Safety and Effectiveness of Single Session Mega Volume Fat Grafting for Breast Augmentation: A Space-Creating Concept and Clinical Experiences

Abstract

Background

The main drawback of fat transfer breast augmentation is the need for multiple sessions of fat injection. For approximately 15 years, stem cells and the Brava device for breast expansion have been discussed and extensively investigated to address relevant challenges. However, the safety and effectiveness of autologous fat transfer as a single-session primary breast augmentation technique has not yet been standardized.

Objectives

The aim of this study was to achieve mega volume fat breast augmentation in a single session by developing a “space-creating” approach that emphasizes the use of highly purified fat to achieve an optimized surgical outcome with large-volume breast augmentation.

Methods

Female patients who underwent aesthetic breast augmentation (October 2013-October 2020) involving the application of this space-creating technique for mega volume autologous fat transfer were retrospectively enrolled. Inclusion criteria were patients with hypomastia, breast asymmetry, and volume replacement following implant removal with BMI ≥18.5 kg/m². After macrospace creation, highly purified fat was injected in several rounds during the procedure. A breast massage was performed between each stage (microspace creation). Breast circumference, nipple–inframammary fold distance, and cup size were recorded during 6 months of follow-up.

Results

Three hundred fifty-eight patients met the inclusion criteria. Average fat injection volumes of 510.9 mL in the right breast and 490.8 mL in the left breast resulted in at least a 2 cup size increase. The significant outcome remained stable at 6 months after surgery.

Conclusions

The space-creating technique and the injection of highly purified fat achieves stable cosmetic outcomes of mega volume breast augmentation in a single session.

Level of Evidence: 4

See the Commentaries on this article here and here.

The main drawback of fat transfer breast augmentation is the need for multiple sessions of fat injection. Breast augmentation has remained one of the most popular aesthetic surgical procedures worldwide for more than 10 years. Although the American Society of Plastic Surgery (ASPS) initially warned that fat-grafting procedures could interfere with breast cancer screening,¹ the ASPS Fat Graft Task Force revised this position in 2009, stating that fat grafting may be used for breasts.²

The major concerns for fat grafting are fat necrosis, oil cyst formation, unpredictable reabsorption rates, and limited augmentation potential. Several studies have reported that fat grafting cannot enlarge the breast by more than 250 mL in 1 session,³ whereas others have concluded that the technique delivers a substantial improvement in appearance and feel relative to implants but may be more suitable for patients who want a maximum increase of approximately 1 cup size.⁴

For approximately 15 years, the use of stem cells and Brava for breast expansion has discussed and extensively investigated to address challenges in achieving fat retention rates and increasing fat injection space. The evolution of this procedure over time has resulted in several variations and refinements of relevant surgical techniques, with the results varying depending on the surgeon’s technique and expertise. How best to achieve safety and efficacy in the use of autologous fat transfer as a single-session breast augmentation technique still needs be determined.

We have developed a “space-creating” technique which we use in combination with highly purified fat to achieve single-session mega volume fat grafting to the breast. A detailed description of the surgical technique is presented, and its efficacy is discussed based on our 8-year clinical experience with the use of this procedure for breast augmentation.

METHODS

We retrospectively enrolled female patients who underwent aesthetic breast augmentation (between 2013 October and 2020 October) with the space-creating technique for mega volume (more than 300 mL) autologous fat transfer. Inclusion criteria for surgery were hypomastia, breast ptosis Grade 1 and 2, required volume replacement after implant removal, or breast asymmetry with BMI ≥18.5 kg/m². Breast reconstruction after mastectomy, severely constricted or tuberous breast deformity, Poland’s syndrome, transgender and BMI ≤18.5 kg/m² patients were excluded. Patients with uncontrolled diabetes mellitus, systemic infections, or conditions requiring anticoagulation therapy were also excluded from the present study. The demographic and clinical data collected comprised age, BMI, amount of fat harvested, amount of purified fat injected per breast, and postoperative complications. Preoperative and postoperative breast ultrasound imaging were performed for routine screening and follow-up. In some cases, patients were willing to undergo MRI for a better preoperative and postoperative evaluation despite the higher expense. Standard preoperative and postoperative photographs were taken (frontal and lateral views). Written consent was provided, by which the patients agreed to the use and analysis of their data. The study was conducted according to the ethical principles outlined in the Declaration of Helsinki as amended in 1964.

