Systematic review of the effectiveness of polyurethane-coated compared with textured silicone implants in breast surgery

Polyurethanes and Their Biomedical Applications

The tunable mechanical properties of polyurethanes (PUs), due to their extensive structural diversity and biocompatibility, have made them promising materials for biomedical applications. Scientists can address PUs' issues with platelet absorption and thrombus formation owing to their modifiable surface. In recent years, PUs have been extensively utilized in biomedical applications because of their chemical stability, biocompatibility, and minimal cytotoxicity. Moreover, addressing challenges related to degradation and recycling has led to a growing focus on the development of biobased polyurethanes as a current focal point. PUs are widely implemented in cardiovascular fields and as implantable materials for internal organs due to their favorable biocompatibility and physicochemical properties. Additionally, they show great potential in bone tissue engineering as injectable grafts or implantable scaffolds. This paper reviews the synthesis methods, physicochemical properties, and degradation pathways of PUs and summarizes recent progress in applying different types of polyurethanes in various biomedical applications, from wound repair to hip replacement. Finally, we discuss the challenges and future directions for the translation of novel polyurethane materials into biomedical applications.

Long-term Insights: Histopathological Assessment of Polyurethane Implant Capsules Over 24 Years

BACKGROUND

Polyurethane (PU)-coated breast implants are known for their strong integration into breast tissue and the formation of capsules around them. However, capsular contracture can pose both aesthetic and clinical challenges.

OBJECTIVES

The objectives of this study were to analyze the biological and morphological characteristics of the capsular tissue surrounding PU-coated implants, irrespective of their contracture status, and to assess their potential suitability as a flap in revisional breast surgery for capsular contracture.

METHODS

A total of 23 tissue samples were harvested from the capsules surrounding PU-coated breast implants in 12 female patients during replacement or revisional surgery. We evaluated collagen abundance, cellular and vascular density, inflammation, collagen band types and alignment, synovial metaplasia, capsule thickness, and the expression of inflammatory biomarkers and myofibroblasts with immunohistochemical techniques. Scanning electron microscopy was employed to assess implant surface characteristics over time.

RESULTS

We found a significant association of capsule contraction with longer implantation durations and greater implant surface roughness (P = .018 and P = .033, respectively). Synovial metaplasia was significantly more frequent in noncontracted capsules (P = .0049). Both capsule types consisted of paucicellular, type I collagen-rich compact fibrous tissue with low vascularization. There was a marked reduction in inflammatory cells within the foreign body granuloma. The expression of inflammatory biomarkers in the capsular tissue was negligible.

CONCLUSIONS

Given the reduced levels of inflammatory and vascular components within the dense, fibrous capsular tissue, we consider them to be viable alternatives for capsular flaps in revisional surgery. This strategy has the potential to mimic the reconstruction achieved with acellular dermal matrix.

LEVEL OF EVIDENCE: 4

Polyurethane Implants in Revisional Breast Augmentation: A Prospective 5-Year Study

BACKGROUND

Revisional surgery for aesthetic breast augmentation remains a challenging procedure. Polyurethane (PU) implants have been found to avoid capsular contracture recurrence as well as to prevent implant displacement by bio-integrating with the pocket.

OBJECTIVES

Our study aimed to assess the use of PU implants in breast revisional surgery and to provide an algorithm.

METHODS

Over a 5-year period, a prospective study was conducted involving consecutive patients undergoing implant revision. Patient demographics, previous breast procedures, and specific surgical details were documented. Postoperative outcomes were followed up.

RESULTS

Out of 92 patients (184 breasts), 78 (156 breasts) were included in the analysis. The average age was 47.5, with a BMI of 22.3 and a mean follow-up of 5 years. A majority (63%) represented secondary revisional cases, while 37% were tertiary cases. Implant size averaged 296 cc, with 53% placed in retropectoral position and 47% prepectoral. Significantly more implants in secondary cases were changed from prepectoral to retropectoral (P = .005), and in tertiary changed from retropectoral to prepectoral (P = .002). Complete capsulectomy was performed in 61.5% and partial in 25.6%. Additional lipofilling was performed in 32%, and concurrent mastopexy in 40%. Revisional surgery in our series had a 1.9% acute complication rate, 4.5% longer-term reoperation rate for corrections, 0.6% implant exchange rate, and no recurrent capsular contracture.

CONCLUSIONS

This is the first study to provide data on outcomes of revisional breast augmentation surgery with PU implants. It shows that polyurethane implants offer consistent stability and have low rates of recurrent capsular contracture in revisional surgery.

LEVEL OF EVIDENCE: 3

Impact of polyurethane versus acellular dermal matrix coating on prepectoral reconstruction outcomes: Interface does matter

BACKGROUND

Interfaces continue to be used in prepectoral breast reconstruction to refine breast appearance, but more clinical data are required to assess their effectiveness. This study compares the rates of capsular contracture, breast esthetics, and patient satisfaction between two commonly used interface materials, acellular dermal matrix (ADM) and polyurethane (PU) foam.

