Silicone Gel Breast Implants Research Articles

Survival properties of third-generation silicone gel breast implants

Survival properties of third-generation silicone gel breast implants

Variability in the properties of silicone gel breast implants.

Several generations of silicone gel breast implants have been produced by implant manufacturers. The primary material usually viewed as the base material in the manufacture of implants is polydimethylsiloxane. Polymeric reactions are notorious for their variability and nonuniformity. The elastomer used in different types of implants can have vastly different properties. Furthermore, the material properties associated with a particular type of implant can vary considerably from one lot to the next. Considering the various designs, styles, and manufacturing techniques associated with silicone gel implants, knowledge of the original properties of the implants before implantation is important in determining the effects of aging in vivo. This study was conducted to investigate differences in key mechanical and chemical properties of silicone gel breast implant materials. The two types of implants chosen for analysis were Silastic I and Silastic II control implants. Material property data were determined for both types of controls and significant differences were found in their values. Lot-to-lot variability was also investigated and found to be significant.

Breast Implant Research: Where We Have Been, Where We Are, Where We Need To Go

This article summarizes the current state and future needs of research into saline-filled and silicone gel breast implants. The authors describe recent investigations into possible causes and potential risk factors for silicone gel and saline implant failure. Also discussed are local complications of breast implantation and the need for revisional operations in augmentation and reconstruction patients. In addition, the effects that surgical, implant, and patient variables have on the aesthetic outcome of surgery are addressed. The last portion of the article lays out future research needs, such as determining the incidence rate of implant failure, reducing the frequency of revisional surgery, and the difficulty of designing better breast implants in the current strict regulatory climate.

Estudo comparativo entre bobinas de corpo e superfície na mamografia por ressonância magnética de próteses de silicone

Ressonância magnética de mamas de pacientes com próteses mamárias de silicone foi realizada utilizando-se parâmetros técnicos predeterminados, comparando-se bobina de superfície dedicada às mamas e bobina de corpo no mesmo grupo. Foram comparadas 43 próteses mamárias do tipo gel de silicone em 24 pacientes. Observou-se que a relação sinal-ruído obtida pela bobina de superfície foi maior que a obtida pela bobina de corpo. Dobras do elastômero foram identificadas com igual resolução pelas bobinas de superfície e de corpo em cerca de 82% à direita e 95% à esquerda. Apenas em cerca de 5% dos casos as dobras foram visibilizadas utilizando-se exclusivamente a bobina de superfície específica para mamas. Demonstrou-se que o sinal do "linguine" encontrado nas próteses é visto pelos dois métodos praticamente igual. Houve apenas um caso em que o sinal do "linguine" foi visto pela bobina de superfície e não pela bobina de corpo. Evidenciou-se também que boceladuras ou deformidade de contornos podem ser avaliadas com alta concordância, utilizando-se tanto a bobina de superfície quanto a bobina de corpo. Concluiu-se que, embora a qualidade da imagem seja melhor com o uso da bobina de superfície, próteses mamárias também poderão ser avaliadas pela bobina de corpo na ausência de uma bobina específica para mamas, com o mesmo resultado diagnóstico.

