A is a Prosthesis used in Cosmetic Surgery to enlarge the size of a woman's Breast s (known as breast augmentation), or to Reconstruct The Breast (e.g., to correct genetic deformities or after a Mastectomy , or during Male-to-female Sex Reassignment Surgery ).
According to the American Society Of Plastic Surgeons , breast augmentation is the third most commonly performed cosmetic surgical procedure in the United States. In 2005 , 291,000 breast augmentation procedures were performed. 10.2 Million Cosmetic Plastic Surgery Procedures in 2005 . American Society of Plastic Surgeons. 15 March 2006. Retrieved 17 April 2006.
There are two contemporary types of breast implant filler materials with many different shapes and textures available:
- , which have a Silicone rubber shell filled with sterile Saline liquid. These implants are currently the only type available outside of clinical trials in the United States , but future regulation may make more filler types available.
- , which have a silicone shell filled with a viscous Silicone gel.
Implants have been used at least since 1865 to augment the size of women's Breast s. The earliest known implant occurred in Germany , in which fat from a Lipoma (benign fatty lump) was removed from a woman's back and implanted in her breast. In the following years, the medical community experimented with implants of various materials, most commonly Paraffin .
The first use of silicone for breast augmentation was immediately following World War II, when doctors in Japan and Las Vegas began injecting it to enlarge women's breasts. Initially they used the industrial kind of silicone that goes into making furniture polish and transformer fluid. Complications like cysts, sores and painful hardening of the breasts were in some cases so severe that women needed mastectomies. According to the '' New York Times '', at least three women died when silicone obstructed their blood vessels and lungs.Natasha Singer. Injecting Silicone, and Risk . ''The New York Times''. 26 January 2006. Retrieved 17 April 2006. Women sometimes sought medical treatment up to 30 years after receiving this type of injection.
Houston, Texas plastic surgeons Thomas Cronin and Frank Gerow developed the first silicone breast prosthesis with the Dow Corning Corporation in 1961 , and the first woman was implanted in 1962 . The implant was made of a silicone rubber envelope (or sac), and was filled with a thick, viscous silicone gel.
When originally introduced by Cronin , medical devices were not regulated in the United States . After the law was changed in 1976 to give the Food And Drug Administration (FDA) the authority to regulate all medical devices, the FDA "grandfathered" many devices that were already on the market, including breast implants. As a result, the long-term safety of the devices had never been documented. In 1992, the FDA restricted the implantation of silicone gel-filled breast implants because of questions about their safety. Silicone implants may be used only under certain controlled conditions. The FDA has not yet lifted the ban for widespread use.1
In Canada , silicone gel-filled prostheses were banned by Health Canada on 6th January 1992 in response to concerns raised in the scientific literature regarding possible illnesses associated with the implants. In 1999 , Health Canada 's Medical Devices Bureau began to make silicone implants available to plastic surgeons again under a Special Access Program. Under the program, surgeons must submit requests to use silicone implants to the Bureau on a case-by-case basis.2
The first generation Cronin-Gerow implants were redesigned in the 1970's in response to surgeons asking for softer and more life-like devices. The original cohesive gel and thick-shell models were replaced in the 1970’s by implants with thinner gel and thinner shells. These more flexible gels were introduced by various companies from 1972-1975, and thinner elastomer shells were introduced in 1972. These "second generation" implants had a greater tendency to rupture and leak, or "bleed" silicone through the porous shell, and complications such as capsular contracture were also quite common.
Another development in the 1970’s was a on the implant shell. According to a Congressional report an estimated 200,000 women received this type of implant before it was discontinued in the early 1990's because of health concerns.3
Polyurethane coating was believed to diminish capsular contracture by causing an inflammatory reaction that discouraged formation of fibrous tissue around the capsule. The manufacturer later withdrew the product after FDA scientists determined that the foam broke down to TDA, a known animal carcinogen.4
FDA scientists advised the low theoretic risk of cancer would not justify removing these implants solely over concerns about TDA.5
Plastic surgeons have found that removing polyurethane-coated implants "can be disfiguring and lead to chronic infection, drainage from the breast and skin ulceration."
While still manufactured in Europe and South America, these implants are not FDA approved for sale in the United States.6
Second-generation implants also included various . These implants had two cavities and two shells, which were either ”patched” together or had one shell floating freely inside the other. The double lumen was an attempt to provide the cosmetic benefits of gel in the inside cavity, while the outside lumen contained saline and could be used for an expander or even for injection of antibiotics or steroids. The failure rate of these implants is higher than for single lumen implants. The contemporary versions of these devices ("Becker Implants") are used primarily for breast reconstruction. The adjustability of the saline chamber allows tissue expansion and subtle volume corrections to be performed after placement.
