Since the introduction of breast implants, COSMETIC

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1 COSMETIC Textured Surface Breast Implants in the Prevention of Capsular Contracture among Breast Augmentation Patients: A Meta-Analysis of Randomized Controlled Trials G. Philip Barnsley, M.D. Leif J. Sigurdson, M.D., M.Sc. Shannon E. Barnsley, M.Sc. Ottawa, Ontario, and Halifax, Nova Scotia, Canada Background: Capsular contracture is a common complication associated with the use of breast implants. Numerous randomized controlled trials addressing the efficacy of textured surface breast implants in reducing capsular contracture have yielded nonuniform results. This meta-analysis addresses the use of textured breast implants in the prevention of capsular contracture. Methods: MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases were searched to identify all randomized controlled trials involving the use of textured versus smooth breast implants. The results of these trials were meta-analyzed to obtain a pooled odds ratio of the effect of textured surfacing on capsular contracture rates. In addition, subgroup analyses were performed based on implant type (saline or silicone gel), type of surface texturing (Siltex or Biocell), placement (subglandular or submuscular), and length of follow-up. Results: Eleven trials were reviewed. Four were excluded because they failed to meet a priori inclusion criteria. The remaining seven trials were meta-analyzed. Only three of these studies found significantly lower rates of capsular contracture with the use of textured implants. However, when all seven studies were pooled, the odds ratio was found to be 0.19 (95 percent confidence interval, 0.07 to 0.52), indicating a protective effect for surface texturing on the rate of capsular contracture. Submuscular placement was the only subgroup in which significance was not achieved. However, this subgroup consisted of a single study, which was dramatically underpowered. Conclusion: The results of this meta-analysis demonstrate the superiority of textured over smooth breast implants in decreasing the rate of capsular contracture. (Plast. Reconstr. Surg. 117: 2182, 2006.) Since the introduction of breast implants, silicone and saline breast implantation for both aesthetic and reconstructive purposes has become one of the most common procedures performed by plastic surgeons. The use of breast implants is associated with a number of complications, including hematoma, seroma, infection, altered nipple sensation, asymmetry, deflation, and capsular contracture. Of particular From the Department of Surgery, Division of Plastic Surgery, Dalhousie University, and Department of Epidemiology and Community Medicine, School of Psychology, University of Ottawa. Received for publication April 2, 2005; revised May 10, Copyright 2006 by the American Society of Plastic Surgeons DOI: /01.prs d5 concern to both the patient and the surgeon is capsular contracture, as moderate to severe contracture occurs in 15 to 45 percent of patients. 1 4 Patients with capsular contracture experience a variable amount of implant distortion, firmness, and pain. 5 Moreover, capsular contractures can be severe enough to require additional operations, resulting in additional costs to the patient, potential for suboptimal results, and higher probabilities of repeated capsular contracture. Interventions attempting to prevent capsular contracture have included antibiotic washes, 6 8 intraluminal steroids, 9,10 submuscular placement, 11 low bleed silicone elastomer shells, 12 systemic antibiotics, underfilling implants, double-lumen implants, and saline-filled implants. 13 Despite these efforts, capsular contracture remains a significant problem with the use of breast implants. Ever since

2 Volume 117, Number 7 Textured Surface Breast Implants polyurethane-coated implants were reported to have lower rates of capsular contracture, the idea of using an implant with a textured surface has received considerable attention and has been the subject of a recent review. 13 Numerous experimental studies have attempted to identify why lower rates of capsular contracture are observed with the use of textured surface implants. These studies have used animal models with textured implants placed both subcutaneously and submuscularly and evaluated the histology of the formed capsules. 5,19 22 A number of these studies found capsules to be tighter and thicker around textured implants compared with smooth implants, 5,19,20 whereas others demonstrated that capsular contracture occurs less often with textured surface implants. 21,22 The experimental evidence is therefore equivocal. Several clinical series have been published addressing the issue of capsular contracture and surface texturing. 