Ultrastructural anatomy of contracted capsules around textured implants in augmented breasts

Advances on Capsular Contracture-Prevention and Management Strategies: A Narrative Review of the Literature

Capsular contracture (CC) is the most relevant complication of both aesthetic and reconstructive breast implant surgery. For many years, experimental and clinical trials have attempted to analyze CC risk factors, clinical features, and appropriate management strategies. It is commonly accepted that a multifactorial etiology promotes CC development. However, the heterogeneity in patients, implants and surgical techniques make it difficult to suitably compare or analyze specific factors. As a consequence, discordant data are present in literature, and a true systematic review is often limited in its conclusions. Hence, we decided to present a comprehensive review of current theories on prevention and management strategies, rather than a specific "solution" to this complication.

Methods

The PubMed database was searched for literature regarding CC prevention and management strategies. Pertinent articles in English, published before December 1, 2022, were compared with selection criteria and eventually included in this review.

Results

Through the initial search, 97 articles were identified, of which 38 were included in the final study. Several articles explored different medical and surgical preventive and therapeutic strategies, showing numerous controversies on appropriate CC management.

Conclusions

This review provides a clear overview of the complexity of CC. The wide variety of clinical situations in term of patients, implants, and surgical techniques prevent the standardization of CC management strategies. By contrast, a patient-customized approach should be preferred, and different strategies should be considered depending on the specific case. Further research is desirable to better ascertain evidence-based protocols with regard to CC prevention and treatment.

Silicone Breast Implant Surface Texture Impacts Gene Expression in Periprosthetic Fibrous Capsules

BACKGROUND

Silicone breast implants with smooth outer shells are associated with higher rates of capsular contracture, whereas textured implants have been linked to the development of breast implant-associated anaplastic large cell lymphoma. By assessing the gene expression profile of fibrous capsules formed in response to smooth and textured implants, insight into the development of breast implant-associated abnormalities can be gained.

METHODS

Miniature smooth or textured silicone implants were surgically inserted into female rats ( n = 10) and harvested for the surrounding capsules at postoperative week 6. RNA sequencing and quantitative polymerase chain reaction were performed to identify genes differentially expressed between smooth and textured capsules. For clinical correlation, the expression of candidate genes was assayed in implant capsules harvested from human patients with and without capsular contracture.

RESULTS

Of 18,555 differentially expressed transcripts identified, three candidate genes were selected: matrix metalloproteinase-3 ( MMP3 ), troponin-T3 ( TNNT3 ), and neuregulin-1 ( NRG1 ). In textured capsules, relative gene expression and immunostaining of MMP3 and TNNT3 was up-regulated, whereas NRG1 was down-regulated compared to smooth capsules [mean relative fold change, 8.79 ( P = 0.0059), 4.81 ( P = 0.0056), and 0.40 ( P < 0.0001), respectively]. Immunostaining of human specimens with capsular contracture revealed similar gene expression patterns to those of animal-derived smooth capsules.

CONCLUSIONS

An expression pattern of low MMP3 /low TNNT3 /high NRG1 is specifically associated with smooth implant capsules and human implant capsules with capsular contracture. The authors' clinically relevant breast implant rat model provides a strong foundation to further explore the molecular genetics of implant texture and its effect on breast implant-associated abnormalities.

CLINICAL RELEVANCE STATEMENT

The authors have demonstrated that there are distinct gene expression profiles in response to smooth versus textured breast implants. Since surface texture may be linked to implant-related pathology, further molecular analysis of periprosthetic capsules may yield strategies to mitigate implant-related complications.

Putative mechanobiological impact of surface texture on cell activity around soft-tissue implants undergoing micromotion

Recent reports of adverse health effects (e.g., capsular contracture, lymphoma) linked to the absence or presence of texture on soft-tissue implants (e.g., breast implants) suggest surface topography may have pathological impact(s). We propose that surface texture influences the transfer of displacements, experienced by an implant undergoing micromotion, to surrounding interfacial extracellular matrix, which in turn impacts the activity of the resident cells and is based on degree of tissue integration. We hypothesize that transfer of displacements due to micromotion promotes interstitial fluid movement that imposes hydrodynamic stresses (pressures, shear stresses) on cells residing in the interfacial tissues and impacts their activity. To address this, we developed a computer simulation to approximate hydrodynamic stresses in the interstitial environment of saturated poroelastic tissues (model soft-tissue implantation sites) generated from oscillatory implant micromotion as a function of the magnitude of translational displacement, direction of motion, degree of tissue integration, and surface roughness of the implant. Highly integrated implants were predicted to generate the highest fluid shear stresses within model tissues, with oscillatory fluid shear stresses up to 80 dyn/cm² for a 20-μm displacement. Notably, application of oscillatory 80 dyn/cm² shear stress to cultured human fibroblasts elicited cell death after 20 h compared to cells maintained under static conditions or exposed to 80 dyn/cm² steady, unidirectional shear. These results indicate that oscillatory interstitial fluid stresses generated by micromotion of an integrated implant may influence the activity of the surrounding cells and play a role in the body's fibrotic response to textured soft-tissue implants.

Histological Analyses of Capsular Contracture and Associated Risk Factors: A Systematic Review

BACKGROUND

Capsular contracture is a severe complication to breast surgery with implants. Previous studies suggest multiple risk factors are associated with capsular contracture, but the etiology is still unknown. We performed a literature review to investigate existing studies on histological analyses of breast implant capsules and how clinical risk factors impact the capsule morphology.

METHODS

The literature search was conducted in PubMed. Studies that performed histological analyses of breast implant capsules were included. Animal studies or studies with a study population of less than five patients were excluded.

RESULTS

Fifty-two studies were included. The histological analyses showed that the breast implant capsules were organized in multiple layers with an inner layer of synovial-like metaplasia which was reported to diminish in capsules with capsular contracture. The remaining layers of the capsule mostly consisted of collagen. The alignment of the collagen fibers differed between contracted and non-contracted capsules, and capsules with higher Baker grade were generally thickest and contained more tissue inflammation. Studies investigating capsules affected by radiotherapy found a more pronounced inflammatory response and the capsules were generally thicker and fibrotic compared with nonirradiated capsules.

CONCLUSIONS

The included studies offer valuable insights into the histological changes caused by capsular contracture and their relation to clinical risk factors. Further studies with larger sample sizes and more strict inclusion criteria are needed to further investigate implant capsules and the role of the synovial-like metaplasia for the development of capsular contracture.

