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). Initial comparison of the deflation rates for smooth (8.8 percent) versus textured (1.8 percent) implants suggested a significant difference between 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-Meier survival analysis plots, which corrected for differences in follow-up times, and log rank tests performed to determine significance. Implant type was found to have a non-significant association with rupture rate. In contrast, the percent fill (implant fill volume per minimum recommended fill volume x 100) was significantly associated with the spontaneous ruptures; a mean difference of 13.9 percent (89.2 percent versus 103.1 percent) was found between the series of deflated implants and the nondeflated implants (p < 0.0001). These data suggest that underfilling is a major cause of deflation.