Abstract: A scissors-like engagement system includes pivotally secured first and second mating elements mutually including, at the ends of the mating elements, surfaces for complementally gripping and holding a projecting segment of an anchor element, in which the external surfaces of the ends of the mating elements define a parabolic surface nesting within a semi-hemispherical recess surrounding the anchor element. The complemental mating surfaces constitute male and female elements extending from, and centrally located within, the mating surfaces. The gripping surfaces are normally parallel to each other when the scissors-like engagement system is in a closed position about the anchor element. The male element of the complemental mating surfaces is an elongate, curvilinear, solid cylindrical member, the line of curvature of which lies equidistant from the surface of the semi-hemispherical recess within which the parabolic surface of the mating elements nest.