Fat Harvesting

Prior to treatment, areas of redundant adipose tissue were marked with the patient in the upright position. The donor site was chosen depending on the volume of adipose tissue required and the fat storage distribution of the patient (the thighs, abdomen, and flanks are the most common sites). The medial and lateral borders and inframammary fold of the breast were preoperatively marked, after which new lines were drawn 1 to 2 cm from the original markings to establish new breast borders. All procedures were performed under general anesthesia plus local infiltration with tumescent solution. A customized 5-mm blunt-edged, 3-hole cannula was used with a conventional liposuction aspirator set to low negative pressure (<400 mmHg) to minimize trauma to aspirated adipocytes.

Fat Purification and Processing

The aspirated adipose tissue was centrifuged at 3000 rpm for 3 minutes according to the Coleman protocol,⁵ and a filter was used to remove the undesired tumescent fraction, oil, and cellular debris. The mechanical processing technique involved passing the fat to and fro between 2 syringes connected by a Luer lock in order to break up the purified and condensed fat to produce smaller fat pellets for injection into the recipient site.

Space Creation and Fat Application

A 5-mm incision was made at the newly marked inframammary fold (1-2 cm below the original), and all dissections were performed through the incision. A sharp V-shaped tip dissector cannula was used to release fibrous bands at the original medial border, lateral border, and inframammary fold. Subsequently, a 10G round-end tapered cannula was used to create multiple small tunnels with back-and-forth motions in the subglandular and subcutaneous planes. We refer to this procedure as the “macrospace creation” procedure. Due to the characteristics of the Asian breast (thin overlying skin), approximately 20% to 30% of grafted fat was injected into the subcutaneous space, and 70% to 80% into the subglandular space, the pectoralis muscle, or in the retromuscular space. From an anatomic point of view, the rest (70%-80%) of the fat is being injected to the subglandular space. However, it is difficult to determine the precise amount of fat injected in different layers by palpation during the surgery. From our experience, injections into the subglandular area, pectoralis major, and subpectoral space produce no differences in surgical outcome. The injections commenced in the subglandular space; between 150 and 200 mL of grafted fat were injected with a 12G blunt-tip cannula into the subglandular space, the pectoralis muscle, and/or the retromuscular space. Following the first round of injection, the breast tissue became congested and slightly tight, and a breast massage was performed for 3 to 5 minutes to promote rearrangement of the injected fat—this is the “microspace creation” process. The breast was massaged in a circular pattern, using the palm slowly and firmly to press any uneven fat bumps under the subcutaneous layer. Then the breast was gently compressed with four fingers and the palm to promote rearrangement of the injected fat and achieve a softness that closely resembles the normal breast. This procedure enhances the diffusion and distribution of fat in the microspace, enabling subsequent fat injections to be performed. Typically, 2 or 3 rounds of fat grafting and intraoperative massage are required to achieve increased volume of breast fat by 2 cup sizes in the subglandular space. Finally, between 100 and 150 mL of fat was injected into the subcutaneous plane, an additional massage was performed, and finally a 2-layer closure of the incision was performed. A final massage was then performed until the breast exhibited adequate softness and contour (see Video, available online at www.aestheticsurgeryjournal.com, which demonstrates the process of fat injection and microspace creation).

Video.

Watch now at http://academic.oup.com/asj/article-lookup/doi/10.1093/asj/sjac024

Postoperative Care

Surgical tape was tightly applied along the breast’s 4 borders (with particular emphasis on the new inframammary fold) for 2 days to prevent margin displacement and shape distortions. Daily underwear usage is recommended after removing the tape. During the postoperative period, compression garments were used for the lipoaspirated areas, and patients were given home care instructions to perform breast massages by lying on a firm mattress in prone position, using the patient's body weight to give pressure to the whole breast and then transferring weight from one side of the breast to the other from time to time. Additional breast massages might be performed by nurses during weekly follow-up visits over an approximately 1-month period. If breast nodules were detected during a postoperative clinical examination, a localized breast massage was performed by a trained nurse until the breast returned to normal softness.