LEVEL OF EVIDENCE III

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 https://www.springer.com/00266 .

Expression of NF-κB-p65 and α-SMA in the Study of Capsules formed by Surface Textured Implants Versus Foam Covered Silicone Implants in a Rat Model

BACKGROUND

We aimed to compare inflammatory and intercellular transcription responses induced by surface textured (ST) implants versus foam covered (FC) silicone implants placed on the dorsal aspect of rats.

METHODS

We utilized 80 female rats of the Wistar lineage. The rats were divided into four subgroups of 20 with one type of implant placed in the dorsum per rat. Analysis was carried out on peri-implant capsules at 90 d and at 180 d post-surgery with microscopic evaluation of inflammatory and immuno-histochemical response of NF-κB-p65 and α-SMA in fibroblasts. This study was carried out at the Evangelical Faculty of Parana and at the Ivo Pitanguy Institute, Brazil in 2015.

RESULTS

The FC exhibited higher levels of acute and chronic inflammation on evaluation in both time frames. The capsule surrounding the ST implants was significantly thicker with well-organized collagen fibres. NFκB-p65 expression in the capsule surrounding the FC implant was more pronounced. There was higher and more significant α-SMA expression in the capsules of the surface textured (ST) silicone implants compared to the foam-covered (FC) silicone implants.

CONCLUSION

Activation of NFκB-p65 plays a key role in the evolution of capsule formation and maintenance of inflammation by regulating the healing process. Similarly, higher and more prolonged levels of inflammation (increased NF-κB-p65 results in increased inflammation) and lower α-SMA (higher α-SMA is protective against capsular contracture) did not directly translate to a thicker capsule and ultimately, capsular contracture in foam covered silicone implants.

Reduced Remodeling Biomarkers Tissue Expression in Nanotextured Compared With Polyurethane Implants Capsules: A Study in Rats

BACKGROUND

In the biological response to biomaterials, the implant shell plays a key role in immune and inflammatory reactions. We hypothesized that the capsules formed around nanotextured implants exhibit an immunohistochemical behavior different to those formed around polyurethane implants.

OBJECTIVES

The aim of this study was to evaluate through immunohistochemistry markers the capsules formed around nanotextured and polyurethane implants.

METHODS

Sixty albino female Wistar rats were divided into 2 groups (nanotextured and polyurethane), with 30 animals in each group. A mini silicone implant was inserted on the back of the animals. After a predetermined period, the animals were killed, and the capsules formed around the implants were studied. The capsules in the 30-, 60-, and 90-day subgroups were analyzed via immunohistochemistry to detect markers for fibroblast α smooth muscle actin (α-SMA), transforming growth factor β (TGF-β), cluster of differentiation 34 (CD34), and CD68, via picrosirius staining to determine the density of type I and III collagen fibers and via hematoxylin and eosin staining to assess capsule thickness. A Wilcoxon-Mann-Whitney test was used to compare the groups, and a Kruskal-Wallis test was used to compare the subgroups.

RESULTS

Lower α-SMA, TGF-β, CD34 and CD68 immunoexpression was observed in the nanotextured 30- and 60-day subgroups than in the corresponding polyurethane subgroups. In the 90-day subgroup, more pronounced α-SMA and CD34 immunoexpression was observed in the nanotextured group; however, TGF-β and CD68 immunoexpression remained lower. The nanotextured implants showed reduced capsular thickness and greater formation of type I collagen in all the analyzed subgroups.

CONCLUSIONS

Nanotextured implants led to reduced immune and inflammatory reactions compared with polyurethane implants according to all analyzed variables.

Comprehensive Comparison Between Shaped Versus Round Implants for Breast Reconstruction: A Systematic Review and Meta-Analysis

BACKGROUND

Prosthetic breast reconstruction has been gaining popularity and a variety of implant options are currently available. Therefore, it is important to evaluate the safety and efficacy of newly developed shaped implants compared with those of conventional round implants. To date, few studies have investigated the outcomes of breast reconstruction with shaped versus round implants.

OBJECTIVES

The present study aimed to comprehensively compare, via meta-analytic methodology, shaped and round breast implant reconstruction in terms of complication profiles and aesthetic satisfaction.

METHODS

PubMed/MEDLINE, Ovid, and Cochrane databases were searched to identify relevant studies presenting the complication rates for shaped and round implant groups. The relative risks of the following complications between the groups were calculated: infection, seroma, capsular contracture, rupture, rippling, reconstruction failure, and implant exchange or removal. Outcomes of aesthetic satisfaction included aesthetic results and patient-reported outcomes.

RESULTS

Meta-analysis of 8 retrospective cohort studies, representing 2490 cases of implant-based breast reconstruction, was performed. There were no significant differences in the risks of infection, seroma, capsular contracture, and reconstruction failure between the 2 groups. The risks of implant rupture and rippling were significantly reduced with shaped implants. In a subgroup analysis of shaped/textured and round/smooth implants, the risk of infection was significantly enhanced in the former, whereas incidences of other complications, including capsular contracture and reconstruction failure, were similar. Aesthetic satisfaction analysis of the 2 groups demonstrated similar outcome scores with favorable overall results.

CONCLUSIONS

Our results suggest that both shaped and round implants might provide favorable breast reconstruction outcomes with similarly low complication rates and aesthetic results.