1,2,23,24 A survival analysis of 1655 breast implants in 752 patients identified a lower rate of contracture involving textured implants, but the difference was not statistically significant. 23 Other retrospective studies have reported the rate of capsular contracture to be 4.8 percent and 4 percent in women with textured implants and 44.8 percent and 21 percent in women with smooth implants. 2,24 In a further series of women who all received textured implants, capsular contracture occurred in 15 percent. 1 Although these studies provide interesting information, randomized controlled trials are required for a definitive understanding of the efficacy of surface texturing on reduced rates of capsular contracture. Numerous randomized controlled trials have been performed representing the best evidence currently available. Unfortunately, they are often underpowered (i.e., they lack adequate numbers of subjects) and have been inconsistent in their findings, thereby making conclusions difficult. A meta-analysis 25 overcomes the problem of small subject numbers by combining data from previous randomized trials to provide a pooled estimate of the risk of developing capsular contracture. A properly performed meta-analysis is felt by many to be the highest level of evidence. 26 The objective of this study was therefore to metaanalyze previous clinical trials to investigate the role of surface texturing on the rate of development of capsular contracture in breast augmentation patients. PATIENTS AND METHODS Literature Search and Study Selection The MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched from their inception (MEDLINE, 1966; EMBASE, 1980) until March of 2004 to identify the randomized controlled trials to be included in the meta-analysis. The strategy aimed to identify trials that evaluated breast implants with textured surfaces. The strategy included the search terms breast implants, implants, artificial, prosthesis, silicones, texture, and contracture. Because of the paucity of literature on the subject, a randomized controlled trial filter was not necessary. All studies identified through the search were subjected to inclusion and exclusion criteria. Studies were included if they used a randomized controlled trial format comparing textured surfaced implants to smooth surface ones in women undergoing breast augmentation. Furthermore, studies were excluded if they did not use capsular contracture as a measured outcome. Capsular Contracture Grading Systems The outcome of interest was clinically significant capsular contracture. Trials examining capsular contracture use either the Baker classification 3 or the Breast Augmentation Classification 27 to identify contracture severity. In both classification systems, classes III and IV represent clinically significant capsular contracture (Tables 1 and 2). Therefore, for the purposes of the meta-analysis, class III or IV contracture in either classification system was considered to be a clinically significant capsular contracture. Table 1. Baker Classification* Grade I II III IV Description Breast absolutely natural, no one could tell breast was augmented Minimal contracture; surgeon can tell surgery was performed but patient has no complaint Moderate contracture; patient feels some firmness Severe contracture; obvious just from observation *Data from Baker, J. Augmentation mammaplasty. In J. W. Owsley, Jr. (Ed.), Symposium on Aesthetic Surgery of the Breast: Proceedings of the Symposium of the Educational Foundation of the American Society of Plastic and Reconstructive Surgeons, and the American Society for Aesthetic Plastic Surgery, in Scottsdale, Ariz., November 23 26, St. Louis, Mo.: Mosby, Pp

3 Plastic and Reconstructive Surgery June 2006 Table 2. Breast Augmentation Classification* Grade I II III IV Description Soft; no deformation Slightly thickened consistency; none to slight deformation Firm to hard; none to slight deformation Hard; severe deformation *Data from Gylbert, L. O. A., Jurell, G., and Olenius, M. Results of subglandular breast augmentation using a new classification method: 18-year follow-up. Scand. J. Plast. Reconstr. Surg. Hand Surg. 23: 133, Data Abstraction Data abstraction was performed independently by two of the authors (G.P.B. and S.E.B.) using a standardized report form. The data abstraction form included fields for study design, sample size, eligibility criteria of patients, treatment regimens, and outcomes. On completion of data abstraction for each trial, each reviewer would complete the Jadad scale to provide information regarding the methodologic quality of the randomized controlled trial. The Jadad scale is a tool that awards points for various components of a randomized controlled trial, including the randomization process, blinding within the trial and follow-up of participants. A randomized controlled trial with a Jadad score of 3 or greater is considered to be of high quality. 