METHODS

A cross-sectional assessment was conducted on all patients who underwent prepectoral direct-to-implant reconstruction with an interface material between June 2018 and June 2022. We compared capsular contracture rates (assessed in-person), esthetic outcomes (evaluated by a three-member panel using a specially designed scale), and patient satisfaction (measured using the Breast-Q questionnaire) among the members of the interface groups.

RESULTS

Among the 79 reconstructed breasts (20 bilateral cases), 35 were reconstructed using ADM and 44 using PU implants. The ADM group had a significantly higher frequency of Baker III/IV capsular contracture compared with the PU group (14.3% vs. 0%, p = 0.014) and lower ratings from the panel in terms of capsular contracture (median 3.7 vs. 4.0, p < 0.001). PU reconstructions scored worse in implant visibility (median 2.3 vs. 3.3, p < 0.001) and rippling (median 3.0 vs. 3.7, p < 0.001). However, after appropriate adjustment for confounders, no significant differences in overall appearance and patient satisfaction were found.

CONCLUSIONS

ADM reconstructions are prone to capsular contracture with all their related esthetic issues, but PU implants have certain cosmetic flaws, such as implant visibility and malposition. Since each technique has its own limitations, neither the experienced surgeons nor patients exhibited a clear preference for either approach.

Nonadherence of Polyurethane Implants: A Retrospective Cohort Study

Background  Biointegration of polyurethane (PU) implants providing their stable position years after surgery ensures predictable results of breast augmentation and reconstruction almost eliminating implant factor as a cause of complications. However, in rare cases PU implants appear to be not connected to the surrounding tissues. The aim of the study was to determine the incidence of PU implant nonadherence after primary breast augmentations and augmentation mastopexies with dual plane implant position, to analyze possible causes, and to propose preventive measures and treatment possibilities of this complication. Methods  The results of primary aesthetic surgeries in 333 patients with dual plane PU implant placement were analyzed. Patients were evaluated clinically, and pictures and videos taken in different periods after the surgery were compared. Particular attention was given to the changes in implant position and the appearance of asymmetries over time. Results  PU implant nonadherence was found in seven patients. It can be divided into primary and secondary and may be complete or partial. Primary nonadherence was found in two cases (0.6%), and secondary in five (1.5%) cases. Possible influencing factors could have been traumatic surgical technique, seroma, hematoma, or physical trauma. The average follow-up was 33 months (1 month-15 years). Conclusion  Biointegration is mandatory for the long-term predictable results with PU implants. PU implant nonadherence leads to implant malposition and may cause typical complications connected to non-PU implants. Improvements in surgical maneuvers, manufacturing process, and weight reduction of the implant may be beneficial for the stability of the results. Level of Evidence  V.

Biocompatibility of polyurethane-coated breast implants: A histological comparison of implant capsules

BACKGROUND

Biocompatibility describes the influence of materials on their biological environment. Implant material in the human body can cause a foreign body reaction and the formation of a capsule around the foreign material. Since capsular formation is the most frequent issue after breast-implant insertion, knowledge and awareness of biocompatibility is crucial, especially since worldwide, breast augmentation continues to be the most popular plastic surgery, with over 1.6 million procedures performed in 2020, according to surveys by the International Society of Aesthetic Plastic Surgery (ISAPS).

MATERIAL AND METHODS

This study includes 80 capsular samples of female patients who underwent revision surgery after breast-implant insertion at the University Hospital Regensburg. Capsules of breast implants with different surface structures (smooth, textured and polyurethane-coated) and shapes (round-shaped, anatomically-shaped) were analyzed histologically after hematoxylin-eosin-staining in respect to capsular thickness and layer formation.

RESULTS

Capsular thickness and layering showed a statistically significant difference between polyurethane-coated and smooth as well as polyurethane-coated and textured implants. Capsules around polyurethane-coated implants presented greater thickness. However, the difference between smooth and textured implants was not statistically significant. Furthermore, the shape of the implants also indicated a statistically significant difference in capsular thickness. Implants of anatomical shape resulted in a thinner capsule than round-shaped breast-implants.

CONCLUSION

In conclusion, this study demonstrated a thicker capsule around polyurethane-coated breast implants and no difference in capsular thickness between smooth and textured breast implants. Anatomically shaped breast-implants presented a thinner capsule than round shaped breast-implants.

