An endoprosthesis has an expanded state and a contracted state, the endoprosthesis includes a stent having an inner surface defining a lumen and an outer surface; and a polymeric coating adhered to the outer surface of the stent. The polymeric coating includes a base and a plurality of protrusions extending outwardly from the base. When the endoprosthesis is expanded to the expanded state in a lumen defined by a vessel wall, the protrusions apply a force that creates an interlock between the vessel wall and the endoprosthesis.