The Tipping Point: Predictors of Implant Flipping in Staged Breast Reconstruction.

Abstract

Surgeon preferences in implant-based reconstruction have increasingly favored firmer gel implants for their superior stability, reduced gel bleed, and lower capsular contracture rates. However, this has paralleled an increase in 180° anterior-posterior implant flipping. Herein, we aim to identify the patient and implant factors contributing to this complication. This is a 5-year retrospective cohort study of 343 patients (502 breasts) who underwent expander-to-implant exchange. For each breast, Delta (expander fill minus implant volume) and delta-to-expander percentage (relative under- or overfilling) were calculated and analyzed by tertiles. Categorical and continuous variables were compared using chi-squared or Fisher's exact and Wilcoxon rank-sum tests, respectively. Multivariable logistic regression identified predictors of implant flipping. Implant flipping occurred in 21 breasts (4.2%) and was associated with higher BMI (median, 29.6 vs. 25.4 kg/m², p=0.014), greater expander fill volumes (575 vs. 425 mL, p=0.006), use of highly-firm implants (86% vs. 51%, p=0.006), and smaller implant-to-expander volume ratios (median, -20 vs. -65 mL, p = 0.013). On multivariable analysis, independent predictors were BMI (aOR 1.1, p=0.047), highly-firm implants (aOR 4.41, p=0.023), and the highest delta-to-expander tertile (aOR 5.09, p=0.041). Implant flipping was linked to higher BMI, firmer implants, and greater implant-to-expander volume mismatch, reflecting a looser pocket. While firmer implants reduce capsular contracture and gel bleed, flipping emerges as a potential trade-off. This risk may be reduced through surgical refinements that optimize implant-pocket dynamics. These findings emphasize the importance of individualized planning during expander-to-implant exchange, especially in patients at elevated risk for malposition.