Oral formulation of Wnt inhibitor complex reduces inflammation and fibrosis in intraperitoneal implants in vivo

The use of implantable biomaterials to replace physiological and anatomical functions has been widely investigated in the clinic. However, the selection of biomaterials is crucial for long-term function, and the implantation of certain biomaterials can cause inflammatory and fibrotic processes, triggering a foreign body reaction that leads to loss of function and consequent need for removal. Specifically, the Wnt signaling pathway controls the healing process of the human body, and its dysregulation can result in inflammation and fibrosis, such as in peritoneal fibrosis. Here, we assessed the effects of daily oral administration of a Wnt pathway inhibitor complex (CD:LGK974) to reduce the inflammatory, fibrotic, and angiogenic processes caused by intraperitoneal implants. CD:LGK974 significantly reduced the infiltration of immune cells and release of inflammatory cytokines in the implant region compared to the control groups. Furthermore, CD:LGK974 inhibited collagen deposition and reduced the expression of pro-fibrotic α-SMA and TGF-β1, confirming fibrosis reduction. Finally, the CD:LGK974 complex decreased VEGF levels and both the number and area of blood vessels formed, suggesting decreased angiogenesis. This work introduces a potential new application of the Wnt inhibitor complex to reduce peritoneal fibrosis and the rejection of implants at the intraperitoneal site, possibly allowing for longer-term functionality of existing clinical biomaterials.

Comparing Polyurethane and Acellular Dermal Matrix Implant Cover in Prepectoral Breast Reconstruction: Short-term Complications

Implant covering with an interface material is the standard in prepectoral breast reconstruction. Acellular dermal matrix (ADM) is frequently used, but it is expensive and associated with complications. Alternatively, we have been using integrated devices consisting of a silicone implant coated with polyurethane (PU) foam. We aimed to compare both techniques in terms of acute complications.

Methods

The authors retrospectively reviewed patients undergoing prepectoral direct-to-implant reconstruction from June 2018 to January 2022. Two cohorts were defined based on the interface material used: ADM versus PU. Total drainage volume, time to drain removal, and acute complications (hematoma, seroma, infection, and explantation) were analyzed.

Results

Forty-four breast reconstructions were performed in 35 patients (10 bilateral); implants were covered with ADM in 23 cases and with PU foam in 21. Median total drainage volume (500 versus 515 cc for ADM and PU, respectively) and time to drain removal (9 versus 8 days) were not affected by the interface material used, but seromas and infections occurred exclusively in the ADM cohort (seromas in four of 23 of cases, P = 0.109; infections in three of 23 cases, P = 0.234). Overall complications occurred more often in cases reconstructed with ADM, but the difference was nonsignificant (P = 0.245).

Conclusions

The use of interface materials is generally considered a prerequisite for state-of-the-art prepectoral breast reconstruction for a variety of reasons, including the prevention of capsular contracture. In this study, PU coating tended to be associated with fewer short-term complications than ADM, including seroma and infection.

BROWSE: A multicentre comparison of nine year outcomes in acellular dermal matrix based and complete submuscular implant-based immediate breast reconstruction-aesthetics, capsular contracture and patient reported outcomes

Approximately 60% of implant-based breast reconstructions (IBBR) are performed with an acellular dermal matrix (ADM), for which, reliable, good quality long-term outcome data is limited. In a retrospective multicentre cohort study, we aimed to determine long-term aesthetic and quality of life outcomes of IBBR with ADM (Strattice™) compared to a submuscular technique.

METHODS

Capsular contracture (Baker III/IV capsule) was determined by clinical examination by an independent researcher. Quality of life was assessed using BREAST-Q and aesthetic outcome by photographic assessment from a breast surgeon, breast care nurse and lay person, blinded to reconstruction type.

RESULTS

We recruited 117 (51 bilateral) patients with ADM reconstructions, median follow-up 62 months (range 29-113) and 49 patients (16 bilateral) with submuscular reconstructions, median follow-up 76 months (range 38-111). 17 (10.1%) ADM reconstructions were Baker 3/4 compared to six (9.2%) submuscular (p = 0.85). Of the Baker 1/2 reconstructions six (3.6%) ADM and eight (13.6%) submuscular had previously undergone revision surgery to correct capsular contracture (p = 0.01). Combining both findings gave an estimated rate of capsular contracture of 13.6% in the ADM group and 21.2% in the submuscular (p = 0.14). A higher mean score for satisfaction with breasts was demonstrated when comparing ADM to submuscular (62 and 55, respectively; p = 0.01) but no significant difference in other BREAST-Q domains. The mean 'general satisfaction' score was higher in the ADM group for all three photograph assessors.

CONCLUSION

This study provides evidence of improved aesthetic outcome and reduction in capsular contracture with ADM reconstruction when compared to submuscular, consistent over long-term follow-up.

Biofilm Formation on Breast Implant Surfaces by Major Gram-Positive Bacterial Pathogens

BACKGROUND

Bacterial biofilm on surfaces of mammary implants is a predisposing factor for several outcomes. Because Gram-positive bacteria are potential agents of biomaterial-associated infections (BAIs), their abilities to form biofilm on breast implants should be elucidated.

OBJECTIVES

The aim of this study was to evaluate biofilm formation on different mammary prosthesis surfaces by major Gram-positive bacterial pathogens involved in BAIs.

METHODS

We initially evaluated biofilm formation on polystyrene plates with and without fibrinogen or collagen for 1 reference strain and 1 clinical isolate of Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. We also tested the ability of clinical isolates to form biofilm on 4 different implant surfaces: polyurethane foam and smooth, microtextured, and standard textured silicone. Biofilm structure and cell viability were observed by scanning electron microscopy and confocal laser scanning microscopy.

