Capsular contracture around silicone implants: the role of intraluminal antibiotics

Histopathological evaluation of the effect of hyperbaric oxygen therapy on capsule occurrence around silicone breast prosthesis: an experimental study

BACKGROUND

In general, capsular contracture is the underlying cause of complications such as pain, stiffening, breast asymmetry, and animation deformity that are seen in the late postoperative period due to the use of silicone breast prostheses. Considering the positive effects of HBO therapy on wound healing, the objective of this study was to investigate the effect of HBO therapy on capsule reaction occurring due to silicone implants.

MATERIAL AND METHODS

Rats were divided into four groups. 1 cm × 1 cm silicone implants with rough surface were inserted in subcutaneous plane on the m spinotrapezius muscle fascia at just right of the dorsal region midline in rats in Group 1, while implants with same properties were inserted beneath m spinotrapezius muscle in rats in Group 2.Implants with the same properties were inserted in the subcutaneous area on the m spinotrapezius muscle in rats in Group 3 and into the area under the muscle in rats in Group 4. Beginning from the first postoperative day, rats in Groups 3 and 4 received HBO therapy for 90 min under 2.5 ATM pressure as one session a day over 15 days.

RESULTS

The mean capsule thickness was statistically significantly lower in the groups treated with HBO compared to the control groups. Fibroblast, neutrophil and macrophage counts were statistically significantly lower in the groups treated with HBO compared to the control groups.

CONCLUSION

We believe that HBO therapy can be used as an adjuvant treatment options to decrease capsule contraction occurring after silicone implant application.

Implantable systems for drug delivery to the brain

Most diseases and disorders of the brain require long-term therapy and a constant supply of drugs. Implantable drug-delivery systems provide long-term, sustained drug delivery in the brain. The present review discusses different type of implantable systems such as solid implants, in situ forming implants, in situ forming microparticles, depot formulations, polymeric-lipid implants, sucrose acetate isobutyrate and N-stearoyl L-alanine methyl ester systems for continuous drug delivery into brain for various brain diseases including glioblastomas, medulloblastoma, epilepsy, stroke, schizophrenia and Alzheimer's diseases. Implantable neural probes and microelectrode array systems for brain are also discussed in brief.

A review of implantable intravitreal drug delivery technologies for the treatment of posterior segment eye diseases

Intravitreal implantable device technology utilizes engineered materials or devices that could revolutionize the treatment of posterior segment eye diseases by affording localized drug delivery, responding to and interacting with target sites to induce physiological responses while minimizing side-effects. Conventional ophthalmic drug delivery systems such as topical eye-drops, systemic drug administration or direct intravitreal injections do not provide adequate therapeutic drug concentrations that are essential for efficient recovery in posterior segment eye disease, due to limitations posed by the restrictive blood-ocular barriers. This review focuses on various aspects of intravitreal drug delivery such as the impediment of the blood-ocular barriers, the potential sites or intraocular drug delivery device implantation, the various approaches employed for ophthalmic drug delivery and includes a concise critical incursion into specialized intravitreal implantable technologies for the treatment of anterior and posterior segment eye disease. In addition, pertinent future challenges and opportunities in the development of intravitreal implantable devices is discussed and explores their application in clinical ophthalmic science to develop innovative therapeutic modalities for the treatment of various posterior segment eye diseases. The inherent structural and functional properties, the potential for providing rate-modulated drug delivery to the posterior segment of the eye and specific development issues relating to various intravitreal implantable drug delivery devices are also expressed in this review.

Influence of rifampin on capsule formation around silicone implants in a rat model

This study investigated the effect of rifampin on the thickness of capsules around silicone implants by bactericidal activity against Stapylococcus epidermidis. Silicone blocks (1 x 1 cm) were placed into pockets created for each of the 40 rats included in the study. In group 1, the operation was performed under aseptic conditions. In group 2, standard S. epidermidis was inoculated into the pocket, whereas rifampin and S. epidermidis were applied in group 3. In group 4, only rifampin was applied topically on implants. After 12 weeks, the peri-implant capsules were removed and examined under a photomicroscope and a scanning electron microscope. The mean thickness of the capsules was 63.307 microm in group 1, 111.538 microm in group 2, 43.076 microm in group 3, and 30.384 mum in group 4. The differences between groups 2 and 3 and groups 2 and 4 were found to be statistically significant (p < 0.001). Rifampin appears to be an agent for preventing peri-implant capsule formation.

Clinical and Morphological Conditions in Capsular Contracture Formed around Silicone Breast Implants

BACKGROUND

A study was performed to investigate histological changes in capsules formed around silicone breast implants and their correlation with the clinical classification of capsular contracture defined by the Baker score. For histological classification, the authors used the classification introduced by Wilflingseder, which identifies four grades of contracture.

METHODS

The study included 24 female patients (average age, 40 +/- 12 years) with capsular contracture after bilateral cosmetic breast augmentation with smooth silicone gel implants (Mentor, Santa Barbara, Calif.). The Baker score was determined preoperatively for each patient. Samples of capsular tissue were obtained from all patients for histologic and immunohistochemical analyses. Capsular thickness, age of the collagen fibers, presence of synovia-like metaplasia on the inner surface of the capsule, number of histiocytes, giant cells, and other inflammatory cells, amount of silicone, foreign body granulomas, and capsule calcification were evaluated.

