Methods/Technique: 42 patients underwent fat augmentation of the buttock in conjunction with liposuction and/or abdominoplasty between 2008 -2010. 32 patients had comparable before and after photos and were selected for the study. The mean age of the patients was 40.31 years. Fat harvest was performed using a Power Assisted Liposuction® technique. Fat was collected in a sterile container and mixed with Cepahazolin 1g solution. It was passed through a sterile strainer and transferred to 30 cc syringes for transfer to the buttock areas. Fat was injected into each buttock with a 2mm cannula until adequate contour and symmetry was achieved. Patients were followed up at week 1, week 3, week 6 and week 12 post surgery. The follow up ranged from 3 months to 20 months (mean follow up was 5.5 months). All patients had liposuction of the abdomen, flank and lower back for harvest of the fat. The mean amount of the lipoaspirate was 4100 cc and the mean amount of fat injected was 1070 cc (535 cc in each buttock). Of the 32 patients, 15 patients had an abdominoplasty in conjunction with the liposuction. Two patients had previous liposuction of the buttock by another surgeon resulting in contour abnormalities. The photos were divided into sets for comparison and placed in a binder. A black marker was placed at the site of the incision on each before and after photo to blind the assessor. Each set was randomized to have a before/after sequence or after/before sequence. Assessment was performed by two professional persons (plastic surgeons). Each assessor was unaware of the nature of the surgery and was asked to assess the shape of the lower back and buttock area only. Comparable three quarter oblique or lateral views were used for comparison. Each assessor was first asked to identify which of the two photos was the after procedure photo and then grade the improvement in the post procedure photo to the pre procedure photo on a scale of 0 to 3. 0 = no change, 1 = minimal 2= moderate and 3= significant improvement. If either rater selected the wrong after photo the numerical score was changed to a negative value. The scores were subjected to the following statistical tests. Inter-rater reliability was assessed for both the after scores and the numerical scores using Cohen’s kappa and the intra-class correlation coefficient, respectively. In addition, summary statistics, t-tests, and 95% confidence intervals were computed for the two raters separately and for the rater’s scores averaged across subject.
Results/Complications:
Of the 32 patients who were included in the study, two patients (6.25%) developed infection. One was treated with oral antibiotics, resulting in a resolution. The second patient needed intravenous antibiotics and liposuction of the area that had developed cellulitis followed by resolution. 3 patients underwent minor revision (9.3%) of the buttock and lower back area with in office liposuction and/or minor fat augmentation under local anesthesia. None of the patients had any induration on palpation and buttocks continued to remain soft and natural at last follow up. On the photo assessment, the two raters were in perfect agreement on the after scores (K=1 ) and correctly identified the after picture for each subject. The intra-class correlation for the numerical scores was 0.689 (p=0.0001 ). The mean of the average ratings across subject was significantly greater than zero (p<0.0001), and the 95% confidence interval for the mean of the average ratings across subject was (2.21, 2.44) indicating at least moderate improvement, on average, in the post procedure photo compared to the pre procedure photo (Table 1).
Table 1. Summary statistics
Rater |
n |
Mean (Max Score =3) |
Std. Dev. |
Range |
p-value |
95% CI |
1 |
32 |
2.69 |
0.59 |
1 - 3 |
<0.0001 |
(2.47, 2.90) |
2 |
32 |
2.19 |
0.86 |
0 - 3 |
<0.0001 |
(1.88, 2.50) |
Avg. |
32 |
2.44 |
0.64 |
0.5 - 3 |
<0.0001 |
(2.21, 2.67) |
Conclusion: Buttock augmentation with fat is a safe and an efficacious technique with minimum morbidity. There is a significant improvement in the shape and the contour of the lower back and the buttock area following buttock augmentation with fat.