Patent ID: 7578849

Claim:
An intervertebral device configured to be positioned between vertebral members, the device comprising: an elongated member having an overlapping configuration defining a first and a second endplate and an intermediate section, the first and second endplates being spaced apart by the intermediate section to form an interior space with open lateral sides and an interior height, the intermediate section including a folded configuration with at least three overlapping vertical sections; an elastic member spaced apart from the intermediate section and positioned between the first and second endplates such that the elastic member is spaced apart from one of the first and second endplates, the elastic member including a height less than the interior height and greater than at least one-half of the interior height, the elastic member being sized to space apart the first and second endplates during movement of the vertebral members; the elastic member includes a first section with a first stiffness and a second section with a second greater stiffness, the elastic member arranged such that the first section deforms upon a first amount of movement of the first and second endplates, and the first and second sections both deform upon a second greater amount of movement of the first and second endplates.