Evaluation of Natural Breasts and Post-Augmentation Breasts with Silicone Implants Using Subject-Specific Finite Element Modeling.

[PURPOSE] To develop and validate a subject-specific finite element (FE) modeling framework that estimates breast hyperelastic parameters from in vivo, gravity-driven deformation, and to investigate whether post-augmentation breasts with silicone implants exhibit altered mechanical characteristics compared with natural breasts.

[METHODS] Left breasts of twelve participants (six normal, six post-augmentation) were modeled from prone MRI, and upright morphology was simulated using a two-step gravity procedure in Abaqus using a first-order isotropic Ogden hyperelastic law, chosen as a simple, widely used model for large soft-tissue deformations. For each breast, the Ogden exponent (α) and shear modulus (μ) were identified as apparent organ-level stiffness parameters by minimizing the Hausdorff distance between the simulated shape and the standing 3D surface scan.

[RESULTS] Natural breasts achieved HDF 0.94-3.09 mm (mean 2.14 mm). Post-augmentation breasts achieved HDF 1.38-2.54 mm (mean 1.90 mm). Across participants, α showed marked inter-individual variability. Post-augmentation cases required higher effective shear modulus than natural breasts.

[CONCLUSION] A subject-specific FE workflow driven by in vivo deformation accurately reproduces standing breast morphology and reveals increased apparent stiffness after implant augmentation. This framework enables individualized parameterization for surgical planning, implant selection, and prediction of post-operative outcomes in breast biomechanics.