Outcome Evaluation

The postoperative results were assessed by patients and a blinded investigator physician who considered preoperative and postoperative photographs (approximately 6 months after surgery) in terms of Global Aesthetic Improvement Scale (GAIS) scores. Breast circumference (BC) at the nipple level was measured preoperatively and 2 weeks, 1 month, and 6 months or later after surgery. The final BC evaluation was performed at least 6 months after surgery (or at the final follow-up visit) because breast volume usually stabilizes at approximately 3 months after fat grafting.⁶ Nipple–inframammary fold distance (NFD) and breast cup size were also assessed preoperatively and postoperatively at the time of final contact (at least 6 months after surgery). For our data analysis, we assigned numeric values to the cup sizes (ie, 1 = A cup, 2 = B cup, 3 = C cup, 4 = D cup, 5 = E cup).

Statistical Analysis

The difference between preoperative and postoperative measurements for BC, NFD, and cup size were analyzed by a paired-samples t test. Statistical significance was recognized when P < 0.001. Data were analyzed with SPSS version 20.0 (SPSS Inc., Chicago, IL).

RESULTS

In total, 358 patients met the inclusion criteria for the present study, which covered an 8-year period. Table 1 summarizes the patient demographics, intraoperative data, and postoperative complications. Mean follow-up was 16.5 months (range, 6-64 months). The patients’ mean age was 32.4 years (range, 18-46 years). Their average BMI was 20.8 kg/m² (range, 18.5-34.2 kg/m²). The mean aspirated volume was 2442.6 mL, and the mean grafted volume in the right and left breast was 510.9 and 490.8 mL, respectively. During the early postoperative period (ie, within the first week after the procedure), an early complication of localized fat graft infections developed in 2 patients (0.6%) with local tenderness, burning, redness, and fever. This complication was resolved by performing surgical debridement with suction drainage to remove the infected fat in the tender and red area. Late complications (ie, after 4 weeks from the procedure) were oil cyst formation in 17 patients (4.7%) and calcification in 13 patients (3.7%). Cases with breast nodules that could not be resolved by massage immediately during the postoperative follow-up required screening with ultrasonography or MRI. After the medical imaging exam, fragmentation and suction drainage with a conventional liposuction aspirator or vacuum-assisted excision were performed. For the routine follow-up, postoperative ultrasound examination was performed 3 months after the procedure.

Table 1.

Patient Demographics, Intraoperative Data, and Postoperative Complications (n = 358)

Age (years)	32.4 (18-46)
BMI (kg/m2)	20.8 (18.5-34.2)
Follow-up (months)	16.5 (6-64)
Aspirated volume (mL)	2442.6 [366.4]
Grafted volume (mL)
Right breast	510.9 (400-875)
Left breast	490.8 (380-850)
Complications
Oil cysts	17 (4.7%)
Calcifications	13 (3.7%)
Surgical site infection	2 (0.6%)

Values are mean (range), mean [standard deviation], or number of patients (%).

Breast circumference outcomes are presented in Table 2. The mean preoperative BC was 79.35 cm; by contrast, the postoperative value was significantly higher at 2 weeks (88.20 cm; P < 0.001), 1 month (85.45 cm; P < 0.001), and 6 months after surgery (84.85 cm; P < 0.001). Table 3 summarizes the NFD and cup size outcomes. The mean postoperative NFD was 7.82 cm (P < 0.001), which was significantly higher than the mean preoperative length of 5.25 cm. Mean cup size was 1.56 preoperatively and 3.82 postoperatively (Figures 1-3), which was a statistically notable difference (P < 0.001; Tables 1, 2).

Table 2.