LEVEL OF EVIDENCE: 4

Thermogel Loaded with Low-Dose Paclitaxel as a Facile Coating to Alleviate Periprosthetic Fibrous Capsule Formation

Medical-grade silicones as implants have been utilized for decades. However, the postoperative complications, such as capsular formation and contracture, have not yet been fully controlled and resolved. The aim of the present study is to elucidate whether the capsular formation can be alleviated by local and sustained delivery of low-dose paclitaxel (PTX) during the critical phase after the insertion of silicone implants. A biocompatible and thermogelling poly(lactic acid- co-glycolic acid)- b-poly(ethylene glycol)- b-poly(lactic acid- co-glycolic acid) triblock copolymer was synthesized by us. The micelles formed by the amphiphilic polymers in water could act as a reservoir for the solubilization of PTX, a very hydrophobic drug. The concentrated polymer aqueous solution containing PTX exhibited a sol-gel transition upon heating and formed a thermogel depot at body temperature. In vitro release tests demonstrated that the entrapped microgram-level PTX displayed a sustained release manner up to 57 days without a significant initial burst effect. Customized silicone implants coated with the PTX-loaded thermogels at various drug concentrations were inserted into the pockets of the subpanniculus carnosus plane of rats. The histological observations performed 1 month postoperation showed that the sustained release of PTX with an appropriate dose significantly reduced the peri-implant capsule thickness, production and deposition of collagen, and expression of contracture-mediating factors compared with bare silicone implants. More importantly, such an optimum dose had an excellent repeatability for the suppression of the capsular formation. Therefore, this study provides a strategic foothold regarding the sustained release of low-dose PTX to alleviate fibrotic capsule formation after implantation, and the microgram-level PTX-loaded thermogel holds great potential as an "all-purpose antifibrosis coating" for veiling the surfaces of various implantable medical devices.

The role of angiogenesis, inflammation and estrogen receptors in breast implant capsules development and remodeling

BACKGROUND

Capsular contracture is the most common complication following breast implant placement. The multiple factors unbalancing the physiological response to the foreign body have not been fully elucidated. The aim of this study was to investigate the role of neo-angiogenesis, inflammation and estrogen receptors in peri-prosthetic tissue development and remodeling.

METHODS

The study enrolled 31 women who underwent expander substitution with definitive implant. Specimens were stained with hematoxylin/eosin, Masson trichrome, immunohistochemistry and immunofluorescence for alpha-smooth muscle actin, estrogen receptor-α (ER-α), estrogen receptor-β (ER-β), Collagen type I and III, CD31 (as a marker of neo-angiogenesis) and vascular endothelial growth factor (VEGF). Inflammatory infiltration was quantified and analyzed. Transmission electron microscopy was performed for ultrastructural evaluation.

RESULTS

Myofibroblasts, mainly localized in the middle layer of capsular tissue, expressed VEGF, ER-α and ER-β. ER-β expression positively correlated with Collagen type I deposition (p= 0.025). Neo-angiogenesis was predominant in the middle layer. CD31 expression positively correlated with Collagen type I expression (p=0.009) and inflammatory infiltration grade (p= 0.004). The degree of inflammatory infiltration negatively correlated with the time from implantation (p = 0.022).

DISCUSSION

The middle layer is key in the development and remodeling of capsular tissue. Myofibroblasts produce VEGF, that induces neo-angiogenesis. New vessels formation is also correlated to the inflammatory response. Collagen deposition is associated with ER-β expression and neo-angiogenesis. These findings may prelude to targeted pharmacologic therapies able to control such interactions, thus hampering the self-sustaining loop promoting the progression of physiologic fibrosis toward pathologic contracture.

Morphologic Features of Magnetic Resonance Imaging as a Surrogate of Capsular Contracture in Breast Cancer Patients With Implant-based Reconstructions

PURPOSE

Capsular contracture (CC) is a serious complication in patients receiving implant-based reconstruction for breast cancer. Currently, no objective methods are available for assessing CC. The goal of the present study was to identify image-based surrogates of CC using magnetic resonance imaging (MRI).

METHODS AND MATERIALS

We analyzed a retrospective data set of 50 patients who had undergone both a diagnostic MRI scan and a plastic surgeon's evaluation of the CC score (Baker's score) within a 6-month period after mastectomy and reconstructive surgery. The MRI scans were assessed for morphologic shape features of the implant and histogram features of the pectoralis muscle. The shape features, such as roundness, eccentricity, solidity, extent, and ratio length for the implant, were compared with the Baker score. For the pectoralis muscle, the muscle width and median, skewness, and kurtosis of the intensity were compared with the Baker score. Univariate analysis (UVA) using a Wilcoxon rank-sum test and multivariate analysis with the least absolute shrinkage and selection operator logistic regression was performed to determine significant differences in these features between the patient groups categorized according to their Baker's scores.

RESULTS

UVA showed statistically significant differences between grade 1 and grade ≥2 for morphologic shape features and histogram features, except for volume and skewness. Only eccentricity, ratio length, and volume were borderline significant in differentiating grade ≤2 and grade ≥3. Features with P<.1 on UVA were used in the multivariate least absolute shrinkage and selection operator logistic regression analysis. Multivariate analysis showed a good level of predictive power for grade 1 versus grade ≥2 CC (area under the receiver operating characteristic curve 0.78, sensitivity 0.78, and specificity 0.82) and for grade ≤2 versus grade ≥3 CC (area under the receiver operating characteristic curve 0.75, sensitivity 0.75, and specificity 0.79).

CONCLUSIONS

The morphologic shape features described on MR images were associated with the severity of CC. MRI has the potential to further improve the diagnostic ability of the Baker score in breast cancer patients who undergo implant reconstruction.

Stealthy role of size-driven stresses in biomechanics of breast implants capsular contracture

Breast Capsular Contracture (BCC) is one of the adverse complications occurring with greater incidence in breast augmentation surgical procedures. Its formation can be interpreted as the conclusive result of the physiological process known as response to a foreign body. From a biochemical standpoint, the formation of the peri-prosthetic capsule is certainly a multifactorial process: many hypotheses concerning its etiology have been suggested in the literature and a number of related pharmacological protocols have been consequently proposed to clinically treat this pathology with the aim to prevent further complications and avoid future re-interventions. However, the vast majority of these theories seems to be only partially supported by clinical outcomes and thus a shared opinion on this matter is still absent among specialists. Within this framework, by starting from clinical observations which highlighted an unexpected correlation between histo-morphological features of fibrotic capsules and overall size of breast implants, the present study investigates the hypothesis that the biomechanical interaction between prosthesis and host tissue may play a crucial role in the biological processes governing the pathological phenomenon at hand. Therefore, to shed light on the underlying mechanisms which could trigger the breast capsular contracture, both simple analytical solutions, in which elasticity and growth are simultaneously taken into account, and more accurate geometrically faithful Finite Element-based numerical simulations have been exploited. The theoretical findings demonstrate that somehow counter-intuitive radial and hoop stress fields occur at the capsula-implant interface in a way such that their combined action, independently from other possible concurrent factors, results significantly amplified for small-size breast prostheses, localized stress peaks in these cases promoting detaching and rippling phenomena actually observed in BCC clinical complications.

