See M. Angell, Science on Trial (1996).
There are two primary types of breast implants: saline-filled and silicone-gel-filled implants. Saline implants have a silicone elastomer shell filled with sterile saline liquid. Silicone gel implants have a silicone shell filled with a viscous silicone gel. There have been several alternative types of breast implants that were developed, such as polypropylene string or soy oil, but these are no longer manufactured.
Implants have been used since at least 1895 to augment the size or shape of women's breasts. The earliest known implant was attempted by Vincenz Czerny, using a woman's own adipose tissue (from a lipoma, a benign growth, on her back). Gersuny tried paraffin injections in 1889, with disastrous results. Subsequently, in the early to mid-1900s, a number of other substances were tried, including ivory, glass balls, ground rubber, ox cartilage, Terylene wool, gutta-percha, Dicora, polyethylene chips, polyvinyl alcohol-formaldehyde polymer sponge (Ivalon), Ivalon in a polyethylene sac, polyether foam sponge (Etheron), polyethylene tape (Polystan) or strips wound into a ball, polyester (polyurethane foam sponge) Silastic rubber, and teflon-silicone prostheses. In recent history, various creams and medicaments have been used in attempts to increase bust size, and Berson in 1945 and Maliniac in 1950 performed a flap-based augmentation by rotating the patient's chest wall tissue into the breast to add volume. Various synthetics were used throughout the 1950s and 1960s, including silicone injections, which an estimated 50,000 women received. Development of silicone granulomas and hardening of the breasts were in some cases so severe that women needed to have mastectomies for treatment. Women sometimes seek medical treatment for complications up to 30 years after receiving this type of injection.
The standard implant in the United States has been saline-filled, ever since the FDA moratorium on silicone gel filled breast implants in 1992. Yet, silicone breast implants have not ceased to exist due to the popularity of the more natural feel offered by this type of implant.
Silicone gel-filled breast implants were first introduced in 1962. In 1976, the Medical Device Amendments were enacted, giving the FDA authority to regulate medical devices such as breast implants. In 1988, the FDA announced that all breast implants would be labeled as class III devices, meaning they are to be considered as medical breakthrough, new technology devices, and devices with poorly established or questionable safety and effectiveness. In addition, the FDA called for implant manufacturers to submit PMAs in which data showing the safety and effectiveness of these devices would have to be approved before the device could be placed on the market. Breast implants were now under careful scrutiny of the FDA. In early 1992, the FDA placed a moratorium on silicone gel breast implants provided to the mainstream market for cosmetic purposes after many women who had received implants complained of pain and illness as a result of the implants leaking. The FDA concluded there was "inadequate information to demonstrate that breast implants were safe and effective." Access to silicone gel-filled breast implants continued to be allowed under controlled clinical studies for reconstruction after mastectomy, correction of congenital deformities, or replacement of ruptured silicone gel-filled implants due to medical or surgical reasons. Implant manufacturers were required to collect clinical trial data and were allowed distribution of the implants to a limited number of augmentation patients for these studies.
In mid-1992, the FDA approved Mentor Corporation's adjunct study protocol for silicone gel-filled breast implants for reconstruction and revision patients. That same year, silicone and breast implant manufacturer, Dow Corning, announced that it would no longer make five implant grades of silicone, but that it would continue to manufacture 45 other medical grades of silicone materials. Just three years later, in 1995, Dow Corning Corp., once the major manufacturer of silicone breast and other implants, faced 19,000 lawsuits, pushing it into bankruptcy.
In 1997, the Department of Health and Human Services began one of the most extensive research studies in medical history by appointing the Institute of Medicine of the National Academy of Science (IOM) to examine potential complications during or after surgery. After reviewing years of evidence and research concerning silicone gel-filled breast implants, the IOM found that "Evidence suggests diseases or conditions such as connective tissue diseases, cancer, neurological diseases or other systemic complaints or conditions are no more common in women with breast implants than in women without implants." Most studies have failed to find a link between silicone breast implants and disease.
In 1998, the FDA approved Inamed Corporation's adjunct study protocol for silicone gel-filled breast implants for reconstruction and revision patients only and also approved, later that same year, the corporation's IDE study for silicone gel-filled breast implants for a limited number of augmentation, reconstruction, and revision patients.
Also in 1998, Mentor Corporation and its subsidiary, Mentor Texas, signed a consent decree of permanent injunction, promising to manufacture its breast implants in compliance with the Quality System Regulation which helps to assure that medical devices are consistently high in quality and are safe and effective. The FDA permitted Mentor Corporation to continue marketing its breast implants because the deficiencies in Mentor Corporation's manufacturing process were not shown to result in a significantly increased risk to women who received this company's breast implants.
