In vivo efficacy of antimicrobe-impregnated saline-filled silicone implants

Optimizing vancomycin release from novel carbon fiber-reinforced polymer implants with small holes: periprosthetic joint infection treatment

Periprosthetic joint infection (PJI) is a catastrophic complication after total hip arthroplasty. A new drug-loaded carbon fiber-reinforced polymer (CFRP) prosthesis with a sustained drug-release mechanism is being developed for one-stage surgery. We aimed to examine the diffusion dynamics of vancomycin from vancomycin paste-loaded CFRP implants. The differences in the in vitro diffusion dynamics of vancomycin paste were investigated using the elution test by varying parameters. These included the mixing ratio of vancomycin and distilled water (1:0.8, 1:1.2, and 1:1.4) for vancomycin paste, and hole diameter (1 mm and 2 mm) on the container. The in vivo diffusion dynamics were investigated using a rabbit model with vancomycin-loaded CFRP implants placed subcutaneously. The in vitro experiments showed that the diffusion effect of vancomycin was highest in the parameters of vancomycin paste with distilled water mixed in a ratio of 1:1.4, and with a 2 mm hole diameter. The in vivo experiments revealed diffusion dynamics similar to those observed in the in vitro study. The drug diffusion effect tended to be high for vancomycin paste with a large water ratio, and a large diameter of holes. These results indicate that the drug diffusion dynamics from a CFRP implant with holes can be adjusted by varying the water ratio of the vancomycin paste, and the hole size on the CFRP implant.

Pharmacological Approaches for the Prevention of Breast Implant Capsular Contracture

Capsular contracture is a common complication associated with breast implants following reconstructive or aesthetic surgery in which a tight or constricting scar tissue capsule forms around the implant, often distorting the breast shape and resulting in chronic pain. Capsulectomy (involving full removal of the capsule surrounding the implant) and capsulotomy (where the capsule is released and/or partly removed to create more space for the implant) are the most common surgical procedures used to treat capsular contracture. Various structural modifications of the implant device (including use of textured implants, submuscular placement of the implant, and the use of polyurethane-coated implants) and surgical strategies (including pre-operative skin washing and irrigation of the implant pocket with antibiotics) have been and/or are currently used to help reduce the incidence of capsular contracture. In this article, we review the pharmacological approaches-both commonly practiced in the clinic and experimental-reported in the scientific and clinical literature aimed at either preventing or treating capsular contracture, including (i) pre- and post-operative intravenous administration of drug substances, (ii) systemic (usually oral) administration of drugs before and after surgery, (iii) modification of the implant surface with grafted drug substances, (iv) irrigation of the implant or peri-implant tissue with drugs prior to implantation, and (v) incorporation of drugs into the implant shell or filler prior to surgery followed by drug release in situ after implantation.

Investigation of Autologous Fat Transfer in Capsule Formation around Silicone Implants in a Rat Model

BACKGROUND

In this experimental study, the authors investigated whether fat placement in the pocket during implant insertion affects capsule formation.

METHODS

Twenty albino Wistar rats, 400 g each, were used. The rats were divided into two groups, A and B, of 10 rats each. At the dorsum of each rat, four pockets (2 × 2 cm each) were dissected, two left and two right of the midline. In each pocket, a 1 × 1 × 1.5-cm silicone implant was inserted. In the two left pockets, only silicone implants were placed (control). In the two right pockets, 0.4 ml of fat was injected around the implant. Animals in group A were killed 2 months postoperatively, and those in group B were killed 4 months postoperatively. The implants were dissected with the capsule and sent for histopathologic examination.

RESULTS

The data of the fat transfer group was compared with control in groups A and B. Capsule thickness, neovascularization, myofibroblast layer thickness, and mast cell population demonstrated no statistically significant difference in either group A (p = 0.385, p = 0.862, p = 0.874, and p = 0.210, respectively) or group B (p = 0.338, p = 1.000, p = 0.288, and p = 0.344, respectively). Inflammation was statistically significantly less (p = 0.07) at 4 months (group B) in the fat transfer group compared to the control group. Likewise, cellularity was statistically significantly less (p = 0.019) at 4 months for the fat transfer group compared with the control group.

CONCLUSION

Fat injection in the pocket during implant placement may reduce inflammation and cellularity of capsules and predispose to faster capsule maturation.

CLINICAL RELEVANCE STATEMENT

PLEASE PROVIDE 1- TO 2-SENTENCE STATEMENT.

