Long-term use of polyurethane breast prostheses: a 14-year experience

I have used polyurethane prostheses for the past 14 years, implanting 220 implants into 130 patients who desired breast reconstruction after subcutaneous mastectomy or cancer ablation or simply breast augmentation. I theorize that a polyurethane-covered implant resists contracture, retaining its compressibility because the fibroblasts proliferate into the polyurethane in many different directions. When the fibrils contract, the forces of contracture counterbalance one another, resisting contracture. However, when smooth prostheses are implanted, fibrils are directed in a circular fashion around the implant and naturally contract, leading to firmer breasts. There were 115 prostheses inserted following subcutaneous mastectomy, and 22 percent developed contracted capsules. Seven implants became exposed because of skin necroses; one was removed because of a Staphylococcus infection; and two patients developed a combination of polyurethane and silicone granulomas. These developed only with the earlier implant, where there was shedding of the polyurethane sponge layer and silicone bled from the low-viscosity silicone used in the earlier implants. No granulomas were noted with the currently used Surgitek Replicon implant. Eighty-five breasts were reconstructed after cancer ablation with polyurethane implants, and the contracture rate was 2.3 percent. Other complications were minimal. A smaller group of patients had augmentation mammaplasty, and 20 prostheses were placed in 10 patients. A 15 percent contracture rate was noted in this group. In this study, 82 percent of patients were followed for up to 14 years. Capsular contractures occurred in 30 implants between 1 and 11 years, for an average recurrence at 6.3 years. The overall contracture rate was 13 percent. Other complications were minimal. All implants were placed subcutaneously or subglandularly, and all were drained.     

Prospective evaluation of late cosmetic results following breast reconstruction: I. Implant reconstruction

The long-term cosmetic outcome of breast implant reconstruction is unknown. The morbidity and cosmetic outcome of 360 patients who underwent immediate postmastectomy breast reconstruction with various types of implants have been analyzed prospectively over a 9-year period. Of these patients, 334 who completed their reconstruction were suitable for evaluation of their cosmetic outcome. The early complication rate (< 2 months) was 9.2 percent, with an explantation rate of 1.7 percent. The late complication rate (> 2 months) was 23 percent, with a pathological capsular contracture rate of 11 percent at 2 years and 15 percent at 5 years and an implant removal rate of 7 percent. The revisional surgery rate was 30.2 percent.The cosmetic results were assessed prospectively using an objective five-point global scale. Every patient was scored at each visit once surgery was completed. The overall cosmetic outcome deteriorated in a linear fashion, from an initial acceptable result of 86 percent 2 years after patients completed their reconstruction to only 54 percent at 5 years. This decline in cosmetic outcome was not associated with the type of implant used, the volume of the implant, the age of the patient, or the type of mastectomy incision employed. Radiotherapy was not a significant factor because only 28 patients were irradiated. Upon Cox model analysis, pathological capsular contracture was the only factor that contributed significantly to a poor cosmetic outcome in which p < 0.0001 (relative risk 6.3). Despite a high revisional surgery rate, deterioration still occurred, suggesting that other unaccounted for variables were responsible. On photographic retrospective review of the patients without capsular contracture who demonstrated deterioration in their cosmetic scores, it became clear that a possible reason for their poor results was late asymmetry produced by the failure of both breasts to undergo symmetrical ptosis with aging.     

Methyl prednisolone in double-lumen gel-saline submuscular mammary prostheses: a double-blind, prospective, controlled clinical trial

At the time of immediate breast reconstruction with submuscular implants, 76 consecutive patients (89 breasts) were randomized into two groups. One received a gel-saline, double-lumen implant with 40 cc of saline added to the outer lumen, while the other received the same implant plus 40 cc of saline and 16 mg methyl prednisolone (40 mg%). Patients were followed for a minimum of 3 years. The groups, which were matched for patient age and implant size, were evaluated at 3, 12, 24, and 36 months for capsular contracture, steroid atrophy, and other complications. With completion of the double-blind study, the patients with submuscular gel-saline implants with only saline added had an overall capsular contracture rate of 38 percent at 3 months, 38 percent at 12 months, and 44 percent at 24 and 36 months. Those with methyl prednisolone had an overall capsular contracture rate of 14 percent at 3 months, and this remained unchanged through the end of the study. The rates of all other complications were comparable. Methyl prednisolone in a dose of 16 mg in 40 cc saline (concentration 40 mg%), when used in the outer lumen of a double-lumen gel-saline implant in a submuscular pocket, is both safe and efficacious in reducing the risk of capsular contracture for a minimum of 3 years in patients undergoing immediate breast reconstruction with submuscular mammary implants.     