28 Statistical Analysis Descriptive statistics of the following variables were performed for each randomized controlled trial: year of publication, outcome, sample size, and quality score. The meta-analysis was conducted using Review Manager software version (The Cochrane Collaboration, Oxford, United Kingdom). There are two commonly used methods of pooling data in meta-analyses. These include pooling summary measures such as odds ratios, and pooling individual patient level data. The former was chosen for this analysis, as individual patient data were not presented in all of the randomized controlled trials used in this analysis. Odds ratios were calculated for each randomized controlled trial. Confidence intervals for each odds ratio were set at 95 percent, and only those that did not span 1 were regarded as statistically significant. An odds ratio of less than 1 would indicate that the odds of developing capsular contracture with textured implants is less than with smooth implants. The odds ratios from individual randomized controlled trials were pooled to obtain an overall odds ratio. Homogeneity between the studies was assessed, and a random effects model was used to control for statistical heterogeneity between the studies. The use of a random effects model was performed to construct better weights for combining the odds ratios of the individual trials, and was conducted within the Review Manager software package. Clinical heterogeneity within the trials was suggested by variability in the type of implants used (saline or silicone), texturing method [Siltex (Mentor Corp., Santa Barbara, Calif.) or Biocell (Inamed Corp., Santa Barbara, Calif.)], and placement (submuscular or subglandular). To address this clinical heterogeneity, subgroup analyses were performed for patients with silicone implants, saline implants, different texturing methods, and subglandular and submuscular placements. RESULTS Ninety-three citations were found through the search strategy. Fourteen unique and potentially relevant randomized controlled trials were identified. 2,6,29 40 Figure 1 shows the basis for inclusion and exclusion of the potentially relevant randomized controlled trials. The 3-year follow-up study excluded in Figure 1 37 was not used in the analysis because it reported earlier follow-up of the larger 10-year trial. 33 A further trial that provided a Baker classification for each patient rather than for each breast was deemed unsuitable for pooling in the meta-analysis. 40 The remaining seven randomized controlled trials met the inclusion criteria. These randomized controlled trials were found using the MEDLINE search strategy; no studies were added by searching EMBASE or the Cochrane Central Register of Controlled Trials. Descriptive statistics of these trials are found in Table 3. The randomized controlled trial with a Jadad score of 2 received a low score because it was not described as double blind and its randomization procedure was unclear. 34,40 This particular randomized controlled trial did not find a statistically significant difference in capsular contracture rates with the use of textured implants. Although the low Jadad score indicates poor methodologic quality, it was included in the analysis because it was still felt to contribute meaningful information. Any bias from its inclusion would be away from finding a significant reduction in capsular contracture with the use of textured surface implants. It is usual practice in conducting a meta-analysis to create a funnel plot to assess publication bias of significant results. With only seven trials addressing the research question, it was decided 2184

4 Volume 117, Number 7 Textured Surface Breast Implants Fig. 1. Inclusion and exclusion of potentially relevant randomized controlled trials (RCTs) identified by the reviewers. that a funnel plot would not be helpful in assessing this form of bias. 41 It is felt, however, that publication bias is not a factor in this meta-analysis, as four of the seven published trials reported statistically insignificant results. Pooling of these studies in the meta-analysis revealed significant heterogeneity (p 0.006); therefore, a random effects model was used and subgroup analyses were performed. The pooled odds ratio was found to be 0.19 (95 percent confidence interval, 0.07 to 0.52) using a random effects model, indicating that capsular contracture was five times as likely to occur with smooth surface implants. A forest plot showing the individual odds ratios of each of the trials and