Patent ID: 7066957

Claim:
An apparatus for engagement relative to two vertebrae of a spine, comprising: a dampening device effective for placement in close proximity to the two vertebrae, the dampening device including a rigid vessel, the vessel including: a first inner wall opposite a second inner wall; two chambers each extending between the first inner wall and the second inner wall, the chambers each containing a fluid and at least one conduit in fluid communication with each of the chambers to control the flow of the fluid therebetween, the fluid in each of the chambers being in contact with the first inner wall and the second inner wall, a mobile separating member extending from the first inner wall to the second inner wall to divide the vessel into the two chambers, the mobile separating member being positioned between the two chambers, and the mobile separating member being in contact with the fluid in each of the two chambers; a screw connected to the mobile separating member to move therewith relative to the vessel; and wherein the dampening device is responsive to relative motion of the two vertebrae when engaged therewith to selectively change an amount of fluid in one of the chambers relative to an amount of fluid in another of the chambers by passage through the at least one conduit, and to cause motion of the mobile separating member relative to the vessel along the first inner wall and the second inner wall, the mobile separating member being structured to maintain separation of the two chambers during the motion.