Rate and incidence of capsular contracture: a comparison of smooth and textured silicone double-lumen breast prostheses

Capsular contracture results in dissatisfaction and deformity among the 2 million women who have had silicone implants. The literature describes contracture rates as high as 74 percent. I present a comparison of rates and incidences of contracture in patients augmented with smooth and textured double-lumen silicone implants. A total of 165 "smooth" and 63 "textured" implant patients were included in this study, which spans 12 years, 1978-1990. All patients underwent bilateral aesthetic augmentation performed by the same surgeon. Of the 165 smooth implant patients, 74 (44.8 percent) experienced contractures requiring treatment. Of the 63 textured implant patients, 3 (4.8 percent) previous contracture patients experienced sudden fibrosis within 3 months. All others remained soft. It appears that deeply textured silicone surfaces delay or decrease the rate and incidence of clinical capsular contracture, at least for 2 years.     

Capsular contracture: a prospective study of the effect of local antibacterial agents

In a prospective, random, double-blind, and concurrently controlled clinical study of 124 patients having augmentation mammaplasty, using multiple independent subjective judges as well as objective compressibility measurements, the use of a variety of local antibacterials in or around inflatable retromammary prosthetic implants reduced the early postoperative onset of class III to IV capsular contracture by sevenfold (85 percent) and the final incidence by more than half (50 percent) (p less than 0.01). We believe this study provides the most unequivocal evidence to date that the cause of capsular contracture in retromammary augmentation is periprosthetic bacterial contamination. Irrigation with a 5 percent povidone-iodine (50 percent Betadine) solution was as effective as other techniques and is currently our procedure of choice.     

Capsular contracture in silicone gel and saline-filled breast implants after reconstruction

Comparisons between results with randomly allotted silicone-gel and saline-filled prostheses in breast reconstruction after mastectomy led to the following conclusions. Neither prosthesis type is ideal. Leakage from saline-filled implants occurred in 2 of the 37 implants, with resultant deflation. Silicone prostheses had a significantly higher rate of capsular contracture [surgeon's evaluation: 54 percent capsular contracture for silicone-gel compared with 20 percent for saline-filled prostheses (p = 0.006); patients' evaluation for the same figures: 54 percent compared with 29 percent (p = 0.03)]. Other authors have shown the presence of silicone in the tissue around silicone-gel-filled silicone implants, but less or none around saline-filled silicone implants. Since the only difference between the two groups was the randomly allotted implants, we assume that the free silicone around silicone-gel-filled prostheses is the major cause of capsular contracture. Since the saline-filled implants showed a 20 percent capsular contracture rate, there could be other causes of capsular contracture in this study. For prevention of contracture, improved implant encapsulation and use of a less reactive filling substance seem to offer possibilities. Surgical technique should aim to preserve the integrity of the prosthesis.     

Long-term results of MISTI gold breast implants: a retrospective study

MISTI Gold breast implants (Bioplasty, St. Paul, Minn.) filled with polyvinylpyrrolidone-hydrogel were developed as a promising alternative to silicone-filled implants. Some studies have reported on the positive effects of the implant, such as improved radiolucency and biocompatibility of the gel; however, there are also reports that such implants increased in volume and were subject to capsular contracture in the human body, resulting in demands for their removal. The purpose of this retrospective study was to analyze the long-term results of a series of patients with MISTI Gold breast implants. Between 1991 and 1993, the authors inserted 83 MISTI Gold implants in 61 patients with an average age of 46 years (range, 16 to 69). The authors were able to follow up 48 patients with 71 MISTI Gold implants. The average follow-up was 68 months (range, 10 to 108 months). The retrospective study found that 59 percent of all MISTI Gold implants were removed after an average period of 4.14 years. The main reason for implant removal was an increase in volume of 38 percent, followed by capsular contracture in 14 percent of all 71 MISTI Gold implants. The average increase in volume of all removed MISTI Gold implants was 43 percent. Capsular contracture was graded as Baker I and II in 63 percent and as Baker III and IV in 37 percent. In conclusion, the authors believe that MISTI Gold implants do not fulfill the criteria of safe breast implants, and they agree with the December of 2000 opinion of the Medical Devices Agency of the Department of Health in London that the hydrogel-filled breast implants should not be used until more information about the filler material and its metabolic fate is available.     