Capsule formation around breast implants

All implants are rapidly coated by the host with glycoproteins forming a thin capsule, and this is a normal response. Where an inflammatory stimulus such as infection is present, the capsule can thicken and become microvascularised and sometimes calcified. This inflammatory stimulus can take the form of leachable chemicals from the implant, or bacteria live or dead. The presence of live bacteria can lead to biofilm development, which is part of the chronic infective, inflammatory process. Staphylococcus epidermidis and Cutibacterium acnes have been implicated in chronic infection around breast implants, and some animal models suggest their involvement in capsule contracture. Molecular methods have revealed an array of microorganisms from samples of removed capsular material, though they are extremely sensitive to contamination. The relevance of the results to capsular contracture remains poorly understood. Bacteria of low virulence are shown associated with capsular contracture and calcification, and measures beyond those conventionally applied need to be investigated to limit perioperative contamination.

The A, B and C's of Silicone Breast Implants: Anaplastic Large Cell Lymphoma, Biofilm and Capsular Contracture

Breast implantation either for cosmetic or reconstructive e purposes is one of the most common procedures performed in plastic surgery. Biofilm infection is hypothesised to be involved in the development of both capsular contracture and anaplastic large cell lymphoma (ALCL). Capsular contracture is one of the principal reasons for breast revision surgery and is characterised by the tightening and hardening of the capsule surrounding the implant, and ALCL is an indolent lymphoma found only in women with textured implants. We describe the types of breast implants available with regard to their surface characteristics of surface area and roughness and how this might contribute to capsular contracture and/or biofilm formation. The pathogenesis of capsular contracture is thought to be due to biofilm formation on the implant, which results in on-going inflammation. We describe the current research into breast implant associated ALCL and how implant properties may affect its pathogenesis, with ALCL only occurring in women with textured implants.

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.

The aetiopathogenesis of capsular contracture: A systematic review of the literature

BACKGROUND

Capsular contracture is the most frequent complication after breast augmentation or reconstruction with breast implants. The immune system plays a prominent role in capsular contracture formation, albeit to an unknown extent. Bacterial contamination in situ has been hypothesized to be causative for capsular contracture. How this relates to the immunological processes involved is unknown. This article aims to provide an overview of immunological and bacterial factors involved in development of capsular contracture.

MATERIALS AND METHODS

We undertook a systematic literature review focused on immunological factors and microbiota in relation to capsular contraction around implants. This systematic review was performed in accordance with the PRISMA guidelines. PubMed, EMBASE, and the Cochrane databases were searched from inception up to October 2016. Included studies were assessed for the following variables: subject characteristics, number of capsules, primary indication for surgery, surgical procedure, follow-up or implant duration, study methods, type of antibiotics or medical therapies and outcomes related to microbiota and immunological factors.

RESULTS

Data on immunological factors and bacterial contamination were retrieved from 64 included studies. Notably the presence of macrophages and Staphylococcus epidermidis within capsules was often associated with capsular contracture.

CONCLUSION

This review provides a clear overview of the immunological factors associated with capsular contracture and provides a hypothetical immunological model for development of the disease. Furthermore, an overview of bacterial contamination and associations with capsular contracture has been provided. Follow-up research may result in clinical recommendations to prevent capsular contracture.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

How smart do biomaterials need to be? A translational science and clinical point of view

Over the last 4 decades innovations in biomaterials and medical technology have had a sustainable impact on the development of biopolymers, titanium/stainless steel and ceramics utilized in medical devices and implants. This progress was primarily driven by issues of biocompatibility and demands for enhanced mechanical performance of permanent and non-permanent implants as well as medical devices and artificial organs. In the 21st century, the biomaterials community aims to develop advanced medical devices and implants, to establish techniques to meet these requirements, and to facilitate the treatment of older as well as younger patient cohorts. The major advances in the last 10 years from a cellular and molecular knowledge point of view provided the scientific foundation for the development of third-generation biomaterials. With the introduction of new concepts in molecular biology in the 2000s and specifically advances in genomics and proteomics, a differentiated understanding of biocompatibility slowly evolved. These cell biological discoveries significantly affected the way of biomaterials design and use. At the same time both clinical demands and patient expectations continued to grow. Therefore, the development of cutting-edge treatment strategies that alleviate or at least delay the need of implants could open up new vistas. This represents the main challenge for the biomaterials community in the 21st century. As a result, the present decade has seen the emergence of the fourth generation of biomaterials, the so-called smart or biomimetic materials. A key challenge in designing smart biomaterials is to capture the degree of complexity needed to mimic the extracellular matrix (ECM) of natural tissue. We are still a long way from recreating the molecular architecture of the ECM one to one and the dynamic mechanisms by which information is revealed in the ECM proteins in response to challenges within the host environment. This special issue on smart biomaterials lists a large number of excellent review articles which core is to present and discuss the basic sciences on the topic of smart biomaterials. On the other hand, the purpose of our review is to assess state of the art and future perspectives of the so called "smart biomaterials" from a translational science and specifically clinical point of view. Our aim is to filter out and discuss which biomedical advances and innovations help us to achieve the objective to translate smart biomaterials from bench to bedside. The authors predict that analyzing the field of smart biomaterials from a clinical point of view, looking back 50 years from now, it will show that this is our heritage in the 21st century.