the overall effect is shown in Figure 2. Subgroup analyses based on the duration of follow-up, implant placement, and type of implant are shown in Figure 3. As a result of sufficient homogeneity, fixed effects analysis was used in the following subgroups: follow-up greater than 3 years, method of surface texturing, saline implants, and submuscular placement. Statistical superiority of surface texturing was found in all subgroups except where implants were placed in the submuscular plane. When both Siltex and Biocell textured implants were considered on their own, it was found that they were both associated with a statistically significant reduction in capsular contracture formation (Siltex, odds ratio, 0.06; 95 percent confidence interval, 0.02 to 0.16; Biocell, odds ratio, 0.34; 95 percent confidence interval, 0.17 to 0.70). The number and types of complications are shown in Table 4. Ten of 532 patients required reoperation for postoperative complications other than capsular contracture. Three of these patients were in the textured implant group, five were in the smooth implant group, and two were not identified as to which group they belonged. A metaanalysis of these complications is shown in Figure 4, with subgroup analysis consisting of complications requiring reoperation, infection, and infection requiring reoperation. Complications that occurred in patients whose treatment group was not reported are not included in Figure 4. There was no statistically significant difference in the num- 2185

5 Plastic and Reconstructive Surgery June 2006 Table 3. Descriptive Statistics of Studies Involved in the Meta-Analysis Length of Follow-Up Average Time to Contracture Jadad Score Outcome Measure Sample Size Implant Type Placement Study Year Submuscular 3 Not reported 12 mo Asplund 1996 BAC 104 implants Third-generation silicone, Dow Corning Silastic II HP/Silastic MSI HP Burkhardt 1994 Baker 90 implants Saline, Mentor 1600/2600 (Siltex) Subglandular mo 9 32 mo Burkhardt 1995 Baker 104 implants Saline, McGhan 68/168 (Biocell) Subglandular 4 5 mo 5 40 mo Coleman 1991 Baker 50 patients Third-generation silicone, Mentor (Siltex) Subglandular 3 Not reported 12 mo Fagrell 2001 Baker 40 implants Saline, Mentor 1800/2800 (Siltex) Subglandular 2 Not reported 5 yr 11 mo 8 yr4mo 12 mo Subglandular 5 Most occurred 3 6 mo postoperatively Hakelius 1992 BAC 50 implants Third-generation silicone, McGhan 40 (Biocell) Tarpila 1997 Baker 42 implants Saline, McGhan 68/168 (Biocell) Subglandular 3 Not reported 12 mo BAC, breast augmentation classification. ber of complications between the textured and smooth implant groups. DISCUSSION The results of our meta-analysis show that capsular contracture occurs approximately five times more frequently with smooth surface implants compared with textured surface implants. Our search strategy identified seven randomized controlled trials addressing the question of whether surface texturing decreases the proportion of patients who develop capsular contractures. Four of these seven trials did not find a statistically significant decrease in this proportion. Nevertheless, when all studies are pooled, the results indicate a protective effect for surface texturing. In all but one of the subgroups analyzed within this metaanalysis, textured surface breast implants significantly decreased the rate of capsular contracture. This subgroup, which consisted of a single study in which all implants were placed in the submuscular plane, found a lower proportion of capsular contracture that was not statistically significant. 29 These findings may be attributable to capsular contracture being more difficult to appreciate in the deeper submuscular plane or textured surface implants having no impact on capsular contracture when placed submuscularly. Of higher likelihood is that the study did not enroll enough subjects to detect a significant difference should it have existed. The study found a decrease in the contracture rate from 15 percent in the smooth implant group to 8.6 percent in the textured implant group, representing a decrease of almost 50 percent. To achieve statistical power of 80 percent to detect this difference, the sample would need to include 356 breasts per group, whereas this study only had 58 in the textured implant group and 52 in the smooth implant group. This was the only study in which implants were placed in the submuscular plane. When Biocell (surface texturing used by Inamed Corporation) and Siltex (surface texturing used by Mentor Corporation) surfaces were evaluated on their own, they were both found to have a statistically significant protective effect on the rate of capsular contracture. As none of the studies compared these surfaces against each other, it was felt that no conclusions could be made regarding which surface is more effective in reducing capsular contracture. When the postoperative complications were evaluated, three of the 10 complications requiring reoperation were in the textured implant group, five were in the smooth implant group, and two 2186

