Failure of silicone gel breast implants: is the mechanical weakening due to shell swelling a significant cause of prostheses rupture?

Ultrasonic elastography for the prevention of breast implant rupture: Detection of an increase with stiffness over implantation time

Breast implants are widely used after breast cancer resection and must be changed regularly to avoid a rupture. To date, there are no quantitative criteria to help this decision. The mechanical evolution of the gels and membranes of the implants is still underinvestigated, although it can lead to early rupture. In this study, 35 breast explants having been implanted in patients for up to 17 years were characterized by ex vivo measurements of their mechanical properties. Using Acoustic Radiation Force Impulse (ARFI) ultrasound elastography, an imaging method for non-destructive mechanical characterization, an increase in the stiffness of the explants has been observed. This increase was correlated with the implantation duration, primarily after 8 years of implantation. With an increase of the shear modulus of up to a factor of nearly 3, the loss of flexibility of the implants is likely to lead to a significant increase of their risk of rupture. A complementary analysis of the gel from the explants by mass spectrometry imaging (MSI) and liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) confirms the presence of metabolites of cholesterol originating from the breast tissues, which most likely crossed the membrane of the implants and most likely degrades the gel. By observing the consequences of the physical-chemical mechanisms at work within patients, this study shows that ultrasound elastography could be used in vivoas a quantitative indicator of the risk of breast implant rupture and help diagnose their replacement.

Aging of non-implanted Natrelle™ gel breast implants

This study questions the aging of non-implanted breast prostheses for a period of 9-60 months. Every 6 months, two non-implanted Natrelle™ prostheses were tested to measure the strength at break, the elongation at break, and the thickness of the shell. Then, the breaking stress was calculated from the preceding quantities. All these quantities were observed by separating the samples taken from the anterior and posterior sides of the prostheses. One-way ANOVA analyses (analysis of variance) were performed to define the influence of aging duration, lot membership, and side. In addition, the elongation at break and the thickness of the shell showed significant variations as a function of aging regardless of the side but without any trend emerging. For other quantities, there were significant disparities between the anterior and posterior sides of the prostheses, differences between prostheses from different lots, and similarities between prostheses from the same lot. Finally, the thickness is an important parameter. Since manufacturing is a manual process, it is necessary to check the thickness, which must be homogeneous on both sides. Always weaker on the anterior side than on the posterior side, it influences the mechanical properties. We recommend, like other studies, that its control be part of the quality controls during manufacturing.

On the Safety of Implanted Breast Prostheses in Accidental Impacts

The employment of breast silicone implants, both in aesthetic and reconstructive medicine, is widespread thanks to their recognized biocompatibility and durability. Some critical situations, for example, in the case of accidental impacts, may induce concerns by potential patients about their use. Dynamic tests reproducing frontal impacts at speeds up to 90 km/h, with anthropomorphic dummies carrying 330 cc prostheses and wearing safety belts, were conducted. Tests showed a significant probability of internal gel loss following implant damage at the highest speed. Moreover, considering that prostheses may remain implanted for many years, the effects of accelerated aging at 37 °C, 60 °C, 75 °C and 90 °C in physiological solution were also investigated. Tensile tests of the shell material and compressive tests of the full prosthesis showed evidence of variation in the prostheses' mechanical characteristics after aging, which affects their stiffness, deformability and strength. These results stress the importance of medical investigations for possible damages of the implanted prostheses in the case of an accident.

How Big Is Too Big? Exploring the Relationship between Breast Implant Volume and Postoperative Complication Rates in Primary Breast Augmentations

There is no consensus regarding implant size as an independent risk factor for complications in primary breast augmentation. Choosing appropriate implant volume is an integral part of the preoperative planning process. The current study aims to assess the relationship between implant size and the development of complications following augmentation mammaplasty.

Methods

A retrospective chart review of patients undergoing primary breast augmentation at the Westmount Institute of Plastic Surgery between January 2000 and December 2021 was conducted. Demographics, implant characteristics, surgical technique, postoperative complications, and follow-up times were recorded. Univariate logistic regression was used to identify independent predictors, which were then included in multivariate logistic regressions of implant volume and implant volume/body mass index (BMI) ratio regarding complications.

Results

A total of 1017 patients (2034 breasts) were included in this study. The average implant volume used was 321.4 ± 57.5 cm³ (range: 110-605). Increased volume and volume/BMI ratio were associated with a significant increase in risk of implant rupture (odds ratio = 1.012, P < 0.001 and 1.282, P < 0.001 respectively). Rates of asymmetry were significantly associated with increases in implant volume and volume/BMI ratio (odds ratio = 1.005, P = 0.004 and 1.151, P < 0.001, respectively). No single implant volume or volume/BMI ratio above which risks of complications significantly increase was identified.

