Dynamic stabilization connecting member with pre-tensioned solid core member

Abstract

A dynamic longitudinal connecting member assembly includes an anchor member having an integral or otherwise fixed elongate core of circular or non-circular cross-section. The core is pre-tensioned and extends through at least one elastic spacer and at least one outer sleeve. The anchor member and the outer sleeve each attach to at least one bone anchor. In operation, the core is held in tension by the spacer.

1 . A medical implant assembly having a first bone attachment structure and a second bone attachment structure cooperating with a longitudinal connecting member, the longitudinal connecting member comprising:
 an anchor member having a rigid portion engageable to the first bone attachment structure and extending along a longitudinal axis;   a flexible extension member extending from the rigid portion and being tensionable along the longitudinal axis;   a compressible outer spacer positioned between the first bone attachment structure and the second bone attachment structure;   a sleeve receiving the flexible extension member in slidable relation with the second bone attachment structure; and   a stiff end structure having opposed tool engaging surfaces, the stiff end structure compressibly attachable to the flexible extension member, the stiff end structure holding the flexible extension member in tension.   
     
     
         2 . The medical implant assembly of  claim 1 , wherein the flexible extension member has a smaller diameter than the rigid portion. 
     
     
         3 . The medical implant assembly of  claim 1 , wherein the flexible extension member is pre-tensioned along the longitudinal axis. 
     
     
         4 . The medical implant assembly of  claim 3 , wherein the flexible extension member is pre-tensioned to a steady state length. 
     
     
         5 . The medical implant assembly of  claim 1 , wherein the compressible outer spacer is held in compression by tensioning the flexible extension member. 
     
     
         6 . The medical implant assembly of  claim 1 , wherein the flexible extension member is receivable within an elastic bumper. 
     
     
         7 . The medical implant assembly of  claim 6 , wherein the stiff end structure is in compressible engagement with the elastic bumper. 
     
     
         8 . The medical implant assembly of  claim 6 , wherein the elastic bumper engages the sleeve. 
     
     
         9 . The medical implant assembly of  claim 6 , wherein the elastic bumper and the compressible outer spacer are positioned entirely outside the sleeve. 
     
     
         10 . The medical implant assembly of  claim 6 , wherein the stiff end structure is positioned entirely outside the elastic bumper. 
     
     
         11 . The medical implant assembly of  claim 1 , wherein the stiff end structure has a smooth non-threaded through bore to engage the flexible extension member. 
     
     
         12 . The medical implant assembly of  claim 1 , wherein the stiff end structure is accessible outside the first bone attachment structure and the second bone attachment structure for further tensioning of the flexible extension member. 
     
     
         13 . The medical implant assembly of  claim 1 , wherein the sleeve is engageable to the second bone attachment structure. 
     
     
         14 . A medical implant assembly having a first bone attachment structure and a second bone attachment structure cooperating with a longitudinal connecting member, the longitudinal connecting member comprising:
 an anchor member having a rigid portion engageable to the first bone attachment structure and extending along a longitudinal axis, the rigid portion having a first diameter;   a flexible extension member extending from the rigid portion and being tensionable along the longitudinal axis, the flexible extension member having a second diameter smaller than the first diameter;   a sleeve receiving the flexible extension member in slidable relation with the second bone attachment structure; and   a stiff end structure compressibly attachable to the flexible extension member, the stiff end structure holding the flexible extension member in tension.   
     
     
         15 . The medical implant assembly of  claim 14 , wherein a compressible outer spacer is held in compression by tensioning the flexible extension member. 
     
     
         16 . The medical implant assembly of  claim 15 , wherein the compressible outer spacer is positioned between the first bone attachment structure and the second bone attachment structure. 
     
     
         17 . The medical implant assembly of  claim 14 , wherein the stiff end structure has a smooth non-threaded through bore to engage the flexible extension member. 
     
     
         18 . The medical implant assembly of  claim 14 , wherein the stiff end structure has opposed tool engaging surfaces. 
     
     
         19 . The medical implant assembly of  claim 14 , wherein the stiff end structure is in compressive engagement with an elastic bumper holding the flexible extension member in tension. 
     
     
         20 . The medical implant assembly of  claim 14 , wherein the rigid portion is fixed to the flexible extension member.