Biodurability of retrieved silicone gel breast implants

This study analyzed the shells of single-lumen silicone gel breast implants within the general context of device durability in vivo. The investigation included the major types of gel-filled implants that were manufactured in the United States in a 30-year period. The implants analyzed were Cronin seamed (two explants and one control), Silastic 0 and Silastic I (18 explants and seven controls), and Silastic II (22 explants and 43 controls). The biodurability of the explants was investigated with measurements of the mechanical and chemical properties of the various types of silicone gel control and explanted shells, with implantation times ranging from 3 months to 32 years. The shell properties measured for the controls and explants included the stress-strain relationships, tensile strength, elongation, tear resistance, moduli, cross-link density, and amount of extractable material in the shell. In addition, the mechanical properties of shells that had been extracted with hexane were analyzed for both explants and control implants. The silicone gel explants investigated in this study included some of the oldest explants of the various major types that have been tested to date. For assessment of long-term implantation effects, the data obtained in this study were combined with all known data from other institutions on the various major types of gel implants. The study also addressed the failure mechanisms associated with silicone gel breast implants. The results of the study demonstrated that silicone gel implants have remained intact for 32 years in vivo and that degradation of the shell mechanical and chemical properties is not a primary mechanism for silicone gel breast implant failure.     

Radiolucent prosthetic gel.

The successful use of silicone breast implants is complicated by their interference with mammography. We have evaluated clinically available implant filling materials and found that a new Bio-Oncotic gel approximates the radiolucency of normal breast tissue. Silicone implants completely obscure areas of the breast in mammography. Recently proposed as a filler material, peanut oil is significantly more radiolucent than normal tissue. Physiologic saline solution compares favorably as a tissue-density-simulating substance. However, saline's lack of lubricating properties results in leakage, making it less than optimal. Bio-Oncotic gel is biologically compatible. We conclude that this gel is the most appropriate filler for breast prostheses. Clinical studies are indicated.     

The effect of breast implants on the radiographic detection of microcalcification and soft-tissue masses

Current implants for breast augmentation containing silicone gel, saline, or both can totally obscure mammographic detection of microcalcifications and soft-tissue masses. To investigate the possibility of developing a more radiolucent implant, radiographs were obtained of silicone shells that contained silicone gel, saline, silicone gel and saline, polyurethane-covered silicone gel, gelatin, sunflower oil, and peanut oil. All radiographs were obtained using a Siemens Mammomat by placing the implant over an American College of Radiology mammography phantom. Results were measured by the ability to visualize or resolve the artifacts in the mammography phantom. The silicone shell alone minimally altered artifact resolution. Silicone shells filled with silicone gel, silicone gel and saline, saline alone, polyurethane-covered silicone gel, and gelatin were equal in radiodensity and completely obscured all phantom artifacts. Silicone shells filled with peanut oil and sunflower oil had equal radiodensity and allowed visualization of large microcalcifications and some soft-tissue masses. Current implants used for augmentation mammaplasty can totally obscure mammographic detection of microcalcifications and soft-tissue masses. A more radiolucent breast implant is possible, and further research is needed to define the best filler material and test its biocompatibility.     

Evaluation of the effect of silicone breast inserts on X-ray mammography and breast tomosynthesis images: A Monte Carlo simulation study

PurposeBreast augmentation is one of the most popular cosmetic surgeries worldwide. The aim of this study is to investigate the effect of breast implant insertion on the detectability and visibility of lesions on mammography and breast tomosynthesis (BT) images.Materials and methodsThree software phantoms, composed of a homogeneous background with embedded silicone gel structures, and two types of breast abnormalities, microcalcifications (µCs) and masses, were generated. Two X-ray breast imaging modalities were simulated: mammography and BT with six incident monochromatic X-ray beams with energies in the interval between 20 and 30 keV. Projection images were generated using an in-house developed Monte Carlo simulator. The detectability of mammographic findings adjacent to the implant material and the influence of the incident beam energy and implant thickness on the feature detection were studied.ResultsIt was found that implants thicker than 26 mm for the case of mammography and 14 mm for the case of BT obscured the visibility of underlying structures. Although BT demonstrated a lack of contrast, this modality was able to visualize µCs under considerable depths of implant. Increasing the incident beam energy led to better visualization of small µCs, while in the case of breast masses, their detectability was limited.ConclusionsSilicone gel implants introduce a limitation in the image quality of mammograms resulting in low detectability of features. In addition, silicone gel implants obscure partially or totally parts of the image, depending on the size and the thickness of the implant as well the energy of the X-rays used.     