Conclusions

Implant rupture and postoperative asymmetries are positively correlated with bigger implant volumes. Implant size could likely be a useful independent predictor of certain complications, especially in patients with high implant to BMI ratios.

Silicone Breast Implant Rupture is More Prevalent in the Dominant Limb Side, A Retrospective Cohort Study

BACKGROUND

Breast implant rupture is associated with multiple risk factors such as implant age, manufacturer, and a history of trauma to the breast. However, the exact mechanism of breast implant rupture remains unclear. We hypothesize that repetitive minor mechanical forces on the implant collectively play a significant role in the cascade that eventually leads to its rupture. Therefore, we expect a more significant cumulative effect on the breast implant in the dominant upper limb side. Thus, we aim to ascertain whether laterality in silicone breast implant rupture is associated with the dominant upper limb.

METHODS

A retrospective cohort study was performed on patients with silicone breast implants who underwent an elective breast implant removal or exchange. All patients had breast augmentations for cosmetic reasons. We collected data on implant rupture laterality and limb dominance together with known risk factors like patient age, implant age, implant pocket, and implant volume.

RESULTS

A total of 154 patients with unilateral implant rupture were included in the study. Among patients with a dominant right limb (n = 133), an ipsilateral rupture was found in 77 patients (58%) (p = 0.036), while in patients with a left dominant limb (n = 21), an ipsilateral rupture was found in 14 patients (67%), (p = 0.036).

CONCLUSIONS

The dominant limb was a significant risk factor for ipsilateral breast implant rupture. The prevailing theory that cyclic envelope movement carries an increased rupture risk is reinforced in this study. Extensive prospective studies are needed to clarify risk factors for implant rupture further.

Preparation and Characterization of 3D-Printed Biobased Composites Containing Micro- or Nanocrystalline Cellulose

Stereolithography (SLA), one of the seven different 3D printing technologies, uses photosensitive resins to create high-resolution parts. Although SLA offers many advantages for medical applications, the lack of biocompatible and biobased resins limits its utilization. Thus, the development of new materials is essential. This work aims at designing, developing, and fully characterizing a bio-resin system (made of poly(ethylene glycol) diacrylate (PEGDA) and acrylated epoxidized soybean oil (AESO)), filled with micro- or nanocellulose crystals (MCC and CNC), suitable for 3D printing. The unfilled resin system containing 80 wt.% AESO was identified as the best resin mixture, having a biobased content of 68.8%, while ensuring viscosity values suitable for the 3D printing process (>1.5 Pa s). The printed samples showed a 93% swelling decrease in water, as well as increased tensile strength (4.4 ± 0.2 MPa) and elongation at break (25% ± 2.3%). Furthermore, the incorporation of MCC and CNC remarkably increased the tensile strength and Young’s modulus of the cured network, thus indicating a strong reinforcing effect exerted by the fillers. Lastly, the presence of the fillers did not affect the UV-light penetration, and the printed parts showed a high quality, thus proving their potential for precise applications.

Current Challenges in Breast Implantation

Breast implantation (BI) is the most common plastic surgery worldwide performed among women. Generally, BI is performed both in aesthetic and oncoplastic procedures. Recently, the prevalence of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) or breast implant illness (BII) has aroused concerns. As a result, several countries, like Australia, Korea or the United Kingdom, introduced national registries dedicated to the safety and quality of BI surgeries. This narrative review aimed to focus on the clinical challenges, management and the current state of knowledge of BI. Both short and long-term outcomes of BI are determined by various alternatives and differences, which surgeons must consider during the planning and performing breast augmentation along with further complications or risk of reoperation. Proper preoperative decisions and aspects of surgical technique emerged to be equally important. The number of performed breast reconstructions is increasing, providing the finest aesthetic results and improving patient’s quality of life. Choice of prosthesis varies according to individual preferences and anatomical variables. A newly diagnosed cases of BIA-ALCL with lacking data on prevention, diagnosis, and treatment are placing it as a compelling medical challenge. Similarly, BII remains one of the most controversial subjects in reconstructive breast surgery due to unspecified diagnostic procedures, and recommendations.