Around 1985, gel implants were introduced that used thicker shells, a barrier-coat elastomer to decrease gel-bleed, and a more cohesive gel filler.
Third-generation implants, developed in the 1990s, are made of cohesive gel that better maintains its form. These implants are used in other countries, and are the implants currently being considered for FDA approval. However, these implants can rupture, and the rate of rupture of contemporary devices is still being determined. Data presented to the FDA from the core and adjunct studies is limited to 3 and 4 year data. The increased cohesion of the gel filler has decreased silicone bleed and is believed to reduce leakage of the gel as compared to earlier devices, although leakage of silicone oil has still been reported in these newer implants. FDA studies indicate that most women with these implants will have at least one ruptured implant within 11-15 years. Research by Holmich and his colleagues, estimated rupture rates of "at least 15%" of implants within the first 10 years.7 Two companies, Inamed Corp and Mentor Corp, provided two to three year rupture data based on Magnetic Resonance Imaging (MRI), which indicated low rupture rates during those first few years, but projecting an accurate device failure rate is not possible based on those data.
Evaluation of "gummy bear" or high-cohesive, form-stable implants is in preliminary stages in the United States. Although these implants are used more widely in other countries, their long-term safety record is still being evaluated. It is speculated that the high degree of gel cohesion in these implants is likely to eliminate or significantly reduce potential silicone migration. Short-term safety and efficacy reports have been favorable, but 10 to 20 year rupture and leakage data are needed to determine whether the silicone leakage problem has been solved.8910
There is some dispute as to who originally invented saline implants. Early saline implants were reported in France in 1965 and in the United States that same year, in New York City. The early models frequently deflated. [http://fermat.nap.edu/books/0309065321/html/56.html . In 1967, Dr. Henry Jenny, a California plastic surgeon, found that gel implants leaked so much silicone that they were covered with a greasy film and left large spots of grease when laid down. [http://query.nytimes.com/gst/fullpage.html?sec=health&res=9E0CE3D9153AF936A25752C0A964958260]. Moreover, he found, the implants ruptured in about 16 percent of cases. Dr. Jenny and Dr. Jeri Smahel of Switzerland followed up their observations with experiments on tissue taken from a woman who had gel implants removed. They found that the silicone leaking from her intact implants had gotten into not only body tissues, but into the bloodstream and, as Dr. Jenny put it, "once in the blood, silicone would undoubtedly be distributed throughout the body." It was later proved that even implants that had not ruptured 'bled' silicone into many organs, including the spleen, liver and bone marrow. [http://query.nytimes.com/gst/fullpage.html?sec=health&res=9E0CE3D9153AF936A25752C0A964958260]. As a result of these concerns, Dr. Jenny designed a saline implant that was sturdier than the earliest models and had a diaphragm valve, known as the "Jenny valve." [http://radiographics.rsnajnls.org/cgi/content/full/20/3/e1].
Original saline implants had a high failure rate and were discontinued in the early 1970s. The current design has thicker, room temperature vulcanized (RTV) shells. After the FDA silicone gel moratorium in the early 1990's, saline implants became the dominant type placed in the United States. Saline implants lacked the ''problems of gel fluid diffusion through the shell into the tissues; axillary adenopathy secondary to silicone; release of gel on implant rupture, which can be removed only incompletely by surgery and includes the possibility of gel migration and granuloma formation; higher incidences of contracture; and greater radiopacity of gel.'' {Link without Title}
Local complications for saline breast implants are similar to those for silicone gel implants. Case reports of bacteria and fungal contamination have been reported. Advantages of saline implants include intraoperative adjustability, ease of removal, decreased capsular contracture rates, and cost (several hundred dollars less per implant than silicone).
As compared to silicone gel however, saline implants are more likely to cause rippling, wrinkling, and be noticeably palpable. Many surgeons also feel that they are more likely to cause an attenuated "bottoming out" appearance of the lower breast pole tissue from the dependent weight of the saline filler. Some of these characteristics can be improved with newer designs, submuscular or partial submuscular placement (the "dual-plane" technique) of the implant and proper implant sizing. CITATION
In patients with more breast tissue, it can be difficult to discern an advantage in feel or appearance to silicone. However, with thin breast tissue coverage, and particularly in the setting of post-mastectomy reconstruction, silicone is felt to be the superior device by most plastic surgeons.
There are several techniques employed in the insertion of breast implants. The choice of technique may depend on the surgeon's personal preferences as much as the patient's relevant anatomy, but there are certain considerations that the surgeon can use to help select the implant and method appropriate to the patient.
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