Assessing Causation in Breast Implant Litigation: The Role of Science Panels

LAURAL L. HOOPER [*] JOE S. CECIL [**] THOMAS E. WILLGING [***] I INTRODUCTION While the idea of court-appointed experts has been supported by individuals concerned with the courts' ability to assess scientific and technical evidence, [1] it has often been resisted by attorneys and judges who confront such evidence. [2] An increasing number of recent cases, however, suggest that court-appointed experts are gaining acceptance, even though appointments remain rare. [3] Such growing acceptance may be due to the increasingly difficult nature of scientific and technical evidence, [4] or to Justice Stephen G. Breyer's recent endorsement of such experts in General Electric Co. v. Joiner. [5] Moreover, recent programs to aid judges in locating qualified experts who are willing to serve will likely encourage further appointments. [6] Nevertheless, the appointment of such experts remains sufficiently rare that problems are difficult to anticipate. In two recent cases--Hall v. Baxter Healthcare Corp. [7] and In re Silicone Gel Breast Implants Products Liability Litigation [8]--federal judges appointed panels of scientific experts to help assess conflicting scientific testimony regarding causation of systemic injuries by silicone gel breast implants. This article will describe the circumstances that gave rise to the appointments, the procedures followed in making the appointments and reporting to the courts, and the reactions of the participants in the proceedings. It will also offer specific suggestions for improving the use of such panels of appointed science experts. Expert panels may be developed and used in a variety of ways; these approaches illustrate only two forms that such panels may take. Part II offers a brief overview of the silicone gel breast implant product liability litigation and the two cases in which science panels were appointed. [9] Subsequent parts compare the procedures used to select the experts, the instruction of the expert panels in their tasks, the preparation of the panels' reports, the depositions and testimony of the panel members, and the costs of the two programs. Part VIII provides a preliminary assessment of the effect of each program based on the participants' impressions and citations to the reports in related litigation. Finally, Part IX summarizes participants' overall reactions to the two procedures and suggests issues for judges to consider when appointing future panels. II OVERVIEW OF SILCONE GEL BREAST IMPLANT LITIGATION Claims of systemic injuries arising from silicone gel breast implants have presented some of the most complex scientific evidence issues in the federal courts. [10] Following the removal of silicone gel breast implants from the market in 1992 by the Food and Drug Administration, more than 400,000 cases were filed in federal and state courts alleging injuries arising from leakage or rupture of the shell that encased the silicone gel. The most troublesome allegation concerned the extent to which the silicone gel caused or exacerbated connective tissue diseases or immune system dysfunction. [11] Research on these issues was being reported even as the cases were being litigated. [12] Moreover, an assessment of this research required an understanding of several areas of science, including epidemiology, toxicology, immunology, rheumatology, chemistry, and statistics. The emerging nature of this research and differing research methodologies have made such cases among the most difficult ever presented in federal c ourts. [13] The federal courts have responded to this wave of difficult cases by consolidating the cases for pretrial proceedings. In 1992; the Judicial Panel on Multidistrict Litigation transferred all silicone gel breast implant product liability cases filed in federal courts to the United States District Court for the Northern District of Alabama before Chief Judge Sam C. …

Prevalence of rupture of silicone gel breast implants revealed on MR imaging in a population of women in Birmingham, Alabama.

Silicone gel breast implants have been reported to rupture, but the prevalence of implant rupture in an unreferred population of women is not known. The objective of this study was to assess the prevalence of implant rupture and the presence of extracapsular silicone gel in an unreferred population of women without regard to the absence or presence of any local or systemic symptoms. Women identified as part of a National Cancer Institute cohort study on breast implants, living in the Birmingham, AL, area were invited to undergo MR imaging of their current silicone gel breast implants at the Kirklin Clinic at the University of Alabama at Birmingham. Three radiologists independently examined and rated all MR images for signs of implant rupture and extracapsular silicone. A total of 344 women with silicone gel breast implants underwent MR imaging. Breast implant rupture was reported by at least two of three radiologists for 378 (55.0%) of the 687 implants in this study. Another 50 implants (7.2%) were rated as indeterminate (suspicious) for rupture. A majority of women in this study, 265 (77.0%) of 344, had at least one breast implant that was rated as ruptured or indeterminate. Radiologists also agreed that silicone gel could be seen outside the fibrous capsule that forms around the implant in 85 (12.4%) of the 687 implants affecting 73 women (21.2%). Factors that affected implant rupture were implant age and location (submuscular or subglandular). The median implant age at rupture was estimated to be 10.8 years with a 95% confidence interval of 8.4-13.9 years. The prevalence of silent or occult silicone gel breast implant rupture is higher than was previously suspected. Most women in this study had MR imaging evidence of at least one ruptured silicone gel breast implant.

Cosmetic breast augmentation surgery: a critical overview.

