Silicon identification in prosthesis-associated fibrous capsules

Breast Prosthesis Syndrome: Pathophysiology and Management Algorithm

The cosmetic use of devices like prostheses to increase breast volume is nothing new. It is calculated that millions of people have been exposed to silicone in several ways, including breast implants, and since 1964 there has been uncertainty regarding their safety. We did not find in the literature any studies that reported the appearance of a specific immunological disease in patients with silicone breast implants. Furthermore, there are also neither case-control studies nor reports of patients proving that symptoms of autoimmune/inflammatory syndrome induced by adjuvants (ASIA) occurred after the placement of silicone implants nor that the patients had pre-existing symptoms. Several studies link silicone to allergic reactions and the development of systemic autoimmune diseases; however, other studies deny this association. There are currently several theories about the effect of silicone on the body. One theory with greater acceptance proposes an adjuvant effect of silicone on the development of autoimmune diseases in genetically predisposed patients. However, the variety of symptoms occurring in patients who develop these pathologies leads to doubts about the relationship between the adjuvant effects of a silicone prosthesis may have with a specific autoimmune disease or a mix of these diseases. The lack of consensus on this topic obliges a full review of what has already been reported in the literature to integrate the knowledge and propose a focus for new research on this matter. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Adverse reactions to injectable soft tissue permanent fillers

BACKGROUND

Synthetic injectable facial fillers with a permanent effect are widely atoxic and nonimmunogenic, but they differ with respect to composition and in chemical and biologic characteristics. Yet, they all act as foreign bodies in the tissues eliciting a host response that try to remove the gel. Inflammatory nodules may develop at the sites of injection-for some fillers, many years later, for others, not. Why is that?

METHODS

Biopsies were contributed by various plastic surgeons from Europe and Australia after requests were made at international congresses and workshops. The study was based on (a) 5 biopsies from unreactive tissue obtained at different times after injection of polyacrylamide hydrogel (Aquamid); (b) 28 biopsies from intermediate or late inflammatory nodules after injection of polyacrylamide hydrogel (Aquamid) (20 cases), a hyaluronic acid-polyhydroxyethylmethacrylate/ethylmethacrylate gel (Dermalive) (2 cases), and a gel consisting of polylactic acid in mannitol/carbomethoxycellulose (New-Fill) (6 cases); and (c) a review of the literature on adverse reactions after injection with permanent fillers.

RESULTS

Clinically unreactive tissues after injection with Aquamid showed modest or no host reaction. Inflammatory nodules showed an increased foreign body reaction and a bacterial infection after injection with Aquamid, and a combination of moderate foreign body reaction, fibrosis, and in some cases also bacterial infection after injection with Dermalive and New-Fill. According to the literature, inflammatory nodules occur no later than 1 year after injection with polyacrylamide hydrogel, but up to 6 years after injection of combination gels (Artecol), and up to 28 years after injection of silicone gel.

CONCLUSIONS

Inflammatory nodules are likely to be caused by a low-grade infection maintained within a biogfilm surrounding the hydrophobic silicone gel and the combination gels. Aquamid gel may prevent formation of a biofilm through its high water-binding capacity, explaining why late inflammatory nodules are not seen after injection of this polyacrylamide hydrogel product.

The immunopathology of siliconosis. History, clinical presentation, and relation to silicosis and the chemistry of silicon and silicone

Recent evidence confirms the fundamental involvement of the human immune system in the reaction to implantation of silicone-based medical devices. An as yet-to-be particularized epitope of many complex substances sharing siloxane structures is presented through the MHC-II apparatus with development and retention of T cell memory. This memory can be tested for in practical terms using one or more forms of silica, which links the immuno-histopathology and autoimmune attributes of "silicosis" with those of "siliconosis." The lesions of siliconosis are typical of those for persistent antigens and delayed, cell mediated hypersensitivity. The basic descriptive pathology of the reaction to silicone has been known since soon after introduction of silicones in medical procedures, with the exception of some details related to the more recent discoveries on the role of cytokines in the immunopathic process. The clinical consequences of siliconosis are common and can be severe in some individuals implanted with silicone devices.

