Knitted Esophageal Stents for Anti-Migration: Structure–Function Relationships Examined with a Biomimetic Swallowing Simulator

Esophageal stent insertion is a key palliative therapy for malignant esophageal strictures, but the postoperative migration rate remains as high as 40%, significantly compromising clinical outcomes. Stent migration behavior is closely related to its structure and mechanical properties; however, the underlying mechanisms remain unclear, and there is a lack of effective in vitro evaluation methods to predict migration risk. Herein, we first developed a novel biomimetic swallowing peristalsis simulation device that highly replicates human physiological environments and swallowing waveforms—addressing the limitations of existing in vitro testing methods. Using this device, we demonstrated for the first time that stent migration is co-regulated by radial force and axial bending stiffness: higher radial force enhances anchoring via increased friction, while lower bending stiffness (superior flexibility) reduces migration risk by maintaining a larger stent–esophagus contact area and improving energy dissipation during swallowing. These conclusions are supported by our theoretical derivations and test results of stents with different densities. In addition, it was found that food viscosity and tumor block also influence stent migration risk. This study elucidates the synergistic mechanism of esophageal stent migration and provides a theoretical foundation and an in vitro validation platform for the design of a new generation of anti-migration esophageal stents.