Finite Element Investigation of the Influence of Strut Diameter on the Mechanical Performance of Balloon-Expandable Biodegradable PLA/PDO Coronary Stents

This study numerically investigates the influence of strut diameter on the deployment behavior of a balloon-expandable biodegradable stent with rhombic cell architecture using finite element analysis. The stent material was represented by a 60/40 poly(lactic acid)/polydioxanone (PLA/PDO) blend. Four stent configurations with strut diameters of 0.15, 0.25, 0.35, and 0.50 mm were analyzed under identical deployment conditions. The numerical evaluation considered von Mises stress together with five deployment indicators: diametral strain, elastic recoil, dog-boning, foreshortening, and longitudinal retraction. The results show that increasing the strut diameter reduces elastic recoil, foreshortening, and longitudinal retraction, thereby enhancing post deployment dimensional stability. However, thicker struts also increase the dog-boning effect, indicating less uniform radial expansion. Among the investigated designs, the stent with a 0.35 mm strut diameter showed a balanced response between deployment uniformity and post deployment mechanical stability under the adopted numerical assumptions. For this configuration, elastic recoil, foreshortening, longitudinal retraction, and dog-boning were approximately 6.2%, 10%, 37%, and 8.9%, respectively. These findings provide practical design guidance for biodegradable polymeric vascular stents.