Despite the ban on silicone gel breast implants in 1992, the last decade witnessed a dramatic increase in the number of cosmetic breast augmentation procedures performed in the United States. According to the American Society of Plastic Surgeons, over 132,000 women in this country underwent the procedure in 1998. This is an underestimate of the actual number of breast augmentations performed annually, as increasing numbers of nonsurgeon physicians are now performing cosmetic surgery. Given the rising number of women who now seek cosmetic breast augmentation surgery, it is likely that women's healthcare providers will be asked by their patients about breast augmentation. This review is designed to provide an overview of the medical and psychological literature on cosmetic breast augmentation. We begin with a history of breast augmentation, including an overview of the controversy of silicone breast implants and the Institute of Medicine's report on their safety published in 1999. We also discuss the psychological characteristics of breast augmentation patients, reviewing both preoperative and postoperative studies. We conclude with suggestions for future research as well as a discussion of the clinical relevance of this area for women's healthcare professionals.

Ten-Year Review of a Prospective Randomized Controlled Trial of Textured versus Smooth Subglandular Silicone Gel Breast Implants

Ten-Year Review of a Prospective Randomized Controlled Trial of Textured versus Smooth Subglandular Silicone Gel Breast Implants

Silicone gel-filled breast implant integrity: a retrospective review of 478 consecutively explanted implants.

Concern has been expressed over the long-term integrity of silicone gel breast implants. There are no large series representing experience with these implants outside of the United States. A retrospective case note review of explanted silicone breast implants was performed; 478 implants have been explanted during the past 11 years and relate to the use of these devices since 1971. Loss of implant integrity was not simply related to its age in vivo. Failure was more likely with implants of the late 1970s and early 1980s (second generation) and with subpectoral placement. Implant failure was independent of capsular contracture as the indication for removal (p = 0.09). There is no evidence that the currently used textured silicone gel breast implants are subject to the same loss of integrity as previous examples of these devices. The life span of these implants, the first of which are approaching 10 years in vivo, is at present unknown. Information concerning the integrity of silicone gel breast implants is essential in the current climate for counseling of both new and old implant recipients.

Current Status of Breast Implant Survival Properties and the Management of the Woman with Silicone Gel Breast Implants

The survival properties of silicone gel breast implants are dependent on their vintage (year of manufacture), duration in situ and manufacturer. A total of 527 gel implants have been explanted and analyzed in the author's laboratories. Of the 28 first-generation implants (1963 to 1972), 27 (96.4%) remained intact after 14 to 28 years in situ (mean 20.8 years). Of the 216 second-generation implants (1973 to mid-1980s) that were explanted from 1992 to 1998, 158 (73%) had disrupted. Kaplan-Meier survival curves demonstrated significantly different survival properties among second-generation manufacturers. Surgitek implants were by far the least durable. After 14 years, all second-generation Surgitek implants had disrupted. By contrast, after 20 years, about half of the Dow Corning and Heyer-Schulte implants remained intact. Among third-generation implants (mid-1980s to 1992), 43 of 46 (93.4%) remained intact after a mean of 6.3 years (range three to 12 years). The three disruptions were Surgitek implants. Implants from other manufacturers remained intact. However, the disruption frequencies of third-generation implants have yet to be measured over the relevant periods of time. Survival patterns appeared to be related to the thickness of the elastomeric shell of the three generations of implants. Mechanical strength analyses of the elastomeric shells of explants have exhibited little or no large scale material degradation, even after as long as 28 years in situ. The mechanism of implant disruption likely involves the ‘fold flaw’ theory, whereby an internal abrasion can develop over time at the site of a fold in the implant wall. Diagnosis of disruption is difficult. Mammography is helpful only if there has been extravasation of silicone gel into breast tissue. Extravasation was observed in only 4.2% of second-generation implants removed from 1992 to 1998. It was not seen with first- or third-generation implants. Ultrasound analyses are not generally helpful to predict disruption because they are very operator dependent and because capsular contracture causes folds in the implant wall, which result in false positives. Magnetic resonance imaging is the most accurate imaging modality to detect implant disruption. However, this technology is not indicated for monitoring implant status because it is too costly and time consuming, and because it has significant limitations, particularly with first-generation and textured implants. Careful explantation and direct visual examination are the standards for diagnosing gel implant disruption. Many implant disruptions are likely ‘silent’, with no specific symptoms or clinical findings. After disruption, none of the following are elevated above the levels seen in control women without implant exposure: serum autoantibodies, blood and serum silicon, and the incidence of breast cancer, autoimmune disease or any other medical disease. There is no evidence to support the existence of any ‘novel’ or ‘atypical’ syndrome associated with gel implants. Women over 30 years of age with breast implants require regular monitoring for breast cancer detection. This should include monthly breast self examination and annual clinical breast examination. In addition, women over 50 years old require annual eight-view mammographic assessment using the implant displacement technique. Even then, breast implants have been shown to interfere with complete imaging, particularly if the implants are subglandular, large or associated with significant capsular contracture. A logical approach to explantation should involve consideration of a patient's personal concerns and anxiety, her implant vintage, the plane of insertion of her implants, her current clinical status and whether she chooses to replace her gel implants. Women requesting explantation require extensive information before deciding on surgery. At explantation, capsulectomy seems to be indicated if there is capsular calcification or major capsular thickening. (Pour le résumé, voir page suivante)