From cadavers to implants: silicon tissue assays of medical devices

A plethora of data has been used to condemn and defend the role of silicone and its association with "adjuvant disease." In the ongoing attempt to enhance our knowledge, we have chosen to identify tissue silicon levels in patients with saline implants or tissue expanders. We have compared these levels with tissue samples from a variety of patients with and without medicinal silicone devices from both the northeast and southwest United States over a 4-year period. All specimens were harvested by a "no touch" technique, non-formalin fixed, frozen, and shipped to an independent toxicology laboratory for analysis. Inductively coupled plasma atomic emission spectroscopy was used to obtain the tissue silicon measurements. Silicon tissue values in cadaveric tissue (n = 20 cadavers; n = 120 specimens) averaged 2.2 mcg/gm of tissue with undetectable silicon levels in over 50 percent of the specimens (range 0 to 45 mcg/gm; median = 0). Silicon levels surrounding port-a-catheter devices (n = 15 patients; n = 15 specimens) averaged 8.04 mcg/gm of tissue (range 0 to 41 mcg/gm; median = 0). Tissue levels in the capsules surrounding saline (n = 10 patients; n = 22 specimens) and silicone implants (n = 31 patients; n = 58 specimens) averaged 292 mcg/gm (range 0 to 1380 mcg/gm; median = 110) and 1439 mcg/gm (range 0 to 9800 mcg/gm, median = 490), respectively. Tissue levels, however, from distant sites (n = 22 specimens) in these same patients were equivalent to the cadaveric nonaugmented values (average = 3.2 mcg/gm; range 0 to 5.8 mcg/gm; median = 2.7). The results imply that there is a continuum of exposure to silicone medical devices based on the mechanical properties of silicone. The data seem to suggest that there may be a progression of measurable tissue silicon levels based on the amount of environmental or device-related silicone exposure a person has over his or her lifetime. It is our hope that these levels will serve as a baseline for our continuing knowledge of implantable medical devices.

Investigation of silicone oil and fumed silica in an adjuvant animal model

Human adjuvant disease is the label given to a syndrome that resembles a connective tissue disease such as scleroderma and that has been hypothesized to follow augmentation mammoplasty with silicone gel implants or silicone with adulerants. To date, there is no proof that pure silicone is the cause of these symptoms. The cases presented in the literature suggest a comparison to the events seen in the rat adjuvant arthritis model. Male Lew/SsN rats (n = 65) were used. To evaluate both the adjuvant and antigenic properties of the gel implant, variations of the standard Freund's complete adjuvant inoculum were prepared. Tested were the abilities of low molecular weight silicone to act as an adjuvant and for fumed silica to act as an antigen by modifying a rat adjuvant arthritis model to include silicone and fumed silica. On day 0, 0.25 ml of each inoculum was injected intradermally into the plantar aspect of the hindfoot of each rat. The foot diameter was recorded at each time period, compared with the contralateral hindfoot, and normalized to controls at regular time periods over the course of 120 days. Silicone oil did not act as an adjuvant. Furthermore, fumed silica alone did not act as an antigen; however, it is capable of eliciting a reaction that is both delayed and uncharacteristic of the rat adjuvant arthritis model. These results indicate that "human adjuvant disease" may be inappropriate and misleading.

Distribution of organosilicon polymers in augmentation mammaplasties at autopsy

Silicone-containing breast implants have been used since 1963 for cosmetic augmentation and breast reconstruction. Currently, there is intense debate regarding the extent and mechanism of migration of silicone from the area of implant. The current study compares tissue distribution of organosilicon polymers between women with and without silicone breast implants to determine the extent of silicone migration from breast implants. Samples were collected at autopsy from 15 individuals with bilateral breast implants with no known history of chest trauma and from 14 age- and sex-matched controls. Capsule, breast, axillary lymph nodes, abdominal fat, liver, lung, and spleen were collected for analysis of organosilicon polymers by atomic absorption spectrometry and for examination by light microscopy. Blood was collected for analysis of rheumatoid factor and antinuclear antibodies. Silicone was observed microscopically in at least one capsule section from all implant cases and in at least one lymph node in 8 of 15 implant cases. Silicone was not observed in lymph nodes from control cases. Organosilicon polymers were extracted from tissue using heptane, and the silicon content of the extract was quantitated by atomic absorption spectrometry. Silicon was detected in all capsules; statistically significant increases of organosilicon polymers were measured in axillary lymph nodes, breast, and abdominal fat from individuals with silicone breast implants when compared with the nonimplant group. Measurable amounts of organosilicon polymers were found in tissues from the nonimplant group. Suitable blood specimens were analyzed for the presence of rheumatoid factor and antinuclear antibodies. All nine implant cases tested were negative for the presence of antinuclear antibodies. Three implant cases which were tested for rheumatoid factor also were negative. We conclude that organosilicon polymers routinely migrate from the site of breast implantation to regional tissues near the implant site. Tissues from nonimplant cases often contained measurable amounts of organosilicon polymers, and tissue distribution was variable within any single individual: this is consistent with the wide-spread use and form of organosilicon polymers.