Effects of Zafirlukast on Capsular Contracture: Controlled Study Measuring the Mammary Compliance

Capsular contracture is a highly distressing, difficult complication after breast augmentation for both the patient and the surgeon. Although capsular contracture is a multifactorial process, one common denominator in the successful treatment of this complication is believed to be the abatement of inflammation. Leukotriene antagonists have recently emerged as effective prophylactic agents in reactive airway diseases. Anecdotal reports have indicated that zafirlukast (Accolate, AstraZeneca) effectively reverses capsular contracture. A prospective study of capsular contracture in 120 female patients in whom a total of 216 prostheses were implanted was performed. The hardness of capsular contracture was assessed by means of the mammary compliance method (Anton Paar Mammacompliance system). The patients were divided into two groups: patients in group A received zafirlukast for a 6-month period, while those in group B received vitamin E. The results show a significant decrease of the values of breast compliance after 6 months in group A but not in group B and that the variation in compliance after 6 months in group A compared to group B is statistically significant. In zafirlukast-treated patients, we observed a reduction in mammary compliance of 7.69% after 1 month, 16.78% after 3 months and 24.01% after 6 months. The present study suggests that zafirlukast may be effective in reducing pain and breast capsule distortion in patients with longstanding contracture who are either not surgical candidates or who do not wish to undergo surgery.

Silicone Implants with Smooth Surfaces Induce Thinner but Denser Fibrotic Capsules Compared to Those with Textured Surfaces in a Rodent Model

Purpose

Capsular contracture is the most frequent long-term complication after implant-based breast reconstruction or augmentation. The aim of this study was to evaluate the impact of implant surface properties on fibrotic capsule formation in an animal model.

Materials and Methods

Twenty-four rats received 1 scaled down silicone implant each; 12 of the rats received implants with textured surfaces, and the other 12 received implants with smooth surfaces. After 60 and 120 days, rats in each group underwent 7-Tesla Magnetic Resonance Imaging (MRI) and high-resolution ultrasound (HR-US), and specimens of the capsules were acquired and used to measure capsule thickness through histology, collagen density through picro sirius red staining, and analyses of expression of pro-fibrotic and inflammatory genes (Collagen1-4, TGFb1, TGFb3, Smad3, IL4, IL10, IL13, CD68) through qRT-PCR. Furthermore, MRI data were processed to obtain capsule volume and implant surface area.

Results

On day 60, histology and HR-US showed that fibrotic capsules were significantly thicker in the textured implant group with respect to the smooth implant group (p<0.05). However, this difference did not persist on day 120 (p=0.56). Capsule thickness decreased significantly over the study period in both smooth and textured implant groups (p<0.05). Thickness measurements were substantiated by MRI analysis and volumes changed accordingly. Implant surface area did not vary between study dates, but it was different between implant types. On day 60, the density of collagen in the fibrotic capsules was significantly lower in the textured implant group with respect to the smooth group (p<0.05), but again this difference did not persist on day 120 (p=0.67). Collagen 1 and CD68 were respectively over- and under expressed in the textured implant group on day 60. Significant differences in the expression of other genes were not observed.

Conclusion

Silicone implants with textured surfaces led to temporarily thicker but less dense fibrotic capsules compared with smooth surfaces. 7-Tesla MRI and HR-US are capable for non-invasive in-vivo assessment of capsular fibrosis in an animal model and can provide unique insights into the fibrotic process by 3D reconstruction and surface area measurement.

Histological characterization of human breast implant capsules

Background

This study investigated the relationships between histomorphological aspects of breast capsules, including capsule thickness, collagen fiber alignment, the presence of α-smooth muscle actin (α-SMA)–positive myofibroblasts, and clinical observations of capsular contracture.

Methods

Breast capsule samples were collected at the time of implant removal in patients undergoing breast implant replacement or revision surgery. Capsular contracture was scored preoperatively using the Baker scale. Histological analysis included hematoxylin and eosin staining, quantitative analysis of capsule thickness, collagen fiber alignment, and immunohistochemical evaluation for α-SMA and CD68.

Results

Forty-nine samples were harvested from 41 patients. A large variation in histomorphology was observed between samples, including differences in cellularity, fiber density and organization, and overall structure. Baker I capsules were significantly thinner than Baker II, III, and IV capsules. Capsule thickness positively correlated with implantation time for all capsules and for contracted capsules (Baker III and IV). Contracted capsules had significantly greater collagen fiber alignment and α-SMA–positive immunoreactivity than uncontracted capsules (Baker I and II). Capsules from textured implants had significantly less α-SMA–positive immunoreactivity than capsules from smooth implants.

Conclusion

The histomorphological diversity observed between the breast capsules highlights the challenges of identifying mechanistic trends in capsular contracture. Our findings support the role of increasing capsule thickness and collagen fiber alignment, and the presence of contractile myofibroblasts in the development of contracture. These changes in capsule structure may be directly related to palpation stiffness considered in the Baker score. Approaches to disrupt these processes may aid in decreasing capsular contracture rates.

Level of Evidence III

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.

Comparison of the postoperative incidence rate of capsular contracture among different breast implants: a cumulative meta-analysis

Background

A large number of clinical studies have reported that the different materials used in breast implants were a possible cause of the different incidence rates of capsular contracture observed in patients after implantation. However, this theory lacks comprehensive support from evidence-based medicine, and considerable controversy remains.

Objectives

In this study, a cumulative systematic review examined breast augmentation that used implants with textured or smooth surfaces to analyze the effects of these two types of implants on the occurrence of postoperative capsular contracture.

Methods

We conducted a comprehensive search of literature databases, including PubMed and EMBASE, for clinical reports on the incidence of capsular contracture after the implantation of breast prostheses. We performed a cumulative meta-analysis on the incidence of capsular contracture in order from small to large sample sizes and conducted subgroup analyses according to the prosthetic material used, the implant pocket placement, the incision type and the duration of follow-up. Relative risks (RR) and 95% confidence intervals (CI) were used as the final pooled statistics.

