Longitudinal connecting member with sleeved tensioned cords

Abstract

A dynamic fixation medical implant having at least two bone anchors includes a longitudinal connecting member assembly having rigid sleeves for attachment to the bone anchors, at least one spacer engaging the bone anchors and the sleeves, and in some embodiments, an end elastic bumper. A flexible cord is initially slidingly received within the rigid sleeves, the spacer and the bumper. The spacer may include an optional inelastic inner liner, with at least one of the sleeves having an extension slidingly receivable within the liner. Some sleeves include apertures for receiving a closure top portion for locking the cord against the sleeve, or alternatively receiving a closure top that does not extend into the aperture, the slip or grip option provided by the aperture in each sleeve resulting in an overall connector with variable segmental stiffness.

What is claimed is: 
     
         1 . A medical implant assembly having at least first and second bone anchors cooperating with a longitudinal connecting member having a tensioned cord, the bone anchors having opposed upstanding arms, the medical implant assembly comprising:
 a) a first non-elastic sleeve for attachment to the first bone anchor, the first sleeve having a first through bore sized and shaped for slidably receiving the tensioned cord, a first aperture formed in the sleeve substantially transverse to the through bore, the aperture sized and shaped for receiving a portion of a first optional cord gripping closure top and a first body portion sized and shaped for being closely received between the bone anchor arms;   b) a second non-elastic sleeve for attachment to the second bone anchor, the second sleeve having a second through bore sized and shaped for slidably receiving the tensioned cord, a second aperture formed in the sleeve substantially transverse to the second through bore, the second aperture sized and shaped for receiving a portion of a second optional cord gripping closure top and a second body portion sized and shaped for being closely received between the second bone anchor arms;   c) a spacer located between the first and second bone anchors, the spacer engaging each of the first and second sleeves, the cord extending through the spacer and held in tension at least first and second ends of the connecting member; and   d) wherein at least one of the first and second sleeves includes an outer flange abutting against an outer surface of the spacer.   
     
     
         2 . The medical implant assembly of  claim 1  wherein the outer flange is a first outer flange and further comprising a second outer flange disposed at an obtuse angle with respect to the first outer flange, each flange being disposed outside of the bone anchor. 
     
     
         3 . The medical implant assembly of  claim 2  further comprising at least one tubular structure extending outwardly from at least one of the flanges. 
     
     
         4 . The medical implant assembly of  claim 1  wherein at least one of the first and second sleeves has a first U-shaped lower surface sized and shaped to frictionally engage a second U-shaped surface of a pressure insert located within the bone anchor. 
     
     
         5 . A medical implant assembly having first and second bone anchors cooperating with a longitudinal connecting member having a tensioned cord, the medical implant assembly comprising:
 a) a non-elastic sleeve for attachment to the first bone anchor, the sleeve having a body portion sized and shaped for being closely received between opposed arms of the first bone anchor;   b) a spacer located between the first and second bone anchors, the cord extending through the spacer and held in tension at at least first and second ends of the connecting member; and   c) a blocker, the first bone anchor being located between the blocker and the spacer, the blocker located near the sleeve, the blocker being fixed to the tensioned cord.   
     
     
         6 . The medical implant assembly of  claim 5  wherein the blocker is adjacent the first bone anchor. 
     
     
         7 . The medical implant assembly of  claim 5  wherein the blocker engages the sleeve. 
     
     
         8 . The medical implant assembly of  claim 5  further comprising a bumper located between the blocker and the first bone anchor. 
     
     
         9 . The medical implant assembly of  claim 5  wherein the second bone anchor is a monoaxial bone screw fixed to the cord. 
     
     
         10 . The medical implant assembly of  claim 5  wherein the at least one sleeve is a first sleeve and further comprising a second sleeve, the second sleeve for attachment to the second bone anchor.