Determination of silicon in serum and tissue by electrothermal atomic absorption spectrometry

OBJECTIVES

To employ an electrothermal atomic absorption spectrometry (ETAAS) method with chemical modifiers for the determination of silicon (Si) in serum and tissues.

METHODS

Si was measured in serum of chronic hemodialysis patients, and in fibrous breast capsule tissues following silicone-gel implant removal. Tissue was dried, and digested with concentrated nitric acid prior to analysis. A chemical modifier, which included lanthanum oxide and ammonium phosphate, was used to dilute the serum, and digested tissue samples (1:4) before atomization. Si was determined at 251.6 nm in a graphite fumace using an atomic absorption spectrophotometer.

RESULTS

The method was linear (to 1000 micrograms/L), and precise (CV 5.9% at 281 micrograms/L and 8.4% at 73 micrograms/L). Recovery of Si in spiked serum and breast tissue samples was between 97-104%. Reference values for women on a normal diet and no exposure to silicone implants gave serum Si to 30 to 209 micrograms/L (n = 60), and breast tissue levels of 0.25 to 2.4 micrograms/g dry wt (n = 48). Si in breast capsule from women exposed to silicone breast implants varied from 29 to 496 micrograms/g dry wt (n = 10). Serum Si in hemodialysis patients (n = 53) ranged from 900 to 3300 micrograms/L.

CONCLUSIONS

We conclude that our chemically modified ETAAS method is suitable for Si determination in normal and elevated human serum and tissue specimens.

Silicon tissue assay: a measurement of capsular levels from chemotherapeutic port-a-catheter devices

A plethora of data has been used to condemn and defend the role of silicone and its association with "adjuvant disease." In the ongoing attempt to enhance our knowledge, we have chosen to identify tissue silicon levels (n = 15) in capsules that form around chemotherapeutic port-a-catheter devices, which consist of a metal dome encapsuled by silicone. We have compared these levels with previously established silicon levels in augmented breast capsules, distant tissue sites in these same augmented women, and nonaugmented cadaveric tissues from various geographic locations in the United States. All specimens were harvested by a "no touch" technique, not formalin fixed, frozen, and shipped to an independent toxicology laboratory for analysis. Inductively coupled plasma atomic emission spectroscopy was employed to obtain the tissue silicon measurements. Results demonstrated silicon values ranging from nondetectable in 9 patients to as high as 41 micrograms/gm. These values fell in between our cadaveric (0.5 to 6.8 micrograms/gm) and augmented tissue silicon levels (18 to 8700 micrograms/gm). Although the sample size is small and the power of statistical analysis is low, there was no correlation between the patient's silicon level and age, type of cancer, type of chemotherapeutic agent, radiation therapy, or length of time the port-a-catheters were in place. Although detectable levels of silicon identified around port-a-catheter devices were higher than expected, it is impossible to make any conclusions about these levels and the role of a potential collagen-vascular disease. What we have shown, however, is that silicone breast implants may not be the only medical device that can elevate tissue silicon levels. Our data seem to suggest that there may be a progression of measurable tissue silicon levels based on the amount of environmental or device-related silicon exposure a person has had at a particular time in his or her life. It is our belief that as we identify these tissue silicon levels, they will serve as a baseline and reference for further scientific studies.