RESULTS

All strains showed strong biofilm formation on polystyrene. After fibrinogen or collagen treatment, biofilm formation varied. With fibrinogen, reference strains of S. aureus and S. pyogenes increased biofilm formation (P < 0.05). Reference strains of all species and the clinical isolate of S. pyogenes increased biofilm formation after collagen treatment (P < 0.05). In general, S. aureus showed higher capacity to produce biofilm. Scanning electron microscopy showed that biofilm attached to all surfaces tested, with the presence of extracellular polymeric substances and voids. Viable cells were more frequent for E. faecalis and S. pyogenes.

CONCLUSIONS

All species produced biofilm on all prosthesis surfaces and under different conditions. Micrographies indicated thicker bacterial biofilm formation on microtextured and/or standard textured silicone by all species, except E. faecalis.

Advances in Biomaterials for Breast Reconstruction

Breast cancer is one of the most commonly diagnosed malignancies in women. Along with increasing demands for breast reconstruction, the attention given to the psychological and aesthetic benefits of breast reconstruction has also increased. As breast reconstruction and augmentation demands increase, biomaterials for breast reconstruction are being developed, and the related industry is growing quickly worldwide. Among the various biomaterials used for breast enlargement, breast implants have undergone a remarkable evolution since the 1960s. Despite unsatisfactory results and unexpected complications, research dedicated to achieving an ideal breast implant has progressed. In accordance with attention to tissue engineering, a three-dimensional (3D) bioprinting technique for breast tissue regeneration has emerged to overcome the current limitations of breast biomaterials. Along with solid implants, injectable liquid-type fillers are also part of ongoing studies.

Long-term outcomes of two-stage, immediate and delayed breast reconstruction with polyurethane-covered versus textured implants: protocol of a prospective, multicentre randomised controlled trial (TIPI trial)

INTRODUCTION

Two-stage implant-based breast reconstruction is the most commonly performed postmastectomy reconstructive technique. During the first stage, a tissue expander creates a sufficiently large pocket for the definite breast implant placed in the second stage. Capsular contracture is a common long-term complication associated with implant-based breast reconstruction, causing functional complaints and often requiring reoperation. The exact aetiology is still unknown, but a relationship between the outer surface of the implant and the probability of developing capsular contracture has been suggested. The purpose of this study is to determine whether polyurethane-covered implants result in a different capsular contracture rate than textured implants.

METHODS AND ANALYSIS

The Textured Implants versus Polyurethane-covered Implants (TIPI) trial is a multicentre randomised controlled trial with a 1:1 allocation rate and a follow-up of 10 years. A total of 321 breasts of female adults undergoing a two-stage breast reconstruction will be enrolled. The primary outcome is capsular contracture at 10-year follow-up which is graded with the modified Baker classification. It is analysed with survival analysis using a frailty model for clustered interval-censored data, with both an intention-to-treat and per-protocol approach. Secondary outcomes are other complication rates, surgical revision rate, patient satisfaction and quality of life and user-friendliness. Outcomes are measured 2 weeks, 6 months, 1, 2, 3, 5 and 10 years postoperatively. Interim analysis is performed when 1-year, 3-year and 5-year follow-up is completed.

ETHICS AND DISSEMINATION

The trial has been reviewed and approved by the Medical Research Ethics Committee of the Erasmus MC, University Medical Centre Rotterdam (MEC-2018-126) and locally by each participating centre. Written informed consent will be obtained from each study participant. The results will be disseminated by publication in peer-reviewed journals.

TRIAL REGISTRATION

NTR7265.

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.

Prepectoral immediate breast reconstruction with polyurethane foam-coated implants: Feasibility and early results in risk-reducing and therapeutic mastectomies

BACKGROUND

There is a renewed interest for prepectoral reconstruction. We aimed to describe the feasibility and the early complications associated with immediate one-stage direct-to-implant (DTI) reconstruction using prepectoral anatomical polyurethane (PU) foam-coated implants alone, for women with breast cancer or mutation carriers undergoing risk-reducing surgery.

METHODS

We performed a single-center, retrospective review of 50 patients (mean age of 49 years), who underwent skin-sparing mastectomy (SSM) or nipple-sparing mastectomy (NSM) and immediate prepectoral PU implant-based reconstruction. All procedures were performed by the same senior operator, from July 2018 to March 2020.

RESULTS

A total of 64 mastectomies (25 SSMs and 39 NSMs) with one-stage prepectoral PU foam-coated implant reconstruction were performed. Out of 50 patients, 6 required surgical revision within 30 days, because of hematoma (2), wound dehiscence (2) infection (1), and full thickness nipple-areolar complex (NAC) necrosis (1). Four patients developed a cutaneous rash with spontaneous resolution. Statistical analysis showed a significant influence of hypothyroidism and previous radiotherapy on the risk of complications. The association with prior radiotherapy (pRT) was not significant using binary logistic regression. When excluding oncological reasons and patient's wish for NAC excision, our decision to perform an NSM was influenced by breast cup size, preoperative measurements, and breast weight.

