The Modern Polyurethane-Coated Implant in Breast Augmentation : Long-Term Clinical Experience

Background: First-generation polyurethane foam-coated breast implants were associated with a low risk of capsular contracture (CC), but the risk of CC with modern polyurethane-coated silicone implants has not been established. Objectives: The authors sought to determine the long-term rates of CC after primary breast augmentation with Microthane, a polyurethane-coated silicone gel implant. Methods: A total of 131 patients (255 breasts) were evaluated in a retrospective study. Data were compiled from postoperative follow-up sessions at 2 weeks; 1, 3, 6, and 12 months; and annually thereafter. Rates of various complications, including CC, were determined. Results: CC developed in 3 of the 255 implanted breasts (1.2%; Baker grade III or IV), and postoperative hematoma occurred in 2 implanted breasts (0.8%). Spontaneous CC that was not associated with other complications was observed in 1 implanted breast (0.4%). All instances of CC occurred before the 31st postoperative month. Conclusions: For patients who undergo primary breast augmentation with modern polyurethane-coated implants, the long-term risk of CC is low. Level of Evidence: 3 Therapeutic Accepted for publication August 18, 2016. Modifications to the shape and composition of breast implants have been made by manufacturers since the introduction of these prostheses in the early 1960s. Today, a patient may choose from a variety of implant shell and content materials. The shell may be textured or smooth and may comprise silicone with or without a coating of polyurethane foam. Implant contents include saline or silicone. High-viscosity, cohesive silicone gel implants have supplanted liquid silicone implants in popularity. Despite advancements in implant types and an abundance of studies addressing implant selection, capsular contracture (CC) remains a common complication of breast augmentation and is the primary reason for reoperation. Plastic surgeons tend to recommend implants that are associated with lower rates of complications (including CC) and decreased likelihood of revisional surgery. In a 25-year study of 1529 patients (3495 implants), first-generation implants covered in polyurethane foam were associated with a relatively low risk of CC. The aim of the present study was to determine the long-term risk of CC with Microthane (Polytech Health & Aesthetics, Dieburg, Germany), a modern polyurethane-coated silicone gel implant. Dr Pompei is Unit Head and Dr Arelli is a Plastic Surgeon, San Camillo Plastic and Reconstructive Surgery Unit, Rome, Italy. Dr Evangelidou is a Plastic Surgeon, Emirates Hospital Group Plastic and Reconstructive Surgery Department, Dubai, United Arab Emirates. Dr Ferrante is a Researcher, National Center of Disease Prevention and Health Promotion, Italian National Institute of Health, Rome, Italy. Corresponding Author: Dr Dora Evangelidou, The Burj Residences Tower 8, Apartment 1803, PO Box 126228, Downtown Dubai, UAE E-mail: dr.evangelidou@gmail.com Breast Surgery Downloaded from https://academic.oup.com/asj/article-abstract/36/10/1124/2664528 by guest on 09 June 2018 METHODS Patients and Study Design The anonymized records of 131 consecutive women (255 breasts) who underwent primary breast augmentation or mastopexy-augmentation with Microthane, a polyurethanecoated silicone gel implant, were reviewed retrospectively. Patients underwent surgery from September 2000 to June 2012. Approval for this study was obtained from the ethics review board of Sandro Pertini Hospital (Rome, Italy), and the study was conducted in accordance with guiding principles set forth in the Declaration of Helsinki. Patients were excluded from the study if they underwent breast augmentation with non–polyurethane-coated devices or if they had previously undergone breast surgery. Surgical Techniques Breast augmentation and augmentation-mastopexy were performed under general anesthesia by standard techniques. All patients received perioperative care from the senior author (S.P.) and members of his team (A.F.) at Sandro Pertini Hospital. Prophylactic antibiotics were delivered intravenously upon initiation of anesthesia, and patients did not receive adrenaline. The first incision was usually inframammary or periareolar. Dissection of a subglandular or dual-plane pocket was performed with electrocautery, and meticulous hemostasis was achieved with bipolar forceps. Before implant placement, the pocket and Microthane implant were irrigated with cefazolin solution, and the surgical team routinely changed their gloves. Early in this study (2000–2003), most patients received round implants, with anatomic implants predominating thereafter. Suction drains were placed to remove pocket fluids and maximize the contact surface between the polyurethane foam shell of the implant and the surrounding tissue. This step was necessary to stabilize the implant and prevent displacement. Postoperative Care and Data Collection Patients continued to receive intravenous antibiotics for 24 hours postoperatively. Suction drains were removed when there was no indication of hematoma and fluid collection was less than 30 mL/d. Two or more members of the surgical team conducted each postoperative follow-up session at 2 weeks; 1, 3, 6, and 12 months; and annually thereafter. Each patient was encouraged to contact the office for additional consultations if new symptoms arose. Patient data, including intervention type, implant size and type, surgical approach, date of surgery, complications (including CC), date CC was detected, and duration of follow-up, were compiled in an Excel database prepared by the senior author (S.P.) (Table 1). For this study, only Baker grade III (ie, a firm breast with a noticeable implant) and Baker grade IV (ie, a painful, hard, distorted breast with stretched, tender skin and implant rigidity upon palpation) were considered indicative of CC. Statistical Analyses All analyses were performed with Stata 13 statistical software (StataCorp LP, College Station, TX). Descriptive statistics included implant size, mean and median patient age, and mean and median follow-up time (in months). Complication rates were evaluated overall and by intervention type, implant size, implant type, and pocket position. Poisson regression models were applied to estimate the risk ratios of complications in the subgroups. CC rates were estimated separately for implants and patients by means of the Kaplan-Meier method for cumulative incidence. Time of CC onset was defined as the time from the initial breast surgery to the diagnosis of CC (in months). Patients who did not experience CC were censored after the final follow-up session or at time of reoperation. For all analyses, P< .05 was considered statistically significant. RESULTS The patients’ mean age was 34.7 years (range, 19–56 years), and the median follow-up period was 110 months Table 1. Information Collected Retrospectively From Patient Cohort Patient identification no. and demographic information