Change in Breast Circumference

	Mean [SD]	Range (min, max)	Mean [SD] (increment)	P
Chest circumference (cm)	73.55 [2.52]	15.0 (68.0, 83.0)	—
BC (cm)
Preoperative	79.35 [2.66]	14.5 (74.0, 88.5)	—	—
Postoperative	88.20 [2.57]	12.0 (82.0, 94.0)	8.85 [1.39]	< 0.001a
1 month postoperative	85.45 [2.62]	14.0 (79.0, 93.0)	6.10 [1.23]	< 0.001b
6 months postoperative	84.85 [2.57]	13.5 (78.50, 92.0)	5.50 [0.84]	< 0.001c

BC, breast circumference; SD, standard deviation.

^aComparison of preoperative and postoperative BC.

^bComparison of preoperative and 1-month postoperative BC.

^cComparison of preoperative BC and 6-month postoperative BC. Comparison of postoperative BC vs 1-month postoperative BC, P < 0.001. Comparison of 1-month vs 6-month postoperative BC, P < 0.001.

Table 3.

Nipple–Inframammary Fold Distance and Cup Size Outcomes

	Preoperative	Postoperative	P
NFD (cm)	5.25 [0.68]	7.82 [0.83]	<0.001
Cup size	1.56 [0.86]	3.82 [0.74]	<0.001

NFD, nipple–inframammary fold distance. Data are expressed as mean [standard deviation]. Cup size equivalent: 1 = A cup, 2 = B cup, 3 = C cup, 4 = D cup, 5 = E cup.

Figure 1.

A 33-year-old female patient (BMI, 19.7 kg/m²) (A, C) before and (B, D) 30 months after autologous fat transfer of 700 and 600 mL to the right and left breast, respectively.

Figure 2.

A 46-year-old female patient with preoperative ptotic breast (BMI, 19.2 kg/m²) (A, C) before and (B, D) 64 months after mega volume autologous fat transfer of 750 and 775 mL to the right and left breast, respectively.

Figure 3.

Preoperative 39-year-old female patient with flat upper breasts (BMI, 22.3 kg/m²) who received fat transfer of 700 and 625 mL to the right and left breast, respectively. (A, C) Preoperative and (B, D) postoperative frontal view and lateral view after 56 months.

Aesthetic satisfaction was determined based on the preoperative and postoperative digital photographs. Both frontal and bilateral oblique views were obtained for aesthetic grading. The surgical outcomes were assessed at 6 months postoperatively, based on GAIS scores assigned by the patient and a blinded physician. One hundred and fifty-two (42%) patients had a GAIS score of 1 (exceptional improvement); 171 (48%) patients had a score of 2 (very improved), and 35 (10%) patients had a score of 3 (improved). Physician rating for GAIS scores was exceptional improvement for 140 (39%) patients, very improved for 172 (48%), and improved for 46 (13%) (Table 4).

Table 4.

Satisfaction Grading

Degree	Description	No. of patients expressing satisfaction (%)	No. of physicians expressing satisfaction (%)
1. Exceptional improvement	Excellent corrective result	152 (42%)	140 (39%)
2. Very improved	Marked but not complete improvement in appearance	171 (48%)	172 (48%)
3. Improved	Improved appearance compared with the initial condition, but a touch-up is advised	35 (10%)	46 (13%)
4. Unaltered	Appearance remains effectively the same as the original condition	0	0
5. Worsened	Appearance has worsened compared with the original condition	0	0

Discussion

In 1987, Bircoll proposed liposuction as a new source of adipose tissue for breast augmentation.⁷ However, despite many years of development, autologous fat transfer to the breast is still subject to some limiting factors, namely the formation of liponecrotic oil cysts, calcifications, indurations, and/or fat necrosis, and the unpredictable reabsorption rate. A comprehensive literature review suggested that these complications are mainly related to technical errors and that results may vary depending on the surgeon’s technique and expertise.³

Some protocols (such as cell-assisted lipotransfer and platelet-rich-plasma- or adipose-stem-cell-enriched grafts) have been developed to overcome the challenges associated with fat transfer and encouraging results have been reported. However, the clinical results associated with these techniques are insufficient to establish its superiority over conventional fat transfer techniques.⁸ The surgeon’s technique and expertise appear to be the more decisive factors in achieving satisfactory outcomes. This finding motivated us to re-evaluate the current approach and principles of fat grafting to the breast and develop new methods that can substantially improve long-term results.