CONCLUSIONS

Early experience with immediate prepectoral DTI reconstruction with PU-covered implants alone suggests that it is a reliable procedure. Prior breast irradiation does not increase postoperative complication rates in our series. NAC preservation was decided according to preoperative lower breast measurements.

Botulinum Toxin Type A as a Tool for Correcting Capsular Contracture after Reconstructive Breast Surgery

Capsular contracture is one of the most common complications after breast reconstruction. Surgical treatment is the main option for capsular contracture correction and includes capsulotomy, capsulectomy, and removal/replacement of the affected implant. However, the surgical trauma from reoperation, along with reduced quality of life, in patients with clinically significant capsular contracture has prompted a search for alternative treatment options. The use of the botulinum toxin type A in the treatment of neurological diseases and of keloid scars in aesthetic practice nudged the idea of using the same toxin for the correction of capsular contractures in breast cancer patients. Botulinum toxin type A injection is an easy procedure requiring no anesthesia or inpatient care. The treatment has few side effects. In addition, the injection does not cause sensory loss or dysesthesia. We described a clinical case of the capsular contracture correction using incobotulinumtoxin A. Capsular contracture IV developed 4 months post surgery after long-term lymphorrhea. Radiation therapy was not performed. According to the internal protocol, the patient was advised to undergo incobotulinumtoxin A treatment instead of surgery. Within 1 week after the second injection, all symptoms decreased—specifically, the general shape of the reconstructed breast. Also, the pain syndrome disappeared.

Influence of Hard Segment Content and Diisocyanate Structure on the Transparency and Mechanical Properties of Poly(dimethylsiloxane)-Based Urea Elastomers for Biomedical Applications

The effect of hard segment content and diisocyanate structure on the transparency and mechanical properties of soft poly(dimethylsiloxane) (PDMS)-based urea elastomers (PSUs) was investigated. A series of PSU elastomers were synthesized from an aminopropyl-terminated PDMS (M¯n: 16,300 g·mol⁻¹), which was prepared by ring chain equilibration of the monomers octamethylcyclotetrasiloxane (D₄) and 1,3-bis(3-aminopropyl)-tetramethyldisiloxane (APTMDS). The hard segments (HSs) comprised diisocyanates of different symmetry, i.e., 4,4′-methylenebis(cyclohexyl isocyanate) (H₁₂MDI), 4,4′-methylenebis(phenyl isocyanate) (MDI), isophorone diisocyanate (IPDI), and trans-1,4-cyclohexane diisocyanate (CHDI). The HS contents of the PSU elastomers based on H₁₂MDI and IPDI were systematically varied between 5% and 20% by increasing the ratio of the diisocyanate and the chain extender APTMDS. PSU copolymers of very low urea HS contents (1.0–1.6%) were prepared without the chain extender. All PSU elastomers and copolymers exhibited good elastomeric properties and displayed elongation at break values between 600% and 1100%. The PSUs with HS contents below 10% were transparent and became increasingly translucent at HS contents of 15% and higher. The Young’s modulus (YM) and ultimate tensile strength values of the elastomers increased linearly with increasing HS content. The YM values differed significantly among the PSU copolymers depending on the symmetry of the diisocyanate. The softest elastomer was that based on the asymmetric IPDI. The elastomers synthesized from H₁₂MDI and MDI both exhibited an intermediate YM, while the stiffest elastomer, i.e., that comprising the symmetric CHDI, had a YM three-times higher than that prepared with IPDI. The PSUs were subjected to load–unload cycles at 100% and 300% strain to study the influence of HS morphology on 10-cycle hysteresis behavior. At 100% strain, the first-cycle hysteresis values of the IPDI- and H₁₂MDI-based elastomers first decreased to a minimum of approximately 9–10% at an HS content of 10% and increased again to 22–28% at an HS content of 20%. A similar, though less pronounced, trend was observed at 300% strain. First-cycle hysteresis among the PSU copolymers at 100% strain was lowest in the case of CHDI and highest in the IPDI-based elastomer. However, this effect was reversed at 300% strain, with CHDI displaying the highest hysteresis in the first cycle. In vitro cytotoxicity tests performed using HaCaT cells did not show any adverse effects, revealing their potential suitability for biomedical applications.

Drainage on augmentation mammoplasty: Does it work?

BACKGROUND

Breast prostheses could be associated with complications, despite many studies on surgical materials and techniques. The role of surgical drainage in preventing complications on breast prostheses surgery is controversial.

OBJECTIVES

This study aimed to evaluate the role and effectiveness of vacuum drainage in the augmentation mammoplasty.

METHODS

A prospective multicentric randomized comparative clinical trial was conducted with 150 patients, who were the candidates for breast augmentation. The candidates were split into two groups to analyze the breast drain role. Group1: closed-suction drainage; measurements were taken every 24 h for 48 h. Group2: control (no drainage); all the patients were submitted to a clinical and postoperative ultrasonography evaluation (7th day and 3rd month). The late consultations (1st-, 2nd-, and 3rd-year postoperative time) were carried out to identify any complication, such as infection, seroma, hematoma, asymmetry, hypertrophic scarring, rippling, implant position, visible edges, and sensibility alteration.