Can the use of hyaluronidase reduce capsule formation?

BACKGROUND

The purpose of this study was to find whether the use of hyaluronidase reduces capsule formation.

METHODS

Ten New Zealand White rabbits were used. Eight pockets were created using an aseptic technique, four on the right side and four on the left side, along the vertebral column of every animal. One piece of silicone from a silicone block was inserted inside every pocket. The dimensions of each piece were 3.5 × 2 × 1.5 cm. In every pocket on the right side of each animal we placed 0.5 ml of hyaluronidase solution. The animals were sacrificed 5 months postoperatively. Capsule formation in the each side of the animals was compared.

RESULTS

Two rabbits presented infection in two pockets and were excluded from the study. There was a statistically significant difference between groups concerning the capsule thickness variable using parametric (P = 0.003) and nonparametric (P = 0.001) analysis [capsule thickness on the right side: 256.46 ± 114.88 (mean ± SD) and on the left side: 369.10 ± 147.81 (mean ± SD); capsule thickness on the right side: 235.69 (104.72) [median (IQR)] and on the left side: 332.12 (188.68) median (IQR)].

CONCLUSION

The use of hyaluronidase may reduce capsule formation around implants.

Inhibition of Staphylococcus aureus biofilms by a novel antibacterial envelope for use with implantable cardiac devices

Biofilm formation on representative implantable medical devices using a known human pathogen (Staphylococcus aureus) was significantly reduced (p < 0.01) at all time points measured (24,48, and 72 hours) by employing a novel antibacterial envelope (AIGIS Rx). The result was demonstrated using a standard US Centers for Disease Control (CDC) bioreactor model and the results were confirmed by Scanning Electron Microscopy (SEM). The antibacterial envelope used in the study is coated with a proprietary combination broad spectrum antibiotics (rifampin and minocycline) embedded in a resorbable polymeric coating. The antibiotics are designed to elute out of the coating over a multi-day period for controlled, site-specific drug delivery. The infection rate for patients receiving pacemakers and defibrillators is increasing faster than the rate of new implants and the growing resistance of S. aureus strains suggests that conventional, systemic antibiotic prophylaxis may have limited future utility. Moreover, emerging evidence suggests that bacterial biofilms result in infections of implantable medical devices. These findings demonstrate the in vitro efficacy of a new means to address potential biofilm-derived Hospital Acquired Infections (HAIs) related to implantable medical devices composed of titanium inclusive of pacemakers and defibrillators by means of a locally delivered, low dose, combination antibacterial treatment.

Pilot study of association of bacteria on breast implants with capsular contracture

Capsular contracture is the most common and frustrating complication in women who have undergone breast implantation. Its cause and, accordingly, treatment and prevention remain to be elucidated fully. The aim of this prospective observational pilot study was to test the hypothesis that the presence of bacteria on breast implants is associated with capsular contracture. We prospectively studied consecutive patients who underwent breast implant removal for reasons other than overt infection at the Mayo Clinic from February through September 2008. Removed breast implants were processed using a vortexing/sonication procedure and then subjected to semiquantitative culture. Twenty-seven of the 45 implants collected were removed due to significant capsular contracture, among which 9 (33%) had >or=20 CFU bacteria/10 ml sonicate fluid; 18 were removed for reasons other than significant capsular contracture, among which 1 (5%) had >or=20 CFU/10 ml sonicate fluid (P = 0.034). Propionibacterium species, coagulase-negative staphylococci, and Corynebacterium species were the microorganisms isolated. The results of this study demonstrate that there is a significant association between capsular contracture and the presence of bacteria on the implant. The role of these bacteria in the pathogenesis of capsular contracture deserves further study.

