Capsular contracture in breast reconstruction

Introduction: In the UK, more than 55000 women are diagnosed with breast cancer each year. There has been a 50% increase in the number of women undergoing immediate breast reconstruction after mastectomy, greater than 85% of these are implant based. One of the most common and unpredictable long-term complications is capsular contracture, occurring in up to 25% of cases. Acellular dermal matrices (ADM), now commonly used in immediate reconstruction, have been associated with reduced rates of capsular contracture but evidence supporting this is limited. Aims: In patients undergoing immediate implant based breast reconstruction with either Strattice™ or a submuscular technique, to determine and compare i) the incidence of capsular contracture and rates of revision surgery ii) patient reported outcomes iii) cosmetic outcomes and iv) short-term clinical outcomes. In vitro, to compare the implant capsule at the ADM interface and the native tissue (pectoralis muscle) interface. Methods: A retrospective multicentre cohort study of patients who underwent immediate implant based reconstruction with Strattice™ or a submuscular technique between January 2009 and December 2015 across three tertiary UK centres. Clinical examination and tonometry was performed, medical photographs and a comprehensive case note review undertaken. Participants completed the BREASTQ. In patients undergoing revision surgery after immediate implant based sub pectoral Strattice™ reconstruction biopsies were taken from two different areas of the capsule (ADM tissue interface versus pectoral tissue interface) and analysed using histology and immunohistochemistry. Results: The outcomes for 553 Strattice™ reconstructions and 242 submuscular reconstructions were compared. Unplanned explantation rate as a complication of primary surgery was 8.5% in the Strattice™-assisted group compared to 5.4% in the submuscular. Revision rates were equivalent between the groups (46.7% vs. 41.1%) but there were less revisions performed in the Strattice?- assisted group for capsular contracture (5.3% vs. 15.6%, p=<0.001). Capsular contracture occurred in 13.5% of the Strattice™ reconstructions compared to 21.5% of the submuscular (p=0.14). There were significantly higher aesthetic satisfaction scores from all three independent assessors in the Strattice™ group. There was no difference in BREAST-Q scores between the two groups. Capsules from 12 reconstructions were analysed at a median time of 6 months (range 5 – 81.5 months) from the last procedure. No difference in severity of inflammation between the two capsules was demonstrated but a difference in location of inflammation and an absence of the inner synovial like metaplasia layer in the ADM capsule was seen. The percentage of myofibroblasts was greater in the ADM capsules (p=0.04). In capsules older than two years there was higher proportion of elastin in the native capsule (p=0.0086). There was a greater proportion of mature collagen in the ADM capsules older than six months (p=NS). Conclusion: Strattice™ reduces capsular contracture whilst improving aesthetic outcomes in implant based breast reconstruction. ADMs may reduce capsular contracture by creating a barrier between the native tissues and implant, leading to a less intense foreign body response which remains dormant over time.