6 Volume 117, Number 7 Textured Surface Breast Implants Fig. 2. Odds ratios of capsular contracture in the studies and the overall pooled estimate. Fig. 3. Subgroup analysis of studies included in meta-analysis. Events represent clinically significant capsular contracture. 2187

7 Plastic and Reconstructive Surgery June 2006 Table 4. Complications in Patients in the Included Trials by Study Group Group Complication Total No. Requiring Reoperation Textured Infection 3 2 Displacement of implant 1 1 Total 4 3 Smooth Infection 1 1 Perforation 1 1 Deflation 2 2 Displaced Implant 1 1 Total 5 5 Unknown Hematoma 4 2 Postoperative bleeding 1 1 Total 5 3 were not reported as to which group they belonged to. The two complications that were not assigned to a particular group could not be included in the meta-analysis of complications. Although the rate of infection was higher in the textured surface group, the incidence was only 1.1 percent, and the difference was not statistically significant. These findings indicate that concerns regarding postoperative infection and other complications should not deter surgeons from choosing textured implants over smooth implants. Rippling of the skin, which has been shown in a retrospective study to be more common in women who receive textured implants, 23 was not addressed in any of the prospective randomized trials included in this meta-analysis. This is the first study in the literature to systematically review and meta-analyze clinical trials evaluating the risk of capsular contracture with the use of textured surface breast implants. As the meta-analysis was only performed on breast augmentation patients, caution should be undertaken when extrapolating the results to the reconstructive population. The short duration of follow-up in these trials could also be considered a limitation. According to Baker, 92 percent of capsular contractures occur within the first 12 months, 42 and as such the standard length of follow-up in these trials is 1 year. As previously described, many interventions have been attempted since Baker s initial report and remain in common use to prevent capsular contracture. These interventions may delay capsular contracture, potentially making a follow-up of 1 year no longer appropriate. The subgroup analysis of randomized controlled trials with greater than 3 years of follow-up addresses this concern and shows that the use of textured Fig. 4. Meta-analysis of all complications assigned to either textured or smooth surface implants in studies included in the metaanalysis. 2188

8 Volume 117, Number 7 Textured Surface Breast Implants implants was associated with a statistically significant reduction in capsular contracture. This suggests that an extended length of follow-up would not change the results of this meta-analysis. A meta-analysis of all complications was not possible because of incomplete reporting among some of the randomized controlled trials. Although complications were identified in the randomized controlled trials, it was not always reported in which group, smooth versus textured, the complications occurred. Nonetheless, only two of the 10 complications requiring reoperation were not assigned to textured or smooth implant groups, and the difference in complication rates between the two groups was not statistically significant. Therefore, it is not expected that this limitation affects the findings. CONCLUSIONS The results of our meta-analysis demonstrate the superiority of textured surface breast implants over smooth surface breast implants in decreasing the proportion of patients who develop capsular contracture. Further research is required to more fully understand the cause of the decreased risk of capsular contracture and to explore the role of textured surface implants in breast reconstruction. Phil Barnsley, M.D. c/o Dr. Leif Sigurdson Halifax Infirmary, Room Summer Street Halifax, Nova Scotia B3H 3A7, Canada barnsley@dal.ca ACKNOWLEDGMENT The authors thank Dean Fergusson, Ph.D., for aid in the development of this meta-analysis. REFERENCES 1. Ersek, R. A., and Salisbury, A. V. Textured surface, nonsilicone gel breast implants: Four years clinical outcome. Plast. Reconstr. Surg. 100: 1729, Ersek, R. A. Rate and incidence of capsular contracture: A comparison of smooth and textured silicone double-lumen breast prostheses. Plast. Reconstr. Surg. 87: 879, Baker, J. 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