An analytical framework for quantifying recoil and foreshortening in ultra-thin cobalt–chromium coronary stents

• Develops a coupled analytical-FEA framework for balloon-expandable thin-walled stents. • Derives closed-form expressions linking stent unit-cell geometry to axial deformation. • Incorporates nonlinear plasticity to accurately predict post-expansion stent behavior. • Validates optimized design achieving 2.7% foreshortening and controlled recoil within 7%. • Extends applicability of thin-walled lattice design to elastic-plastic biomedical structures. Ultrathin cobalt-chromium (Co-Cr) stents offer superior clinical outcomes but face inherent mechanical trade-offs, particularly regarding radial stiffness and recoil. While finite element analysis (FEA) is the standard for optimizing these designs, it is computationally expensive, and existing analytical models often fail to capture the complex elastoplastic deformation of balloon-expandable architectures. To address this gap, this study introduces a hinge-resolved, closed-form analytical framework for predicting the elastoplastic deployment behavior of balloon-expandable stents. The model explicitly links unit-cell geometry, including hinge radius, link length, and cell number, to critical performance metrics such as foreshortening and recoil, capturing both crimped and expanded configurations. Analytical predictions showed close agreement with nonlinear FEA across all configurations. Through parametric optimization, foreshortening was reduced from 17% in the baseline design to 2.7%, while recoil was maintained at 3.7%, well within FDA regulatory thresholds. These results demonstrate that increasing the circumferential cell count, link length and hinge radius minimizes foreshortening, whereas decreasing them reduces recoil. Overall, the proposed framework provides a rapid, interpretable, and computationally efficient tool for early-stage design optimization of laser-cut stents, effectively bridging the gap between analytical theory and complex numerical simulation.