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Prospective Controlled Study of Chin Augmentation by Means of Fat Grafting

Basile, Filipe V. M.D.; Basile, Antonio R. M.D.

Plastic and Reconstructive Surgery: December 2017 - Volume 140 - Issue 6 - p 1133–1141
doi: 10.1097/PRS.0000000000003895
Cosmetic: Original Articles
Video Discussion
Press Release

Background: Although fat grafting is a valuable tool for different areas of plastic surgery, its use in the chin area has never been evaluated. A variety of methods are available for adjusting suboptimal chin morphology, and they each present drawbacks.

Methods: A prospective controlled study was performed to evaluate whether fat grafting increases the chin volume and sagittal projection and to determine the magnitude and nature of the observed changes. Forty-two consecutive patients underwent chin augmentation by means of fat grafting between October of 2014 and January of 2016. All patient images were analyzed using a software program (Fiji package of ImageJ), which creates a three-dimensional version of the chin that is used to produce reliable estimates of the volume and gain in sagittal projection.

Results: All 42 patients showed an increase in the sagittal projection and total volume at 4 weeks and 6 months after surgery. The sagittal projection increased from 4 mm to 12 mm (average, 8.9 mm) and from 3 mm to 11 mm (average, 7 mm) after 4 weeks and 6 months, respectively. The total volume increase ranged from 3 to 11 ml (average, 8 ml) after 4 weeks and from 3 to 8 ml (average, 7.4 ml) after 6 months.

Conclusion: Fat grafting to the chin area is a reliable method for improving chin volumes (to a maximum of approximately 10 cc in our study) and sagittal projections (to a maximum of approximately 11 mm in our study).

CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Supplemental Digital Content is available in the text.Video Discussion by Bernard Markowitz, M.D., is Available Online for this Article.

Ribeirao Preto, São Paulo, Brazil

From private practice.

Received for publication December 18, 2016; accepted June 23, 2017.

Disclosure: The authors have no financial interest to declare in relation to the content of this article.

Supplemental digital content is available for this article. Direct URL citations appear in the text; simply type the URL address into any Web browser to access this content. Clickable links to the material are provided in the HTML text of this article on the Journal’s website (www.PRSJournal.com).

A Video Discussion by Bernard Markowitz, M.D., accompanies this article. Go to PRSJournal.com and click on “Video Discussions” in the “Digital Media” tab to watch.

Filipe V. Basile, M.D., Av Prof Joao Fiusa 2300, Ribeirao Preto, São Paulo, Brazil, fibasile@gmail.com

Chin augmentation remains a popular cosmetic surgical procedure in the United States, and 17,451 procedures were performed in 2015.1 The correction of sagittal deformities of the chin presents a seemingly simple surgical challenge. However, despite the simplicity, a variety of methods are available to adjust suboptimal chin morphology, and they range from osseous genioplasty to autologous osseous implants, alloplastic implants, and injectables.2–12 Alloplastic chin augmentation remains the most common method.13 Each method presents advantages and disadvantages that require the surgeon to perform individual evaluations to determine the method that will yield the best aesthetic results.14 Recently, a critical appraisal of chin anatomy has brought more attention to preoperative morphology and anatomical details, such as left chin weakness and other asymmetries that are frequently present but overlooked.15 Clearly, sagittal advance and frontal symmetry are essential to surgical success. However, focusing on all anatomical particularities could present a challenge for corrections that use prefabricated implants. Several authors have reported negative sequelae from chin surgery, such as palpability and implant visibility,4 and the frequency of this surgery has decreased by 35 percent from 2000 to 2015, whereas the total cosmetic surgical procedures decreased by only 10 percent in this period.1

The use of autologous fat injections has been anecdotally reported for the augmentation of chin contours and, despite the proven efficacy of fat grafting as a contouring tool, it remains a relatively unpredictable technique. Reported graft retention rates vary from 10 to 90 percent when injected into different locations, such as the breast and buttocks.13–16 Fat injections to the chin region have never been systematically evaluated. However, this method is considered to be simpler than implant placement or osseous genioplasty, and it may be used as a primary form of augmentation or as an adjunct to more traditional augmentation surgery.