In 1999, the IOM released a comprehensive report on both saline-filled and silicone gel-filled breast implants entitled Safety of Silicone Breast Implants. The determination was that there was insufficient evidence to establish that either or both types of breast implants cause systemic health effects and that there was no new health or safety issues associated with the use of both types of implants. The IOM concluded that local complications are "the primary safety issue with silicone breast implants", making a clear distinction between local complications and systemic health concerns. Bothersome results such as rupture, pain, capsular contracture, disfigurement, and infection, were stated to be possible local complications that could require medical intervention or repeat surgeries. The IOM report can be read online at http://books.nap.edu/catalog/9602.html. A consumer booklet on the IOM study, Information for Women about the Safety of Silicone Breast Implants, can be read at http://books.nap.edu/catalog/9618.html.
In 2000, the FDA granted approval of Mentor Corporation's and Inamed Corporation's saline-filled breast implant PMAs, showing data on the types and rates of local complications experienced by patients. [The 3-year complication rates are summarized in a FED press release available at http://www.fda.gov/bbs/topics/NEWS/NEW00727.html] “Despite complications experienced by some women, the majority of those women still in the Inamed Corporation and Mentor Corporation studies after three years reported being satisfied with their implants.” Both PMAs were approved for breast augmentation to females of at least 18 years of age and for breast reconstruction.
[The approval letter, the labeling at the time of approval, and the Summary of Safety and Effectiveness (SSED) are available at http://www.fda.gov/cdrh/pdf/p990075.html for Mentor Corporation and at http://www.fda.gov/cdrh/pdf/p990074.html for Inamed Corporation. Updated clinical data from Mentor Corporation's (http://www.mentorcorp.com) and Inamed Corporation's (http://www.allergan.com) ongoing postapproval studies for these PMAs are available in the patient labeling on FDA's website at http://www.fda.gov/cdrh/breastimplants, as well as on the websites for both companies.]
The manufacturers continued to improve their gel-filled products, developing a more cohesive gel implant, and continued with their studies. In November of 2006, the FDA approved the new and improved silicone gel-filled breast implants produced by the two manufacturers, Mentor Corporation and Allergan, both for breast reconstruction and for cosmetic breast augmentation. Cosmetic use of the implants was restricted to women aged 22 and older. The approval was given with a number of conditions including a requirement to complete 10-year studies on women who have already received the implants and a 10 year study on the safety of the devices in 40,000 women. The post-approval studies will be closely monitored by the FDA.]]. The FDA warned that the implants are not without risk and that women receiving implants should have regular MRI exams to watch for any signs of rupture or leakage. It was also mandated that patients be given brochures explaining the risks.
Currently the FDA has approved silicone gel-filled breast implants and over a million women around the world have already received these implants.
Breast implants are used for:
Patients seeking breast augmentation have been reported as being usually younger, healthier, from higher socio-economic status, and more often married with children than the population at large. Many of these patients have reported greater distress about their appearance in a variety of situations, and have endured teasing about their appearance. Studies have identified a pattern (shared by many cosmetic surgery procedures) that suggest women who undergo breast implantation are slightly more likely to have undergone psychotherapy, have low levels of self-esteem, and have higher prevalences of depression, suicide attempts, and mental illness (including body dysmorphia) as compared to the general population.
Post-operative surveys on mental health and quality of life issues have reported improvement on a number of dimensions including: physical health, physical appearance, social life, self confidence, self esteem, and sexual function. Longer term follow-up suggests these improvements may be transitory, with the exception of body esteem related to sexual attractiveness. Most patients report being satisfied long-term with their implants even when they have required re-operation for complications or aesthetic reasons.
The surgical procedure for breast augmentation takes approximately one to two hours. Variations in the procedure include the incision type, implant material, and implant pocket placement.
Breast implants for augmentation may be placed via various types of incisions:
Saline-filled breast implants were first manufactured in France in 1964, introduced by Arion with the goal of being surgically placed via smaller incisions. Current saline devices are manufactured with thicker, room temperature vulcanized (RTV) shells than earlier generations of devices. These shells are made of a silicone elastomer and the implants are filled with salt water (saline) after the implant is placed in the body. Since the implants are empty when they are surgically inserted, the scar is smaller than is necessary for silicone gel breast implants (which are filled with silicone before the surgery is performed). A single manufacturer (Poly Implant Prosthesis, France) produced a model of pre-filled saline implants which has been reported to have higher failure rates in vivo.