Results

This meta-analysis included 16 randomized controlled trials (RCTs) and two retrospective studies. The cumulative comparison of textured and smooth breast implants showed statistical significance at 2.13 (95% CI, 1.18-3.86) when the fourth study was entered into the analysis. With the inclusion of more reports, the final results indicated that smooth breast implants were more likely to be associated with capsular contracture, with statistical significance at 3.10 (95% CI, 2.23-4.33). In the subgroup analyses, the subgroups based on implant materials included the silicone implant group and the saline implant group, with significant pooled statistical levels of 4.05 (95% CI, 1.97-8.31) and 3.12 (95% CI, 2.19-4.42), respectively. According to implant pocket placement, a subglandular group and a submuscular group were included in the analyses, and only the subglandular group had a statistically significant pooled result of 3.59 (95% CI, 2.43-5.30). Four subgroups were included in the analyses according to incision type: the inframammary incision group, the periareolar incision group, the transaxillary incision group and the mastectomy incision group. Among these groups, only the pooled results of the inframammary and mastectomy incision groups were statistically significant, at 2.82 (95% CI, 1.30-6.11) and 2.30 (95% CI, 1.17-4.50), respectively. Three follow-up duration subgroups were included in the analyses: the one-year group, the two- to three-year group and the ≥five-year group. These subgroups had statistically significant results of 4.67 (95% CI, 2.35-9.28), 3.42 (95% CI, 2.26-5.16) and 2.71 (95% CI, 1.64-4.49), respectively.

Conclusion

In mammaplasty, the use of textured implants reduces the incidence of postoperative capsular contracture. Differences in implant pocket placement and incision type are also likely to affect the incidence of capsular contracture; however, this conclusion awaits further study.

Alleviation of capsular formations on silicone implants in rats using biomembrane-mimicking coatings

Despite their popular use in breast augmentation and reconstruction surgeries, the limited biocompatibility of silicone implants can induce severe side effects, including capsular contracture - an excessive foreign body reaction that forms a tight and hard fibrous capsule around the implant. This study examines the effects of using biomembrane-mimicking surface coatings to prevent capsular formations on silicone implants. The covalently attached biomembrane-mimicking polymer, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), prevented nonspecific protein adsorption and fibroblast adhesion on the silicone surface. More importantly, in vivo capsule formations around PMPC-grafted silicone implants in rats were significantly thinner and exhibited lower collagen densities and more regular collagen alignments than bare silicone implants. The observed decrease in α-smooth muscle actin also supported the alleviation of capsular formations by the biomembrane-mimicking coating. Decreases in inflammation-related cells, myeloperoxidase and transforming growth factor-β resulted in reduced inflammation in the capsular tissue. The biomembrane-mimicking coatings used on these silicone implants demonstrate great potential for preventing capsular contracture and developing biocompatible materials for various biomedical applications.

Breast implant capsule flaps and grafts: a review of the literature

BACKGROUND

A breast implant capsule forms as a physiological response to the foreign material. Over the past decades, authors started to consider the breast implant capsule as a new source of tissue, thus describing several capsular flaps and grafts. The aim of this article is to provide an overview of the applications and indications for the use of capsular tissue flaps and grafts in reconstructive and aesthetic surgery.

METHODS

A review of the literature on breast implant capsule grafts and flaps was conducted. The reported surgical techniques were described and compared for indications and complications. The studies were evaluated and compared for number of patients and follow-up.

RESULTS

The search yielded a total of 21 citations. Patient population was reported in 11 studies for capsular flaps and 2 articles for capsular grafts. Between 1997 and 2012, a total of 74 patients underwent surgery with the use of capsular tissue. Among these, 60 patients had a capsular flap (81 %) and 14 (19 %) had a capsular graft. Complications were experienced in 5 patients (6.7 %).

CONCLUSIONS

Capsular flaps and grafts are indicated mainly to address breast implant-related problems. The breast implant capsule represents a versatile and reliable source of tissue for both aesthetic and reconstructive surgery.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266.

The capsular hammock flap for correction of breast implant ptosis

A well-defined inframammary fold (IMF) is essential in providing an aesthetically pleasing and stable result in breast procedures. The position of the IMF on the chest wall determines the "footprint" of the breast, and hence the breast and chest aesthetic as a whole. Implant malposition is reported in the literature to occur in 5-8 % of primary breast augmentation patients. This occurs most commonly in a caudal direction, which is the most difficult problem to correct, as reported by Tebbett (Clin Plast Surg 28:425-434, 2001). Numerous surgical techniques to correct the malpositioned IMF have been described, including periosteal anchorage techniques as reported by Persichetti et al. (Ann Plast Surg 70:636-638, 2013), periareolar approaches that secure the IMF to the rib cage, and superiorly based capsular flaps. Here we describe a novel simple capsular flap technique using the lower anterior capsule, which is divided and formed into an inferiorly based flap and used as a "hammock" to re-establish the IMF and support the implant. As the capsule is made of a compact fibrous shell with a dense collagen network and excellent blood supply, using it as a flap to reposition and maintain the implant is ideal. Previous studies and tests have shown the reliability of capsule-based flap reconstruction due to the capsule's intrinsic strength and good vascularity, as shown by Rubino et al. (Ann Plast Surg 46:95-102, 2001). We describe our series of 12 primary breast augmentation patients with caudal implant malposition who underwent IMF reconstruction and implant repositioning with this technique. We explain our simple and repeatable technique that shows a stable and very durable result in repositioning the IMF and implant, with no recurrence of implant ptosis.

LEVEL OF EVIDENCE V

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.

Local Delivery of Nicotine does not Mitigate Fibrosis but may Lead to Angiogenesis

As with most implanted biomaterials, the wound healing response following implantation of a silicone breast implant leads to the formation of a fibrotic capsule. This can result in capsular contracture, a painful complication that often necessitates the removal of implant. It is well established that nicotine and nicotinic agonists inhibit inflammatory signaling. Based on the link between the inflammatory response and capsule formation, we hypothesized that local delivery of nicotine from the implant may lead to the reduction in inflammation and capsule thickness, which may ultimately reduce the incidence of capsular contracture. Nicotine was loaded into PDMS membranes using a previously established method. The loaded materials were implanted into the submammary pockets between the third and fourth mammary glands of rats. To confirm that the nicotine was acting locally and not systemically, serum cotinine, the primary metabolite of nicotine, was measured by ELISA at 3 days. Thirty days post implantation, the animals were euthanized and the tissue samples were fixed for histological analysis. Blood vessel density was measured immunohistochemically, while the capsule thickness was evaluated microscopically. While the presence of the nicotine metabolite, cotinine, in the serum at the early time points demonstrated that the nicotine was released locally from the devices, there were no significant differences in the capsule thickness between the control and experimental implants. However, the results indicated that there were differences in angiogenesis with the local delivery of nicotine, which may have other implications for the development of biomaterials.

