Thickness and tension of the gluteal aponeurosis and the implications for subfascial gluteal augmentation

The aim of this study is to elucidate the thickness and tension of the gluteal aponeurosis (GA) as related to subfascial gluteal augmentation. Twenty buttocks from 10 Korean fresh cadavers (age range: 69-92years, five men and five women) were dissected. Five radial lines were made from the greater trochanter (GT) to the highest point of origin of the gluteus maximus muscle (GM), the posterior inferior iliac spine (PSIS), the piriformis line (P), the coccyx (Co) and the ischial tuberosity (IT). The upper four lines were intersected by three curvilinear lines that divided them by a quarter, half and three-quarters ratios, and the lowest line was divided by a third ratio and a two-thirds ratio. At the 14 intersecting points, the force needed to break the 6mm width of the GA was measured. The thickness of the GA was also measured with a digital caliper. The GA was widest at the GT-Co line (161.7±15.8mm), and it was narrowest at the GT-IT line (106.5±21.2mm). At most of the points (12 among the 14 points), the breaking strength of the GA was greater than 20Newtons (N). The breaking strength of the GA did not vary significantly according to the locations (P=0.568, anova). The breaking strength of the males (22.8±6.6N) was significantly greater than that of the females (20.3±7.5N, P=0.003, t-test). The thickness of the GA varied according to the locations (0.4±0.2mm to 0.7±0.3mm). The thickness of the GA of the upper part (GT-GM line: 0.64±0.24mm; GT-PSIS line: 0.66±0.23mm; GT-P line: 0.66±0.24mm) was significantly greater (P=0.040, 0.017, 0.018, respectively) than that of the lower part (GT-IT line: 0.49±0.18mm). The GA of the males (0.70±0.23mm) was significantly thicker than that of the females (0.53±0.21mm, P<0.001, t-test). We conclude that the GA is capable of holding gluteal implants in the proper position, as the average force to break up the 6mm width of the GA in females was greater than 20N.