Textured-surface saline-filled silicone breast implants for augmentation mammaplasty

The earliest silicone breast implants were smooth-surface, silicone rubber devices filled with either silicone gel or saline. Because of persistent problems with capsular contracture, polyurethane-covered silicone implants were developed as an alternative. Particularly in the short run, these alternatives proved highly successful at reducing the incidence of capsular contracture. By 1990, polyurethane-covered implants were rapidly becoming the preferred implant choice of many plastic surgeons, but for legal, regulatory, financial, and safety reasons they were withdrawn from the market by Bristol-Myers in 1991. Meanwhile, during the late 1980s, surface texturing and improved materials became available on other silicone breast implants and expanders. Most studies suggest that textured-surface silicone gel-filled implants, saline-filled implants, and tissue expanders have less frequent capsular contracture than their smooth-surface counterparts.     

The biophysical and histologic properties of capsules formed by smooth and textured silicone implants in the rabbit.

Capsular contracture remains the major complication of reconstructive and aesthetic breast surgery. The purpose of this investigation was to determine if a silicone implant with a textured surface will form a capsule of significantly different biophysical and histologic properties than conventional smooth silicone. Thirty smooth and 30 textured silicone tissue expanders were implanted under the panniculus carnosus of rabbits. After 3 months, measurements related to contracture were performed on anesthetized animals in an investigator-blinded, controlled manner. Intraexpander pressures were measured as saline was injected over time. We found a significant correlation between intraexpander pressures, applanation tonometry, and Baker class. Histology revealed a thicker, more adherent, and inflammatory capsule around the textured silicone implants as compared with the smooth silicone implants. Dynamic pressures were plotted against volume of saline within the two types of implants. Statistical analysis revealed that the textured implants form a tighter and thicker capsule than the smooth implants after 3 months of observation (p less than 0.005).     

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.     

Calcification properties of saline-filled breast implants

Three patients requested explantation of their saline-filled breast implants. Bilateral calcification had occurred in all six implants. Four of the implants were manufactured by McGhan Corporation (Santa Barbara, Calif.), and two, by the Simaplast Company (Toulon, France). All implants had been inserted in the subglandular plane and had been in place for 7 to 23 years. At the time of explantation, patients were 32, 34, and 44 years old. Calcification on the surface of the implants and capsules was analyzed. Implant surface calcification was clinically evident on all six implants, appearing as ivory-colored, tenaciously adherent deposits, only on the anterior surface of the implant. Capsular calcification, which was observed only microscopically, was characterized by poorly organized, irregularly shaped, calcified agglomerates; this calcification also occurred only on the anterior surface of the capsule, adjacent to the area of calcification on the implant. Ultrastructural analysis of scrapings from the implant surface showed large, electron-dense aggregates of crystals, with individual crystals measuring approximately 40 x 10 x 10 nm. In contrast, capsular calcification was characterized by two patterns of deposition, spherulitic aggregates of needle-shaped crystals and areas of metaplastic bone. The individual crystals were approximately 40 x 10 x 10 nm. Energy-dispersive x-ray spectroscopy of specimens from the areas of calcification on the implant and capsule surfaces demonstrated calcium and phosphorus. Electron diffraction of crystals from the implant and capsule surfaces demonstrated the D-spacings characteristic of calcium apatite. There were many differences between the calcification properties of these six saline implants and those of silicone gel implants. For example, mineralization has not been observed on the surface of gel implants, but in these saline implants it occurred primarily on the implant surface. Also, capsular calcification has been observed clinically in gel implants across the surface of the capsule (except at the site of attachment of a Dacron patch), but in this study it was observed only microscopically and was located on the anterior surface of the capsule, adjacent to the area of calcification on the implant. In addition, crystals 100 times larger than those observed on the six saline implant capsules have been observed on the surface of gel implant capsules. A model is presented to explain the mechanism of calcification associated with breast implants and to explain the observed differences between saline-filled and gel-filled implants.     

