Exhaustive soxhlet extraction for the complete removal of residual compounds to provide a nonleaching silicone elastomer.

All commercially available silicone devices contain freely diffusible silicone oils, uncured oligomers, and other impurities (such as catalysts). These residuals have been found in quantities as high as 20% by weight in commercially available silicone medical devices. The fate and effects of these residuals have been the topic of much debate recently. In this study, a method for complete removal of these residual compounds was investigated. The total amount of extractable residuals was determined through exhaustive Soxhlet extraction of 5 silicone elastomers. LIM 6030 had 6.29%, LIM 6070 had 5.74%, Q7-4750 had 3.02%, Q7-4780 had 3.22%, and SE1935 had 0.13% extractables by weight. The amount of silicon containing residuals leaching from both the extracted and nonextracted samples was also evaluated for 3 and 18 days by inductively coiled plasma (ICP) analysis. A significant amount of leachable compounds, reported as microg Si/mg solid sample, was found in all nonextracted elastomers with the exception of SE1935 compared to blanks. The amount of leachable compounds found in the extracted elastomers was not found to be significantly higher than the amount found in the blanks. The residual compounds in silicone elastomers may be completely removed by exhaustive Soxhlet extraction and the resulting polymer does not leach silicon-containing compounds in vitro.

Silicone gel breast implant failure and frequency of additional surgeries: analysis of 35 studies reporting examination of more than 8,000 explants.

Although it is well known that silicone gel breast implants (SGBIs) produce many "local" complications (i.e., pain, hard fibrous capsules, disfigurement, chronic inflammation, implant shell failure) and necessitate frequent surgical revisions, no large cohort retrospective quantitative analysis of clinical data has been reported to date, especially for the prevalence of failures and additional surgeries. Data from 35 different studies that encompass more than 8000 explanted SGBIs have now been analyzed and are reported here. Because examination of a prosthesis when explanted is the definitive method for determining shell integrity, the only studies that were used were ones that reported implant duration, the total number of SGBIs explanted, and the number of SGBIs for which shell rupture or failure ("not intact") was confirmed upon surgical removal. An exponential regression plot of data indicated a direct correlation of implant duration with percent shell failure (r2 = 0. 63 and r = 0.79 ). SGBI failure was found to be 30% at 5 years, 50% at 10 years, and 70% at 17 years. The failure rate was 6% per year during the first 5 years following primary implant surgery. ANOVA comparison of three implant age groups (mean implant durations of 3. 9, 10.2, and 18.9 years) indicated a highly significant statistical correlation of percent failure with implant duration (p < 0.001). Complications necessitating at least one additional surgery occurred for 33% of implants within 6 years following primary implant surgery. Shell failure was found to be an order of magnitude greater than the 4 to 6% rupture prevalence suggested by the AMA Council on Scientific Affairs in 1993, the 0.2 to 1.1% cited by manufacturers at that time, and the 5% rupture that was stated to be "not a safety standard that the FDA can accept."