A dynamic bone anchor for anchoring a spine stabilization assembly which supports the spine while providing for the preservation of spinal motion. The dynamic bone anchor provides load sharing while preserving range of motion and reducing stress exerted upon the bone anchors and spinal anatomy. The dynamic bone anchor includes a deflectable post connected by a ball-joint to a threaded anchor. Deflection of the deflectable post is controlled by a compliant ring. The force/deflection properties of the dynamic bone anchor may be adapted to the anatomy and functional requirements of the patient. The dynamic bone anchor may be used as a component of a dynamic stabilization system which supports the spine while providing for the preservation of spinal motion.