Predicting Lower Pole Deformation in Breast Augmentation: A Biomechanical Analysis of Implant-to-Breast Matching Ratios.

Background: Predicting post-surgical morphometric changes in breast augmentation remains challenging. A key alteration is the increase in nipple-to-inframammary crease (N-IMC) distance, which affects aesthetics. This study quantifies N-IMC changes after subfascial breast augmentation and develops a predictive model incorporating anatomical and implant-related factors.

Methods: A retrospective analysis of 408 patients undergoing subfascial breast augmentation was conducted. Pre- and postoperative morphometric measurements, including N-IMC, suprasternal notch-to-nipple (SSN-N), and breast width, were analyzed. Additional parameters, such as lateral sternal margin thickness (LSM) and implant size, were assessed using multiple linear regression and stepwise selection. Two implant-to-breast matching ratios were introduced: the Rib Ratio (implant projection-to-breast width) and the Mib Ratio (implant width-to-available breast width).

Results: N-IMC distance increased by 52.98% on average, with variability influenced by patient anatomy and implant selection. LSM (p = 0.0015), SSN-N change (p = 0.0019), and Mib Ratio (p = 0.0482) were significant predictors. The Rib Ratio had the highest predictive capacity, explaining 67.85% of lower pole deformation variability.

Conclusion: Implant selection and breast tissue characteristics significantly impact post-surgical morphometry. The Rib Ratio offers a standardized metric for implant selection, enhancing preoperative planning and aesthetic outcomes. Its adoption in clinical practice is recommended to improve surgical consistency.