A dynamic stabilization system (10) for stabilizing a vertebral segment of a spine. The system includes a first vertebral anchor (12a), a second vertebral anchor (12b) and a cord (30). The system may also include a spacer (24) positioned between the first and second vertebral anchor through which the cord extends. The first vertebral anchor is configured to be secured to a first vertebra and the second vertebral anchor is configured to be secured to a second vertebra. The cord is extendable from the first vertebral anchor to the second vertebral anchor. The cord has a variable stiffness through a range of displacement, wherein the stiffness of the cord increases as an applied tensile force on the cord is increased.