Capsular contracture after breast reconstruction with silicone-gel and saline-filled implants: a 6-year follow-up

A major problem after breast reconstruction with augmentation mammaplasty is contracture of the fibrous capsule around the prosthesis. In a series of 72 breasts in 65 women, silicone-gel and saline-filled implants were randomly selected prior to breast reconstruction. The results were judged with respect to consistency, tenderness, wrinkles, and sounds by two independent plastic surgeons according to the breast augmentation classification (BAC) and by the patients themselves. Capsular contracture was found by the surgeons in 50 percent of the gel implant group and in 16 percent of the saline implant group, which is in conformity with the results of the follow-up 5 years earlier. The incidence of deflation was 16 percent in the saline group and occurred in different sizes of both overinflated and underinflated prostheses. The degree of slow leakage from saline implants will be discussed. Despite the high rate of contractures in the gel group, 85 percent of all patients were satisfied with the result of the reconstruction.     

The correction of capsular contracture by conversion to "dual-plane" positioning: technique and outcomes

Little has been published regarding the treatment of patients with long-established capsular contracture after previous submuscular or subglandular breast augmentation. This study reviews 7 years of experience in treating established capsular contracture after augmentation mammaplasty by relocating implants to the "dual-plane" or partly subpectoral position. A retrospective chart review was performed on all patients who were treated for capsular contracture using this technique between 1993 and 1999. Data collected included the date of the original augmentation, the original implant location, date of revision and type of implant used, length of follow-up, outcome, and any ensuing complications. Different surgical techniques were used, depending on whether the prior implant was located in a subglandular or submuscular plane. All patients had revisions such that their implants were relocated to a dual plane, with the superior two thirds or so of the implant located beneath the pectoralis major muscle and the inferior one third located subglandularly. Of 85 patients reviewed, 54 had their original implants in a submuscular position and 31 had their initial augmentation in a subglandular position. Of the 54 patients whose implants were initially submuscular, 23 patients (43 percent) had silicone gel implants, 15 patients (28 percent) had double-lumen implants, and the remaining 16 patients (30 percent) had saline implants. Of the 31 patients whose implants were initially subglandular, 20 patients (65 percent) had silicone gel implants, three patients (10 percent) had double-lumen implants, and the remaining eight patients (26 percent) had saline implants. Fifty-one patients (60 percent) had replacement with saline implants (37 smooth saline, 14 textured saline), whereas 34 (40 percent) had silicone gel implants (seven smooth gel, 27 textured gel). The average time from previous augmentation to revision was 9 years 9 months. The average follow-up time after conversion to the dual-plane position was 11.5 months. Only three of 85 patients required reoperation for complications, all of which involved some degree of implant malposition. Of patients converted to the dual plane, 98 percent were free of capsular contracture and were Baker class I at follow-up, whereas 2 percent were judged as Baker class II. There were no Baker level III or IV contractures at follow-up. The dual-plane method of breast augmentation has proved to be an effective technique for correcting established capsular contracture after previous augmentation mammaplasty. This technique appears to be effective when performed with either silicone or saline-filled implants.     