Current status of breast implant survival properties and the management of the woman with silicone gel breast implants

Current status of breast implant survival properties and the management of the woman with silicone gel breast implants

Effect of surgical insertion on the local shell properties of SILASTIC®II silicone gel breast implants

The reasons for the failure of silicone gel breast implants are unclear. One potential failure mechanism is the weakening of the implant shell during its insertion into the breast. Such local weakening could eventually lead to implant failure. We recently reported on the effect of implant surgery on the overall mechanical properties of SILASTIC®II gel-filled implants. In the earlier study, the mechanical properties of 34 Dow Corning SILASTIC®II gel-filled breast implants from the same manufacturing lot were measured. Twenty of the thirty four implants were not implanted but were evaluated to establish a baseline of control data. The other fourteen lot-matched implants were inserted into a subglandular pocket through an inframammary incision in a cadaver breast and then removed. The experimental augmentation scenario was designed to represent actual breast implantation as closely as possible. The mechanical properties of the anterior and posterior sides of the control implants (not implanted) and explants (implanted in a cadaver) were measured and compared to determine whether differences existed between the explant and control groups. We found that the implantation surgery process did slightly reduce the average tensile strength. Although not as statistically significant, other mechanical properties such as breaking energy and moduli were less for the explants than the controls. The reduction was a relatively small percentage in the context of overall shell properties. Elongation and tear resistance were unaffected. Our findings suggested that the surgical act of implanting a breast implant has a small but detectable weakening effect on the average tensile strength, breaking energy and moduli of the elastomeric shell of the device. The present study is an extension of the previous investigation. Here we have analyzed the explant shell region where the surgeon's fingers forced the implant through the incision. Our results indicate that the implant shell can be locally damaged due to the implantation process.

On the Safety of Silicone Gel Breast Implants

On the Safety of Silicone Gel Breast Implants

On the Safety of Silicone Gel Breast Implants

On the Safety of Silicone Gel Breast Implants

Silicon assays in women with and without silicone gel breast implants--a review.

