Shear-Wave Elastography as an Objective Diagnostic Tool for Capsular Contracture After Breast Implant Surgery: A Comparative Study

Background/Objectives: Capsular contracture (CC) is the most frequent complication of breast implant surgery, affecting up to 20% of augmentation and up to 40% of post-mastectomy reconstruction patients. Diagnosis relies on the Baker classification with poor interobserver reliability (κ = 0.55). This study evaluated shear-wave elastography (SWE) as an objective diagnostic tool for CC via quantitative measurement of periprosthetic capsule stiffness. Methods: A prospective single-center comparative study (Romania) enrolled 26 augmentation patients (50 breasts) with asymptomatic Baker I/II CC as controls, and 25 breasts with confirmed Baker III/IV CC in post-mastectomy reconstruction patients as the study group. Stiffness was measured using the SuperSonic MACH 30 platform (mean, median, min, max, SD in kPa). Analysis included Mann-Whitney U tests, ROC curves with bootstrapped 95% CIs, and Youden’s J index. Confounder analyses (Spearman correlations, multivariable logistic regression, partial correlations) assessed the independence of SWE findings from implant depth, periprosthetic tissue thickness, region-of-interest (ROI) diameter, and body mass index (BMI). Results: All four primary stiffness parameters differed significantly between groups (p 0.97). Control median stiffness was 32.6 kPa versus 138.0 kPa in the study group. All four parameters achieved outstanding discriminative performance (AUC 0.988–0.994); SWE median yielded the highest AUC (0.994; 95% CI 0.980–1.000). A threshold of 82 kPa provided 100% sensitivity, 98% specificity, and 100% NPV. Baker Grades III (~92 kPa) and IV (~147 kPa) also differed significantly (p = 0.0001). No covariate (implant depth, periprosthetic tissue thickness, ROI diameter, BMI) significantly influenced SWE values within either group (all intra-group Spearman ρ p > 0.05), and SWE median stiffness remained the sole significant predictor in the fully adjusted multivariable model (adjusted OR = 1.18, 95% CI 1.08–1.31, p < 0.001). Conclusions: SWE objectively differentiates normal periprosthetic capsules from clinically significant CC with outstanding accuracy. An 82 kPa median stiffness threshold offers a reproducible, non-invasive complement to the Baker classification and provides a foundation for elastography-based CC staging.