RESULTS

A total of 150 female patients were operated with 300 breast implants placed into subglandular pocket. In the first 24 h postoperative (D1), the drainage volume ranged from 12 ml to 210 ml (mean= 74.90 ml; SD= 43.29 ml). After 24 h, on the second day (D2), the collected volume ranged from 10 ml to 120 ml (mean= 44.76 ml; SD= 24.80 ml). The total drainage volume in the 48 h ranged from 22 ml to 320 ml (mean= 119.7 ml; SD= 62.20 ml). The breast ultrasonography series (BUSGS) analysis was done on the 7th day and 3rd month in both groups. There was no significant difference between G1 and G2 groups (p = 0.05 and 0.25, respectively). In the follow-up, some patients (33-44%) declared sensitivity disturbing on the nipple-areola complex (NAC) and lower breast segment.

CONCLUSIONS

The closed-suction breast drainage in breast augmentation was associated with high cost and time-consuming and not demonstrated any benefit in a recent postoperative time.

Immediate Breast Reconstruction after mastectomy with polyurethane implants versus textured implants: A retrospective study with focus on capsular contracture

BACKGROUND

Capsular contracture (CC) is the most common complication following Immediate Breast Reconstruction (IBR) with breast implants. Different implant surfaces were developed aiming to reduce the incidence of CC. We evaluated the incidence and degree of CC after Direct-to-Implant (DTI) IBR with insertion of textured (TE) or polyurethane (PU) covered implants.

METHODS

A retrospective review of consecutive patients treated at our Institution with mastectomy and one-stage IBR and implant reconstruction between 2013 and 2018, with or without post mastectomy radiation therapy (PMRT), was conducted. Immediate breast reconstruction was performed by implanting 186 PU covered implants and 172 TE implants.

RESULTS

Three-hundred-twelve women underwent 358 DTI IBR with PU or TE implants, were analyzed with a median follow-up time of 2.3 years (range 1.0-3.0). The overall rate of CC Baker grade III and IV was 11.8% (95%CI: 8.4-16.3), while, after PU and TE implant placement it was 8.1% (95% CI: 4.1-15.7) and 15.8% (95% CI: 4.1-15.7) [p = 0.009]), respectively. Irradiated breasts developed CC more frequently rather than non-irradiated breasts (HR = 12.5, p < 0.001), and the relative risk was higher in the TE group compared with the PU group (HR = 0.3, p = 0.003).

CONCLUSIONS

After mastectomy and one-stage IBR, the use of PU covered implants is associated with a lower incidence of CC compared to TE implants. This advantage is amplified several folds for patients who necessitate PMRT. Footnote: Capsular contracture (CC); Immediate Breast Reconstruction (IBR); Directto- Implant (DTI); Textured (TE); Polyurethane (PU); Post mastectomy radiation therapy (PMRT); Nipple Sparing mastectomy (NSM).

Outcome of complete acellular dermal matrix wrap with polyurethane implant in immediate prepectoral breast reconstruction

Background

Polyurethane implants have been used on and off in breast reconstruction since 1991 while prepectoral breast reconstruction has gained popularity in recent times. In this study, we present our outcomes from the use of acellular dermal matrix (ADM) complete wrap with polyurethane implants in prepectoral breast reconstruction.

Methods

This is a retrospective review of prospectively maintained database from 41 patients receiving complete ADM wrap with prepectoral polyurethane implants over a 3-year period. Selection criteria were adapted from a previous study (4135 Trust Clinical Audit Database) evaluating prepectoral reconstruction with Braxon matrices. Patient demographics, operative data, surgical complications, and outcomes were collected and analyzed.

Results

A total of 52 implant reconstructions were performed in 41 patients with a mean follow-up of 14.3 months (range, 6–36 months). The overall reported complication rates including early (less than 6 weeks) and late complications. Early complications included two patients (4.9%) with wound dehiscence. One of which had an implant loss that was salvageable. Another patient (2%) developed red-breast syndrome and two women (4.9%) developed with seroma treated conservatively. Late complications included one patient (2%) with grade II capsular contraction, 12 patients with grade I-II rippling and two patients (4.9%) with grade III rippling.

Conclusions

We present our experience of prepectoral polyurethane implant using complete ADM wrap. This is one of the few papers to report on the outcome of the prepectoral use of polyurethane in immediate implant-based breast reconstruction. Our early observational series show satisfactory outcome and long-term results are warranted by a large multicenter study.

The Use of Anatomic Implants in Aesthetic Breast Surgery

Anatomic implants were introduced in the late 1980s, gaining popularity through the 1990s and beyond. The moratorium on silicone meant that the use of theses devices was less diffuse in the US and has remained so. Fifth-generation devices had improved form stability with more aggressive texturization to enhance soft tissue interaction. The ability to vary height, width and projection independently creates much versatility in their use for complex anatomical situations producing natural results. The impact of BIA-ALCL has had a significant impact on their use.

