%). For fat enrichment, platelet-rich-plasma and adipose stem cells were routinely used by 12.9% and 9.7% of respondents, respectively. A 3- to 4-mm cannula with three holes was the most preferred instrument for large-volume fat harvesting (69.5%). For small-volume fat grafting, 2-mm cannulas (75.8%) with Mercedes tip (27.3%) were used most commonly. For processing, decantation of fat was performed by 56.5% of respondents (without exclusivity). For handheld injections (without exclusivity), respondents preferred a 1- to 2-mm cannula with a 1 cm³ syringe. The most popular method of outcome assessment was photographic evaluation.

Conclusions:

The respondents’ tendencies were similar to those reported in the previous literature, with some exceptions, such as the technique for preparing fat and enrichment. A wider cross-sectional survey, involving national delegates and global representatives of plastic surgeons, is anticipated.

Takeaways

Question: Fat grafting techniques used by global experts in regenerative medicine.

Findings: The 30-item online survey with members of the ISPRES showed their practices were similar to those reported in the previous literature, with some exceptions, such as the technique for preparing fat, enrichment, and choice of cannulas.

Meaning: In the absence of a global consensus on fat grafting, this study analyzed and revealed a trend among specialists from different countries.

INTRODUCTION

Autologous fat grafting, spun into the spotlight by Coleman in 1995, revolutionized plastic surgery practices.¹ Ever since its introduction, fat grafting has had an impactful application in a wide spectrum of plastic surgery procedures, ranging from and not limited to, craniofacial surgery, reconstructive breast surgery, aesthetic surgery, burn surgery, and regenerative medicine.^2-5 The expanding use of fat grafting can be ascribed to its favorable qualities such as availability, biocompatibility, cost effectiveness, and minimal donor site damage.⁶

Based on the volume requirements, fat grafting can be categorized into small-volume fat grafting (<100 ml, primarily for facial rejuvenation), large-volume fat grafting (100-200 ml, for breast and body contouring), and mega-volume fat grafting (>300 ml, for breast reconstruction and buttock augmentation).⁷

Despite the rising trends in application, a consensus-based practice method (harvest, processing, and injection) is yet to be developed. The absence of substantial supporting evidence that clearly shows the superiority of one approach over its counterparts is to account for this quandary.⁸ A summary of trends in fat grafting was published by an international expert consensus on breast fat grafting in 2019. However, due to a very small number of respondents, it could not be translated as a guide to clinical practice.⁹ Furthermore, the difficulty in assembling an acceptable panel of experts with adequate worldwide representation has a significant impact on the efforts to standardize fat grafting methods around the world.

In order to evaluate and identify the trends of fat grafting practices, we aimed to conduct and demonstrate results from a global survey among plastic surgeons on their practices and preferences in low and high-volume fat grafting techniques. This information will aid us in our future endeavors to conduct randomized multicentric trials on specific aspects of the most widely employed and trusted techniques in fat grafting.

METHODS

Following International Society of Plastic Regenerative Surgeons (ISPRES) board approval, a 30-item questionnaire online survey was designed for distribution to a randomized cohort of ISPRES members during July 2–16, 2021. Participation in the survey was voluntary, and participants could exit the survey without submitting their responses at any time. No participant compensation was provided. The questionnaire was created to gather demographic information, techniques, and experiences related to large volume fat grafting (100–200 ml) for the breast and body, as well as small-volume fat grafting (<100 ml) primarily for facial rejuvenation, depressed scars, hemi facial atrophy, regenerative approach, etc. A descriptive analysis (mean, frequency) was performed using SPSS software, v 26.0 (IBM, Armonk, N.Y.). (See appendix, Supplement Digital Content 1, which displays the survey questionnaire. http://links.lww.com/PRSGO/C435.) (See spreadsheet, Supplement Digital Content 2, which displays the master chart. http://links.lww.com/PRSGO/C436.)

