a stent or other endoprosthesis is provided from a single strand of biocompatible and resilient material into which spring coils are formed by winding the strand through in excess of 360 °. the thus - formed coil springs are positioned along outside edges of the endoprosthesis , with legs joining the coil springs in order to form a generally zig - zag structure . when the endoprosthesis is compressed for endoluminal delivery , the coil springs allow for large angular deflection between adjoining legs while avoiding plastic deformation of the coil or of the legs .