This study was performed to ascertain whether fat grafting increases chin volume and sagittal projection and to determine the magnitude and nature of the observed changes. Clinical findings regarding the safety and complications of such procedures were also evaluated.

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PATIENTS AND METHODS

Forty-two consecutive patients underwent chin augmentation by means of fat grafting, and the procedures were performed by the authors between October of 2014 and January of 2016. All of the patients agreed to participate in the study, and institutional review board approval was obtained. The primary surgical motivation was to correct deficiencies in the sagittal dimension at the pogonion (the most anterior point on the contour of the chin) with or without width deficiencies lateral to the symphysis. Cases requiring vertical augmentation were not included in this study.17 Secondary cases and patients with dental occlusion problems were not included in this study.18

To increase reproducibility, the inferior abdomen was the donor site of the fat graft for all 42 patients. (See Video, Supplemental Digital Content 1, which demonstrates the surgical technique of chin augmentation by means of fat grafting, available in the “Related Videos” section of the full-text article on PRSJournal.com or, for Ovid users, available at http://links.lww.com/PRS/C432.) All of patients were treated as outpatients under total intravenous sedation using propofol infusion. Patients were prepared with chlorhexidine solution. The donor site was infused using a solution that consisted of 100 ml of normal saline with 50 mg (0.05%) of lidocaine and 0.1 ml of epinephrine. Liposuction was performed using a 2-mm blunt cannula. A 20-cc syringe was used to collect the fat, which was subsequently subjected to gravity separation by decantation for 5 minutes. Decantation was performed in the same syringe used for aspiration to avoid further manipulation of the fat. No washing, centrifugation, or additional manipulation was performed. The syringe plunger was consistently retracted until the 10-cc mark and locked in this position to produce the same negative pressure in all 42 cases. After decantation, the fat was transferred to one or more 3-cc syringes for injection. The fat was then injected into the chin on a supraperiosteal (subcutaneous) plane with a blunt 2-mm cannula using a fanning technique. The shape and volume of the injected fat was determined individually by the injection technique and the desired aesthetical goals in each case. The volume of the injection was recorded in each case. The volume needed in each case depended on visual and skin pressure assessments by the surgeon. Generally, two ports were used, including one lateral and one caudal port. Steri-Strips (3M, Two Harbors, Minn.) was used for draping around the injected area. The patients used no special garments. The patients were instructed to resume normal activity 1 day after surgery, including work, eating, and driving. Exercise was not to be performed for 15 days after surgery. No antibiotics were prescribed.

Video

Video

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Image Analysis

Three sets of eight photographs were taken from every patient before surgery and 4 weeks and 6 months after surgery. Photographs were integrated, matched, and analyzed using the Fiji (Fuji Corp., Tokyo, Japan) package of ImageJ (National Institutes of Health, Bethesda, Md.).19 Several plug-ins were used to analyze the images.20 The software allowed us to stack the images and create a three-dimensional version of the chin, which was used to generate a reliable estimate of the gain in volume and sagittal projection.21 The basic surface landmarks used to calculate the volume and sagittal projection are shown in Figure 1.

Fig. 1

Fig. 1

The geometric properties of the chin (e.g., volume, projection, and surface area) vary depending on the size, sex, and ethnic background of the patient.10 Although measurements of the chin projection length and width can be performed directly and fairly easily, direct volume measurements can be difficult. Thus, we used a computer three-dimensional reconstruction in the Fiji package of ImageJ to evaluate the chin volume and surface area based on the normal chin geometry.21 Considering that the chin has an oval shape, we produced a chin shape modeling tool in which the chin’s curvature can be calculated from several points around the edge of the chin and the chin’s projection and volume can be calculated assuming that the shape formed follows the ellipsoid rules for the volume calculation of solids.22 The coefficients and mathematical formula used in these models can be used to precisely calculate the shape, volume, and surface area of the chin from digital images as shown in Figure 2.