Flector tissugel used to treat capsular contracture after breast augmentation surgery

Capsular contracture constitutes the main postoperative complication after breast augmentation by implant placement. To date, no systemic treatment known allows for improvement that does not simultaneously put the patient at risk for secondary complications of a more general nature. Flector Tissugel is the sole locally active antiinflammatory patch. Its durable local antiinflammatory effect is associated only with a risk for rare and highly limited side effects. After approximately 3 weeks of treatment, a high frequency of change from capsular contracture Baker 2 or 3 to Baker 1 occurs, provided the application was started no later than 3 months after the onset of capsular contracture.

Bacterial colonization is of major relevance for high-grade capsular contracture after augmentation mammaplasty

Many studies indicate that subclinical bacterial colonization plays a pivotal role in capsular contracture. Nevertheless, it has not been clarified whether bacterial stimuli are only associated with high-grade (Baker III/IV) or low-grade (Baker I/II) capsular contractures. The study included 45 female patients suffering from unilateral capsular fibrosis following augmentation mammaplasty with silicone implants (smooth: n = 28; textured: n = 17). In total, there were 16 (35.6%) bacterially contaminated swabs. No significant difference could be detected between colonization rates of smooth (52.9%) and textured (25.0%) implants (z = 1.575, P = 0.115). Interestingly, no colonization was detected for Baker I/II contractures, but the colonization rate for Baker III/IV contractures amounted to 66.7%, showing a highly significant difference between the 2 groups (z = 4.351, P < 0.001). Our study shows significant differences in bacterial contamination rates between high-grade and low-grade capsular contractures. One might speculate that bacterial stimuli accelerate the process of inflammation and fibrosis in patients who tend to develop capsular fibrosis.

Enhancing Patient Outcomes in Aesthetic and Reconstructive Breast Surgery Using Triple Antibiotic Breast Irrigation: Six-Year Prospective Clinical Study

BACKGROUND

Capsular contracture remains one of the most commonly reported complications in aesthetic and reconstructive breast patients. Previous in vitro studies from the authors' laboratory have recommended a new triple antibiotic povidone-iodine irrigation (2000) and subsequently a triple antibiotic non-povidone-iodine-containing irrigant (2001) to optimize broad-spectrum coverage of various bacteria implicated in capsular contracture; however, the clinical efficacy of these in vitro studies remains unproven. The purpose of this study was to determine the clinical efficacy for the previously reported triple antibiotic breast irrigation. The cost-effectiveness of universal application of irrigation solutions in breast prosthesis surgery was analyzed as well.

METHODS

Patients undergoing aesthetic and reconstructive breast implant procedures were treated with a standardized operative technique, including the use of triple antibiotic breast irrigation by a single surgeon. Capsular contracture was assessed using a simplified Baker scale and graded by two independent caregivers to maximize objectivity and consistency. Additional complications were also recorded, including reoperation. Patient charges for antibiotic irrigation and reoperation for contracture were determined and compared.

RESULTS

A total of 335 patients operated on since 1997 were evaluated prospectively. They ranged in age from 18 to 86 years, and the mean follow-up was 14 months (range, 6 to 75 months). The rate of grade III/IV capsular contracture in the study groups was 1.8 percent for patients undergoing primary breast augmentation. Patients undergoing augmentation-mastopexy had a grade III/IV contracture rate of 0 percent. Breast reconstruction patients had a 9.5 percent rate of grade III/IV contracture.

CONCLUSIONS

Triple antibiotic breast irrigation is clinically associated with a low incidence of capsular contracture compared with other published reports, and its clinical efficacy supports previously published in vitro studies. Application of triple antibiotic irrigation is recommended for all aesthetic and reconstructive breast procedures and is cost effective.

A Rabbit Model for Capsular Contracture: Development and Clinical Implications

BACKGROUND

Capsular contracture remains one of the most common complications involving aesthetic and reconstructive breast surgery; however, its cause, prevention, and treatment remain to be fully elucidated. Presently, there is no accurate and reproducible pathologic in vitro or in vivo model examining capsular contracture. The purpose of this study was to establish an effective pathologic capsular contracture animal model that mimics the formation of capsular contracture response in humans.

