A medical device has a structure differentiated in terms of its stiffness or elasticity. Such stiffness differentiation is achieved through the use of superelastic or shape-memory materials which transition between a relatively malleable phase to a stiffer phase at a transition temperature which is adjustable by heat treatment. A differentiation of the stiffness of the structure forming the medical device is achieved by differentially adjusting the transition temperature of select portions of the medical device before the medical device is placed in its operational mode, usually implanted in a body at body temperature.