Characteristics of a population of women with breast implants compared with women seeking other types of plastic surgery

Several previous studies have shown that breast implant patients demonstrate a number of differences compared with the general population. However, studies have not compared patients with breast implants with women receiving other types of plastic surgery, of interest because this latter group has been proposed as a comparison group for assessing the long-term health effects experienced by breast implant patients. Questionnaire data obtained from 7447 breast implant patients and 2203 patients with other types plastic surgery were collected during the course of a retrospective cohort study, to determine whether implant patients demonstrate different characteristics compared with a more restricted group of patients. In contrast to previous investigations that compared implant patients with the general population, distinctive differences with respect to family income, number of pregnancies, alcohol consumption, cigarette smoking, or histories of previous gynecologic operations or operations for benign breast disease were not found. However, implant patients were significantly more likely than other plastic surgery patients to be white, have low levels of education, have early ages at first birth, be thin, and be screened frequently for breast disease. Furthermore, implant patients reported somewhat greater use of exogenous hormones and familial histories of rheumatoid arthritis. These results support the notion that other plastic surgery patients are a more appropriate comparison group than women in the general population for studies of the health effects of breast implants; however, there continue to be distinctive characteristics possessed by breast implant patients, which need to be taken into account in an assessment of what disease effects can be uniquely attributed to silicone breast implants.     

"Bleeding" of silicone from bag-gel breast implants, and its clinical relation to fibrous capsule reaction.

We present evidence of the following. 1. Modern silicone bag-gel breast implants leak silicone gel through the bag. 2. The amount of silicone leaked by an intact implant varies from one implant to another, and is not constant for any type or brand. 3. The leaked silicone, together with fibrous thickening and various degrees of inflammation will be found in capsules surrounding the implants if extensive biopsies are taken and many sections are examined.     

Breast reconstruction using an inflatable breast implant with detachable reservoir

An inflatable breast implant having a detachable filling reservoir is described. Once in position, the implant can be filled under controlled conditions postoperatively. The implant functions either as a tissue expander or as a delayed-filling implant in the initial stages of the procedure. Once the desired breast size is achieved, the reservoir is removed, leaving the filled implant in position. This implant has been used successfully in various types of breast reconstructive procedures, including both primary and secondary reconstruction following modified mastectomy, immediate reconstruction following subcutaneous mastectomy, secondary reconstruction following radical mastectomy combined with the latissimus dorsi flap, and following the removal of silicone gel implants with associated capsular contracture. A total of 23 patients, representing 34 breasts, are reported on. The results have been encouraging over a period of 20 months of follow-up.     

Breast augmentation: choosing the optimal incision, implant, and pocket plane

A retrospective study of 220 patients was performed to review surgical design in breast augmentation. Three specific issues were studied: incision site, implant variables, and pocket plane selection. The influence of these three factors on aesthetic results in both primary and secondary cases was the focus of the analysis. No attempt was made to address long-term issues such as capsular contracture or saline implant deflation rates. In 77 primary augmentation patients and 80 unilateral augmentations for symmetry in breast reconstruction, there were the following untoward results: 11 revisions for unilateral malposition, change to a different implant shape, or change to a larger implant size; four deflations of saline implants requiring replacement; and four conversions of saline to silicone gel implants. In 63 secondary cases, there were two hematomas and two infections requiring implant removal and subsequent replacement. Operative technique in breast augmentation is described, as are recommendations for each of the options associated with the three variables studied.     