Types of Errors Made During Breast Augmentation with Polyurethane Implants: A Systematic Review

BACKGROUND

Implementation of polyurethane-covered (PU) implants into practice requires a reassessment of the experience and a learning curve period. Occasional publications describe a few difficulties in this regard. However, there are no publications covering the spectrum of errors. The absence of definite information and contradictory findings makes the learning curve longer leading to many unsatisfactory results.

MATERIALS AND METHODS

The systematization is based on the 12 years of experience with over 1000 patients and previously published data. A literature review was conducted using PUBMED with the following keywords: polyurethane or foam or sponge and breast and implant. A total of 285 articles were found (last accessed 08/13/2019). All articles concerning polyurethane implants were studied along with any articles found describing the surgical techniques applied to them. Additional references found in the above-mentioned articles were also included in the study.

RESULTS

All errors can be divided into planning errors, errors in pocket development and surface-dependent errors, for which the polyurethane surface is the main reason. Surface-dependent errors include the errors connected to positioning and biointegration. The possible causes of late seroma with PU implants are discussed.

CONCLUSIONS

The polyurethane surface should not be considered textured in the clinical point of view. Previous experience with non-PU implants cannot be transferred to PU implants. The learning curve is unavoidable. The systematization of errors with PU implants facilitates a decision-making process during the primary and secondary surgery and lowers the risk of the unsatisfactory results.

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 Table of Contents or online Instructions to Authors www.springer.com/00266.

Comparison of inflammatory response and synovial metaplasia in immediate breast reconstruction with a synthetic and a biological mesh: a randomized controlled clinical trial

The aim of this study was to compare inflammatory response and synovial metaplasia in implant-based immediate breast reconstruction with a biological mesh (Veritas^®) with that of a synthetic mesh (TIGR^® Matrix Surgical Mesh). We hypothesize that the inflammatory response and formation of synovial metaplasia might be different and the rate of capsular contracture therefore different. The patients were recruited from the Gothenburg TIGR^®/Veritas^® Study (ClinicalTrials.Gov identifier NCT02985073). All referrals for bilateral immediate breast reconstruction were assessed for inclusions. During the operation, the patients were randomized to which sides the biological and the synthetic mesh were going to be applied. During the implant exchange biopsies were taken. Biopsies were taken from 30 breasts in 15 patients. There seem to be more myofibroblast and neovascularization in the biological meshes than in the synthetic and the collagen fibers seem to be aligned in an irregular pattern with both parallel and vertical fibers. In the synthetic meshes, there were more giant cells and foreign body reaction and the collagen fibers were loosely and well aligned, oriented parallel to the surface of the implant. Synovial metaplasia was seen in the majority of both the biological and the synthetic meshes. The histological patterns in early capsules from biological and synthetic meshes vary considerably. Nonetheless, it is unknown what role different cell types have in capsular formation in the long run and there was no difference in clinical capsular contracture at the clinical follow-up in this study.

Removal of Polyurethane Implants

Polyurethane (PU) implants are associated with great difficulties in extraction if secondary surgery is needed. The published data are contradictory, often misleading, making the decision for the secondary surgery complicated, the time period and the procedure itself not optimal, thus negatively influencing the final result.

MATERIALS AND METHODS

Typical videos of PU implant removal in different periods after primary surgeries with polyurethane implants were selected for the study. The videos show the strength and extent of the tissue ingrowth and the manipulations needed for implant extraction in different periods from the initial procedure. Classifications of the types of adhesion and adhesion patterns are introduced.

CONCLUSIONS

The data provided in this article facilitate the decision-making process if secondary surgery is indicated. Secondary surgery should be performed in the first 30 days after the initial surgery or in the period after 6 months. The optimal layer for removal of the PU implant depends on the time after the primary surgery. The polyurethane implant should be exchanged after 1 month if the properties of the polyurethane foam are expected to be used.

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, refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Smooth Muscle Alpha Actin Immunoexpression (α-Sma) and CD-117 Antibody (C-Kit) in Capsules Formed by Polyurethane Foam-Coated Silicone Implants and with Textured Surface: A Study on Rats

BACKGROUND

One of the undesirable complications that might occur after breast augmentation with silicone implants is capsular contracture. In its etiology, the relations between mast cells and myofibroblasts play an important role in collagen synthesis. Mast cells are able to activate fibroblasts into myofibroblasts, through paracrine secretions, inducing collagen production. The objectives of this study were to analyze the myofibroblast concentration through the α-SMA immunomarker and evaluate the intensity of mast cell expression against the C-Kit immunomarker.

MATERIAL AND METHOD

Sixty-four Wistar rats were used, divided into two groups (polyurethane foam and textured surface) with 32 animals in each. The animals received silicone implants on the back, below the panniculus carnosus, and after the determined period, they were killed and the capsules formed around the implants were studied. The capsules were analyzed employing the immunohistochemical technique, with the α-SMA and C-Kit immunomarkers in subgroups of 30, 50, 70 and 90 days.