Patients and Study Design
The anonymized records of 131 consecutive women (255 breasts) who underwent primary breast augmentation or mastopexy-augmentation with Microthane, a polyurethanecoated silicone gel implant, were reviewed retrospectively.Patients underwent surgery from September 2000 to June 2012.Approval for this study was obtained from the ethics review board of Sandro Pertini Hospital (Rome, Italy), and the study was conducted in accordance with guiding principles set forth in the Declaration of Helsinki.Patients were excluded from the study if they underwent breast augmentation with non-polyurethane-coated devices or if they had previously undergone breast surgery.

Surgical Techniques
Breast augmentation and augmentation-mastopexy were performed under general anesthesia by standard techniques.All patients received perioperative care from the senior author (S.P.) and members of his team (A.F.) at Sandro Pertini Hospital.Prophylactic antibiotics were delivered intravenously upon initiation of anesthesia, and patients did not receive adrenaline.The first incision was usually inframammary or periareolar.Dissection of a subglandular or dual-plane pocket was performed with electrocautery, and meticulous hemostasis was achieved with bipolar forceps.Before implant placement, the pocket and Microthane implant were irrigated with cefazolin solution, and the surgical team routinely changed their gloves.Early in this study (2000-2003), most patients received round implants, with anatomic implants predominating thereafter.
Suction drains were placed to remove pocket fluids and maximize the contact surface between the polyurethane foam shell of the implant and the surrounding tissue.This step was necessary to stabilize the implant and prevent displacement.

Postoperative Care and Data Collection
Patients continued to receive intravenous antibiotics for 24 hours postoperatively.Suction drains were removed when there was no indication of hematoma and fluid collection was less than 30 mL/d.Two or more members of the surgical team conducted each postoperative follow-up session at 2 weeks; 1, 3, 6, and 12 months; and annually thereafter.Each patient was encouraged to contact the office for additional consultations if new symptoms arose.
Patient data, including intervention type, implant size and type, surgical approach, date of surgery, complications (including CC), date CC was detected, and duration of follow-up, were compiled in an Excel database prepared by the senior author (S.P.) (Table 1).For this study, only Baker grade III (ie, a firm breast with a noticeable implant) and Baker grade IV (ie, a painful, hard, distorted breast with stretched, tender skin and implant rigidity upon palpation) were considered indicative of CC.