Saline-filled implants were most common implant used in the United States during the 1990s due to restrictions that existed on silicone implants, but were rarely used in other countries. Good to excellent results may be obtained, but as compared to silicone gel implants, saline implants are more likely to cause cosmetic problems such as rippling, wrinkling, and to be noticeable to the eye or the touch. Particularly for women with very little breast tissue, or for post-mastectomy breast reconstruction, silicone gel implants are considered as superior. In patients with more breast tissue in whom submuscular implant placement is used, saline implants can look very similar to silicone gel.
Thomas Cronin and Frank Gerow, two Houston, Texas, plastic surgeons, developed the first silicone breast prosthesis with the Dow Corning Corporation in 1961. The first woman was implanted in 1962. Silicone implants are generally described in terms of five generations which segregate common characteristics of manufacturing techniques.
The Cronin-Gerow implants were made of a tear drop shaped silicone rubber envelope (or sac), filled with a thick, viscous silicone gel with a Dacron patch (to reduce rotation of the implant)on the posterior shell.
In response to surgeons' requests for softer and more lifelike implants, breast implants were redesigned in the 1970s with thinner, less cohesive gel and thinner shells. These implants had a greater tendency to rupture or "gel bleed" silicone through an intact implant shell, and complications such as capsular contracture were quite common. It was predominantly implants of this generation that were involved in the American class action-lawsuits against Dow-Corning and other manufacturers in the early 1990s.
Another development in the 1970s was a polyurethane foam coating on the implant shell which was very effective in diminishing capsular contracture by causing an inflammatory reaction that discouraged formation of fibrous tissue around the capsule. These implants were later briefly discontinued due to concern of potential carcinogenic breakdown products from the polyurethane. A review of the risk for cancer from TDA by the FDA later concluded that the risk was so small so as not to justify recommending explantation of the devices from individual patients. Polyurethane implants are still used in Europe and South America, but no manufacturer has sought FDA approval for sale in the United States. Second-generation implants also saw the introduction of various "double lumen" designs. These implants were essentially a silicone implant inside a saline implant. The double lumen was an attempt to provide the cosmetic benefits of gel in the inside lumen, while the outside lumen contained saline and its volume could be adjusted after placement. The failure rate of these implants is higher than for single lumen implants due to their more complex design. The contemporary versions of these devices ("Becker Implants") are used primarily for breast reconstruction.
Third & fourth generation implants, from the mid 1980s, represented sequential advances in manufacturing principles with elastomer-coated shells to decrease gel bleed, and are filled with thicker, more cohesive gel. The increased cohesion of the gel filler reduced potential leakage of the gel compared to earlier devices and the more substantial shell improved durability as compared to 2nd generation implants. A variety of both round and tapered anatomic shapes are available from different implants in this group. The anatomic or shaped implants are uniformly impregnated with a textured surface to reduce rotation, while round devices are available in both smooth or textured surfaces.
Evaluation of "gummy bear" or solid, high-cohesive, form-stable implants is in preliminary stages in the United States but these implants have been widely used since the mid 1990s in other countries. The semi-solid gel in these type of implants largely eliminates the possibility of silicone migration. Studies of these devices have shown significant potential improvements in safety and efficacy over the older implants with low rates of capsular contracture and rupture.
Polypropylene breast implants, also known as string breast implants, are a form of breast implant using polypropylene developed by Dr. Gerald W. Johnson. Due to a number of medical complications, the device has been banned in the European Union and United States. They work by absorbing fluid and expanding inside the body, resulting in extreme breast sizes. They are rarely seen outside of the adult entertainment industry.
The placement of implants is described in relation to the pectoralis major muscle.
Thousands of women claim that they have become ill from their implants; complaints include neurological and rheumatological problems. Some studies have suggested that subjective and objective symptoms of women with implants may improve when their implants are removed.
As studies have followed women with implants for a longer period of time, more data have become available on systemic diseases as well as autoimmune symptoms. Several large studies from the national health registry in Denmark found implant recipients no more likely to be diagnosed with an increased incidence of classic auto-immune symptoms as compared to women of the same age in the general population, and that musculoskeletal symptoms were generally lower among women with implants compared with women with other cosmetic surgery and women in the general population. Recent longitudinal follow-up of these patients has confirmed previously reported findings.
