Dynamic Spinal Stabilization Assembly with Elastic Bumpers and Locking Limited Travel Closure Mechanisms

Abstract

A dynamic stabilization assembly includes a core, typically in the form of a tensioned cord, at least one pair of bone anchors, a spacer surrounding the core located between the bone anchors, at least one elastic bumper and at least one fixing or blocking member. The core is slidable with respect to at least one of the bone anchors, the spacer and the bumper. The bumper is compressed. Bone screws of the assembly include closure structures that lock against the bone screw independent of any fixing or sliding of the core with respect to the bone screw.

What is claimed is: 
     
         1 . A medical implant assembly comprising:
 a bone anchor having a receiver;   a channel defined by the receiver;   a cord extending from a first end to a second end, the cord extending through the channel and moveable relative to the receiver;   a rigid end structure having an opening, the first end of the cord extending into the opening; and   a closure structure releasably engaged to the rigid end structure, the closure structure holding the cord in tension within the opening when captured.   
     
     
         2 . The medical implant assembly of  claim 1 , wherein the rigid end structure is a second bone anchor. 
     
     
         3 . The medical implant assembly of  claim 2 , wherein the second bone anchor has a receiver, the opening being a channel defined by the receiver of the second bone anchor. 
     
     
         4 . The medical implant assembly of  claim 1 , further comprising:
 a compressible member having a bore, the cord extending through the bore.   
     
     
         5 . The medical implant assembly of  claim 4 , wherein the compressible member is disposed between the rigid end structure and the bone anchor. 
     
     
         6 . The medical implant assembly of  claim 4 , wherein the compressible member is a spacer.