Schendel1 concludes that separating the stromal vascular fraction (SVF) and injecting it along with the lipoaspirate improves the results of facial fat injection. The author claims that his study is the first to document facial fat enrichment using three-dimensional measurements. A draft of Schendel’s original manuscript is also available online at the researchgate.net website,2 with a reference to the Journal. However, this citation is actually to an abstract,3 not the manuscript,2 leading the reader to believe that this article was accepted and published in Plastic and Reconstructive Surgery. Instead of a control group, Schendel compares his figure for fat retention, 68 percent,1 with a 41.2 percent rate cited in another study.4 Such external comparisons are always limited by confounding variables. For example, the referenced study includes face lift patients, smaller injection volumes, older patients, and fewer injection sites.4 Even if control patients were available, Schendel’s study (n = 10) would have insufficient statistical power to detect a significant treatment difference. Furthermore, the eligibility criteria and inclusion rate are not specified.
Photographs feature different focal distances, chin elevation, and head rotation.1 Left oblique photographs are substituted for right oblique photographs. Importantly, the frontal before-and-after photographs are reversed. The author1 claims that a pink area around the mouth in the three-dimensional superimposed image is evidence of a volume increase (this area appears blue in the abstract image3). This pink area extends to the lower chin and jawline, areas that were not injected. The forehead appears blue, indicating volume loss (opposite to the usual three-dimensional color scheme, in which blue represents an increase and red is a decrease4). Obviously, any apparent volume loss in the forehead is spurious. This imaging effect is created by tipping the chin up slightly. Hence the importance of precisely registering facial landmarks.4 In five patients (50 percent), the total fat injection volume was 12 cc or less. One patient received approximately 56 cc of fat injection, skewing the data. The standard deviation (15.34 cc) is almost as great as the mean fat volume (18.4 cc). Such variation precludes statistical tests based on normally distributed data. The average stromal vascular fraction cell count is reported as 4.8 × 105 and 4.97 × 104 per cc, without the actual data, range, or standard deviation.1–3
The author claims that his imaging technique is “accurate in this scenario to 0.3 mm,” erroneously referencing a study by Khambay and Ullah.5 Another referenced article (likely the intended one) published by Schendel et al.6 claims this extraordinary degree of accuracy when comparing a three-dimensional simulation to an actual three-dimensional scan in orthognathic surgery, a different application of the imaging technology. The gold standard for measuring fat volume is magnetic resonance imaging.7 Existing three-dimensional technology has not been compared to magnetic resonance imaging to establish validity.4 Moreover, slight differences in facial fullness can be caused by hormonal factors, hydration, menstrual cycle, and weight changes.4 Weights were evidently monitored, but not reported.1
The 68 percent figure represents the pooled volume of “fat” (really an estimate derived from the imaging method) at an average 12 months’ follow-up for all 10 patients divided by the total volume injected at surgery. If the percentages are individualized, the results appear different, with a mean 79.6 percent and range of 29 percent to 167 percent. The author concedes there was no significant correlation between stromal vascular fraction cell counts and fat retention (p > 0.05).1 If the stromal vascular fraction is equally proportioned,1 an improved fat retention might be simply explained by the greater fat volume injected.
A V-shaped malar depression persists in postoperative photographs.1 Today, many operators use much higher volumes (e.g., 45 cc7) when injecting the face. Preparation of a stromal vascular fraction is a tedious procedure. The extra time, resources, and expense need to be justified. Smith et al.8 report no advantage in cell viability from washing the fat or centrifuging it, and recommend against unnecessary manipulation or delayed reinjection. Fisher et al.9 report that filtration and centrifugation both effectively remove fluid fractions and result in comparable graft retention, with minimal loss of the stromal vascular fraction in the discarded filtrate. Ironically, Schendel is the medical director of Genesis Biosystems (Lewisville, Texas),1 which manufactures a closed filtration system that eliminates the need for centrifugation and allows expeditious fat injection (Fig. 1) containing a (nonseparated) stromal vascular component, saving time and minimizing fat handling. Unfortunately, “stem cell” face lifts are promoted by some operators.10 It is best to avoid claiming that a process truly enriches the fat transfer until such an effect is reliably demonstrated.10
The patient provided written consent for the use of her images.
The author has no financial interest to declare in relation to the content of this correspondence. The author received no financial support for the research, authorship, and publication of this correspondence.
Eric Swanson, M.D.
11413 Ash Street
Leawood, Kan. 66211
1. Schendel SA. Enriched autologous facial fat grafts in aesthetic surgery: 3D volumetric results. Aesthet Surg J. 2015;35:913–919
3. Schendel SA. Esthetic facial augmentation by combined fat and SVF: 3D computer results [Abstract]. Plast Reconstr Surg. 2014;134(4S-1 Suppl):101
4. Gerth DJ, King B, Rabach L, Glasgold RA, Glasgold MJ. Long-term volumetric retention of autologous fat grafting processed with closed-membrane filtration. Aesthet Surg J. 2014;34:985–994
5. Khambay B, Ullah R. Current methods of assessing the accuracy of three-dimensional soft tissue facial predictions: Technical and clinical considerations. Int J Oral Maxillofac Surg. 2015;44:132–138
6. Schendel SA, Jacobson R, Khalessi S. 3-Dimensional facial simulation in orthognathic surgery: Is it accurate? J Oral Maxillofac Surg. 2013;71:1406–1414
7. Swanson E. Malar augmentation assessed by magnetic resonance imaging in patients after face lift and fat injection. Plast Reconstr Surg. 2011;127:2057–2065
8. Smith P, Adams WP Jr, Lipschitz AH, et al. Autologous human fat grafting: Effect of harvesting and preparation techniques on adipocyte graft survival. Plast Reconstr Surg. 2006;117:1836–1844
9. Fisher C, Grahovac TL, Schafer ME, Shippert RD, Marra KG, Rubin JP. Comparison of harvest and processing techniques for fat grafting and adipose stem cell isolation. Plast Reconstr Surg. 2013;132:351–361
10. Eaves FF 3rd, Haeck PC, Rohrich RJ. ASAPS/ASPS position statement on stem cells and fat grafting. Plast Reconstr Surg. 2012;129:285–287
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