RESULTS

The myofibroblast concentration was higher in the polyurethane group when compared to the textured group (30 days p = 0.105; 50 days p = 0.247; 70 days p = 0.014 and 90 days p = 0.536). The intensity of mast cell expression was more pronounced in the polyurethane group when compared to the textured group (30 days p = 0.798; 50 days p = 0.537; 70 days p = 0.094 and 90 days p = 0.536).

CONCLUSIONS

Polyurethane-coated implants induced higher concentrations of myofibroblasts and higher expression of mast cells, when compared to the textured surface implants.

NO LEVEL ASSIGNED

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 .

A Different Perspective on Breast Implant Surface Texturization and Anaplastic Large Cell Lymphoma (ALCL)

Anaplastic large cell lymphoma (ALCL) is a rare form of lymphoma involving cells of the immune system. It is currently gaining interest because of an association between the development of ALCL and an increased risk in women who have had breast implant surgery. Although not confirmed, many theories exist as to the etiology of this association in women, and there is growing concern that ALCL is more prevalent in women with textured breast implants. In particular, the risk of developing ALCL appears to be related to increasing implant texturization or "surface roughness." This paper examines the current manner of defining and characterizing breast implant surface texture and challenges the appropriateness of applying this technology and linking it to ALCL. It is not a comprehensive review of the etiology of capsular contracture and ALCL, but it proposes an alternative perspective on surface texture measurements from that currently employed and its role in researching the etiology of ALCL. The authors hope that their article will provoke thought and reflection when considering the issues currently being highlighted with regard to texturing of breast implants.

Early fragmentation of polyester urethane sheet neither causes persistent oxidative stress nor alters the outcome of normal tissue healing in rat skin

Silicone breast implant is associated with complications inherent to the surgical procedure. Prosthesis coating with polyurethane, however, commonly reduces the incidence of such complications. In this paper, the authors evaluated the inflammatory histomorphometric profile and oxidative damage associated to the implant of polyester urethane sheets. Forty-eight Wistar rats were divided into Sham or polyester urethane groups (n = 8/group) and underwent a polyester urethane implant in the dorsal skinfold. Tissue samples were collected on days seven, 30, and 90 after surgery and subjected to histomorphometric analysis and biochemical tests. Results were analyzed by one-way ANOVA (p ≤ 0.05). Peri-implant tissue samples exhibited characteristic inflammatory response associated with the biomaterial, with increased vascularization on day seven and augmented levels of IL1-b and TNF-a after 30 days. Peri-implant fibrocystic population was small on day seven, but increased considerably after 90 days. A rise in the carbonyl group levels of skin samples in the polyester urethane group was observed on day seven. Findings suggest that polyester urethane sheets undergo biodegradation at an early stage after implantation, followed by increased vascularity and microencapsulation of biomaterial fragments, without persistent oxidative damage. Fiber arrangement inside the collagen matrix results in a fibrotic scar because of polyester urethane degradation.

Surface Areas of Textured Breast Implants: Implications for the Biofilm Theory of Capsule Formation

Supplemental Digital Content is available in the text.

Background:

Increased surface area of mammary implants is suggested as a causative agent for the development of biofilms, which may lead to capsular contraction. The aim of this study was to quantify the surface areas of round implants of different textures and examine how these data can be interpreted with regard to clinical observation.

Methods:

Surface areas of textured round breast implants were calculated from previously reported confocal scanning microscopic assessment, and dimensions sourced from 3 breast implant manufacturers (McGhan, Mentor, and Silimed). Statistical comparisons were made between manufacturers for different implant volumes, profiles, and texturing.

Results:

There was a difference in surface area between manufacturers for all implant profiles and between manufacturers for equivalent volume implants (F (3, 253) = 2,828.87; P < 0.001). Silimed polyurethane implants (mean area = 6.12 × 10⁶ mm²) was the highest. Natrelle (mean area = 1.2 × 10⁶ mm²) was the next highest, followed by Siltex (mean area = 4.8 × 10⁵ mm²). Mentor smooth implants (mean area = 4 × 10⁴ mm²) had the lowest mean surface area. There were no differences in surface area between the different profiles for Siltex, Silimed polyurethane, and Mentor smooth implants of the same volume.

Conclusions:

The increased surface area produced by texturing, although different between manufacturers, seems to provide protection against capsular contraction. Correlation with clinical data indicates that the surface area alone cannot account for these differences. Smooth implants, which have the smallest surface area have the highest incidence of capsular contraction. These data are at odds with the biofilm theory of capsular contraction.

Case of late hematoma after breast augmentation

We present a case report of a patient who experienced a late, spontaneous breast hematoma 26 years after primary breast augmentation. Late hematomas are a rare complication of breast augmentation with uncertain etiology. In this case, there was no trauma, calcifications, or implant rupture. We believe the patient’s hematoma was secondary to erosion of a capsular vessel due to capsular contracture.