Trilucent breast implants: voluntary removal following the Medical Device Agency recommendation. Report on 115 consecutive patients

In June of 2000, the U.K. Medical Device Agency recommended the removal of Trilucent implants as a precautionary maneuver in response to reports of local inflammatory reactions. This decision allowed the authors to operate on 115 consecutive patients between June of 2000 and January of 2001. On the preoperative examination, the authors found a very high incidence of rippling (66 percent), whereas capsular contracture was seen in only three patients (2.6 percent). Rippling was significantly more common in patients with subglandular implants. Five implants were found ruptured during the operation. This figure, together with the relative ease of implant breakage at removal, shows a premature deterioration of the implant shell. The authors also comment on implant bleeding, which seems common in this type of breast implant. The authors think that this is a possible cause for the rippling phenomenon, resulting from a reduction of the implant content. On the basis of these findings, the authors conclude that Trilucent implants are associated with a poor cosmetic outcome and a high rate of complications.     

Breast reconstruction using an inflatable breast implant with detachable reservoir

An inflatable breast implant having a detachable filling reservoir is described. Once in position, the implant can be filled under controlled conditions postoperatively. The implant functions either as a tissue expander or as a delayed-filling implant in the initial stages of the procedure. Once the desired breast size is achieved, the reservoir is removed, leaving the filled implant in position. This implant has been used successfully in various types of breast reconstructive procedures, including both primary and secondary reconstruction following modified mastectomy, immediate reconstruction following subcutaneous mastectomy, secondary reconstruction following radical mastectomy combined with the latissimus dorsi flap, and following the removal of silicone gel implants with associated capsular contracture. A total of 23 patients, representing 34 breasts, are reported on. The results have been encouraging over a period of 20 months of follow-up.     

Ten-year review of a prospective randomized controlled trial of textured versus smooth subglandular silicone gel breast implants

Although textured silicone breast implants have been shown to reduce the incidence of capsular contracture, there is little evidence if this effect is maintained in the long term. It has been 10 years since the double-blind randomized trial in which 53 patients received either Mentor smooth (26) or textured silicone gel implants (27). Of the 14 patients who were not known to have developed a contracture in the smooth group, 11 were reviewed. Three had bilateral contractures. In the textured group, 18 of the 24 patients not known to have contractures were reviewed. None had developed contractures. At 10 years, the incidence of capsular contracture was 65 percent of patients with smooth implants (an increase of 6 percent on the 3-year results) and 11 percent for the textured implant patients (no change on the 3-year results). A database containing the details of 1100 patients reinforces these results by examining the differences in contracture rates of textured, smooth, and polyurethane-coated implants. The effect of submuscular placement on reducing contracture rates regardless of texturing is discussed, as is the apparent increase in capsular contracture in patients who smoke.     

Saline-filled breast implant safety and efficacy: a multicenter retrospective review

Our center undertook an industry-funded, outcomes-based, multicenter, retrospective review to evaluate the safety and efficacy of saline-filled breast implants. Our review was part of a pre-market approval review process mandated by the U.S. Food and Drug Administration. The design of our review was modeled on a Plastic Surgery Educational Foundation outcomes study previously conducted by our center. For this study, several significant changes were made to our previous protocol, including improved patient tracking, stronger biostatistical support, and a mandatory 10-year minimum patient follow-up period. Physician-reported and patient-reported data on 450 patients with 882 saline-filled breast implants placed between January 1, 1980, and June 30, 1986, were obtained. Mean patient follow-up period was 13.0 years. Most implants (93.9 percent) were placed for breast augmentation. Seventy-four percent were placed in a submammary position; 25.6 percent, subpectorally; and 0.2 percent, subcutaneously. The overall complication rate was 20.2 percent. Reoperation for capsular contracture or implant deflation was necessary in 104 of 450 patients (23.1 percent). Deflation occurred in 73 implants (8.3 percent) and was underreported according to the physicians' record review alone. This deflation rate is higher than the 5.5 percent previously reported by our center. However, 26 of these 73 deflations (35.6 percent) occurred in a single cohort of patients at one center using Surgitek saline implants. If this cohort is excluded, the deflation rate drops to 5.8 percent, a figure more consistent with data published in the literature and found in our previous study. Of the 73 deflations, spontaneous deflation was reported for 50 (74.6 percent), and the remainder were iatrogenic. Actuarial survival of the non-Surgitek implants was 98.4 percent to 99.8 percent at 5 years and 96.9 percent to 98.9 percent at 10 years (95 percent confidence interval). Risk factors for implant deflation included the use of Surgitek saline-filled implants (odds ratio = 17.5, p < 0.01), use of Heyer-Schulte and Mentor model 1800 implants (odds ratio = 3.0, p < 0.01), and implant size greater than 450 cc (odds ratio = 1.01, p < 0.02). Risk factors for capsular contracture included submammary implant position (odds ratio = 2.05, p = 0.03) and implant size greater than 450 cc (odds ratio = 1.01, p < 0.01). Overall, satisfaction was high: 93 percent of patients were "satisfied" or "very satisfied" with their implants. As in our earlier study, risk factors for patient dissatisfaction were reconstruction after mastectomy (odds ratio = 7.6, p = 0.011), significant breast firmness (odds ratio = 6.2, p < 0.001), and patient desire for smaller implants (odds ratio = 3.0, p = 0.020). In conclusion, our review provides additional outcomes-based evidence that saline-filled breast implants remain a safe, effective alternative to silicone gel-filled models.     

