Patent ID: 8372116

Claim:
A bone anchor-based spinal dynamic stabilization system, comprising: a. a first bone anchor assembly engageable with a first vertebra, the bone anchor assembly comprising an inner surface defining a U-shaped cavity; b. a second bone anchor assembly engageable with a second vertebra and having an articulation surface including an arcuate outer surface; and c. a resilient element defining a longitudinal axis, the resilient element comprising: i. an end portion defining a projection extending along the longitudinal axis and perpendicularly from a proximal end of the end portion configured for disposal in the U-shaped cavity to attach the resilient element to the first bone anchor assembly, and ii. a resilient portion including a cup-shaped inner cavity being disposed at a distal end of the resilient element such that the cup-shaped inner cavity has a center aligned with the longitudinal axis and is configured for disposal of and engagement with the arcuate outer surface of the articulation surface of the second bone anchor assembly, wherein the resilient portion is attached to the end portion and the resilient portion comprises a passage at least partially therethrough, the end portion comprises a passage at least partially therethrough, and a tether is disposed within the passage of the resilient portion and the passage of the end portion to attach the resilient portion to the end portion; wherein the resilient element is configured to be adjustable between the first vertebra and the second vertebra by movement of the projection within the U-shaped cavity such that the articulation surface is positioned relative the cup-shaped inner cavity when the first vertebra and the second vertebra are in a neutral position, and wherein the resilient element is configured to be separable from the second bone anchor assembly and is positionable between the first bone anchor assembly and the second bone anchor assembly to resiliently resist the movement of the first bone anchor assembly and the second bone anchor assembly towards each other.