Capsular flaps for the management of malpositioned implants after augmentation mammoplasty

Among the reasons for reoperation after augmentation mammaplasty is the malpositioned implant, especially a lowered inframammary fold or symmastia, which is difficult to repair. The peri-implant capsule, a physiologic response to a foreign body, is naturally formed and suitable for use as a flap because of its high vascularity. In addition, it is sufficiently tough for suspension of the implant. The authors introduce the idea that the capsular flap is very useful for the correction of symmastia or a lowered inframammary fold. In such situations, the capsular flaps are used to prevent migration of the implant after raising of the inframammary fold or defining of the midline with capsulorrhaphy. This technique successfully corrected the malpositioned implants in this study, and all the patients were satisfied. There was no recurrence of a lowered inframammary fold or symmastia. These findings suggest that the capsular flap should be considered a safe and effective option for the management of malpositioned implants.

Modification of cysteinyl leukotriene receptors expression in capsular contracture: follow-up study and definitive results

Periprosthetic capsular contracture represents a specific iatrogenic phenomenon with different side effects. Recently, interesting data have disclosed a potential role of leukotrienes as important mediators of inflammation in the reactivation process of capsular contracture. Some preliminary studies have assessed the efficacy of leukotriene antagonists in the prevention and treatment of capsular contracture. These clinical data are still lacking of a potential biomolecular basis. The aim of our present study was to evaluate the expression of the protein receptor cysteinyl leukotriene receptors (CysLTR). We included 50 patients with severe capsular contracture (Baker III-IV) and a control group consisting of healthy patients who underwent an implant replacement. In both groups, we performed the protein extraction and semiquantitative analysis for the determination of protein concentration on myofibroblasts and macrophages. Western Blot analysis of protein levels shows a significant increase in the expression of CysLTR in patients with capsular contracture. Our final results show that the increase in the levels of mRNA coding for CysLTR actually translates into an effective increase in protein levels of these mRNA transcripts. These findings could at least partially provide a biomolecular basis that justifies the use of specific antileukotriene drugs in the treatment of this disease.

The influence of external ultrasound on the histologic architecture of the organic capsule around smooth silicone implants: experimental study in rats

BACKGROUND

Capsular contracture is the main complication related to breast silicone implants, and its prevention remains a medical challenge. The authors present experimental research examining the effect of external ultrasound on the formation and contracture of peri-implant capsules.

METHODS

In this study, 42 male Wistar rats had a 2-mm smooth surface implant placed in a dorsal submuscular pocket. They then were separated into "ultrasound" and "control" groups that received repeated external applications either with or without the ultrasound power on. Ultrasound applications were given three times a week for a period of 90 days. After that, both groups were housed under the same conditions with no application scheduled. Five animals of each group, killed at 30, 60, 90, and 180 days, had their implants removed along with the capsule, which received a special histologic preparation via annular sectioning that provided wide circumferential observation of the capsular tissue. Sections were stained with hematoxylin/eosin stain, Masson's trichrome stain, and Pricrosirius Red stain for regular microscopic evaluation under normal and polarized light.

RESULTS

Histologic data showed that capsules from the ultrasound and control groups had statistically significant differences. Ultrasound application developed a capsular architecture similar to that shown within textured silicone implants, and its effect had an early definition with subsequent stabilization.

CONCLUSION

The authors conclude that early and repeated external ultrasound application enhances the thickness, cellular count, and vascularity of smooth silicone capsular tissue, whereas it diminishes the pattern of parallel orientation of collagen fibers.

Histologic analysis of zafirlukast's effect on capsule formation around silicone implants

BACKGROUND

The most common complication experienced by patients who have undergone mammary implant surgery is capsular contracture. This matter concerns physicians and patients, but to date, there is no effective way to avoid this complication. Surgical intervention usually is required. In 2002, the use of zafirlukast, a leukotriene inhibitor (a drug used for asthma treatment), was reported for the treatment of capsular contracture, with good results.

METHODS

For this study, 30 female Wistar rats were used. These animals received two silicone implants each: one with a smooth surface and one with a textured surface. All the animals received daily intraperitoneal injections for 90 days and were divided as follows: control group (C) receiving only saline solution, experimental group 1 (E-I) receiving 1.25 mg/kg/day of zafirlukast, and experimental group 2 (E-II) receiving 5 mg/kg/day of zafirlukast. Histologic analysis used hematoxilin and eosin to verify vessels, capsule thickness, and inflammatory cells. Immunoistochemical analysis with smooth muscle anti-actin antibody was used for myofibroblast verification. Picro-Sirius under polarized light was used for collagen analysis.

RESULTS

Textured implant experimental groups presented smaller numbers of vessels, thinner capsules, lower collagen density, and smaller numbers of mastocytes and eosinophils than the control group. No significant differences were found in smooth surface implants, as compared with the control group.

CONCLUSION

Zafirlukast reduced the occurrence of factors directly and indirectly connected with capsular contracture.

An objective assessment of botulinum toxin A effect on superficial skin texture

The botulinum toxin A (BTX-A) role on elimination of hyperkinetic wrinkles is consolidated, although relying on subjective methods of assessment. A prospective open-label study was performed on 10 patients to objectively analyze superficial skin texture changes caused by BTX-A in the glabellar area. Skin areas were reproduced by silicon replica technique at baseline, 1 month, and 6 months after treatment. Takahashi's parameters (roughness, anisotropy, microsulcus number, and width) were obtained from scanning electron microscopy (SEM) analysis and compared using the Wilcoxon signed rank test. SEM images showed skin texture changes, and software analysis gave parameters for statistical analysis, allowing an objective evaluation. Statistically significant parameter modifications were evidenced. BTX-A effectiveness in wrinkle treatment was confirmed, and no differences in skin texture parameters from baseline to toxin action end were noted.

Silsesquioxane nanocomposites as tissue implants

BACKGROUND

Silicone implants are being used increasingly worldwide, especially in breast augmentation procedures. The most common morbidity observed is capsular contracture, which occurs in 15 percent of cases. To overcome this problem, the authors have developed a novel nanocomposite based on polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane (POSS-PCU) for use as tissue implants.