Silicon tissue assays: a comparison of nonaugmented cadaveric and augmented patient levels

Tissue silicon assays were performed on 10 nonaugmented cadavers and 25 augmented women to confirm our previous cadaveric data and to establish silicon levels at local and distant sites in augmented women undergoing explant and further reconstruction. All assays were performed by inductively coupled plasma atomic emissions spectroscopy (ICP-AES). Cadaveric tissues were sampled from six sites: liver, spleen, breast, nipple, axilla (soft tissue and nodes), and subcutaneous tissue (abdominal). Augmented women undergoing explant surgery had a portion of their implant capsule, breast tissue, and for those undergoing autogenous reconstruction, a portion of the autogenous donor site or distant tissue sampled. Twenty-four women had silicone implants; one had saline. Results revealed baseline silicon levels in all 10 non-augmented cadavers. These results were equivalent to our previous data, confirming the validity of these baseline data. Silicon tissue levels in the 25 augmented women revealed elevated levels within the implant capsule and surrounding breast tissue. However, silicon levels obtained from distant sites in augmented women were equivalent to the baseline nonaugmented cadaveric levels. There was no correlation between intact or ruptured implants and symptoms of collagen-vascular disease. In conclusion, study validates our original data of baseline silicon levels in nonaugmented cadavers. Contrary to what some may perceive as silicone floating throughout the body, we have found elevated levels around the implant only, and levels at distant tissue sites were equivalent to the baseline cadaveric data.

Silicone breast implants: immunotoxic and epidemiologic issues

Silicone gel implants for breast augmentation and reconstruction have been in use since 1962. Significant local complications include capsular contracture, rupture, gel "bleed", and spread of the implant material to regional lymph nodes (1-7) as well as histologic findings of foreign body granulomas in the capsular tissue and in lymph nodes (7-9). Through magnetic resonance spectroscopy and atomic emission spectroscopy, silicon compounds were found in the blood of some women with silicone breast implants; silicone and silica have also been found in liver (10). Well-publicized case reports have raised significant concerns regarding an association between implants and systemic disease. However, despite the availability of silicone implants for over 30 years, controlled epidemiological studies were not carried out until 1992. Currently available epidemiologic data are extremely limited. In part, because the majority of implants were used after 1981, the incidence of long-term problems is not yet known. In 1992, due to the unavailability of studies demonstrating the safety of implants, the U.S. Food and Drug Administration advised that silicone breast implants should be used only in reconstructive surgery and as part of clinical trials (11). This decision spurred a wave of research on the bioreactivity of silicone and clinical observations of patients with implants. Herein, we review the adverse immune effects following contact with silicone as well as the epidemiologic data available.

Kinetic study of release of silicon compounds from polysiloxane tissue expanders

The release behavior of typical commercial tissue expanders has been examined by carrying out two kinds of experiments: 1) Determination of chemical nature and its modification after in vivo use by X-ray photoelectron spectroscopy for chemical analysis. This study has been paralleled by scanning electron microscopy with associated energy dispersive X-ray analysis of surface, as well as by silicon compounds analysis of tissues around implants. 2) Kinetic examination of silicon compounds released by the biomaterial in physiologic solution at 36 +/- 0.3 degrees C. Results of these investigations have shown independently that the starting material was not a filler-free, pure polymer, but a composite, reinforced elastomer, with the reinforcing agent most seemingly represented by silicon dioxide. Release of latter, with a relatively fast kinetics, is compatible with data of the simulating laboratory runs in the physiologic solution. All these facts seem to rule out any hypothesis of a prevailing siloxane oligomer migration. The correlation of kinetic and physicochemical tests with the in vivo behavior is discussed.

Autoimmune connective tissue disease and connective tissue disease-like illnesses after silicone gel augmentation mammoplasty

Since first reported in 1982, published anecdotal reports have appeared with increasing frequency of patients in whom autoimmune connective tissue diseases developed after mammary augmentation with silicone gel-filled elastomer envelope-type prostheses. Although scleroderma has been reported most often, other diagnoses have included systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, and mixed connective tissue disease. Other patients have ill-defined connective tissue-like illnesses often referred to as "human adjuvant disease." The occurrence of dermatomyositis and polymyositis after silicone breast implants appears to be infrequent. We report two new cases of dermatomyositis after silicone exposure. In addition, a comprehensive review of the literature pertaining to rheumatic disease and silicone gel augmentation mammoplasty is presented to provide some perspective on this highly complicated and controversial subject.