Statistical Analyses
All analyses were performed with Stata 13 statistical software (StataCorp LP, College Station, TX).Descriptive statistics included implant size, mean and median patient age, and mean and median follow-up time (in months).Complication rates were evaluated overall and by intervention type, implant size, implant type, and pocket position.Poisson regression models were applied to estimate the risk ratios of complications in the subgroups.CC rates were estimated separately for implants and patients by means of the Kaplan-Meier method for cumulative incidence.Time of CC onset was defined as the time from the initial breast surgery to the diagnosis of CC (in months).Patients who did not experience CC were censored after the final follow-up session or at time of reoperation.For all analyses, P < .05 was considered statistically significant.
Of the 255 implanted breasts, 4 were lost to follow-up, 3 were censored at CC diagnosis, and 9 were censored at reoperation to treat complications other than CC.These 9 patients who underwent reoperation were censored because more than 1 breast surgery was an exclusion criterion for this study.Moreover, it would not have been possible to determine conclusively which operation contributed to the CC if it developed after the secondary breast surgery.
At least 1 complication occurred in 19 implanted breasts (7.4%) (Table 3).Malposition occurred during surgery for 4 breasts (3 patients) implanted in the subglandular plane with anatomic implants.Two patients underwent reoperation to treat this complication; the third patient chose not to undergo treatment.Bilateral rippling was observed in 2 patients (4 implanted breasts).One of these patients underwent 1 session of lipofilling at another office and subsequently was lost to follow-up.The other patient did not undergo treatment for rippling.Two patients experienced unilateral implant rupture 4 years postoperatively; these patients underwent bilateral explantation and implant replacement in a single surgical session.
Cutaneous erythema with spontaneous resolution was observed for 2 patients.Two patients experienced early seroma (at postoperative weeks 8 and 10, respectively) and were treated conservatively.No patient experienced late seroma.Spontaneous inferior dislocation of the implant (ie, displaced lower than the inframammary fold) occurred unilaterally for 1 patient in the fifth postoperative year.This patient did not undergo treatment for inferior implant dislocation.To our knowledge, the mechanism for this complication is unknown.
Baker grade III or IV CC was observed for 3 of the 255 implanted breasts (1.2%; 3 patients); the cumulative incidence of CC during a 14.6-year period is depicted in Figure 1.For 2 of these implanted breasts, CC occurred after hematoma was diagnosed.The other implanted breast developed CC spontaneously despite absence of previous complications.Two of the 3 patients who experienced CC were lost to follow-up  after the first postoperative year.The remaining patient indicated that she found the aesthetic results acceptable and the CC was not painful (grade III); she did not undergo additional treatment.The Kaplan-Meier estimation of cumulative incidence of CC over 14.6 years was 1.2% for implants (95% confidence interval [CI], 0.39%-3.65%)(Figures 1 and 2) and 2.3% for patients (95% CI, 0.74%-6.93%)(Figure 2).Complication rates by intervention type, implant size, and pocket position are presented in Table 4.
Five patients (7 implanted breasts) with complications of the primary surgery chose to undergo reoperation.Two of these patients, both of whom experienced unilateral rupture after the primary breast surgery, also underwent surgery of the contralateral implanted breast (ie, 9 total reoperated breasts) (Table 5).These patients sought a secondary bilateral procedure to modify the size of both implants.The remaining revisional surgeries corresponded to 3 implanted breasts (2 patients) with malposition and 2 implanted breasts (1 patient) with rippling (Table 5).
No statistically significant differences in the incidence of CC or any other complication were observed with regard to pocket position (ie, subglandular or dual-plane),