RESULTS

There was a positive correlation between capsular thickness (p < 0.05) and Baker score. Silicone-containing deposits were found in all four histological capsule types. A trend toward greater capsular thickness was documented in patients with severe inflammatory reaction. These patients also had more clinical symptoms. Greater capsular thickness was associated with a higher number of silicone particles and silicone-loaded macrophages in the peri-implant capsule.

CONCLUSIONS

The authors demonstrated a positive correlation (p < 0.05) between the clinical classification (Baker score I to IV) and the histological classification introduced by Wilflingseder (Wilflingseder score I to IV). An exact histological classification is needed to describe precisely the morphological changes in capsular contracture.

Detection of subclinical infection in significant breast implant capsules

The pathogenesis of fibrous capsular contracture after augmentation mammaplasty is still debated. One hypothesis implicates low-grade bacterial infections as a cause. The presence of a staphylococcal biofilm in a patient with recurrent capsular contracture was previously reported. A comparative, prospective, blinded, clinical study of implants and capsules removed from patients with or without significant capsular contracture was conducted to investigate the association of biofilm contamination, breast implants, and capsular contracture. Capsule and implant samples obtained during explantation were tested by routine microbiological culture, sensitive broth culture (after maceration and sonication), and scanning electron microscopy. Clinical parameters were correlated with microbiological findings. A total of 48 implant and/or capsule samples were obtained from 27 breasts during a 22-month period. Of the 27 breasts, 19 exhibited significant contracture (Baker grade III/IV). The mean duration of implantation was 9.2 years (range, 0.4 to 26.0 years). Routine swab cultures obtained at the time of explantation were negative for bacterial growth for all samples. The sensitive broth culture technique yielded 24 positive samples (50 percent, n = 48). An analysis of capsules demonstrated that 17 of 19 samples obtained from patients with significant contracture were positive, compared with only one of eight samples obtained from patients with minimal or no contracture (p = 0.0006). Fourteen of the 17 positive cultures from significantly contracted breasts yielded coagulase-negative staphylococci, mainly, species of the Staphylococcus epidermidis group. The presence of coagulase-negative staphylococci was also significantly associated with capsular contracture (p = 0.01). There was no significant difference in the frequency of culture positivity for saline versus silicone implants (p = 0.885). Scanning electron microscopy confirmed the presence of extensive biofilm on implants and within capsules.Biofilm, in particular, S. epidermidis biofilm, was detected for a significant proportion of patients with capsular contracture. This implicates biofilm disease in the pathogenesis of contracture, and strategies for its prevention should be explored.

Therapeutic applications of implantable drug delivery systems

In the past, drugs were frequently administered orally, as liquids or in powder forms. To avoid problems incurred through the utilization of the oral route of drug administration, new dosage forms containing the drug(s) were introduced. As time progressed, there was a need for delivery systems that could maintain a steady release of drug to the specific site of action. Therefore, drug delivery systems were developed to optimize the therapeutic properties of drug products and render them more safe, effective, and reliable. Implantable drug delivery systems (IDDS) are an example of such systems available for therapeutic use. The application of currently available implantable drug delivery systems is the main focus of this review. IDDS can be classified into three major categories: biodegradable or nonbiodegradable implants, implantable pump systems, and the newest atypical class of implants. Biodegradable and nonbiodegradable implants are available as monolithic systems or reservoir systems. The release kinetics of drugs from such systems depend on both the solubility and diffusion coefficient of the drug in the polymer, the drug load, as well as the in vivo degradation rate of the polymer, especially, in the case of the biodegradable systems. Controlled release of drug from the implantable pump is generally achieved utilizing the microtechnology of electronic systems and remote-controlled flow rate manipulation through the maintenance of a constant pressure difference. The third atypical class includes those which have been recently developed such as ceramic hydroxyapatite antibiotic systems used in the treatment of bone infections, intraocular implants for the treatment of glaucoma, and transurethral implants utilized in the treatment of impotence. The major advantages of these systems include targeted local delivery of drugs at a constant rate, less drug required to treat the disease state, minimization of possible side effects, and enhanced efficacy of treatment. Also, these forms of delivery systems are capable of protecting drugs which are unstable in vivo and that would normally require a frequent dosing intervals. Due to the development of such sustained release formulations, it is now possible to administer unstable drugs once a week to once a year that in the past required frequent daily dosing. Preliminary studies using these systems have shown superior effectiveness over conventional methods of treatment. However, one limitation of these newly developed drug delivery systems is the fact that their cost-to-benefit ratio (cost/benefit) is too high which restricts their use over conventional dosage forms. Hopefully, in the future, new implantable systems can be developed at a lower cost, thereby minimizing the cost-to-benefit ratio and therefore, be used extensively in standard therapeutic practice. Some of the most recently discovered implants are in the early developmental stages and more rigorous clinical testing is required prior to their use in standard practice.