Silicone toxicology

Silicone, a man-made polymer containing the element silicon, has been used in a variety of medical devices including breast implants. Silicone was used, in part, because it was suggested to have the property of biological inertness. Inert materials do not affect chemical, physiological, or immunological processes. Silicone is not inert. Silicone from breast implants "bleeds" through the surrounding envelope and is present in the surrounding capsule or migrates to other distant locations. Silicone and/or the multiple chemical contaminants elicit foreign body reactions associated with granulomatous inflammation and fibrosis. Silicone and its contaminants have the potential for significant toxicity in the implant recipient.

In vivo experimental analysis of silicone implants on bone and soft tissue

We report experimentally produced silicone microparticles (synovitis) in 47 white rabbits and discuss the implications for clinical practice. Silastic HP100 (Dow Corning Wright, Arlington, TN) finger hinges (size 5) were inserted in 20 rabbit's knees. The upper tibia was replaced with Swanson design great toe implants in another 15 rabbits; articular cartilage was removed and endosteal drilling was performed in 6 animals as a "sham" arthroplasty. Small silicone blocks were inserted in the proximal tibial endosteal canal of 6 others. Animals were followed by monthly x-ray films and killed at 2, 4, 6, 12, and 16 months. Implant wear, bone surfaces, and soft tissue were examined under the operating microscope and by light microscopy; implant surfaces were examined with scanning electron microscopy. X-ray changes included reactive endosteal bone formation around implant stems as early as 1 month postoperatively; at 2-3 months the new bone line was clearest but it became progressively homogeneous and less evident. Extensive cortical erosion around the stems was observed in one third of the animals. Neither ossification nor lysis was observed around the silicone block. Proliferative synovitis was found at post-mortem examination beginning after 4 months; femoral condylar erosions were observed in most animals after 12 months. Wherever there was bone destruction, silicone particles were confirmed by x-ray spectrography.

Fine-needle aspiration cytology of silicone granulomas in the augmented breast

We studied 12 aspirates from 10 patients who underwent diagnostic fine-needle aspiration cytology (FNAC) of an augmented or reconstructed breast. Six patients were augmented with silicone gel-filled implants and four patients had silicone liquid injections. FNAC indications included a painful or suspicious mass. Excisional biopsy was performed in six cases after FNAC. The findings of eight cases included modestly cellular smears composed of loosely cohesive histiocytes containing vacuoles of various sizes. Multinucleated foreign body giant cells, fragments of dense, amorphous fibrous tissue, and fibroblast nuclei stripped of cytoplasm were also present. Two patients showed a mixture of inflammatory cells characteristic of intramammary lymph nodes or lymphoid aggregates. We conclude that silicone granulomas of the breast show a characteristic set of findings on FNAC which enable a cytopathologist to render a specific diagnosis given an appropriate history of breast augmentation.

Silicone gel breast implants, breast cancer and connective tissue disorders

Recent worldwide media speculation that silicone gel-filled breast implants may be linked to an increased incidence of breast and other cancers, and connective tissue disease (particularly systemic sclerosis) has caused concern to the medical profession and public alike. Until carefully controlled studies have been performed to prove the safety of these implants, the US Food and Drug Administration has restricted their use to research and breast reconstruction. Research has so far failed to prove a causative relationship between silicone implants and cancer or connective tissue disorders.

Development of an animal model for testing human breast implantation materials

Although breast implant materials have been tested in laboratory species since the early 1950s, a standardized evaluation system does not currently exist in which human-made polymers are exposed directly to the mammary milieu of female animals. The present study evaluated such a model as the basis for future experiments on long-term tissue effects. Polyesterurethane disks, 6 mm in diameter x 3 mm thick, were inserted bilaterally beneath the axillobrachial and inguinal mammary/fat pads of 50 9-wk-old female B6D2F1 mice (4 implants each). Implant sites were examined histologically at time points 24 hr to 47 wk after surgery. An acute inflammatory reaction at the implant edges began within 24 hr, and macrophages were found lining the smooth polyurethane fiber surfaces at the periphery by day 2. Multinucleated foreign body giant cells formed by day 4, and by week 4 giant cells contained polyurethane fragments within the cytoplasm, implying degradation of the material. Implant sites showed declining subacute inflammatory responses and increasing fibrosis by week 5. By 13 wk, the polyurethane disks appeared to be integrated into the growing adipose and mammary tissues. Although not apparent on gross inspection, microscopic examination showed that polyurethane fibers moved progressively into adjacent tissues and were always associated with chronic granulomatous inflammation. Histologic findings in the present study are strikingly similar to the human response to polyurethane-coated breast implants. These results suggest the applicability of this model to appropriately test mammaplasty materials in mammary tissues.