When large volumes of fat graft are required, a common concern among surgeons is the survival rate of the grafted fat in a limited tight space. Several studies have suggested that predictable and satisfying results can be achieved by performing autologous fat transfer in several sessions.^2,4,5,9 However, Coleman et al reported that in patients who received a single-session graft volume of up to 460 mL in a single breast, a noticeable change in size and contour was achieved in the long term.⁵ This finding aroused the feasibility of large-volume fat injection. Our experience indicated that the use of more condensed adipose tissue and an increased graft-to-recipient interface limits the influence of interstitial fluid pressure and increases neovascularization, which are crucial for large fat graft survival. The processing and placement techniques for lipoaspirates are key factors for achieving satisfactory long-term results.

To address the drawback of a tight breast skin envelope without substantially increasing interstitial fluid pressure, Khouri et al recommended the use of the Brava external breast expander for 4 weeks prior to surgery. The use of this device enables an increase in tissue compliance and potential recipient space during the creation of an abundant stromal/vascular scaffold.¹⁰ However, the Brava system is rarely accepted by our patients because a multistage procedure may still be required, and patients usually prefer a noticeable aesthetic outcome after a single session of surgery. The concept of creating a large pocket in implant mammoplasty can be applied in lipoaugmentation by creating multiple macrospaces and microspaces, which can be used as an alternative to the Brava system. We release fibrous bands with a V-shaped cannula and create multiple tunnels with a round-end tapered cannula. The result is a 3-dimensional honeycomb cavity that allows for fat placement and survival through plasma diffusion until neovascularization takes place.

For fat purification and processing, we hypothesized that previously reported reabsorption rates could be attributed to the inadequate purification of harvested fat, resulting in the residual presence of a substantial fraction of water and nonfatty elements in the initially grafted fat. Therefore, we prefer the term “volume retention rate” to “fat absorption rate” for this phenomenon. Several studies have recommended sedimentation, centrifugation, and filtration of the aspirated fat as measures to purify the lipoaspirates.^4,10,11 During the last 8 years, we have tested the difference between multiple processing methods in terms of nonfatty content vs fat density fractions, and we have discovered that, relative to sedimentation-only methods, centrifugation at 3000 rpm for 3, 5, or 8 minutes can filtrate 10% more nonfatty components. Furthermore, centrifuged fat that underwent additional filtration exhibited more nonfatty component content than fat that only underwent sedimentation or centrifugation (Figure 4). We believe that highly purified fat tissue played a crucial role in the notable retention amount that was observed (Figure 5). From our study, filtration procedure also plays an important role in fat purification. To shorten the operation time, we centrifuge the fat for 3 minutes and then filter it.

Figure 4.

Differences in fat condensation. Centrifugation at 3000 rpm for 3 minutes (B), 5 minutes (C), or 8 minutes (D) produced filtrates with 10% more nonfatty components than a sedimentation-only procedure (A). Centrifuged fat subjected to additional filtration (E) exhibited less nonfatty component content than fat subjected to a sedimentation-only procedure.

Figure 5.

MRI of a patient who received fat transfer into the subglandular space of 800 and 750 mL to the right and left breast, respectively. The MRI shows the total injection amount and amount retained in each breast at 6 months postoperatively.

In addition to the release of fibrous bands, formation of tunnels (macrospace creation), and execution of a strict protocol for fat purification, we performed an intraoperative massage (microspace creation) for 3 to 5 minutes after each injection to facilitate the rearrangement of the injected fat, thereby increasing the graft-to-recipient interface and ensuring adequate neovascularization of the fat. Through each round of massage, the breast envelope (which was initially tight after the fat injection) acquired sufficient compliance and softness to receive more grafted fat. Similar procedures were previously proposed for the correction of surface irregularities after fat grafting, particularly following injections to the upper pole of the breast. To redistribute fat, enhance fat diffusion, and soften the breast, Zocchi et al and Abboud et al proposed manual reshaping¹² and external vibration.¹³ With respect to the softening of breasts and enhanced diffusion of fat, we discovered that repeated intraoperative massages are a major breakthrough for allowing additional large amounts of fat to be injected. Intraoperative massages not only enable reshaping but also allow for more fat injections. Several studies have shown that the average amount of fat injection is around 250 mL on each side of the breast; ³ after the release of fibrous bands, formation of runnels, and intraoperative massages, we have been able to achieve an average injected fat volume of 500 mL on each side (Table 1).