During the past 5 years, as the failure properties of silicone gel breast implants have emerged, there has been considerable interest in measuring the levels of silicone and silicon in blood, serum, breast milk, and body tissues. Assays have been done in control patients without implant exposure, and in patients with silicone gel implants in an attempt to predict implant failure. Nuclear magnetic resonance measurements of silicone compounds have not been helpful because of their low sensitivity of detection. However, all compounds containing the element silicon, which includes silicone, have been measured accurately. Modern techniques, such as electrothermal atomic absorption spectrometry, direct-current plasma emission spectrometry, and inductively coupled plasma emission spectroscopy have allowed precise measurement of silicon in body fluids and tissues. Using these techniques, recent studies have demonstrated consistent levels of silicon in the blood and plasma of control women without exposure to implants. In one study, plasma silicon was shown to be 140 +/- 10 ng per milliliter. In four other studies, serum silicon levels in control patients were the following: mean, 130 +/- 70 ng per milliliter; mean, 170 +/- 100 ng per milliliter; median, 100 ng per milliliter (range, 30-209 ng per milliliter); and 10 to 250 ng per milliliter. Three independent studies have shown that women with silicone gel implants have higher blood and serum silicon levels than control subjects, but their values were still within the range of control subjects. One study has shown that the mean silicon level in breast milk was not significantly different between 15 implant patients and 34 control patients. The measurement of silicon in control breast tissue has shown consistent results in three different studies, with most tests varying from <0.2 to 2.2 microg per gram dry weight. Three studies have shown that capsules from women with silicone gel breast implants had markedly elevated silicon levels compared with control breast tissue. Median silicon levels varied from 9,980 to 14,390 microg per gram dry weight. There was no significant difference in capsule silicon level between intact and ruptured implants or associated with implant duration in situ or year of implantation. Four studies have shown that capsules from saline implants had elevated levels of silicon compared with control tissue, but their silicon levels were much lower than those of gel implants. The median levels of silicon in the capsules of these studies were as follows: 7.7, 71.5, 198, and 1,100 microg per gram dry weight. Based on current knowledge, because of the large variability among patients, the use of silicon measurements in blood, serum, breast milk, or implant capsule tissue has no clinical role for the effective monitoring of implant leakage in women with silicone gel breast implants.

Analysis of risk factors associated with rupture of silicone gel breast implants.

Despite many recent studies on breast implant rupture, there is no general consensus on causation or incidence. Existing studies have not reported a multivariate analysis of risk factors associated with breast implant rupture. Most studies lack adequate sample size to study the effect of implant type, manufacturer, and other patient-related factors that might affect rupture. This study addresses all of these shortcomings. Patients undergoing implant removal by a single surgeon between 1990 and 1996 were examined for rupture and for 16 potential risk factors. The association between rupture and various factors was analyzed by univariate and multivariate analyses. A total of 842 patients underwent removal of 1619 implants. Increasing age of implant [p < 0.0001; adjusted odds ratio (OR), 1.20; 95% confidence interval (CI), 1.15 to 1.23], retroglandular location (p = 0.0002; OR, 1.93; CI, 1.37 to 2.71), Baker contracture grades III and IV (p = 0.005; OR, 1.52; CI, 1.14 to 2.03), and presence of local symptoms (p = 0.05; OR, 1.37; CI, 1.00 to 1.89) were associated with rupture. When different implant types were compared with smooth gel implants, after adjustment, double-lumen (p < 0.0001; OR, 0.33; CI, 0.22 to 0.50) and polyurethane-covered implants (p < 0.0002; OR, 0.33; CI, 0.20 to 0.57) had significantly lower rupture rates. When various manufacturers were compared with Dow Corning after adjusting for other factors, rupture rates were significantly lower for McGhan (p < 0.0001; OR, 0.41; CI, 0.26 to 0.65), whereas higher for Surgitek (p < 0.019; OR, 1.52; CI, 1.05 to 2.18). Significant risk factors for breast implant rupture were identified: older implants, retroglandular implant location, implant contracture, local symptoms, certain implant type, and certain manufacturer. Although the results of this study are based on a nonrandomized explant population from a single surgeon's practice, knowledge of these risk factors will permit better interpretation of future data on rupture. The knowledge will enable the medical community to better advise their breast implant population regarding durability and appropriate time for removal or replacement.

