Facial Aesthetic Fat Graft Retention Rates After Filtration, Centrifugation, or Sedimentation Processing Techniques Measured Using Three-Dimensional Surface Imaging Devices
Autologous fat grafting (AFG) has become a cornerstone in facial aesthetic surgery, offering a natural solution for volume restoration and contour enhancement. Despite its widespread use, achieving consistent long-term retention of transplanted fat remains a significant challenge. This review synthesizes evidence from clinical studies that evaluated the retention rates of fat grafts processed via three common techniques—filtration, centrifugation, and sedimentation—using three-dimensional (3D) surface imaging devices.
Introduction to Fat Grafting and Retention Challenges
Autologous fat grafting dates back to the late 19th century, with refinements in harvesting, processing, and injection techniques over subsequent decades. Peer’s pioneering work in the 1950s introduced the concept of fat resorption rates, highlighting the variability in graft survival. Despite advancements, unpredictable retention rates persist, influenced by factors such as donor site selection, harvesting methods, and post-harvest processing. Among these variables, processing techniques—centrifugation, filtration, and sedimentation—have been widely debated. Centrifugation, popularized by Coleman, involves spinning aspirated fat to separate viable adipocytes from non-essential components. Filtration methods, such as cotton pad or specialized membrane systems, isolate adipose tissue by removing oils and fluids. Sedimentation relies on gravity to separate components over time. Each technique aims to maximize graft viability, but comparative efficacy remains unclear.
The introduction of 3D surface imaging devices has revolutionized volumetric analysis in aesthetic surgery. These systems, including Vectra 3D, Artec 3D, and Konica Minolta Vivid 910, generate precise 3D models with a standard deviation of approximately 2% compared to real volumes. Unlike computed tomography (CT) or magnetic resonance imaging (MRI), 3D imaging is non-invasive, radiation-free, and allows repeated assessments in standing patients. This technology has enabled rigorous quantification of fat retention, providing a standardized metric to compare processing techniques.
Methodology for Comparative Analysis
A systematic review of 77 articles from PubMed, Embase, Cochrane Library, and Web of Science identified 10 clinical studies meeting inclusion criteria. Studies were selected based on their use of 3D imaging for volumetric measurement, follow-up periods ≥3 months, and exclusion of cell-assisted lipotransfer (CAL) to isolate the impact of processing techniques. Data from 515 patients were analyzed, focusing on retention rates, processing methods, and complications.
Inclusion criteria required explicit reporting of injection volumes, retention rates, and procedural details such as donor sites (abdomen or thigh predominated) and injection planes (subcutaneous, intramuscular, or multiple layers). Exclusion criteria removed studies involving trauma, congenital defects, or non-3D imaging modalities.
Retention Outcomes Across Processing Techniques
The 10 studies revealed significant variability in retention rates (21% to 82%) across techniques and follow-up periods (3–36 months). Key findings include:
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Centrifugation:
- Retention rates ranged from 27.1% to 65.7%. Wu et al. (2018) reported 34% retention at 12 months with centrifugation (1000 rpm, 3 min). Zhu et al. (2016) observed 44.5% retention after 12 months using low-speed centrifugation (1000 rpm, 2 min). Notably, Huang et al. (2018) achieved 65.7% retention for temporal augmentation, attributed to multiple grafting sessions (average 1.5 procedures per temple).
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Filtration:
- Cotton pad filtration demonstrated superior retention in Wu et al. (2018), with 41% at 12 months compared to centrifugation (34%) and sedimentation (31%). Gerth et al. (2014) reported 41.2% retention using Puregraft filtration bags over 10–36 months. An et al. (2017) noted a non-significant trend favoring filtration (26.1% at 12 months) over sedimentation (21%).
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Sedimentation:
- Gravity sedimentation yielded the lowest retention in most studies. Basile et al. (2017) reported an outlier value of 82.3% for chin augmentation, though their method of calculating “remaining volume” via total chin volume changes may have inflated results. An et al. (2017) and Wu et al. (2018) recorded sedimentation retention at 21%–31%, underscoring its inconsistency.
Meta-analysis of pooled data revealed overlapping confidence intervals among techniques, precluding statistical significance. However, filtration and centrifugation consistently outperformed sedimentation in trend analyses.
Technical Nuances and Volumetric Considerations
Variability in retention rates within the same technique highlights the role of procedural nuances:
- Centrifugation: Speed and duration critically impact adipocyte viability. Studies using 3000 rpm for 3 minutes (Sasaki et al., 2015; Lin et al., 2017) reported lower retention (38%–44%) compared to low-speed protocols (1000 rpm), suggesting excessive force may damage cells.
- Filtration: Pore size and material influence outcomes. Cotton pads retain higher stromal vascular fraction (SVF) cells than membrane systems, potentially enhancing graft survival.
- Injection Volume: Smaller volumes (<10 mL) for localized areas (e.g., nasal dorsum) correlated with higher retention (44.5% at 3 months, Lin et al., 2017), whereas multi-site injections (20–35 mL) showed lower retention (27.1%–34%, Wang et al., 2017).
Complications and Safety Profiles
Among 515 patients, 22 complications were documented:
- Donor-site hematoma (1 case).
- Mild postoperative erythema (2 cases).
- Chronic edema (2 cases).
- Overcorrection (2 cases).
- Skin irregularities (6 cases).
- Headache or dysesthesia (7 cases).
No severe adverse events (e.g., necrosis, infection) were reported, affirming the safety of all three techniques.
Discussion: Bridging Evidence and Clinical Practice
The absence of standardized protocols remains a barrier to optimizing fat grafting. While filtration and centrifugation show promise, their superiority over sedimentation lacks statistical validation. This discrepancy may stem from heterogeneous study designs, including variations in:
- Donor Sites: Thigh-derived adipocytes exhibit higher metabolic activity than abdominal fat, potentially influencing retention.
- Injection Techniques: Subcutaneous vs. intramuscular placement alters graft vascularization and survival.
- Follow-Up Timing: Early resorption (3–6 months) versus late remodeling (12+ months) affects volumetric measurements.
3D imaging mitigates subjective assessments but requires operator expertise. Automated systems, such as Precision Light, may enhance reproducibility in future studies.
Conclusion and Future Directions
This review underscores the need for large-scale randomized trials to isolate the impact of processing techniques. Incorporating biomarkers (e.g., SVF cell counts) and advanced imaging may elucidate biological mechanisms driving retention. Meanwhile, surgeons should prioritize patient-specific factors—donor site, injection volume, and recipient site vascularity—over processing method alone.
doi.org/10.1097/CM9.0000000000000016
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