RESULTS

The survey was completed by 62 ISPRES members, 93.5% of the participants were board-certified plastic surgeons. The mean age of the surveyed members was 53(±9.7 SD) years. The majority of the members (69.4%) work predominantly in aesthetic plastic surgery. (See table, Supplement Digital Content 3, which displays the respondent demographics. http://links.lww.com/PRSGO/C437.)

Experience with Large-volume Fat Grafting

Donor Site Selection

The most common choice of donor area was based on the patient’s fat availability (59.7%). In addition, 35.5% surgeons preferred the abdomen as the donor site, and only three (4.8%) preferred the patients to choose the donor area. Nevertheless, when asked which zones they prefer to remove fat, when possible, abdomen (88.7%) was the most common site, followed by flanks (62.9%). (See table, Supplement Digital Content 4, which displays large volume fat grafting survey results. http://links.lww.com/PRSGO/C438.)

Fat Grafting Harvesting Infiltration Solution, Harvesting Instrument, and Technique

The most common infiltration solutions used in high volume fat transfers were 3:1 ratio tumescent solution (41.9%), successively followed by super wet solution (40.3%) and wet solution [100–300 ml of liquid (with or without epinephrine) at each site to be treated; (14.5%)].

Most respondents chose multiple options for the preferred cannula size, tip, holes and method used for fat harvest. The most common instrument preferred for large-volume fat harvesting were 3- to 4-mm cannula (69.5%). Respondents’ preference of type of cannula tip and holes for fat harvest in large-volume procedures were the three-hole standard cannulas. Handheld suction (59.7%) was the most preferred fat harvest method followed by vacuum machine suction (46.8%.)

Fat Graft Processing

Following fat harvest, 56.5% (n = 35) of the respondents (without exclusivity) performed decantation of fat, whereas 43.5% performed centrifugation. Routine addition of PRP (platelet-rich plasma) and adipose stem cells have been reported by 12.9% and 9.7% respondents, respectively. Furthermore, 13 respondents report using additional processing steps to isolate, prepare and store adipose stem cells (Fig. 1).

Fig. 1.

Percentage of routine addition of PRP, adipose stem cells, or others.

Fat Injection

For handheld injections (without exclusivity), respondents prefer 1- to 2-mm cannula with 1 cm³ syringe (58.1%), closely followed by 1- to 2-mm cannula with 10 cm³ syringe (56.4%).

Assessment of Outcome

Outcome assessment of fat graft survival using preoperative and postoperative picture evaluation (59.7%) was most commonly practiced, followed by clinical assessment (21%) of fat graft survival by the surgeon. Only 14.5% of participants had their fat survival assessment using preoperative and postoperative 3D images (Fig. 2).

Fig. 2.

Percentage of employment of fat reabsorption assessment modalities in respondent population.

Fat Transfer in Cosmetic Breast Augmentation and Application of Pre-expansion Devices for Breast Augmentation

The most commonly preferred plane for fat injection in cosmetic breast augmentation were gland and subcutaneous tissue. Only 8.1% (n = 5) of respondents routinely use pre-expansion devices for breast augmentation before fat grafting.

Experience with Small-volume Fat Grafting

The majority (53.3%) of the responders performed none or less than 25% of the small volume fat grafts under general anesthesia. More than half of the small volume fat grafting procedures were performed under general anesthesia by 29% of the surgeons. However, only 8% of practitioners performed all procedures under anesthesia (Table 1).

Table 1.

