Magnetic resonance imaging and explantation investigation of long-term silicone gel implant integrity.

Background: Information about silicone gel implant longevity is sparse. Magnetic resonance imaging studies have superseded explantation studies in the search for data on their long-term integrity. Unfortunately, the majority of studies are based predominantly on second-generation implant cohorts. Although magnetic resonance imaging is acknowledged to be the best imaging modality, the results of any study are entirely dependent on its ability to differentiate ruptured from intact implants.

Methods: A single, textured, third-generation implant type was chosen, to reduce the number of variables. The largest cohort of patients in our database had subglandular Mentor Siltex gel implants (Mentor Medical Systems, Santa Barbara, Calif.). They were contacted and offered a magnetic resonance imaging scan. All patients with at least one radiologically ruptured implant were then offered explantation.

Results: One hundred forty-nine patients with bilateral subglandular implants (median +/- SD age, 8.9 +/- 2.3; range, 4.8 to 13.5 years) were imaged and reported by two independent radiologists. Twenty-three patients were reported to have 33 radiologically ruptured implants. Twenty-one patients (30 radiologically ruptured implants) agreed to explantation. Statistical analysis using maximum likelihood estimation of survival curve for cross-sectional data suggests that implant rupture starts at 6 to 7 years and that by 13 years approximately 11.8 percent of implants will have ruptured.

Conclusion: Although these results cannot necessarily be extrapolated to other implant types and manufacturers, they provide further information about the natural history of implant integrity, better enabling us to counsel prospective and current implant recipients.