Soft stabilization assemblies with pretensioned cords
View Patent ↗A soft 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, typically, 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 and cooperating spacer.
1. A longitudinal connecting member assembly for supporting a portion of a spine of a patient, the longitudinal connecting member assembly comprising:
a longitudinal connecting member comprising a solid rod connected to a tensionable cord at one end thereof, wherein the tensionable cord comprises a core member that is compressible and when not compressed has a diameter that is less than a diameter of the solid rod;
at least a first and a second bone anchor, each including a closure for locking the respective bone anchor, wherein the solid rod is secured to the first bone anchor by the respective closure, the tensionable cord extending between the first and second bone anchor and being in slidable relation with respect to the second bone anchor when the bone anchors are locked by the respective closures;
an adjustable multi-part end structure configured to allow tensioning and retensioning of the tensionable cord, wherein the adjustable multi-part end structure comprises a non-threaded through-bore to receive the tensionable cord therethrough; and
an elastomeric bumper, wherein the elastomeric bumper is slidably positioned on the tensionable cord between the adjustable multi-part end structure and the second bone anchor, and wherein the elastomeric bumper is compressible when the tensionable cord is tensioned and secured to the multi-part end structure;
the tensionable cord being tensionable by securement to the adjustable multi-part end structure prior to attachment to the spine of the patient and retensionable before and after attachment to the spine of a patient by securement to the adjustable multi-part end structure, the tensionable cord being tensionable and retensionable only from the end that is received through the adjustable multi-part end structure.
2. The assembly of claim 1 , wherein the adjustable multi-part end structure is configured as a blocker.
3. The assembly of claim 2 , wherein the blocker and the bumper are configured in an overlapping orientation.
4. The assembly of claim 1 , further comprising a sleeve in slidable relation with the tensioned cord secured to the adjustable multi-part end structure and securable to the second bone anchor, wherein after the second bone anchor is locked by the closure and secured to the sleeve, the sleeve and the second bone anchor are in slidable relation with respect to the tensioned cord.
5. The assembly of claim 4 , wherein the elastomeric bumper is positioned between the sleeve secured to the second bone anchor and the adjustable multi-part end structure, and the elastomeric bumper is spaced apart from the second bone anchor by the sleeve.
6. The assembly of claim 4 , wherein the sleeve engages the spacer positioned on the tensionable cord at a location between the first and second bone anchors in an overlapping orientation.
7. The assembly of claim 6 , wherein the spacer has a width and a height, the height running from a top surface to a bottom surface, the height being greater than the width and the through-bore being located closer to the top surface than to the bottom surface.
8. The assembly of claim 4 , wherein the sleeve when secured to the second bone anchor by the closure extends outside of a receiver connected to the second bone anchor.
9. The assembly of claim 1 , further comprising a spacer having a through-bore that slidingly receives the tensionable cord therethrough, wherein the spacer is positioned at a location between the first and second bone anchors.
10. The assembly of claim 9 , wherein the spacer is compressible.
11. The assembly of claim 9 , wherein the spacer is elastic.
12. The assembly of claim 9 , wherein the spacer is substantially tubular and the spacer through-bore runs along a central axis thereof.
13. The assembly of claim 1 , wherein the adjustable multi-part end structure comprises a releasable setscrew.
14. The assembly of claim 13 , wherein the adjustable multi-part end structure has a first non-treaded through-bore for receiving the tensionable cord therethrough and a second threaded through-bore configured to threadably receive the releasable setscrew therein.
15. The assembly of claim 1 , wherein the second bone anchor is a polyaxial bone screw.