Low Volume Fat Grafting Survey Results

Low Volume Fat Grafting
Variables	No. (%)
Preferred method of harvest for fat grafting
Handheld suction	43 (69.5)
Vacuum machine suction	11 (17.7)
Low pressure pump assisted	2 (3.2)
Ultrasonic assisted harvest	2 (3.2)
Laser-assisted harvest	1 (1.6)
Others	3 (4.8)
Favorite harvesting technique
Cannulas 1 mm	12 (19.5)
Cannulas 2 mm	47 (75.8)
Micro cannula	10 (16.1)
Spring with wide bore needle	3 (4.8)
Preferred type of cannula tip and holes
12 hole	16 (25.8)
Basket	3 (4.8)
Candy cane	1 (1.6)
Mercedes	17(27.4)
One hole standard	14 (22.6)
Spatula	2 (3.2)
Three hole standard	14 (22.7)
Toledo	1 (1.6)
Two hole standard	14 (22.6)
Preferred processing technique
Decantation	31 (50)
Centrifugation	29 (46.8)
Filtration	10 (16.1)
Wash and filter with closed sterile devices	7 (11.3)
Wash and filter	2 (3.2)
No processing/direct fat injection	2 (3.2)
Roll of gauze	1 (1.6)
Others	5 (8)
Favourite facial fat injection method
Handheld syringe/cannula	61 (98.4)
Ratchet gun	1 (1.6)
Instrument preference for handheld injection
Cannulas 1–2 mm	54 (87.1)
18–23G needle	6 (9.7)
14G needle	2 (3.2)

The most common instrument preference for low volume setting fat harvest was reported to be 2-mm cannula (75.8%). The most preferred cannula tip and holes for fat harvest was Mercedes (27.4%), closely followed by 12 holes (25.8%). Handheld suction (69.5%) was the most preferred fat harvest method.

The majority (50%) still prefer decantation for fat processing, whereas 46.8% prefer centrifugation. For injection of fat, 87.1% of respondents prefer 1- to 2-mm cannulas. Handheld syringes/cannulas were the preferred device by all the surgeons for facial fat injection, except for one respondent who reported preferring ratchet guns over other modalities for fat injection. The trends have been summarized in Table 2.

Table 2.

ISPRES Trends in Fat Grafting

ISPRES Trends in Fat Grafting
Donor site selection	Patient’s fat availability
Infiltration solutions	3:1 ratio; tumescent solution
Cannulas	3- to 4-mm cannulas three-hole standard
Harvest method	Handheld suction
Graft processing	Decantation
Fat injection	to 2-mm cannula 1 cm3 syringe
Assessment of outcome	Preoperative and postoperative picture

DISCUSSION

Autologous fat transplantation has positively impacted plastic surgeons’ ability to perform surgical restoration in a smart and bio-reliable manner.¹⁰ Despite being used in clinical practice for two and half decades, there is a lack of a standardized methodology. Recent developments in adipose cellular biology have brought the debate about fat grafting uniformity to the forefront. This can be attributed to the nonfeasibility of automatic translation of experimental and animal studies data for human application.¹¹

Our survey received responses from 62 of the 213 active members of the International Society of Regenerative Plastic Surgeons. Although the response rate was low, it was scientifically significant because membership in the society requires a high level of knowledge in fat transfer and regenerative medicine. To become a member of ISPRES, candidates must be actively practicing plastic surgeons who have completed their degree training in an accredited institution and have demonstrated an interest in regenerative plastic surgery (to the satisfaction of the executive committee).

A national survey in the United States by Kling et al in 2013 received 456 responses and provided valuable information on fat grafting practices. However, it was not specific to expert fat grafting practitioners and was geographically biased, being restricted to a single country.¹² In 2019, Nava et al conducted an expert consensus; however, the number of experts in this study was limited to only 16. Our survey has nearly four times the number of respondents.¹³

In body contouring procedures, appropriate donor site selection for fat harvest is of unequivocal importance to produce satisfactory outcomes all the while maintaining a desirable overall contour with minimal donor site morbidity in terms of both cosmesis and functionality.⁷ The results of our survey are in conjunction with reports in the current literature suggesting abdomen, gluteal region, inner knee, and the flanks to be amongst the most common fat harvest locations.⁸ Furthermore, equal adipocyte viability among abdomen, thigh, flank and knee donor locations is observed when fat is immediately removed and untreated.^14,15 These findings encourage surgeons to harvest fat based on maximum anatomical availability, thereby reducing donor-site morbidity as observed in the trends in our survey.¹⁶