Pathologic fractures: a complication of microparticulate synovitis

We report seven cases of pathologic fracture in adult patients that were seen an average of 5 years (range from 33 to 114 months) after silicone wrist (three) and trapezial (four) arthroplasty. All patients had initially done well after their operation. At return, all had radiographic evidence of generalized implant and intramedullary bone destruction, the latter always including endosteal scalloping and widening from cortical resorption. These radiographic changes may be less striking than the discrete osteolytic lesions seen after degeneration of carpal implants. Our patients represent examples of pathologic fracture as the end stage of untreated microparticulate synovitis, a consequence of prosthetic wear. Our experience suggests that careful and continuous follow-up justified after insertion of stemmed silicone implants, and that patients should be informed of the potential late complications of this procedure, including pathologic fracture.

Reactive synovitis after silicone arthroplasty

A number of patients with silicone rubber implants performed by us and other surgeons initially had excellent results; however, they returned with swelling and discomfort. We studied 18 patients ranging in age from 16 years to 57 years who presented 8 to 78 months (average, 31.7 months) after silicone arthroplasty (four scaphoid, six lunate, one scapholunate, four finger, two wrist, one trapezium, and one ulnar head for metacarpal hemiarthroplasty). Erosive osteolysis was seen on x-ray films, with progressive destruction evident in patients followed serially. None of the patients' conditions responded to conservative care. The severity of the proliferative, inflammatory synovitis and the foreign material in the multinucleated giant cells correlated with the interval since arthroplasty. Implant surface analysis by scanning electron microscope and x-ray spectrometer showed that silicone microparticles were the result of implant degeneration and erosion. All joint cultures were negative. Silicone particulate synovitis and destruction were arrested by the removal of the implant, a synovectomy, and curettage of the lytic lesions at salvage (resection arthroplasty or arthrodesis). Patients who have had silicone arthroplasties should be followed indefinitely, at regular intervals, by x-ray films and clinical examination.

Silicone granulomas: report of three cases and review of the literature

Since silicone is rapidly becoming one of the most commonly used biomaterials in modern medicine, pathologists will be observing increasing numbers of cases of silicone-related disease. Although numerous case reports have established that silicone elicits a characteristic response in tissues, the varying tissue reactions to silicone gels, liquids, and elastomers (rubber) have not been emphasized. Three cases are reported, and the literature is reviewed to illustrate the varying features of tissue reaction to silicone in its different forms. The first case is an example of silicone lymphadenopathy in an inguinal lymph node. This case demonstrates exuberant foreign body granuloma formation in response to particles of silicone elastomer. The second case involves a patient who had facial subcutaneous liquid silicone injections, and the third case is that of a woman in whom breast carcinoma developed 13 years after mammary augmentation with liquid silicone injections. These two cases illustrate the characteristic reaction to silicone liquid, with numerous cystic spaces and vacuoles in the soft tissues but minimal or no foreign body giant cell reaction. Scanning electron microscopy and energy dispersive x-ray analysis were performed in the first two cases, confirming the presence of silicon. Silicone migration and the clinical significance of various silicone-induced lesions are discussed.

Silicone synovitis of the wrist

Foreign body giant cell synovitis and focal bony destruction requiring secondary surgery developed in nine patients after carpal and radiocarpal arthroplasty with silicone rubber implants. Synovitis followed silicone rubber replacement of the lunate in four patients, the carpal scaphoid in two patients, and the trapezium in one patient, trapezial resurfacing hemiarthroplasty in one patient, and total wrist arthroplasty in one patient. All the removed implants were deformed. Some had changed in color from clear white at the time of insertion to yellow-white or deep yellow upon removal. Scanning electron microscopy of a silicone rubber implant of the lunate removed from one patient revealed extensive fibrillation in the capitate fossa. Light microscopy of the synovium revealed hyperplasia and hundreds of fragments of silicone particulate debris throughout the tissue adjacent to the implant. The silicone debris was surrounded by multinuclear foreign body giant cells in the eight patients from whom the synovium was studied. All patients required revision surgery. We believe that in the patients studied, synovitis represented a biologic reaction to the silicone fragments found scattered throughout the synovium for the following reasons: The synovitis found was not present before surgery (except in the patient with rheumatoid arthritis); the synovitis found was not associated with the condition for which replacement arthroplasty was performed (except in the patient with rheumatoid arthritis); synovitis subsided after implants were removed; and synovitis was noted histologically in areas of silicone debris and appeared directly related to silicone seeding. Fibrillation, fragmentation, and local seeding of silicone after carpal or radiocarpal arthroplasty appear related to gradual deformation of the implant, which was the result of repeated compressive loading and shearing. Clinically significant complications of rubber carpal or radiocarpal arthroplasty with silicone rubber implants may develop from silicone synovitis.