Influence of Breast Implant Surface Finishing on Physicochemical and Mechanical Properties before and after Extreme Degradation Studies

The influence of the surface finishing of breast implants on physicochemical and mechanical properties, before and after extreme degradation experiments, was investigated in this study. Removal of superficial layers after degradation was verified for both smooth and rough membranes, in which local erosion was verified. FTIR results demonstrated the generation of low-molecular-weight structures in all samples due to exposure to acidic and basic environments. Furthermore, smooth samples presented higher degrees of crosslinking than rough samples. Considering the mechanical properties, no difference was verified between smooth and rough samples as received and after degradation studies. However, the pH of the degradation solution had an influence on mechanical properties of the material and a basic environment caused greater deterioration of the mechanical properties compared to acidic conditions.

Hepatobiliary complications from ruptured silicone breast implants - a comprehensive literature review

Cronin and Gerow first introduced silicone breast implants in 1962; they now serve as first-line for breast augmentation. Breast augmentation is effective in restoring both physical and psychological well-being in women post-mastectomy.

Many studies in the literature on complications of silicone breast implant rupture focus on lymphomas and capsular contractures. Only a few studies discuss the hepatobiliary complications.

By reviewing the literature over the past 30 years, the authors aim to analyse the clinical presentation, diagnostic findings, as well as management outcomes amongst women with ruptured silicone implant-related hepatobiliary complications. To the best of our knowledge, this is the first comprehensive review on this topic.

Comprehensive characterization of silica-modified silicon rubbers

In this study a commercially liquid silicone rubber was filled with fumed silica particles in different concentrations and evaluated for medical applications. The thermal, morphological and mechanical properties of silicone/silica composite samples were studied before and after aging, flexural tests and immersion in saline environment. Understanding the effect of silica content, aging conditions and thickness (from 0.6 to 2 mm) of the samples on the behavior of these materials in different environments is crucial for applications as implantable devices. Before inducing any mechanical stress, tensile strength was found to increase for samples containing 3 or 5 wt% of fumed silica, depending on the thickness. A similar trend was observed after 10⁶ flexes for tensile strength, storage modulus and hardness at room temperature, which increased with the concentration of fumed silica. Moreover, tensile strength decreased with increasing the thickness of the samples from 0.6 to 2 mm. The thermal degradation was found to start at higher temperature in the case of the composites as compared with neat silicone, however, the glass transition and melting temperatures were only slightly modified by the presence of the silica particles, regardless the mechanical aging. The MTT assay using L929 fibroblasts mouse cells showed a good short-time cytocompatibility for both silicone elastomer and the composite with 3 wt% fumed silica. Similarly, the measurement of the cytokine secretion revealed no inflammatory response.

Biomechanical analysis of intact versus ruptured Poly Implant Prothèse breast implants

Despite there being many studies that have evaluated breast implant rupture, there is no consensus about causes and incidence. Most studies lack a multifactorial analysis of what causes breast implants to rupture. To fill this gap, an experimental protocol was developed to compare ruptured and intact Poly Implant Prothèse (PIP) breast implants from the same woman. These conditions guarantee that the physical/biological variables are the same for each pair of ruptured and intact implants. A total of 1008 samples from 22 PIP explants (11 intact and 11 ruptured) and three control PIP implants were analysed. The mechanical properties (tensile strength) of the ruptured and intact implants were compared according to brand, lot, implantation time and demographic conditions. In general, statistically significant differences were found between the intact and ruptured PIP implants. Ruptured implants were thinner (0.73 ± 0.10 mm versus 0.91 ± 0.11 mm) and weaker (7.42 ± 2.65 MPa versus 9.59 ± 2.37 MPa) than intact implants. Intact and ruptured implants have shown distinct mechanical behaviours and variations in thickness. Our understanding is that these differences may be associated with the typical manufacturing process of breast implant shells. These results stress the importance of thorough control of the shell thickness. Given its relevance, shell thickness should be used as a quality control measure for homologation purposes. Thus, the homogeneity of the shell should be considered as a relevant parameter during the manufacturing process. This will translate into an improved quality of life for patients and will potentiate safer and longer lasting products.

Mechanical and surface chemical analysis of retrieved breast implants from a single centre

INTRODUCTION

Breast implants are associated with complications such as capsular contracture, implant rupture and leakage often necessitating further corrective surgery. Re-operation rates have been reported to occur in up to 15.4% of primary augmentation patients and up to 27% in primary reconstructions patients within the first three years (Cunningham, 2007). The aim of this study was to examine the mechanical and surface chemical properties as well as the fibroblast response of retrieved breast implants in our unit to determine the in vivo changes which occur over time.