The literature provides conflicting evidence on the relationship between donor site infiltration before fat harvest and adipocyte cellular biology.¹⁷ Additionally, reports conclude that pre-harvest infiltration may cause only temporary alterations in the adipocyte cellular process with no substantial effect on the long-term viability of fat.^18,19 The aforementioned evidence justifies the practice consensus observed in our respondent population on the infiltration used. Both super wet and tumescent solutions, widely used by respondents of this survey, have been documented in the literature to reduce blood loss 1% to 2% of the aspirated volume.²⁰

Reports in current literature fail to provide consensus on optimal cannula diameter for fat transfer procedures. Erdim et al demonstrated greater adipocyte viability when a 6 mm cannula is used when compared with its smaller counterparts (2 and 4 mm).²¹ Similarly, Kirkham et al demonstrated increased histological integrity, less immune infiltration, and fibrosis incidences in fat grafts obtained using a larger cannula (5 mm) when compared with a 3-mm cannula.²² On comparing 2-mm and 3-mm cannulas, Rubino et al concluded that using the latter enhanced adipocyte density.²³ Furthermore, a prospective study by Ozsoy and colleagues demonstrated the greater number of viable adipocytes can be obtained when a 4-mm cannula is used instead of 2- to 3-mm cannulas.²⁴ In 2018 James et al demonstrated that 14G cannulas can leave centers of necrosis, thus suggesting smaller cannulas or smaller volumes per pass.²⁵ The higher preference for 3- to 4-mm cannulas seen in our survey results can be attributed to the existing evidence demonstrating enhanced cell viability when larger diameter cannulas are used. Although the consensus on cannula size still remains nonexistent, it is well acknowledged in the current literature that a cannula should be large enough to avoid shear stress and appropriate to preserve adipocytes and SVF cells.^22–24

Exhaustive contradictory debate on various fat preparation protocols have been evidenced in the current literature.^19,26–29 Filtration demonstrates no difference in fat survival, despite shortcoming in techniques, like incidence of smaller fat grafts post-centrifugation and nodule formation when no treatment, centrifugation, normal saline wash, lactated Ringer solution and a combination of centrifugation and various washes were employed as preparatory methods pre-injection.^19,30 Adipose tissue processing trends in our respondent population show varied use, which prevents drawing conclusions. Interestingly, although centrifugation is considered the most popular processing method, most of our respondents preferred decantation in both small and large volume transfer probably because it has been shown to exhibit better lipotransfer effects (volume retention) when compared with centrifugation.³¹ The absence of strong objective data and discord between experimental and patient-based study results fail to derive a consensus regarding the best method.

Using breast pre-expansion devices for aesthetic breast augmentation increases adipocyte survival.¹⁹ Its advantage can be attributed to increase in angiogenesis and decrease in ischemia due to tissue compression. According to Del Vecchio and colleagues, mega-volume fat grafting to the breast is a reliable technique, but the gross variability in outcomes largely depends on the type of breasts, which can be the reason only 6.4% of our respondents’ population use it in their practice.³²

The addition of PRP to fat grafting has been validated as a fruitful means of reducing adipocyte graft resorption.^33–36 Regardless of the emergence of supporting evidence, only 12.8% of our respondents add PRP to fat grafting. This minor proportion can be attributed to a lack of standardization, primarily due to a lack of evidence indicating the best method of collecting PRP.

