External support for restoring valvular competence to veins, to be implanted about a vein, along its length. It includes a posterior and an anterior arcuate frame shell, in an elongated material. The posterior frame shell includes two branches of said elongated material penetratingly shaped for an easy insertion thereof behind the posterior wall of the vein, through two paths prepared by the surgeon. Each frame shell includes a respective traction side including longitudinal rectilinear side traction branch elements. The two frame shells are conformed to be juxtaposed to each other about the vein by longitudinal sides thereof. The traction sides are intended to be engaged to the vein by opposite valve intercoinmissural walls via surgical sutures or hook elements to dilate the intercommissural diameter of the vein by traction, so as to absorb the slackening of an incompetent venous valve by extending its cusps.