Flexible spine stabilization system

Abstract

A system for flexibly stabilizing a vertebral motion segment by connecting a first vertebra and a second vertebra is disclosed. The system includes an elongate connection element with end portions interconnected by a flexible coupling member. The system includes first and second attachment portions for connecting the connection element to the vertebrae. A first resilient member is positioned between the first end portion and the first attachment portion, and a second resilient member is positioned between the first attachment portion and the second attachment portion. The system is designed such that the second resilient member is compressed when the first and second attachment portions move towards each other, and the first resilient member is compressed when the first and second attachment portions extend away from each other.

What is claimed is: 
     
         1 . A method of flexibly stabilizing a vertebral joint, comprising:
 providing an elongate connection element having an elongate flexible coupler extending between a first end and a second end along a longitudinal axis, a first attachment portion, a second attachment portion, a first resilient member positioned between the first end and the first attachment portion, and a second resilient member positioned between the first attachment portion and the second attachment portion;   wherein the elongate connection element permits motion of the first attachment portion relative to the second attachment portion, wherein the first and second attachment portions compress the second resilient member when the first and second attachment portions move towards each other, and wherein the first end and first attachment portions compress the first resilient member when the first and second attachment portions extend away from each other;   securing the first portion of the elongate connector to a first bone fastener attached to a first vertebral body;   securing the second portion of the elongate connector to a second bone fastener attached to a second vertebral body adjacent to the first vertebral body.   
     
     
         2 . The method of  claim 1 , wherein the step of providing includes providing a cord as the elongate flexible connector. 
     
     
         3 . The method of  claim 1 , wherein the step of providing includes providing a polyethylene cord as the elongate flexible coupler. 
     
     
         4 . The method of  claim 1 , wherein the first end portion and second end portion are rigidly fixed to the coupling member. 
     
     
         5 . The method of  claim 4 , wherein the elongate connector element includes first and second spools disposed near the first and second end, respectively, wherein the step of providing includes providing the elongate connection element whose first and second spools pierce the elongate flexible coupler. 
     
     
         6 . The method of  claim 4 , wherein the elongate connector element includes first and second spools disposed near the first and second end, respectively, wherein the step of providing includes providing the elongate connection element whose first and second spools clamp the elongate flexible coupler. 
     
     
         7 . The method of  claim 1 , wherein the step of providing includes providing an elongate connection element which is curved in a neutral position to accommodate the lordosis in the spine. 
     
     
         8 . The method of  claim 1 , wherein the first and second resilient members are made of a urethane material. 
     
     
         9 . The method of  claim 1 , wherein the step of securing the first portion of the elongate connector includes securing the first portion of the elongate connector to a first pedicle screw attached to the first vertebral body. 
     
     
         10 . The method of  claim 9 , wherein the pedicle screw is a multi-axial pedicle screw. 
     
     
         11 . The method of  claim 8 , wherein the step of providing includes providing the first and second resilient members whose durometer is between about shore  80  A to about shore  100  A. 
     
     
         12 . The method of  claim 1 , wherein the step of providing includes providing the first and second resilient members having a different hardness from each other. 
     
     
         13 . The method of  claim 2 , wherein the step of providing includes providing the first attachment portion, second attachment portion, first resilient member and second resilient member which are coaxial with the cord. 
     
     
         14 . The method of  claim 4 , wherein the step of providing includes providing the first attachment portion which is slidable with respect to the elongate flexible coupler. 
     
     
         15 . The method of  claim 14 , wherein the first and second attachment portions comprise spools. 
     
     
         16 . The method of  claim 14 , wherein the second end portion comprises an elongate rod. 
     
     
         17 . The method of  claim 1 , wherein the first and second attachment portions are configured to extend away from each other by up to 4 mm.