Variability in patient composition and anecdotal evidence contradict its use in oncological sites.³³ Additional reports based on a recent clinical trial assessing the effectiveness of PRP’s utility in facial rejuvenation suggest that adding PRP to adipose stem-cell–enriched fat can lead to increased inflammation and undesirable vascular changes.³⁷ On the other hand, the addition of adipose-derived stem cells to fat grafting has been documented to minimize fat atrophy and increase vascularization.³⁴ Kølle et al’s study comparing groups receiving fat grafts enhanced with adipose derived stem cells and nonenriched fat grafts elucidated higher fat graft retention when compared with the controls.³⁸

Despite these promising results, our findings show reluctance to use the aforementioned enrichment modality (only 13% of respondents use adipose-derived stem cells) due to the possibility of an exaggerated pre-clinical feasibility demonstration complicating the translation of the methodology in clinical settings.

According to reports in the literature on trends in autologous fat transfer, there is a lack of agreement on an assessment modality to monitor fat viability after transplant.¹⁸ This is reflected in our survey results, as respondents use a variety of assessment tools, with the majority using preoperative and postoperative pictures (59.7%), general clinical assessment (21%), and 3D imaging comparison (preoperatively and postoperatively) (14.5%). Interestingly, we could observe three respondents using nonspecific forms of personalized patient questionnaires as a fat grafting outcome assessment tool, highlighting the possibility of holistically enhancing fat grafting surveillance by incorporating patient perspective evaluation in the existing graphical-based assessment modalities. It is worth mentioning that one of the study’s limitations is the lack of information on when the fat surveillance assessment is done during the postoperative follow-up.

In this study, we found that most surgeons prefer not to use general anesthesia when transferring a small volume of fat. Regarding the use of cannulas, it was observed that the majority use small cannulas (<2 mm), which is reflected in the current literature.³⁹

Despite the advancements in fat transfer, there is still no reliable method of maintaining 100% fat retention yet, but the current research is based on the idea that fat survival is best when it is close to a blood supply. Fat is thought to survive within 2 mm of an arterial supply, but fat placed beyond that distance will necrotize and leave only scar tissue.²⁹ There is some variation in cannula size and other alternative techniques that are thought to improve graft success. In our survey, for injection, 87.1% respondents preferred 1- to 2-mm cannulas, and handheld syringe/cannula was the preferred device by all for facial fat injection. Many authors have described using a 14-gauge blunt tip or curved microcannula for injection, whereas others have used a 2- to 3-mm cannula for reinjection.^{21,24,28,40,41}

The autologous fat grafting trends demonstrated in our study provide empirical evidence of lack of best-approach consensus. Furthermore, the authors anticipate multi-institutional comparative studies to address the lack of standardization in fat grafting approach protocols followed by a conference consensus panel to establish a global best-approach protocol based on superior supporting literature produced through future studies.

CONCLUSIONS

Evidence-based studies incorporating randomized controlled, prospective, multicenter trials are imperative to understand which variables influence positive fat grafting clinical outcomes. Our research shows preliminary findings analyzing the current practices and preferences of the ISPRES community. The respondents’ tendencies were similar to the previous literature, with some exceptions, such as the technique for preparing fat and enrichment, as well as the disparity in responses in the use of cannulas. A cross-sectional survey study of a wider scope, involving national delegates and global representatives of plastic surgeons is anticipated.

ACKNOWLEDGMENTS

The study did not involve any patient related data, and thus was exempted from IRB approval. This project would not have been possible without the support and guidance of all the ISPRES board members. In particular, we would especially like to thank Nelson Piccolo, Brian Kinney, Ewa Siolo, Peter J. Rubin, Alexandra Condé-Green, Valerio Cervelli, Riccardo Mazzola, Patrick Tonnard, Norbert Pallua, Dae-Hyun Lew, Feng Lu, and Aris Sterodimas. Finally, we would like to thank Jaqueline Luna, who has been integral to this study in distributing and collating the survey forms.

Supplementary Material

gox-11-e4849-s001.pdf ^{(148.2KB, pdf)}

gox-11-e4849-s002.xlsx ^{(148KB, xlsx)}

gox-11-e4849-s003.pdf ^{(25.5KB, pdf)}

gox-11-e4849-s004.pdf ^{(35.9KB, pdf)}