METHODS

Ethical approval was obtained. 47 implants were retrieved. Implantation time ranged from 1 month to 388 months (Mean 106.1 months). Tensile strength, elongation, Young's modulus and tear strength properties were measured using Instron 5565 tensiometer on anterior and posterior aspects of the implant. Attenuated total reflectance-fourier transform infra-red spectroscopy (ATR-FTIR), wettability and scanning electron microscopy (SEM) analysis was performed on the shell surfaces. Bicinchoninic acid assay was performed to determine shell protein content. The fibroblast response was determined by seeding HDFa cells on the retrieved implants and cell metabolism measured using Alamar Blue™ assay.

RESULTS

Mechanical properties fall with increasing duration of implantation. There were no significant changes in ATR-FTIR spectra between ruptured and intact implants nor significant changes in wettability in implants grouped into 5 year categories. SEM imaging reveals surface degradation changes with increasing duration of implantation.

CONCLUSIONS

With increasing duration of implantation, mechanical properties of the breast implants fall. However this was not associated with surface chemical changes as determined by ATR-FTIR and wettability nor protein content of the shells. Thus the reduction in mechanical properties is associated with breast implant failure but further research is required to elucidate the mechanisms.

Is short term intraoperative application of disinfectants harmful to breast implants in breast reconstruction? An experimental study and literature survey

OBJECTIVES

Bacterial contamination of breast implants and biofilm formation has been discussed as a major reason for implant loss and capsular contraction. Intra- and perioperative treatment of breast implants with disinfectants to prevent bacterial contamination has been frequently reported. Given the increasing awareness of concerns about product liability the question of whether short-time irrigation of implants with antimicrobial substances during the operative procedure would potentially alter the integrity of the implant shell has attracted legal and medical interest. In this study we therefore investigated whether irrigating breast implants with antimicrobials commonly used in clinical practice with a clinically relevant application time would affect the physical integrity of the implant shell.

MATERIALS AND METHODS

Samples, which were previously punched from the shell of explanted standard silicone gel filled breast implants in a defined way, were exposed to different disinfectant solutions for two minutes. Multiple defined specimens from 5 different explants from 4 different producers (including PIP) were tested. The testing included tensile strength and disruption tests.

RESULTS

In our prospective test series we could not find a significant influence of a single distinct disinfectant on silicone shell implant surfaces.

CONCLUSION

Despite the potential legal implications that might be considered when a surgeon manipulates an implant with disinfectants intraoperatively, we find it worthwhile to state that from a material and surgical standpoint there is no evidence that short-time treatment of alloplastic materials would be detrimental to the physical properties of the implant shell.

In vitro investigation into the forces involved during lipofilling

Breast augmentation using implants is the most common aesthetic and reconstructive breast surgical procedure. Complications such as implant rupture maybe related to surgical technique and damage to the implant. Autologous fat transfer (lipofilling) using metallic cannulae has become a standard adjunctive, yet there is little evidence on lipofilling safety in the presence of implants. The aims of this study are to verify the effects of different cannulae and to quantify the forces applied by surgeons during lipofilling. Silicone gel-filled textured implants (200 mL), mounted on a specially constructed mould were ruptured with two different cannulae: type A (hole at tip: sharp) and type B (hole away from tip: blunt), driven at three speeds (10, 100 and 1000 mm/min), and the force at rupture was recorded. In addition, the maximum 10 forces over a 30-s period applied by 11 plastic surgeons against a breast implant in an in vitro environment were recorded using a load cell attached to a type-A cannula. Statistical analysis of comparative results was performed using t-tests, with p < 0.05 considered significant. Results showed that the implant ruptured at forces up to 25% lower when cannula A was used compared to cannula B. This supports current technique in lipofilling in the use of a blunt tipped cannula. There was a significant difference between some displacement rates only, due to the viscoelastic nature of the material. The tactile force that surgeons use during lipofilling was modelled in vitro and showed a range of maximum forces between 0.23 and 16.8 N, with a mean maximum value of 6.9 N. Limitation of this study is that it may not reflect in vivo behaviour of breast implants. More studies are needed to confirm the safety of breast lipofilling in the presence of implants using these data as a starting point.

An experimental analysis of shell failure in breast implants

Breast implant durability and the mechanisms of rupture are important topics in the medical community, for patients, manufactures and regulatory medical agencies. After concerns about the Poly Implant Prosthesis (PIP) implants, the need for understanding the adverse outcomes and the failure mode to improve the breast implants increased. The objective of this research is to analyze and describe the rupture characteristics of failed explanted PIP implants to study the modes and causes of rupture. Eleven explanted PIP implants were analyzed by visual inspection and scanning electron microscopy (SEM). To simulate hypothetical ruptures caused by cyclic mechanical stress (fatigue) in the implant shell, two control implants were submitted to fatigue tests, and analyzed with SEM. Small ruptures (either Hole or split) striations were found, which normally appear due to fatigue phenomena. Similar striations were also found in specimens (control) tested under laboratory controlled conditions. In the context of this work, the striations found in explants constitute a significant finding as they point to the occurrence of fatigue phenomena associated with mammary implants rupture. This research, also demonstrates that rupture surface analysis of explanted breast implants has the potential to become a useful indicator for assessing implant rupture mechanisms.

