INFLUENCE OF UNDERFILLING ON BREAST IMPLANT DEFLATION

The authors report a series of 407 patients with a total of 709 saline breast implants (average follow-up, 7.1 years). In this retrospective series, the overall deflation rate was 6.6 percent (47 of 709). Initi al comparison of the deflation rates for smooth (8.8 percent) versus t extured (1.8 percent) implants suggested a significant difference betw een the implant types. However, further analysis of the data revealed that smooth implants had a longer average follow-up period and tended to have lower fill volumes. These data were re-examined using Kaplan-M eier survival analysis plots, which corrected for differences in follo w-up times, and log rank tests performed to determine significance. Im plant type was found to have a nonsignificant association with rupture rate. In contrast, the percent fill (implant fill volume per minimum recommended fill volume x 100) was significantly associated with the s pontaneous ruptures; a mean difference of 13.9 percent (89.2 percent v ersus 103.1 percent) was found between the series of deflated implants and the nondeflated implants (p < 0.0001). These data suggest that un derfilling is a major cause of deflation.