Capsular Contracture in Implant-Based Breast Reconstruction: A Comprehensive Narrative Review of Pathophysiology, Risk Factors, and Contemporary Controversies.

Capsular contracture (CC) remains the most common long-term complication of implant-based breast reconstruction (IBBR), significantly impacting cosmetic outcomes, patient satisfaction, and reoperation rates. Despite substantial advances in surgical technique, implant technology, and perioperative management, the incidence of clinically significant contracture persists at approximately 3-5% at five years in non-irradiated patients and escalates dramatically-to 20-50%-in those receiving postmastectomy radiation therapy (PMRT). The etiology is multifactorial, involving subclinical biofilm formation, a dysregulated host immune and foreign-body response, and radiation-induced fibrosis. This narrative review synthesizes contemporary evidence on the pathophysiology, clinical assessment, and modifiable risk factors for CC in IBBR, with particular emphasis on implant surface characteristics (smooth, textured, and polyurethane[PU]-coated), placement plane (prepectoral versus subpectoral), the role of acellular dermal matrices (ADMs), reconstruction timing (direct-to-implant versus two-stage), and the complex interplay with radiotherapy-including radiation timing, fractionation, and emerging delivery techniques. We also address ongoing controversies, including the lack of standardized objective diagnostic criteria, the comparative effectiveness of ADM versus PU-coated implants, and the optimal sequencing of radiation relative to reconstruction. By integrating the latest evidence from very recent major meta-analyses and national registries, this review provides an updated synthesis. We further propose an evidence-based clinical decision framework for CC risk mitigation. This review aims to inform individualized surgical decision-making and identify priority areas for future investigation.