Fig. 2

Fig. 2

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Morphometric Analysis

The two parameters used to evaluate chin augmentation were the sagittal projection and total volume variation (which includes sagittal and frontal gains). The preoperative sagittal projection and total estimated volume were compared preoperatively and at 1 and 6 months postoperatively. The total volume variation was defined as increases in the volume, which was measured using the previously described methods, as shown in Figures 1 and 2. Variations in the sagittal projection were defined as increases in length, which was measured using the previously described methods.

Analyses of the volume of fat grafted in each case and the postoperative volume gains were also performed. In addition, the injection volume was correlated with the absorption rate. All of the patients were clinically evaluated at 1 week, 4 weeks, and 6 months postoperatively, and any complications were recorded.

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Statistical Analysis

All of the statistical analyses were performed with the SAS software program version 9.2 (SAS Institute, Inc., Cary, N.C.). Comparisons between the sagittal projection and the volume before and after the intervention were evaluated using an analysis of variance, which compared the volume and projection at different postoperative times. The Pearson coefficient was used to analyze possible correlations between the injected fat volume and the absorption rates. Statistical significance was set at p < 0.05.

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RESULTS

All 42 patients showed an increase in sagittal projection and total volume at 4 weeks and 6 months after surgery. Details regarding the projection and volume are depicted in Tables 1 and 2. Data regarding the fat volume injection and absorption are depicted in Table 3.

Table 1

Table 1

Table 2

Table 2

Table 3

Table 3

The sagittal projection increased from 4 mm to 12 mm (average, 8.9 mm) after 4 weeks and from 3 mm to 11 mm (average, 7 mm) after 6 months. The total volume varied from 3 to 11 ml (average, 8 ml) after 4 weeks and from 3 to 8 ml (average, 7.4 ml) after 6 months (Fig. 3). The total fat injected ranged from 4 to 10 ml (average, 7.5 ml) (Fig. 3). Mean percentage of fat survival was 82.3 percent in our study after 6 months. Patient ages ranged from 19 to 50 years (mean, 28 years). The study included 32 female patients and 10 men.

Fig. 3

Fig. 3

The most common complications, in descending order, were as follows: mild postoperative erythema [two cases (4.76 percent)] and contour irregularity [one case (2.38 percent)]. Figure 4 shows three cases of the 42 included in the study.

Fig. 4

Fig. 4

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DISCUSSION

In the authors’ practices, silicone implants and osseous genioplasty are the methods of choice for chin augmentation. Fat grafting was initially implemented in the chin as an adjunct measure for improving the results associated with the more traditional methods listed above. After achieving satisfactory results, this technique became an important tool used by the authors for improving the profile with primary chin surgery or as a complement to face lifts and rhinoplasty. Weakness of the chin may be associated with almost 30 percent of rhinoplasties, depending on the population examined.3 Nevertheless, many rhinoplasty patients are not ready to commit to an implant to improve the chin area, and the authors found that in these cases, the patients are much more likely to accept fat grafting to improve the chin contour. This finding is consistent with observations of other procedures in recent years, with many patients rejecting gluteal implants and moving toward fat grafting, which is usually perceived by the public as a less invasive procedure.23–28 Figure 5 shows a case of fat injection to the chin associated with rhinoplasty.