METHODS

New Zealand White rabbits (n = 32) were subdivided into experimental (n = 16) and control groups (n = 16). Each subgroup underwent placement of smooth saline mini implants (30 cc) beneath the panniculus carnosus in the dorsal region of the back. In addition, the experimental group underwent instillation of fibrin glue into the implant pocket as a capsular contracture-inducing agent. Rabbits were euthanized from 2 to 8 weeks after the procedure. Before the animals were euthanized, each implant was serially inflated with saline and a pressure-volume curve was developed using a Stryker device to assess the degree of contracture. Representative capsule samples were collected and histologically examined. Normal and contracted human capsular tissue samples were also collected from patients undergoing breast implant revision and replacement procedures. Tissue samples were assessed histologically.

RESULTS

Pressure-volume curves demonstrated a statistically significantly increased intracapsular pressure in the experimental group compared with the control group. The experimental subgroup had thicker, less transparent capsules than the control group. Histologic evaluation of the rabbit capsule was similar to that of the human capsule for the control and experimental subgroups.

CONCLUSIONS

The authors conclude that pathologic capsular contracture can be reliably induced in the rabbit. This animal model provides the framework for future investigations testing the effects of various systemic or local agents on reduction of capsular contracture.

Voies de recherche pour la mise au point de nouvelles prothèses mammaires

Despite the improvement of breast implant quality across the last decade, the perfect implant does not exist. Therefore research should manage to improve those implants. In this article we have tried to identify different directions to investigate for better prosthesis: improvement of the shell, the filling and the form. Moreover, other targets as fat transfer or other permanent soft tissue filler also need further experimental and clinical investigation.

Les complications postopératoires en chirurgie d'augmentation mammaire

Augmentation mammoplasty is one of the most popular and frequently performed aesthetic operations. The implants are not, however, without complications; and many have been reported in order to this surgical procedure: hematoma, infection, seroma, capsular contracture, rupture ... Current surgical practices and modern implants used for breast augmentation produce fewer complications than procedures and devices of the past. The aim of this work is to index most common post operative breast complications. The prevention and the treatment procedure of these complications are also reported. A good knowledge of all these points seems to be essential to improve the quality of the final results and patients satisfaction.

In Vitro Activity and In Vivo Efficacy of Antimicrobial-coated Vascular Grafts

The serious medical consequences and costly management of infections associated with vascular grafts have prompted an expanding interest in examining the preventive efficacy of antimicrobial-coated vascular grafts. The purpose of antimicrobial coating of vascular grafts is to reduce bacterial colonization of the device and, hopefully, the occurrence of clinical infection. In this study we demonstrated that expanded-polytetrafluoroethylene vascular grafts coated with minocycline and rifampin provide broad-spectrum antimicrobial activity in vitro, as reflected by zones of inhibition, against Staphylococcus epidermidis, S. aureus, Enterococcus faecium, and Pseudomonas aeruginosa. We also showed in a rabbit model that subcutaneously placed minocycline/rifampin-coated vascular grafts have lower rates of staphylococcal device colonization (1/24 = 4% vs. 8/30 = 27%, p = 0.033) and device-related infection (0/24 = 0% vs. 6/30 = 20%, p = 0.028) than uncoated grafts. These promising results encourage the clinical evaluation of vascular grafts coated with minocycline and rifampin.

The effectiveness of sodium 2-mercaptoethane sulfonate (mesna) in reducing capsular formation around implants in a rabbit model

The development of capsular contracture is the most common complication associated with the insertion of breast implants. The authors studied the role of sodium 2-mercaptoethane sulfonate (mesna) in reduction of capsular formation in a rabbit model. Two 40-cc textured saline implants were placed dorsally into each of the 20 rabbits in the study. At the time of insertion of the implants, 10 ml of a 10% solution of mesna was instilled into one of the pockets and normal saline was instilled into the other. The implants were removed and a capsulectomy was performed at 5 months. The capsules were examined histologically for qualitative differences between the two groups. Quantitative analysis of the thickness of the capsule and the myofibroblast populations was also performed and compared between the two groups. The mean total thickness of the capsule around the implants was 496.8 microm in the mesna-treated group compared with 973.7 microm in the saline-treated group (p < 0.001). Likewise, the thickness of the myofibroblast layer was reduced in the mesna-treated group at 283.2 microm versus 555 microm in the saline-treated group (p < 0.0001). The capsules were also relatively less vascular in the mesna-treated group. Because of its ability to reduce the extent of capsular formation and to diminish development of myofibroblasts in the capsules, mesna would appear to be a useful adjunct in the prevention of capsular contracture formation.