Use of stacked polyurethane-covered mammary implants in aesthetic and reconstructive breast surgery

The use of stacked polyurethane-covered mammary implants has proven useful in improving results in the correction of deficiencies of mammary form and projection that can occur in certain cases of congenital and acquired breast deformity. The method has been used in 57 patients (102 breasts). The rate of significant complications, including seroma, rash, infection, hematoma, and capsular contracture, has been low (1 to 6 percent). Polyurethane-covered implants will maintain their position when used in a stacked system because of their unique biophysical characteristics, which include tissue bonding and a high friction coefficient between the implant surfaces.     

The incidence of experimental contracture varies with the source of the prosthesis

Nominally equivalent gel-filled miniprostheses supplied by three different manufacturers were placed subcutaneously in rats under identical conditions in a double-blind comparison. The incidence of experimental contracture, defined by grossly visibly asymmetrical distortion of the implant, was 0, 9, and 91 percent for the different manufacturers, consistent with previous observations. Differences among the different implants with respect to the density of the fibrillar capsule structure, the cellularity, and the amount of extruded gel did not correlate with the incidence of contracture. Contracture rate was inversely proportional to the relative degree of filling of the prostheses, as reflected in deviations from the nominal hemispherical shape, and to the viscosity of the gel filling. For implants of the same type, the incidence of contracture was higher when the prosthesis was underfilled. Contracted capsules were more fibrous and contained more cells with microfilament bundles. It is concluded that the physical and geometric properties of silicone implants are critical in the expression of contracture and that these properties vary significantly among prosthesis manufacturers.     

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.     

Use of a permanent tissue expander for breast reconstruction

The use of tissue expansion in breast reconstruction is a recognized alternative surgical approach. The second generation of tissue-expanding prostheses is the permanent reverse double-lumen expander. In a series of 100 breast reconstructions using a permanent tissue expander, the clinical benefits of producing a moderate degree of mound ptosis along with observed reduction in pain during expansion are discussed. Additional advantages to the use of the device are the cost savings realized, elimination of a second procedure and a second anesthetic exposure, and a high degree of patient acceptance and satisfaction. This study includes breast reconstruction following mastectomies for malignant and premalignant disease, as demonstrated in 75 delayed and 25 immediate reconstructions, with the longest follow-up being 3 years. Complications of infection (3 percent), significant capsular contracture (4 percent), and implant failure (3 percent) are the most frequent and major complications observed yet. In no instance was breast reconstruction rendered unachievable in the face of these complications. The demonstrated results achieved with permanent tissue-expanding prosthesis, complemented by the obvious benefits and a low rate of significant complications, endorse this method as a viable alternative approach in reconstructive breast surgery.     