Self-reported symptoms among women after cosmetic breast implant and breast reduction surgery

A retrospective cohort study was performed in Sweden to evaluate the possibility that an individual symptom or constellation of illness symptoms related to silicone occurs in women after breast implant surgery. A random sample (n = 2500) of all women in the Swedish national implant registry who underwent breast augmentation surgery with alloplastic breast implants during the years 1965 through 1993 was compared with a sample (n = 3500) of women who underwent breast reduction surgery during the same period, frequency matched to the implant patients for age and calendar year at the time of surgery. In total, 65 percent of the breast implant patients (n = 1546) and 72 percent of the breast reduction patients (n = 2496) completed a self-administered questionnaire covering 28 rheumatologic and other symptoms and lifestyle and demographic factors. Practically all of the 28 symptoms inquired about were reported more often by women in the breast implant cohort, with 16 (57 percent) significantly more common in breast implant recipients. In contrast, few significant differences or consistent patterns were observed in the length of time since the implant and in the type (silicone or saline) or volume of the implant. Although women with breast implants report a multitude of symptoms more often than women who have breast reduction surgery, the lack of specificity and absence of dose-response relationships suggest that the excess of reported symptoms is not causally related to cosmetic implants.     

Long-term health status of Danish women with silicone breast implants

Long-term safety data are important in the evaluation of possible adverse health outcomes related to silicone breast implants. The authors evaluated long-term symptoms and conditions and medication use among 190 Danish women with cosmetic silicone breast implants compared with 186 women who had undergone breast reduction surgery and with 149 women from the general population. Breast implant and reduction surgeries were performed from 1973 to 1988 at one public hospital and one private plastic surgery clinic. Among women with breast implants, the average implantation time was 19 years, 60 percent (n = 114) had only one implantation, and 10 percent (n = 19) had undergone explantation before the time of study (1997 to 1998). The authors found no material differences in self-reported diseases or symptoms among study groups, except for breast pain, which was reported nearly three times as often by women with implants than by women with breast reduction (odds ratio, 2.8; 95 percent confidence interval, 1.4 to 5.3). Approximately 80 percent of women in each study group reported at least one symptom. No consistent differences were observed in the seroprevalences of antinuclear antibodies or other autoantibodies. Self-reported use of psychotropic drugs was higher among women with breast implants than among either control group. The authors conclude that long-term cosmetic breast implantation may cause capsular contracture and breast pain but does not appear to be associated with other symptoms, diseases, or autoimmune reactivity. The authors' finding of excess use of drugs for treatment of depression and anxiety among women with breast implants may warrant further investigation.     

Effect of povidone iodine on silicone gel breast implants in vitro: implications for clinical practice

Irrigation of breast implants and breast implant pockets with various solutions, including povidone iodine, has been a common practice among plastic surgeons for many years. Recent reports of potential weakening of silicone tubing have led the Food and Drug Administration to pronounce any contact of povidone iodine with breast implants a contraindication. An in vitro experimental study was undertaken to assess the effect of povidone iodine on the physical properties of silicone breast implant shells. Identical specimens were obtained from the shells of silicone breast implants according to published standards. The specimens were randomly assigned to eight groups of five and incubated in various solutions of decreasing concentration of povidone iodine (10% to 0.01%), and a control group (0.9% saline) was used. The containers were stored in a warming cabinet at 37 degrees C for 4 weeks. Testing of the specimens for tensile strength following 4 weeks of incubation showed no significant difference among any of the groups, including the control group. In addition, no correlation was shown between the concentration of the solution used and the tensile strength of the specimens.     