METHODS

These polymers were implanted in six healthy sheep (n = 6) for 36 months and a siloxane served as the positive control. After explantation, these polymers were extracted, as was the surrounding capsule, if any. Attenuated total reflectance Fourier transform infrared spectroscopy analysis was performed to look for signs of surface degradation on the polymers and histopathologic and electron microscopic examinations were performed to study the interaction between the biomaterial and the host environment in greater detail.

RESULTS

After implantation, the authors observed minimal inflammation of the nanocomposite within the sheep model as compared with the siloxane control. Contact angle measurements and fibrinogen enzyme-linked immunosorbent assay tests were then conducted on the POSS-PCU nanocomposite to determine the reason for this behavior. The increased fibrinogen adsorption on POSS-PCU, its amphilicity, and large contact-angle hysteresis indicated that POSS-PCU inhibits inflammation by adsorbing and inactivating fibrinogen on its surface. In complete contrast, the control siloxane in the same setting demonstrated very significant inflammation and degradation, resulting in capsular formation. Naturally, there was no evidence of degradation of the nanocomposite compared with the siloxane control.

CONCLUSIONS

POSS-PCU nanocomposites have enhanced interfacial biocompatibility and better biological stability as compared with conventional silicone biomaterials, thus making them safer as tissue implants.

Explantation of 41-Year-Old Implants Following Primary Breast Augmentation

The long-term affects of primary breast augmentation is a topic of controversy. This case report will highlight the long-term outcome in a woman with Ivalon sponge breast implants and the reasons for explantation. The focus of the manuscript will include mammography, capsular contracture, and late hematoma.

The influence of radiotherapy on capsule formation and aesthetic outcome after immediate breast reconstruction using biodimensional anatomical expander implants

BACKGROUND

Capsular contracture occurs more frequently when immediate breast reconstruction (IBR) is associated with radiotherapy (RT) in a post-mastectomy field. The aim of this study was to investigate the impact of RT on surgical outcome after IBR using a single implant type.

METHODS

One hundred and thirty-six breast reconstructions were studied in 114 patients: 62 reconstructions were performed using submuscular implants alone and 74 had an implant-assisted latissimus dorsi myocutaneous flap using a McGhan 150 biodimensional permanent expander implant. Data were prospectively collected on capsule contracture, geometric measurements, photographic assessments and pain scores. The median follow-up was 4 (range, 2-5) years.

RESULTS

The mean age of the 114 patients studied was 45 (range, 20-77) years. Forty-four reconstructed breasts received RT. Capsule formation was detected in 13/92 (14.1%) reconstructed breasts with no RT and in 17/44 (38.6%) reconstructed breasts with RT. On univariate analysis, RT was the only variable related to capsule formation (p<0.001). Significant differences in geometric measurements of symmetry were identified in patients with capsules compared with those without capsules. Photographic assessments were worse in the capsule group: mean photo score 8 (95% CI 8, 8.5) compared with the no capsule group 6.5 (95% CI 5, 7.5), p<0.001. Persistent pain two years or more after surgery was present in 8/30 patients with capsules and 1/106 with no capsule group, p<0.01. Capsule formation is three times more likely to occur after IBR in association with an RT field. However, as more than 60% of patients do not get capsules despite RT at four years, implant-assisted tissue expansion techniques using a biodimensional device is a viable breast reconstructive option in selected cases.

Capsular Contracture of the Breast

BACKGROUND

Breast reconstruction and augmentation have become a standard surgical treatment worldwide as advancements in medicine and technology enable safer and simpler procedures. A variety of implants is used to mimic a natural breast both in appearance and texture. The most common complication of such procedures is capsular contracture encircling the implant, occurring in approximately 10%. As to date, the contracture is mainly estimated by a physical examination of the breast, which is standardized according to the Baker score.

METHODS

In a cross-sectional study, we compared the clinical assessment of capsular contractures to a radiologic thickness of the capsule, as evaluated by ultrasound (US) and magnetic resonance imaging (MRI). A total of 20 patients, with 27 implants, were evaluated in the study. All patients were examined by a single senior plastic surgeon and divided into 4 groups according to their clinical Baker score estimation. Following, a US imaging of the implant with emphasis on capsular evaluation was performed. The MRI results, recently done prior to the study, were reevaluated in relation to capsular findings.

RESULTS

Thirteen breasts had a clinical capsular contraction with a Baker score of I, 8 breasts with a Baker score of II, and 6 breasts with a Baker score of III-IV. The US and MRI images of breasts graded III-IV revealed a thickened capsule (mean of 2.39 mm by US and 2.62 mm by MRI) compared with the capsular imaging of the breasts with the lower clinical Baker scores (mean of 1.14 mm by US and 1.39 mm by MRI). These differences were statistically significant according to the Kruskal-Wallis test, with P values of 0.002 and 0.017, respectively. Both MRI and US studies revealed distinct appearance of the thickened capsule.

CONCLUSION

It seems the capsular thickness as portrayed by US and MRI correlates well with the Baker scoring system and at the same time provides the physician with an objective and consistent evaluation. However, since clinical assessment can be difficult to interpret at times, objective-imaging modalities can be effectively used to assess capsular thickening in women with a clinical suspicion of capsular contraction. A revised classification of capsular contracture, taking into account the imaging of the capsule, is suggested.

The use of biomedical sensors to monitor capsule formation around soft tissue implants

Piezoelectric sensors have been shown to respond reproducibly to changes in tissue mechanical properties surrounding an implant over a 4-month period. The vibrational amplitude at a frequency corresponding to the radial resonance shows a statistically significant change over time. The initial period of inflammation is marked by a significant reduction in amplitude, which is indicative of an increase in viscous dissipation of the tissue. As collagen displaces the cellular response, the amplitude continues to decrease. Finally, as the tissue matures, the capsule becomes stiffer, and the viscous dissipation lessens. These results are consistent with qualitative assessments of explanted capsules. Strain gauges encased in a monolithic block of silicone exhibited a greater degree of variability, yet show similar trends over time. The strain increases in the initial 4-week period and remains relatively steady over the following 4 weeks. Beyond 8 weeks, the gauges begin to extrude from the animal or suffer a loss of electrical continuity. Steps are being taken to improve the strain sensor longevity in the animals.