Fig. 5

Fig. 5

The main goal of this study was to evaluate the predictability of this method. Different methods of evaluating fat grafting have been used; however, objective preoperative and postoperative measurements have been reported in only 21.1 percent of articles focused on fat grafting.16 Although several studies have provided clinical data and subjective evaluation of fat transfer to the buttocks and breast, objective measurements are not common.16,24–28 Many authors agree that standardized protocols are needed to correctly predict and evaluate the fat graft response.16 Photography was meticulously standardized relative to patient position; camera position; focal length of the lens; and the angle and position of the patient chin with respect to the floor, the cervical area, and the camera (lateral rotation). Furthermore, three sets of preoperative photographs (taken at least 1 week apart) of 12 patients were used to compare chin volumes as a calibration before the study was started and never produced a difference greater than 2 percent (average, 1.6 percent). Despite the use of magnetic resonance and other imaging methods, evaluating the fat graft response is problematic for many areas of the body, such as the buttocks and the breast.24–29 The chin area, however, is particularly favorable compared with the gluteal area in the reliability and feasibility of measurements and evaluations. Because only a small area of subcutaneous fat tissue overlies the bone of the chin, increases in volume and sagittal projections are easily evaluated. The use of morphometric analyses has also improved our ability to accurately evaluate volume changes, and this approach could be expanded to other areas of the body. Thus, evaluations of fat absorption following grafting will be based on more precise and reliable data. We believe that the widespread use of more direct methods of measurement (e.g., morphometric analysis) and hard data instead of subjective appearance might improve the results in the field of fat graft research. Our 17.7 percent average resorption rate was consistent with the results of a number of studies focused on fat absorption in different areas of the body using different methods16–26; however, our study is the first to evaluate fat absorption in the chin region.29 The standard deviation of 11.6 percent shows that the method provides consistent and predictable results.

In addition, we were able to evaluate the relationship between the injected volume and absorption rate. The authors feared that with a higher volume of injected fat, the pressure inside the tissue and local conditions would eventually lead to higher rates of fat reabsorption because of cell damage. In our study, however, the volume of injected fat was not related to the absorption rate, as shown in Figure 3.

As expected, the volume after 4 weeks of injection was greater than the initial total volume injected, and this finding is clearly related to tissue edema that eventually disappeared after 6 months. Few complications were reported. Mild postoperative erythema [two cases (4.76 percent)] was treated conservatively, and contour irregularity [one case (2.38 percent)] was treated with additional fat grafting in the office under local anesthesia.

Asymmetry was not a complaint after fat grafting to the chin in our study. We actually were able to correct minor asymmetries using this technique that are difficult to correct with an implant.

In addition, three of the 42 cases returned for additional fat grafting in the office under local anesthesia because they felt that the increased sagittal projection did not meet their expectations (although all three of these cases gained more than 6 mm in sagittal projection). These patients considered their results satisfactory after the additional procedure.

The average patient age was 28 years in our study, and our patients mainly were women (32 women and 10 men). We feel that another important issue is the evaluation of changes to the chin with age. Furthermore, it is important to remember that patients of different ages may respond differently to fat grafts to the chin area. These questions should be addressed when using fat grafts to both the face and other parts of the body as a surgical tool.

The 6-month period used for the final assessment was not selected randomly. The majority of recent clinical studies evaluating fat grafts use a 6-month postoperative time as a reference.30 We understand that the principal pathways for tissue regeneration using fat grafts and the metabolic pathways that may affect the resorption rates of fat grafts are incompletely understood. However, significant evidence suggests rapid resorption following ischemia and an acute inflammatory response. Greater than 90 percent resorption occurs within 4 weeks of the procedure.30–33 Thus, the results after 6 months will not differ significantly from those at 12 months or 5 years. Furthermore, it is important to remember that the grafted fat is live tissue that may increase or decrease in size following weight gain and thereby alter the graft volume.

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CONCLUSIONS

Fat grafting to the chin area is a reliable method for improving the chin volume (to a maximum of approximately 10 cc in our study) and sagittal projection (to a maximum of approximately 11 mm in our study). This procedure can be used as a primary method of chin augmentation and as an adjuvant to traditional surgery, and it is easily accepted by the patient as a tool for improving chin projection associated with rhinoplasty and face lift. Three-dimensional morphometric measurement is an effective method to evaluate changes in volume after chin fat grafting. This method may also be considered in evaluating fat grafting of other areas of the body.

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PATIENT CONSENT

Patients provided written consent for the use of their images.

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