Irradiation after immediate tissue expander/implant breast reconstruction: outcomes, complications, aesthetic results, and satisfaction among 156 patients

Chest wall irradiation is becoming increasingly common for mastectomy patients who have opted for immediate breast reconstruction with tissue expanders and implants. The optimal approach for such patients has not yet been defined. This study assesses the outcomes of a reconstruction protocol for patients who require irradiation after tissue expander/implant reconstruction. The charts of all patients who underwent immediate tissue expander/implant reconstruction at Memorial Sloan-Kettering Cancer Center between January of 1995 and June of 2001 and who had not previously undergone irradiation were retrospectively reviewed. A subgroup of patients who required chest wall irradiation after mastectomy and reconstruction was identified. Those patients were treated according to the following treatment algorithm: (1) reconstruction with tissue expander placement at the time of mastectomy , (2) tissue expansion during postoperative chemotherapy, (3) exchange of the tissue expander for a permanent implant approximately 4 weeks after the completion of chemotherapy, and (4) chest wall irradiation beginning 4 weeks after the exchange. All irradiated patients with at least 1 year of follow-up monitoring after the completion of radiotherapy were evaluated with respect to aesthetic outcomes, capsular contracture, and patient satisfaction. A control group of nonirradiated patients was randomly selected from the cohort of patients treated during the study period. During the 5-year study period, a total of 687 patients underwent immediate reconstruction with tissue expanders. Eighty-one patients underwent postoperative irradiation after placement of the final implant. A total of 68 patients who received postoperative chest wall irradiation underwent at least 1 year of follow-up monitoring after the completion of radiotherapy, with a mean follow-up period of 34 months. Seventy-five nonirradiated patients were evaluated as a control group. Overall, 68 percent of the irradiated patients developed capsular contracture, compared with 40 percent in the nonirradiated group (p = 0.025). Eighty percent of the irradiated patients demonstrated acceptable (good to excellent) aesthetic results, compared with 88 percent in the nonirradiated group (p = not significant). Sixty-seven percent of the irradiated patients were satisfied with their reconstructions, compared with 88 percent of the nonirradiated patients (p = 0.004). Seventy-two percent of the irradiated patients stated that they would choose the same form of reconstruction again, compared with 85 percent of the nonirradiated patients. The results of this study suggest that tissue expander/implant reconstruction is an acceptable surgical option even when followed by postoperative radiotherapy and should be considered in the reconstruction algorithm for all patients, particularly those who may not be candidates for autogenous reconstruction.     

Breast augmentation using the expander mammary prosthesis

The expandable mammary prosthesis that has been successfully used for breast reconstruction has been modified for breast augmentation procedures. A new microreservoir that can be buried subcutaneously for extended periods has been developed. The unique design of this implant allows its size to be adjusted postoperatively as many times as desired, thus eliminating the possibility of a second operation to replace an implant whose size is unsatisfactory. Accurate, aesthetically satisfactory results are possible because the volume adjustments are made after the swelling has decreased and the implant has settled into position. Almost all patients offered this opportunity requested postoperative volume adjustments. The results of 59 patients are reported. The surgery was performed over a 3-year period, with the average follow-up time being 6 months. The incidence of capsular contracture has been less than 10 percent. Leakage was a problem in the original implant design; however, since the introduction of the new valve, there has been no leakage to date.     

Measurement of capsular contracture: the conventional breast implant and the Pittsburgh implant

At present, there is no accurate, reliable method of experimentally measuring capsular contracture. This study had four goals: (1) to define the parameters of capsular contracture employing principles of biomechanics of soft tissues, (2) to develop laboratory techniques to measure the parameters, (3) to design an implant that mechanically impedes the process of encapsulation, and, (4) to test this implant against a conventional one. We have developed a breast implant (the Pittsburgh implant) with an altered surface topography. Its silicone shell is punctuated by projections 1 mm in height and 1 mm in diameter. Two techniques were devised to measure contracture. The first involved measuring the force deformation along a coronal axis. The second involved measuring hydrostatic pressures within the implant resulting from the injection of known quantities of saline. Measurements were performed in vivo on 36 animals. By both force and pressure measurements, the Pittsburgh implant showed less capsular contracture (p = 0.12 and 0.012, respectively). Histology revealed that the prototype surface alters the linear arrangement of myofibroblasts and redirects the laminar collagen into a waveform pattern. We conclude from this experimental study that an altered surface topography may serve as a means of rendering a capsule less mechanically effective. We feel that the proposed methods can be used in the laboratory to characterize the extent of capsular contracture.