Cyto- and histocompatibility of multilayered DNA-coatings on titanium

DNA-containing biomaterial coatings offer potential beneficial effects for both soft and hard tissue implants because of the structural properties of DNA. In the current study, the aim was to assess the in vitro cyto- and in vivo histocompatibility of multilayered DNA-coatings generated using the electrostatic self-assembly technique, with poly-D-lysine or poly(allylamine hydrochloride) as the cationic counterparts of anionic DNA. Multilayered DNA-coatings were fabricated on titanium substrates. Noncoated titanium substrates served as controls. In vitro experiments with rat primary dermal fibroblasts (RDF) assessing their viability were performed using a Live/Dead assay and an MTT-based assay. The presence of multilayered DNA-coatings did not affect RDF cell viability. On the other hand, an increased proliferation was demonstrated on both types of multilayered DNA-coatings. An in vivo rat model was used to study the soft tissue histocompatibility of subcutaneously inserted implants during implantation periods of 4 and 12 weeks. Light microscopic analysis revealed that all implants were surrounded by a fibrous capsule containing alpha-smooth muscle actin, and that the presence of a multilayered DNA-coating did not induce any adverse effects in terms of inflammation and wound healing. Histomorphometrically, no significant differences in capsule quality or thickness were observed dependent on multilayered DNA-coating or implantation period. The cyto- and histocompatibility of multilayered DNA-coatings demonstrated in this study allows their use and functionalization with appropriate compounds to modulate cell and tissue responses in dental and medical implantology.

Electrostimulation: uses and applications for periprosthetic capsular contracture: experimental model

BACKGROUND

Studies have documented an increase in collagen production and acceleration of the scarring process when galvanic electrostimulation of less than 300 mV is used, but the effects of electrostimulation with characteristics different from those usually studied are unknown.

METHODS

Electrostimulators were designed and manufactured specifically for the study. A total of 40 rats were divided into 10 groups, with 4 randomly selected rats in each group. Five groups received smooth implants, and the remaining five groups received textured implants. The first group was designated as the control group, and the remaining four groups received electrostimulation in differing amounts from the 3rd to the 15th postoperative day.

RESULTS

The type of implant used was not a determining factor in the degree of capsular contracture encountered. In the groups that received less than 300 mV, showed greater capsule thickness than the control group. The group that received 600 mV, had a thinner periprosthetic capsule than the control group and all the other groups. All the results were statistically significant.

CONCLUSIONS

Electrostimulation using direct galvanic current with reversal of polarity on postoperative day 3 at intensities of 600 mV inhibits the process of periprosthetic capsular formation in rats.

Capsular Flap for Correction of Contour Deformities of the Breast

We describe a technique in which the breast implant capsule is used to fill localized depressions in the breast, including those under the nipple-areola complex. Capsules have been reported to persist long-term and their high vascularity renders them suitable for use as flaps.

A Prospective Study of Anti-Aging Topical Therapies Using a Quantitative Method of Assessment

BACKGROUND

In the treatment of photoaged skin, glycolic acid works by removing superficial portions of the epidermis and stimulating dermis regeneration. Vitamins A, C, and E should stimulate collagen production and antioxidants should prevent free radical damage and skin aging. However, the effectiveness of different therapies has often relied on subjective methods of assessment. Histologic analysis has seldom been used because of the drawback of permanent scarring. In the literature, the use of a quantitative method for the assessment of facial rejuvenation has been described: the silicone replica technique. The authors' aim was to promote and recommend the use of this technique and, in particular, to test the effect of glycolic acid and multivitamin- and antioxidant-based products on skin texture.

METHODS

The authors performed a prospective, randomized, double-blind, controlled study on 30 women treated topically in the outer canthal region (crow's-feet area). Patients were divided into three groups (groups A, B, and C); each group consisted of five patients between the ages of 31 and 40 years and five patients between the ages of 41 and 50 years. Group A was treated by glycolic acid application, initially at home for 2 weeks, followed by a higher concentration administered in the office weekly for six applications. Group B was treated by topical application at home of a multivitamin product daily for 3 months. Group C was treated with a cream base (placebo) for 3 months and represented the control group. Skin areas under treatment were photographed and reproduced by the silicone replica technique at baseline and at the end of treatment. This technique reproduces exactly the skin's texture. Digital images were obtained from skin replicas and analyzed by specific software for different parameters: roughness, microsulcus number, and width. Pretreatment and posttreatment values were compared using the Wilcoxon signed-rank test.

RESULTS

In group A, microsulcus number and width were statistically decreased, but roughness was not. In groups B and C, parameters were not statistically modified.

CONCLUSIONS

The silicone replica technique allowed a quantitative analysis of results obtained with different topical therapies. In particular, it confirmed the efficacy of glycolic acid in skin rejuvenation.

The effect of seprafilm and interceed on capsule formation around silicone discs in a rat model

The insertion of a foreign substance, such as a breast implant into mammalian soft tissues, evokes a wound healing response that culminates in a dense connective-tissue envelope or capsule surrounding the implant. Several biodegradable products, such as Seprafilm (carboxymethylcellulose and hyaluronic acid) and Interceed (oxidized regenerated cellulose), have been demonstrated to inhibit adhesions in abdominal and gynecologic surgery. The ability of these cellulose compounds to inhibit capsule formation was addressed in this investigation. Twenty-eight rats were implanted intermuscularly with either plain silicone discs (10 animals), discs wrapped in Seprafilm (10 animals), or discs covered with Interceed (8 animals). Additional control animals (6 animals) consisted of two that had sham operations, two animals implanted with Seprafilm only, and two more implanted with Interceed only. Animals were sacrificed in pairs at varying time intervals after implantation (2, 4, 8, 12, and 16 wk), and the tissues around the silicone discs were analyzed with light microscopy. Control animals were sacrificed at 8 wk. Both Interceed and Seprafilm slowed the formation of a capsule around the implanted silicone discs as both products were degraded. Evidence of residual material, presumably Seprafilm and Interceed, was seen intracellularly in animals 3 to 4 mo, respectively, after implantation. However, neither material prevented the eventual formation of a fibrous capsule around the silicone discs. The results of this study suggest that encapsulating foreign substances with these types of biodegradable materials will not significantly hinder capsule formation. A more direct attack on the wound healing mechanism may provide a definitive solution for capsule problems with implanted materials.