Textured or smooth implants for breast augmentation? Three year follow-up of a prospective randomised controlled trial

Silicone breast implant surface texturing has been shown to reduce the short-term incidence of adverse (Baker III/IV) capsular contracture in augmentation mammaplasty in double-blind randomised controlled trials. It is, however, undetermined whether the textured surface merely delays the onset of severe contracture or its effect on capsular contraction is persistent. The current study reviewed, after three years, 49 of the 53 patients who had undergone subglandular breast augmentation mammaplasty in a randomised double-blind study with textured or smooth silicone gel-filled implants in 1989. The incidence of adverse capsular contracture was 59% for smooth implants and 11% for textured ones (P = 0.001; chi 2 = 10.60). Eight patients (31%) with smooth prostheses underwent breast implant exchange for severe capsular contracture between the one and three year assessments, compared with a revisional surgery rate of only 7.4% (2/27 patients) for the textured group (P < 0.04). These adverse capsular contracture and revisional breast implant surgery rates clearly demonstrate that the effect of textured implants in reducing capsular contracture in augmentation mammaplasty found at one year is maintained at three years, and suggest that it may be long lasting.

The role of the contractile fibroblast in the capsules around tissue expanders and implants

The occurrence, structure and contractility of myofibroblasts in the capsules around tissue expanders and static implants has been studied in the rat, pig and humans. The capsules showed a characteristic layered structure with myofibroblasts being the predominant cell type. Capsular strips contract in vitro in a manner characteristic of fibroblast contraction. The contractile ability decreased with the time since expander insertion; and increased with expander exposure, peri-expander infection and clinical evidence of adverse capsular contracture. An hypothesis is proposed that capsular contracture is analogous to wound contraction, and that intraimplant pressure usually inhibits capsular contraction. Evidence is shown from intraexpander pressure measurements to support this hypothesis. The clinical implications for tissue expansion and breast augmentation are discussed.

Textured or smooth implants for breast augmentation? A prospective controlled trial

This study examines the hypothesis that textured surface silicone implants reduce the incidence of adverse capsular contracture in breast augmentation. A total of 53 patients were entered into a prospective study; they were randomly assigned to receive either smooth or textured implants which were placed in the submammary plane. Of these, 50 patients were assessed at 12 months by a panel of observers who did not know which type of implants had been used. Adverse capsular contracture (Baker grades 3 and 4) was found in 28 breasts augmented with smooth surface implants (58%) and in 4 breasts in the textured surface implant group (8%). This reduction in adverse contracture using textured surface implants was highly significant (p less than 0.0001). Careful trial design is essential in studies of this sort in order that we can obtain useful data regarding the causes and prevention of adverse capsular contracture.

In vitro alterations in human fibroblast behavior secondary to silicone polymers

The etiology of fibrous capsular contractures in patients with silicone prostheses is unclear. However, cellular responses to the silicone polymers of the prostheses have not been examined. The exposure of human dermal fibroblasts to the components of the silicone gel prosthesis results in a significant change in cellular configuration and a progressive reduction in cell proliferation as determined by total matrix protein assays and hemocytometer cell counts. Transmission electron microscopy, however, documents a twofold increase in the rough endoplasmic reticulum when cells are exposed to the silicone gel. These findings suggest significant alterations in the behavior of human fibroblast subpopulations in response to silicone polymers.

Constant compression caliper for objective measurement of breast capsular contracture

The main problem with silicone implants in augmentation mammaplasty and breast reconstruction is the development of capsular contracture. The universal method for evaluating the degree of firmness of the breast is the subjective palpation technique and the classification according to Baker. Many objective methods using calipers for measurements of compression, different devices for indentation and discs for applanation tonometry have been described, but none of these have been widely accepted. In this paper a new measuring instrument is presented based on the principle of a constant compression force between two caliper jaws applied to the breast. The inverse value of the compressibility of the breast is read on a scale on the device. This objective method correlates acceptably with the palpation technique according to the Breast Augmentation Classification (BAC) (12), which is a modification of Baker's classification (1978), except for the first follow-up.

A critical look at capsule contracture in subglandular versus subpectoral mammary augmentation

A critical comparison of the contracture rate in subglandular versus subpectoral augmentations was done in a personal series (senior author's) of 100 consecutive augmentation patients, 50 with subglandular augmentation and 50 with subpectoral augmentation. The average followup for the series was 27 months. Baker's classification of capsule contracture was utilized. Overall contracture rate in the subglandular group was 58% (29 of 50 patients) while in the subpectoral group it was 22% (11 of 50 patients), p less than 0.0002. Considering only the more severe contractures (Baker III & IV), the subglandular patients had 48% (24/50) while the subpectoral patients had 14% (7/50), p less than 0.0002. Comparing the more severe contractures in individual breasts, the subglandular group had 41% and the subpectoral group had 8%, p less than 0.0001. We conclude that in this personal series of patients, subpectoral placement of the prosthesis has significantly reduced but not eliminated the occurrence of capsule contracture without sacrificing a normal breast appearance.