Development of topical BAPN delivery system for acute spinal cord injury in dogs

Topical sustained release of various medications by a subdurally implantable device at the site of spinal cord injury is considered advantageous in the treatment of early symptoms of tissue damage. A typical case is the interference with collagenous scar by beta-aminopropionitrile, inhibiting collagen polymerization. Four materials, silicone, polyethylene, polytetrafluoroethylene (PTFE), and polyacrylonitrile-based hydrogel were evaluated for biocompatibility in subcutaneous implantations. The hydrogel, the least reactive, was then compared with silicone sheets as subcural implants. The histology favored the hydrogel as the most inert material, which was then used for the construction of soft, pliable pouches, releasing the drug through the hydrated wall at a rate controlled by an osmotic pump.

Transmission electron microscopic identification of silicon-containing particles in synovial fluid: potential confusion with calcium pyrophosphate dihydrate and apatite crystals

Silicon-containing particles were identified by transmission electron microscopy (TEM) in thin sections of two synovial fluids, which also contained calcium pyrophosphate dihydrate (CPPD) crystals, aspirated during acute attacks of pseudogout. Such particles, which are interpreted as probably being artefacts from glassware, were electron dense and similar in appearance to some CPPD or hydroxyapatite crystals.

A comparison of capsule formation following breast augmentation by saline-filled or gel-filled implants

A retrospective analysis of data on 307 patients was made. The incidence of firmness in breasts augmented by saline-filled prostheses was compared to the incidence in breasts augmented by gel-filled prostheses. A statistically significant lower rate of constricting capsule formation was found in the saline-inflated group.

Clinicopathologic correlations in pseudocapsule formation after breast augmentation

In 2,000 patients who underwent augmentation mammoplasties with different types of prostheses, the thickness of the pseudocapsules around gel-filled implants was greater than that of the pseudocapsules forming around inflatable implants. This observation was corroborated by an independent histologic study. Deposition of liquid silicone into the pseudo-capsules as well as the adjacent breast tissue and migration into capillaries was demonstrated. Until an impermeable shell or a non-transgressive gel can be manufactured, gel-filled implants should not be used.

The presence of silicone in breast capsules

The presence of silicon-containing compounds in the capsules of women undergoing secondary surgical procedures has been identified by energy dispersion X-ray analysis. The birefringence and surface configuration qualities have been examined by polarized light-microscopic and electron-microscopic methods. The data indicate that silicone polymer (polydimethyl siloxane) is present both within cells and in the intercellular matrix of the capsule; the source of this material is the silicone gel-filled implant. A histiocytic and foreign-body giant-cell response was found to be associated with the silicon-containing compounds. It remains conjectural whether this chronic response is associated with the pain present in significant breast capsule formation.

Molecular microanalysis of pathological specimens in situ with a laser-Raman microprobe

A laser-Raman microprobe has been used to identify microscopic inclusions of silicone polymer in standard paraffin sections of lymph node. This example of organic chemical microanalysis in situ in pathological tissue represents an extension of microanalytical capabilities from elemental analysis, performed with electron and ion microprobes, to compound-specific molecular microanalysis.

Foreign material in the capsules around breast prostheses and the cellular reaction to it

Thirteen capsules which had formed around breast prostheses were examined, using the technique of splitting the capsule wall. A foreign material in droplet form was present in all the capsules. The foreign material was taken up by phagocytes, and the cytological evidence is that it has cytotoxic activity. It was shown that the material migrates to the vessels in the outer layer of the capsule and may reach the lumen of those vessels. On the basis of the microscopic appearance and the results of infrared spectrum analysis, the foreign material in the capsules was assumed to be silicone.