Several studies have established that women who elect to undergo breast augmentation or other plastic surgery tend to be healthier and more affluent than the general population, prior to surgery and afterwards. For example, two large studies of plastic surgery patients found a decreased standardized mortality ratio in both breast implant and other plastic surgery patients, but an increased risk of respiratory cancer deaths in breast implant recipients compared to other forms of plastic surgery. Smoking was statistically controlled in one study and not in the other, but the authors speculated that there could potentially be differences in smoking that might contribute to the higher lung cancer deaths among women with implants. Another large study with long-term follow-up of nearly 25,000 Canadian women with implants reported: "Findings suggest that breast implants do not directly increase mortality in women."
In 2001 a study suggested an increase in fibromyalgia among women with extracapsular silicone gel leakage, compared to women whose implants were not broken or leaking outside the capsule. This association has not been repeated in a number of related studies, and the US-FDA concluded "the weight of the epidemiological evidence published in the literature does not support an association between fibromyalgia and breast implants."
While there is a general international consensus that silicone implants have not been shown to cause systemic illness, excluding the possibility that a small group of patients may become ill through (as of yet) unknown mechanisms may prove difficult. The US-FDA notes that "researchers must study a large group of women without breast implants who are of similar age, health, and social status and who are followed for a long time (such as 10-20 years) before a relationship between breast implants and these diseases can conclusively be made."
Specific complications to indwelling breast implants that have received notable attention involve surveillence and treatment for implant rupture and the phenomena of capsular contracture.
Breast implants can potentially remain intact for decades in the body, but all such devices will fail at some point. When saline breast implants break, they often deflate quickly and can be easily removed. Prospective studies of saline-filled breast implants showed rupture/deflation rates of 3-5% at 3 years and 7-10% at 5 years for augmentation patients.
Among the suspected mechanisms for rupture are damage during implantation or other procedures, degradation of the implant shell, blunt or penetrating chest trauma, and in rare instances from the pressure of traditional mammograms.
The age and design of the implant are the most important factors in rupture, but estimating ruptures rates of contemporary devices has been difficult, as most previous reports mixed heterogeneous groups of devices in non-randomized populations. The only available literature with longer term available MRI data on single lumen 3rd/4th generation silicone implants comes from Europe and has reported silent rupture rates of an implant at between 8% to 15% at or around a decade (or 15-30% of patients). The first series of MRI evaluation of the highly-cohesive (5th generation) gel implants suggests improved durability, with a rupture rate reported at 1% or less at a median age of six years.
Its been suggested that clinical exams alone are inadequate to evaluate suspected rupture after a study reported that only 30% of ruptures in asymptomatic patients are accurately detected by experienced plastic surgeons, compared to 86% detected by MRIs The US-FDA has recommended that MRIs be considered to screen for silent rupture starting at three years after implantation and then every two years thereafter. Other countries have not endorsed routine MRI screening, and have taken the position that MRI should be reserved only for cases involving suspected clinical rupture or to confirm mammographic or ultrasound studies suggesting rupture.
When silicone implants break they rarely deflate, and the silicone from the implant can leak out into the space around the implant. An intracapsular rupture can progress to outside of the capsule (extracapsular rupture), and both conditions are generally agreed to indicate the need for removal of the implant. Extracapsular silicone has the potential to migrate, but most clinical complications have appeared to be limited to the breast and axillae in the form of granulomas (inflammatory nodules) and axillary lymphadenopathy (enlarged lymph glands in the armpit area). The specific risk and treatment of extracapsular silicone gel is still controversial.
Capsules of tightly-woven collagen fibers form as an immune response around a foreign body (eg. breast implants, pacemakers, orthopedic joint prosthetics), tending to wall it off. Capsular contracture occurs when the capsule tightens and squeezes the implant. This contracture is a complication that can be very painful and distort the appearance of the implanted breast. The exact cause of contracture is not known. However, some factors include bacterial contamination, silicone rupture or leakage, and hematoma. Capsular contracture may happen again after this additional surgery.
Methods which have reduced capsular contracture include submuscular implant placement, using textured or polyurethane-coated implants, limiting handling of the implants and skin contact prior to insertion and irrigation with triple-antibiotic solutions.
Correction of capsular contracture may require surgical removal or release of the capsule, or removal and possible replacement of the implant itself. Closed capsulotomy (disrupting the capsule via external manipulation), a once common maneuver for treating hard capsules, has been discouraged as it can cause implant rupture. Nonsurgical methods of treating capsules include massage, external ultrasound, treatment with leukotriene pathway inhibitors (Accolate, Singulair),and pulsed electromagnetic field therapy.
