A Computational Framework for the Design and Mechanical Assessment of Biodegradable Airway Stents: Interaction with Rabbit Tracheal Tissue and Preliminary In Vivo Observations.

Current airway stents, including silicone and metallic devices, remain associated with important complications such as migration, restenosis, mucus retention and the need for repeated interventions. Biodegradable stents offer a promising alternative by providing temporary mechanical support while avoiding the long-term presence of a permanent implant. However, the influence of stent geometry and material properties on their mechanical performance and interaction with airway tissue is still not fully understood. This study presents a computational framework integrating computer-aided design and finite element analysis to investigate the mechanical behaviour of biodegradable tracheobronchial stents. Two stent architectures (X-pattern and W-pattern) were analysed over a range of wire thicknesses using two biodegradable materials: a PLA/PCL; 70/30 wt.% blend and AZ31 magnesium alloy. Radial compression, diameter recovery after radial compression and stent-tissue interaction simulations were performed to evaluate the influence of geometry, material selection and design parameters on device performance. The results suggested that both stent geometry and material properties strongly influence the mechanical behaviour of biodegradable airway stents, although they affect different aspects of the stent-tissue interaction. The X-pattern consistently exhibited greater resistance to radial compression, lower elastic diameter recovery after radial compression and improved maintenance of the expanded lumen compared with the W-pattern. Material properties primarily affected the magnitude of the mechanical response, as further confirmed by the quantitative contact-pressure analysis, with AZ31 providing greater radial support, while the spatial distributions of stress and strain within the tracheal wall were mainly governed by the stent architecture. Based on the computational analyses, X-pattern stents manufactured from the PLA/PCL; 70/30 wt.% blend were selected for in vivo evaluation in a rabbit model. Endoscopic observations revealed tissue features that were qualitatively consistent with the mechanical patterns predicted by the numerical simulations, although no direct causal relationship can be established from the available observations. These findings support the ability of the proposed framework to represent the principal aspects of stent-tissue interaction. The proposed computational framework provides a practical tool for the rational design and mechanical assessment of biodegradable airway stents and may facilitate the future development of customised airway prostheses.