The correction of capsular contracture by conversion to "dual-plane" positioning: technique and outcomes

Little has been published regarding the treatment of patients with long-established capsular contracture after previous submuscular or subglandular breast augmentation. This study reviews 7 years of experience in treating established capsular contracture after augmentation mammaplasty by relocating implants to the "dual-plane" or partly subpectoral position. A retrospective chart review was performed on all patients who were treated for capsular contracture using this technique between 1993 and 1999. Data collected included the date of the original augmentation, the original implant location, date of revision and type of implant used, length of follow-up, outcome, and any ensuing complications. Different surgical techniques were used, depending on whether the prior implant was located in a subglandular or submuscular plane. All patients had revisions such that their implants were relocated to a dual plane, with the superior two thirds or so of the implant located beneath the pectoralis major muscle and the inferior one third located subglandularly. Of 85 patients reviewed, 54 had their original implants in a submuscular position and 31 had their initial augmentation in a subglandular position. Of the 54 patients whose implants were initially submuscular, 23 patients (43 percent) had silicone gel implants, 15 patients (28 percent) had double-lumen implants, and the remaining 16 patients (30 percent) had saline implants. Of the 31 patients whose implants were initially subglandular, 20 patients (65 percent) had silicone gel implants, three patients (10 percent) had double-lumen implants, and the remaining eight patients (26 percent) had saline implants. Fifty-one patients (60 percent) had replacement with saline implants (37 smooth saline, 14 textured saline), whereas 34 (40 percent) had silicone gel implants (seven smooth gel, 27 textured gel). The average time from previous augmentation to revision was 9 years 9 months. The average follow-up time after conversion to the dual-plane position was 11.5 months. Only three of 85 patients required reoperation for complications, all of which involved some degree of implant malposition. Of patients converted to the dual plane, 98 percent were free of capsular contracture and were Baker class I at follow-up, whereas 2 percent were judged as Baker class II. There were no Baker level III or IV contractures at follow-up. The dual-plane method of breast augmentation has proved to be an effective technique for correcting established capsular contracture after previous augmentation mammaplasty. This technique appears to be effective when performed with either silicone or saline-filled implants.     

Biocompatibility of radiolucent breast implants

Current implants for breast augmentation containing silicone gel, saline, or both are radiopaque on mammographic examination and can totally obscure microcalcifications and soft-tissue masses. The effect of these implants on the detection of early breast cancers in patients who have undergone augmentation mammaplasty remains unproven and controversial. Implants filled with medium-chain triglycerides (peanut oil) are radiolucent on mammographic examination and allow visualization of both soft-tissue masses and microcalcifications. To investigate the biocompatibility of radiolucent implants, 10 cc of sterile, nonpyrogenic peanut oil was injected subcutaneously into rats using silicone gel as a control. Twenty-one rabbits had two 125-cc silicone shell implants inserted on either side of the chest wall. The right-sided shell was filled with 125 cc of sterile saline, and the left-sided shell was filled with 125 cc of sterile, nonpyrogenic peanut oil. Results were determined by both histologic and radiographic examination. Rats injected with peanut oil equivalent to 7 percent of their body weight rapidly absorbed the freely injected oil without detriment. Histologic examination of the lungs, liver, kidneys, and tissues adjacent to the injection sites demonstrated no abnormalities. There was no evidence of allergic, toxic, inflammatory, or neoplastic response. Eighteen of 21 rabbits survived more than 3 months. Radiographs showed the oil-filled implants to be radiolucent, whereas the saline-filled controls obscured the surrounding soft and bony tissues. Histologic examination demonstrated a fibrous capsule surrounding both types of implants. Histologic examination of the lungs, liver, and kidneys showed no significant abnormalities. These and previous studies have shown peanut oil to be biocompatible when freely injected either intramuscularly or subcutaneously. This study demonstrates that a radiolucent, peanut oil-filled implant is biocompatible in animals and that further long-term studies for its use in humans are merited.     