In 2006, researchers published a controversial study that claimed to identify the previously undocumented presence of toxic platinum oxidative states in vivo. A letter from the editors of the publishing journal, Analytical Chemistry, subsequently expressed concern over the research's experimental design and urged the journal's readers to "use caution in evaluating the conclusions drawn in the paper. The FDA reviewed this study and the existing literature, concluding that the body of existing research did not support their findings, and that the platinum in new implants is likely not ionized and therefore would not represent a significant risk to women.
An observation that patients with implants are more often diagnosed with palpable tumors (but not larger ones) suggest that tumors of equal size may be more easily palpated in augmented patients, and this may compensate somewhat for the potential impairment of mammography. This palpability is due to thinning of the breast by compression, innately smaller breasts a priori, and that the implant serves as a base against which the mass may be differentiated.
The presence of a breast implant does not influence the ability for breast conservation (lumpectomy) surgery for women who subsequently develop breast cancer, and does not interfere with delivery of external beam radiation (XRT) treatments that may be required. Fibrosis of breast tissue after XRT is common and an increase in capsular contracture rates would be expected.
It appears that re-operation rates in cosmetic cases can be improved by more carefully matching individual patients' soft-tissue characteristics to the type and size of implants used. Using appropriate device selection and proper technique, re-operation rates at up to seven years followup have been reported as low as 3%, as compared with the 20 percent re-operation rate at 3 years in the most recent Food and Drug Administration study.
|Year||Country||Systemic Review Group||Conclusions|
|1991–1993||United Kingdom||Independent Expert Advisory Group (IEAG)||The IEAG concluded that there was no evidence of an increased risk of connective tissue disease in patients who had undergone silicone gel breast implantation and that there was no scientific case for changing practice or policy in the UK in respect of breast implantation|
|1996||USA||US Institute of Medicine (IOM)||Not "sufficient evidence for an association of silicone gel- or aline-filled breast implants with defined connective tissue disease".|
|1996||France||Agence Nationale pour le Developpement de l'Evaluation Medicale (ANDEM)||"Nous n’avons pas observé de connectivite ni d’autre pathologie auto-immune susceptible d’être directement ou indirectement induite par la présence d’un implant mammaire en particulier en gel de silicone..." (We did not observe connective tissue diseases to be directly or indirectly associated with (in particular) silicone gel breast implants)|
|1997||Australia||Australia’s Therapeutic Devices Evaluation Committee review||"current high quality literature suggest that there is no association between breast implants and connective tissue disease-like syndromes (atypical connective tissue diseases)"|
|1998||Germany||Germany’s Federal Institute for Medicine and Medical Products||concluded that "silicone breast implants neither cause auto-immune diseases nor rheumatic diseases and have no disadvantageous effects on pregnancy, breast feeding capability or the health of children who are breast fed. There is no scientific evidence for the existence of silicone allergy, silicone poisoning, atypical silicone diseases or a new silicone disease"|
|2000||USA||Review request of the United States Federal Judiciary||"no evidence of an association between...silicone-gel-filled breast implants specifically, and any of the individual CTDs, all definite CTDs combined, or other autoimmune or rheumatic conditions."|
|2000||European Union||European Committee on Quality Assurance & Medical Devices in Plastic Surgery (EQUAM)||"Additional medical studies have not demonstrated any association between silicone-gel filled breast implants and traditional auto-immune or connective tissue diseases, cancer, nor any other malignant disease....EQUAM continues to believe that there is no scientific evidenxce that silicone allergy, silicone intoxication, atypical disease or a 'new silicone disease' exists."|
|2001||Great Britain||UK Independent Review Group (UK-IRG)||"there is no evidence of an association with an abnormal immune response or typical or atypical connective tissue diseases or syndromes"|
|2001||USA||Review for court appointed National Science Panel||The panel evaluated both established and undifferentiated connective tissue diseases and concluded that there was no evidence of an association between breast implants and these CTDs.|
|2003||Spain||STOA Report to the European Parliament Petitions Committee||Regarding new scientific evidence, the currently available information shows that there is not solid evidence linking SBI to severe diseases (such as breast cancer or connective tissue diseases).|
As studies have followed women with implants for a longer period of time, more information has been made available to assess these issues. A 2004 Danish study, reported that women who had breast implants for an average of 19 years were no more likely to report an excess number of rheumatic symptoms than control groups. A large study of plastic surgery patients found a decreased standardized mortality ratio in both breast implant and other plastic surgery patients, but a relatively increased risk of lung cancer deaths in breast implant recipients compared to other forms of plastic surgery. The authors attributed this to differences in smoking rates. Another large study of nearly 25,000 Canadian women with implants recently reported a 43 percent lower rate of breast cancer compared with the general population and a lower-than-average risk of developing cancer of any kind.