A prosthesis (110；210) comprises a plurality of stent members which are formed of strut elements (120) connected by apexes, wherein the proximal apexes (122；226a) of a first stent member (116a；216a) and the distal apexes (124；224b) of a second stent member (116b；216b) have a shaped portion which is flat or concave. The proximal apexes (122；226a) are arranged to engage the distal apexes (124；224b) when the prosthesis is subjected to longitudinal compression forces and the shaped portion of the apexes prevents interdigitation of the stent members. End marker elements (220,320) may have similarly shaped lateral extensions (222,322) arranged to engage the distal apexes (224a) of the first stent member.