Analysis of Risk Factors Associated with Rupture of Silicone Gel Breast Implants

Analysis of Risk Factors Associated with Rupture of Silicone Gel Breast Implants

A formal risk assessment of silicone breast implants

In 1992, the United States Food and Drug Administration (FDA) announced that breast implants filled with silicone gel would be available only through controlled clinical studies despite the fact that they had been used for mammoplasty in millions of women around the world for more than 30 years. The safety of silicone gel breast implants had come into question after several reports on a possible association between the implants and subsequent development of connective-tissue diseases. Risk assessment refers to the systematic, scientific characterization of potential adverse effects of human exposures to hazardous agents or activities. The following risk assessment is intended to review the current scientific evidence for the safety of silicone gel-filled breast implants since the FDA’s decision in 1992. There now appears ample evidence from the scientific literature for the safety of these prostheses.

At Law: Science in the Courtroom A New Approach

Judges, legislators, policymakers and often base decisions concerning health risks on evidence and testimony from scientists, physicians, and other experts. Unfortunately, the quality of this information can be questionable and its implications unclear. How are nonscientists to determine which expert presentations provide the strongest basis for law and policy? The controversy over the safety of silicone gel breast implants exemplifies what can go wrong when scientific data on health risks are inadequate and unclear. Since the 1980s, intense effort and immense sums of money have been devoted to resolving the question of whether women with silicone gel implants are more likely to develop connective tissue and autoimmune disorders such as lupus, rheumatoid arthritis, and atypical connective tissue disease. Now, more than thirty years after implants entered the clinical setting and sixteen years after the Food and Drug Administration first notified implant manufacturers that safety data would be required, reasonably clear answers to this question are emerging. The emerging consensus is due in part to innovative approach adopted by several courts handling litigation related to implant safety. The approach draws from two sources. In Daubert v. Merrell Dow Pharmaceuticals, Inc.,[1] the Supreme Court assigned to trial judges a gatekeeper role in determining whether scientific testimony is sufficiently reliable to be admitted into evidence. According to Daubert, judges evaluating the trustworthiness of scientific testimony are to consider several different factors, including whether the scientific claims a party seeks to introduce (1) can be and have been tested, (2) have undergone peer review and publication, and (3) are generally accepted in the scientific community. Judges also are to consider whether the techniques by which those claims were established have a known or potential error rate and are subject to professional standards. The Federal Rules of Evidence allow judges to obtain guidance on the admissibility of scientific evidence from independent scientific experts so that they need not rely solely on experts presented by the adversarial parties. Based on these rules, some federal judges handling breast implant litigation have asked independent scientists to evaluate research that addresses the possibility of a causal relationship between implants and connective tissue and immune disorders. The most influential assessment comes from a National Science Panel appointed in 1996 by Judge Samuel Pointer, who is coordinating pretrial proceedings for implant litigation in the federal courts. In December 1998 the panel concluded that research to date fails to supply evidence of a causal link between implants and connective tissue and immune disorders.[2] Expert Analysis The report is lengthy, systematic, and detailed, but nonetheless clearly written and comprehensible to the nonscientist--essential features of any document that will be used in a legal or policy context. Its four chapters review (1) silicone toxicity studies in animals, (2) studies of immune responses that could lead to health problems in implant recipients, (3) epidemiological data on the possible association between implants and the relevant disorders, and (4) the strength of the association between implants and symptoms that could be related to rheumatic or autoimmune disorders. Each chapter was approved by the whole panel but was primarily drafted by one of the panel's four experts, trained respectively in toxicology, immunology, epidemiology, and rheumatology. Attorneys for the plaintiffs and defendants were permitted to submit forty articles and other documents to each expert, but the panelists performed independent literature searches as well. Extensive references and appendices allow other scientists to evaluate the panel's conclusions. The panelists characterize their report as an analysis of the most rigorous and relevant scientific information currently available. …

A ten-year experience using polyurethane-covered breast implants.

The purpose of this study is to disclose the low incidence (0.98%) of capsular contracture using polyurethane-covered silicone gel breast implants. Four hundred seven surgical interventions were performed during the 10-year period, 404 for hypomastia and 3 for breast reconstruction.