DISCUSSION
We determined the cumulative incidence of CC for 14.6 years and found that CC increased steadily from 0% to 1.2% during the first 2.5 years postoperatively and remained constant for 12 years thereafter (Figure 1).Specifically, the 3 cases of CC diagnosed in this study occurred 8, 12, and 13 months postoperatively (Table 6).Castel et al 1 described a patient who experienced CC 29 years after implantation with first-generation polyurethanecoated devices.Additional studies are needed to establish the long-term incidence of CC with modern implants coated in polyurethane foam.
Since the first descriptions of polyurethane-covered implants by Ashley in 1970 2 and 1972, 3 the number of polyurethane coatings has increased from 1 to 5. In addition, a barrier between the polyurethane coating and silicone contents has been added, and the process of vulcanization during implant manufacture has improved. 4Early versions of these devices involved stiff, nonelastic polyurethane that was adhered with glue 4 and was not securely attached to the implant core. 5These implants likely were prone to deterioration and detachment of the polyurethane foam over time, resulting in silicone bleed.
Compared with modern versions, we suggest that earlygeneration polyurethane implants posed a higher risk of long-term CC.Other authors have hypothesized that complete detachment of the polyurethane foam from the implant shell would result in prosthesis with characteristics of a smooth implant. 1 However, this assertion can only partially explain why CC occurred with these implants after several decades.The increased risk of late silicone bleed and implant rupture could increase the risk of late CC.
It is widely accepted that hematoma increases the risk of CC, especially early-onset CC. 4 Two of the 3 cases of CC in our study occurred in implanted breasts that had developed hematoma in the early postoperative period.CC was diagnosed in these breasts 8 and 12 months postoperatively.Therefore, the results of our study are in accordance with these previous findings.
The rate of CC following primary breast augmentation with Microthane was substantially lower than the rates of CC after primary augmentation with smooth or textured silicone implants.We found that 2.3% of patients experienced CC during 14.6 years of follow-up.In 2014, Spear and Murphy 6 found that CC occurred in 17.2% and 19.9% of patients who underwent implantation with textured or smooth silicone implants, respectively ][9][10][11][12][13] The Microthane implant has been given CE marking, indicating that this device conforms to the safety, health, and environmental protection requirements of the European Economic Area.
The most common complication in this study was implant malposition, which was the result of poor placement intraoperatively, rather than implant dislocation over time.If an implant is incorrectly placed during surgery, it can Since the first descriptions of polyurethane-covered implants by Ashley in 1970 2 and 1972, 3 the number of basic shell layers has increased.In addition, a barrier between the polyurethane coating and silicone contents has been added, and the process of vulcanization during implant manufacture has improved. 4Early versions of these devices involved stiff, nonelastic polyurethane that was adhered with glue 4 and was not securely attached to the implant core. 5These implants likely were prone to deterioration and detachment of the polyurethane foam over time, resulting in silicone bleed.be difficult to correct its position postoperatively with conservative methods, such as elastic bands or downwardpressure garments.The surface of the Microthane implant is highly adhesive to tissues of the breast pocket, making the implant resistant to rotational or downward forces.Smooth and textured implants lack this feature.Presumably owing to this adhesion, no rotation was observed for breasts augmented with anatomic implants.Moreover, the risk of revisional breast surgery (eg, to treat an oversized pocket or a pocket displaced laterally or medially) likely was reduced.We suggest taking advantage of the unique adhesion of polyurethane-coated implants to achieve favorable results without the need for time-consuming manipulations or expensive materials.
Tissue integration of the polyurethane foam is a dynamic, highly variable process.When we perform explantation soon after primary implantation, the procedure is prolonged because the foam has already adhered tightly to the surrounding tissues.When we carry out explantation several years after implantation, we have observed that some islands of polyurethane foam have integrated into the capsule, and others remain adherent to the textured wall of the implant (data not shown).However, even this partially integrated implant can be removed with scissors or simple manual maneuvers.
Reoperation was performed for 9 of the 255 implanted breasts (3.5%); this reoperation rate is within the range published in the literature (1.2% to 19.9%) 1,7,14 We assume that the 2 patients in our study who experienced CC and were lost to follow-up underwent revisional surgery at another institution.Even with this assumption, malposition, not CC, was the most common complication necessitating reoperation in the current study, a finding that contrasts with that of Handel et al. 7 The primary limitation of this long-term study was the loss of patients to follow-up (3 patients, 2.3%).These patients experienced complications of the primary surgery (CC for 2 patients, rippling for 1 patient) and sought treatment elsewhere; thus, data for these patients are incomplete.Other authors have advocated polyurethane-coated implants for patients who present for reoperation after experiencing severe or recurring CC with non-polyurethane-coated implants. 15,16We assert that modern polyurethane-coated implants should be considered for primary augmentation, not just for revisional surgery when CC occurs with smooth or textured implants.

CONCLUSIONS
Primary breast augmentation with Microthane, a modern polyurethane-coated silicone gel implant, results in low long-term risk of CC.The authors advocate utilization of these implants for primary augmentation, rather than only for revisional treatment.

Figure 1 .
Figure 1.Kaplan-Meier estimation of cumulative incidence (and 95% confidence interval) of capsular contracture (CC) for a series of 255 implanted breasts (131 patients) over 14.5 years.All patients underwent primary breast augmentation with Microthane, a modern polyurethane-coated silicone gel implant.

Figure 2 .
Figure 2. Kaplan-Meier estimation of cumulative incidence of capsular contracture (CC) by implant (blue curve) and by patient (red curve) for a series of 131 patients (255 implanted breasts) over 14.5 years.All patients underwent primary breast augmentation with Microthane, a modern polyurethane-coated silicone gel implant.

Table 1 .
Information Collected Retrospectively From Patient Cohort

Table 2 .
Characteristics of Patient Cohort a All patients underwent augmentation with polyurethane-coated silicone gel implants.

Table 3 .
Complications of Primary Augmentation With Microthane (N = 255 Implanted Breasts) a Instances of malposition were the result of poor placement intraoperatively, rather than dislocation over time.b CC was defined as Baker grade III or IV.

Table 4 .
Overall Complication Rates by Intervention Type, Implant Size, and Implant Pocket CI, confidence interval; NA, not applicable; RR, relative risk.a All patients received polyurethane-coated silicone gel implants.

Table 5 .
Complications, Other Than CC, Treated With Revisional SurgeryPatients who underwent surgery for this complication also received replacement of the contralateral, nonruptured implant.b Instances of malposition were the result of poor placement intraoperatively, rather than dislocation over time. a