Dynamic stabilization connecting member with molded connection
View Patent ↗A dynamic fixation medical implant having at least two bone anchors includes a longitudinal connecting member assembly having at least one transition portion and cooperating outer sleeve, both the transition portion and sleeve being disposed between the two bone anchors. The transition portion includes a rigid length or rod having apertures therein and a molded plastic length that extends through the apertures, thus attaching the plastic length to the rigid length. The sleeve surrounds the transition portion and extends between the pair of bone anchors, the sleeve being compressible in a longitudinal direction between the bone anchors.
1. In a medical implant assembly having at least first and second attachment structures cooperating with an elongate longitudinal connecting member, the improvement wherein the connecting member comprises:
a) a rigid rod portion secured within the first bone attachment structure;
b) an elongate polymer co-axially connected to the rod portion near an outer end thereof, the elongate polymer cooperating with the bone attachment structures to provide movement between the structures, the elongate polymer being held in tension between the first and second bone attachment structures; and
c) an outer compressible sleeve being positioned between the first and second bone attachment structures and providing surrounding support for the elongate polymer and cooperating bone attachment structures, the sleeve at least partially covering the rigid rod portion co-axially connected to the elongate polymer.
2. The improvement of claim 1 , wherein the elongate polymer is secured within the second bone attachment structure.
3. The improvement of claim 1 , wherein the first bone attachment structure is a polyaxial screw.
4. The improvement of claim 1 , wherein the sleeve engages at least one of the bone attachment structures.
5. The improvement of claim 1 , wherein the sleeve engages the first bone attachment structure.
6. The improvement of claim 1 , wherein the sleeve engages the second bone attachment structure.
7. The improvement of claim 1 , wherein the sleeve engages both of the bone attachment structures.
8. The improvement of claim 3 , wherein the polyaxial bone screw having a receiver, a shank, and a retainer, and wherein the shank is configured to be bottom-loaded into the receiver and retained by the retainer therein.
9. In a medical implant assembly having at least two bone attachment structures cooperating with an elongate longitudinal connecting member, the improvement wherein the connecting member comprises:
a) a transition portion disposed adjacent at least one of the bone attachment structures, the transition portion having
i) a rigid segment attached to at least one bone attachment structure and having an end extending outwardly from the bone attachment structure; and
ii) an elongate polymer segment cooperating with the bone attachment structures and being pre-tensioned, an end part of the elongate segment secured to the rigid segment portion; and
b) an outer sleeve at least partially covering the rigid segment end part, the outer sleeve being positioned between the bone attachment structures and being under compression.
10. The improvement of claim 9 wherein the elongate polymer segment is a bar of rectangular cross-section.
11. The improvement of claim 9 wherein the rigid segment has a bore near the end part and the elongate polymer segment is partially disposed within and completely fills the bore.