In vivo aging characteristics of silicone gel breast implants compared to lot-matched controls

A study was conducted to investigate the effect of in vivo aging on the physical, mechanical, and chemical properties of Silastic II gel-filled breast implants. In the study, the properties of 16 Silastic II gel-filled explants (retrieved from eight patients), with in vivo duration times ranging from 4 months to 13 years, were compared with lot-matched control (unimplanted) samples. Tensile and tear strength properties were measured for both explant and control shells by using identical testing protocols. The tensile strength properties of shells, which were extracted with hexane to remove non-cross-linked silicones, were also measured. Swelling measurements were used to determine the average molecular weight between cross-links (or entanglements). In addition, scanning electron microscopy was applied in the comparison of the morphological features of the explants and their lot-matched controls. The results of the study suggest that the silicone polymer used to fabricate the shells does not undergo appreciable degradation for up to 13 years in vivo. The study represents an investigation of the world's largest known inventory of explanted breast implants with lot-matched controls.     

Untreated silicone breast implant rupture

Implant rupture is a well-known complication of breast implant surgery that can pass unnoticed by both patient and physician. To date, no prospective study has addressed the possible health implications of silicone breast implant rupture. The aim of the present study was to evaluate whether untreated ruptures are associated with changes over time in magnetic resonance imaging findings, serologic markers, or self-reported breast symptoms. A baseline magnetic resonance imaging examination was performed in 1999 on 271 women who were randomly chosen from a larger cohort of women having cosmetic breast implants for a median period of 12 years (range, 3 to 25 years). A follow-up magnetic resonance imaging examination was carried out in 2001, excluding women who underwent explantation in the period between the two magnetic resonance imaging examinations (n = 44). On the basis of these examinations, the authors identified 64 women who had at least one ruptured implant at the first magnetic resonance imaging examination and, for comparison, all women who had intact implants at both examinations (n = 98). Magnetic resonance images from the two examinations were compared and changes in rupture configuration were evaluated. Comparisons were also made for self-reported breast symptoms occurring during the study period and for changes in serum values of antinuclear antibodies, rheumatoid factor, and cardiolipin antibodies immunoglobulin G and immunoglobulin M. The majority of the women with implant rupture had no visible magnetic resonance imaging changes of their ruptured implants. For 11 implants (11 percent) in 10 women, the authors observed progression of silicone seepage, either as a conversion from intracapsular into extracapsular rupture (n = 7), as progression of extra-capsular silicone (n = 3), or as increasing herniation of the silicone within the fibrous capsule (n = 1); however, in most cases, these changes were minor. Some changes could be ascribed to trauma, but others seemed spontaneous. There was no increase in levels of autoantibodies during the study period in either study group. Women with untreated implant ruptures reported a significant increase in nonspecific breast changes (odds ratio, 2.1; 95 percent confidence interval, 1.2 to 3.8) compared with women without ruptures. On the basis of this first study of women with untreated silicone breast implant rupture, the authors conclude that implant rupture is a relatively harmless condition, which only rarely progresses and gives rise to notable symptoms. Even so, because of a small risk of silicone spread, the authors suggest that women with implant ruptures be followed clinically, if not operated on. Because implant ruptures often occur asymptomatically, any woman with silicone implants, regardless of rupture status, should be evaluated at regular intervals.     

Label‐free stimulated Raman scattering imaging reveals silicone breast implant material in tissue

Millions of women worldwide have silicone breast implants. It has been reported that implant failure occurs in approximately a tenth of patients within 10 years, and the consequences of dissemination of silicone debris are poorly understood. Currently, silicone detection in histopathological slides is based on morphological features as no specific immunohistochemical technique is available. Here, we show the feasibility and sensitivity of stimulated Raman scattering (SRS) imaging to specifically detect silicone material in stained histopathological slides, without additional sample treatment. Histology slides of four periprosthetic capsules from different implant types were obtained after explantation, as well as an enlarged axillary lymph node from a patient with a ruptured implant. SRS images coregistered with bright‐field images revealed the distribution and quantity of silicone material in the tissue. Fast and high‐resolution imaging of histology slides with molecular specificity using SRS provides an opportunity to investigate the role of silicone debris in the pathophysiology of implant‐linked diseases.