The effect of silicone gel bleed on capsular contracture:  a generational study.
BACKGROUND
Capsular contracture has multiple causes, all of which lead to increased inflammation and scarring. There have been five generations of silicone breast implants; the most recent are filled with a highly cohesive gel thought to reduce capsular contracture. No independent data exist to support this claim.


METHODS
Eight Göttingen swine were each implanted with eight 50-cc custom gel implants. In phase 1 of the study, the implant shells were photochemically altered to produce a low-bleed shell or a high-bleed shell to simulate a second-generation implant. In phase 2, both the third/fourth generation and the newest, fifth generation (highly cohesive gel) devices were implanted. Half the implants were punctured with a 3-ml punch biopsy to simulate a ruptured implant. Capsule and implant specimens were harvested at 1 and 3 months and analyzed with a Bose strain gauge. Intracapsular fluid was tested for silicon levels with atomic emission spectrometry. Histologic analysis was prepared with hematoxylin and eosin, Masson trichrome, and α-smooth muscle actin immunohistochemistry stains.


RESULTS
Gel bleed correlated with capsule stiffness in a dose-dependent manner (p < 0.05). High-bleed second-generation implants had the stiffest capsules, and nonruptured third- and fourth-generation implants had the softest. Histologic examination revealed an intermediate layer of spindle-like cells staining positive for α-smooth actin in the most contracted capsules.


CONCLUSIONS
There is a dose-dependant relationship between silicone gel bleed and capsule compliance that is independent of the cohesivity of the silicone. Capsule thickness and a fibrotic, α-smooth muscle actin-positive layer are present within the most contracted capsules.
Atlanta, Ga. From the Division of Plastic Surgery, Emory University.
Hunter R
HR
Moyer
Bahair H
BH
Ghazi
Albert
A
Losken
D000818:Animals; D019928:Breast Implantation / Q000009:adverse effects* / Q000379:methods; D018427:Breast Implants / Q000009:adverse effects*; D003286:Contracture / Q000209:etiology / Q000503:physiopathology; D004195:Disease Models, Animal; D005260:Female; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011897:Random Allocation; D012307:Risk Factors; D012422:Rupture, Spontaneous / Q000209:etiology / Q000503:physiopathology; D012680:Sensitivity and Specificity; D020034:Silicone Gels / Q000009:adverse effects* / Q000494:pharmacology; D034421:Sus scrofa; D013552:Swine
D020034:Silicone Gels