Predicting Final Implant Volume in Two-stage Prepectoral Breast Reconstruction

Two-stage implant-based breast reconstruction remains the most commonly performed reconstructive modality following mastectomy. Although prior studies have explored the relationship between tissue expander (TE) features and permanent implant (PI) size in subpectoral reconstruction, no such study exists in prepectoral reconstruction. This study aims to identify pertinent TE characteristics and evaluate their correlations with PI size for prepectoral implant-based reconstruction.

This study analyzed patients who underwent two-stage prepectoral tissue expansion for breast reconstruction followed by implant placement. Patient demographics and oncologic characteristics were recorded. TE and PI features were evaluated. Significant predictors for PI volume were identified using linear and multivariate regression analyses.

We identified 177 patients and 296 breast reconstructions that met inclusion criteria. All reconstructions were performed in the prepectoral plane with the majority using acellular dermal matrix (93.8%) and primarily silicone implants (94.3%). Mean TE size was 485.4 cm³ with mean initial fill of 245.8 cm³ and mean final fill of 454.4 cm³. Mean PI size was 502.9 cm³ with a differential fill volume (PI-TE) of 11.7 cm³. Multivariate analysis identified significant features for PI size prediction, including TE size (R² = 0.60; P < 0.0001) and TE final fill volume (R² = 0.57; P < 0.0001). The prediction expression for TE final fill and TE size was calculated as 26.6 + 0.38*(TE final fill) + 0.61*(TE size).

TE size and final expansion volume were significant variables for implant size prediction. With prepectoral implant placement gaining popularity, the predictive formula may help optimize preoperative planning and decision-making in prepectoral reconstructions.