Patent ID: 7815663

Claim:
A vertebral rod comprising: a first elongated rod section; a second elongated rod section aligned along an axis with the first section; an intermediate section positioned between the first and second sections, the intermediate section comprising a member with a turn and an upper section and a lower section, the intermediate section being open between the first and second sections opposite from the turn, each of the upper and lower sections including inner surfaces that intersect at the turn and overlap to form an interior portion; an elastic member positioned in the interior portion of the intermediate section directly between the first and second sections along the axis; the elastic member distinct from the first, second, and intermediate sections and differing in material composition therefrom; the elastic member connected to the inner surfaces of both the upper and lower sections; the intermediate section and elastic member configured to provide variable resistance to movement of the first and second sections, the elastic member being in compression during a first type of movement of the first and second sections and being in tension during a second type of movement; wherein the elastic member is configured such that the axis exits the first section, enters the elastic member, passes through the elastic member, exits the elastic member, and enters the second section all without exiting the elastic member more than once.