The ability to increase breast size by more than 1 cup size is another major concern regarding the use of autologous fat transfer for cosmetic purposes. In contrast to silicone gel implants (which require between 130 and 150 mL on average to increase breasts by 1 cup size),¹⁴ the volume of grafted fat required to achieve a 1-cup increase was reported to be between 250 and 400 mL.⁴ This difference in volume is attributed to the compressibility characteristics of adipose tissue vs silicone in breast implants. The elastic modulus of breast adipose tissue is in the range of 0.5 to 25 kPa; however, the values are much higher for the pectoralis muscle and fascia and for synthetic materials similar to the silicone used in breast implants.¹⁵ Thus, autologous fat grafting should be refined to allow for a predictable long-term sufficient volume augmentation that reliably meets patients’ cosmetic goals.

In cases where fat grafting replaces removed implants, Coleman et al observed a size limitation for a single-session fat-grafting procedure and proposed the addition of a secondary procedure.⁴ In our study, all patients who underwent implant removal and immediate augmentation with a single-session mega volume autologous fat injection were able to maintain similar volumes. Mega volume fat grafting to subcutaneous, subglandular, and precapsular spaces provided satisfactory outcomes for volume and contour.

By implementing the innovative concept that the senior author developed through clinical experience, a grafted fat volume of roughly 500 mL on each side resulted in a predictable long-term increase of 2 to 2.5 cup sizes, which was equivalent to a fat volume of 190 to 250 mL for a 1-cup-size augmentation. Many studies have discussed the issue of autologous fat transfer for breast augmentation; however, the multiple sessions required for mega volume fat transfer still remain a crucial disadvantage. This study provides innovative methods to solve the difficulty of achieving mega volume breast augmentation in a single session. Compared to previous studies, the major breakthroughs are the processing to produce more highly purified fat and the creation of additional space, which together increase the retention amount and allow more fat to be placed in the breast. This innovative technique can not only achieve an optimal breast size in a single session, but also maintains a stable outcome in follow-up. The end result shows that this new technique of mega volume autologous fat transfer can also be considered as an alternative to implant mammoplasty.

There are 2 limitations in this study that should be noted. First, the patient population in this study only included patients with BMI >18.5 kg/m²; patients whose BMI was <18.5 kg/m² were excluded due to them having insufficient fat for single-session mega volume fat breast augmentation. Second, although MRI is a validated method for measuring fat graft retention in the breast,¹⁶ it is difficult to reach a quantitative scientific conclusion about the fat retention rate in this study due to the lack of a comparable MRI database. The cost of MRI makes patients unwilling to undergo this analysis for preoperative and postoperative evaluation. We nevertheless still keep collecting MRI data because we believe the retention rate needs to be addressed further in future studies.

Conclusions

The use of autologous fat grafting for breast augmentation has been debated with respect to its ability to deliver satisfactory aesthetic results when performed as an alternative to implantation surgery. The limited interstitial space at the recipient zone and the potential need for multiple sessions are factors that discourage the use of the technique from both the surgeon and patient perspectives.

Our experience over the past 8 years indicates that the combined use of our space-creating technique and highly purified fat is a safe and effective method for performing single-session large-volume autologous fat transfer for breast augmentation and achieving stable long-term results.

Acknowledgments

The authors are grateful to Dr Fu-Chan Wei, Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, who corrected flaws in the paper and contributed with writing assistance.

Disclosures

The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.

Funding

The authors received no financial support for the research, authorship, and publication of this article.

Author notes

Dr C. W. Hsiao is a plastic surgeon in private practice in Taipei, Taiwan.

Dr K. Y. Hsiao is a plastic surgeon in private practice in Taipei, Taiwan.