US Patent 7261739 Intervertebral spacer device having arch shaped spring element

An intervertebral spacer device having a pair of opposing plates for seating against opposing vertebral bone surfaces, separated by at least one spring mechanism. The preferred spring mechanism is an arched strip spring. In a first embodiment there are multiple springs positioned independently about the area of the opposing plates. In a second embodiment there is a single arched strip spring modified to mount onto a ball-shaped head. The lower plate of this second embodiment includes a post extending upwardly from the inner surface of the plate, the post including a ball-shaped head. The spring and post members are flexibly coupled such that the upper and lower plates may rotate relative to one another.