Silicone breast implant rupture: a review

Silicone breast implants have been in use for nearly 6 decades. In this time they have undergone significant changes in design and use. They have been subject to intense scrutiny with regard to safety and efficacy, including an almost 10 years moratorium on their use. The current generations of implants have been followed via the manufacturer's Core studies in order to obtain long term data regarding safety and complications. The results of the more recent studies are compiled in this review. Rupture rates are initially very low and begin to increase after 6-8 years of implantation. Implant rupture may be detected by physical exam, ultrasound or magnetic resonance imaging (MRI). The majority of silicone implant ruptures are clinically undetectable. Symptomatic patients may present with capsular contracture, breast lumps or changes in breast shape. The most common cause of implant rupture is instrument damage during placement. Implant rupture may be confined to the peri-prosthetic capsule or may extravasate into the breast tissue. Patients with ruptured implants have been studied closely and the consensus of the literature states there are no health risks associated with implant rupture. Symptomatic patients with ruptured implants should be offered the choice of observation, or explantation and capsulectomy with or without replacement.

Mechanical Performance of Poly Implant Prosthesis (PIP) Breast Implants: A Comparative Study

BACKGROUND

There is societal concern regarding potential health problems associated with breast implants. Much of this distrust climate was a reaction to the Poly Implant Prosthesis (PIP) scandal. Studying the mechanisms of implant rupture is an important step for their improvement. The mechanical behaviour of breast implant shells was studied on explanted and virgin implants. Implants from both PIP and another brand (brand X), currently in the market, were considered.

METHODS

To study the mechanical behaviour of the shell, a total of 940 samples from 11 explants and 5 control implants were analysed. The experimental protocol follows the ISO standards for shell integrity and determination of tensile stress-strain properties. Pearson correlation analyses and the multi-factor ANOVA statistical tests were performed using mechanical test data.

RESULTS

Both PIP control and explants had significant variations of stress (P = 0.0001) and shell thickness (P = 0.000) throughout the implant. The stress was directly related to shell thickness. Shell thickness varied significantly for PIP implants, exceeding the manufacturer's specifications. Regarding the other brand, thickness variation was within manufacturer's specifications.

CONCLUSIONS

The heterogeneous nature of PIP implants was confirmed. The implant shell thickness should be considered as a relevant parameter during the manufacturing process, for quality control purposes. These results may contribute to dispel mistrust and doubt surrounding breast implants, among the medical community and patients.

LEVEL OF EVIDENCE III

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Surface and mechanical analysis of explanted Poly Implant Prosthèse silicone breast implants

BACKGROUND

The recent events surrounding Poly Implant Prosthèse (PIP) breast implants have renewed the debate about the safety profile of silicone implants. The intentional use of industrial-grade instead of certified medical-grade silicone is thought to be responsible for reportedly higher frequencies of implant rupture in vivo. The differences in mechanical and viscoelastic properties between PIP and medical-grade silicone implant shells were investigated. Surface characterization of shells and gels was carried out to determine structural changes occurring after implantation.

METHODS

Breast implants were obtained from women at the Royal Free Hospital (London, UK). PIP implants were compared with medical-grade control silicone implants. Tensile strength, tear resistance and elongation at break were assessed using a tensile tester. Surfaces were analysed using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Spearman correlation analyses and Kruskal-Wallis one-way statistical tests were performed for mechanical data.

RESULTS

There were 18 PIP and four medical-grade silicone implants. PIP silicone shells had significantly weaker mechanical strength than control shells (P < 0·009). There were negative correlations between mechanical properties of PIP shells and implantation times, indicative of deterioration of PIP shells over time in vivo (r(s) = -0·75, P = 0·009 for tensile strength; r(s) = -0·76, P = 0·001 for maximal strain). Comparison of ATR-FTIR spectra of PIP and control silicones demonstrated changes in material characteristics during the period of implantation suggestive of time-dependent bond breakage and degradation of the material.

CONCLUSION

This study demonstrated an increased weakness of PIP shells with time and therefore supports the argument for prophylactic removal of PIP breast implants.