Spinal stabilization device
A flexible connection unit for use in a spinal fixation device that includes: a longitudinal member having first and second ends and a flexible member interposed between the first and second ends, at least one of the first end and second end configured to be engaged by a first bone securing member; and at least one spacer located between the first and second ends, the spacer comprising a resilient element and a ring element encircling at least a portion of the resilient element, wherein the ring element is configured to be engaged by a second bone securing member.
1. A flexible connection unit for use in a spinal fixation device, the flexible connection unit comprising:
a longitudinal member having a first end portion, a second end portion and a flexible member interposed at least partially between the first and second end portions, at least one of the first end portion or the second end portion configured to be engaged by a first bone securing member; and
a spacer located at least partially between the first and second end portions, the spacer comprising:
(1) a rigid ring element having a length and having a first inner bore extending the length of the ring element; and
(2) a resilient element including a first resilient portion, a second resilient portion and a connecting portion, the first resilient portion is configured to abut the first end portion, the second resilient portion is configured to abut the second end portion, and the connecting portion extends through the first inner bore connecting the first resilient portion to the second resilient portion such that the ring element is spaced apart from the first and second end portions, and the resilient element further defines a second inner bore configured to receive the flexible member such that the flexible member extends through the first and second inner bores.
2. The flexible connection unit of claim 1 wherein at least one interior edge of the ring element is rounded.
3. The flexible connection unit of claim 2 wherein both interior edges of the ring element are rounded.
4. The flexible connection unit of claim 1 wherein the ring element has a circular cross-sectional shape.
5. The flexible connection unit of claim 1 wherein a cross-sectional profile of the flexible member is smaller than a cross sectional profile of at least one of the first or second end portions.
6. The flexible connection unit of claim 1 wherein the resilient element is made of a material comprising organic polymer, elastomer, naturally occurring resin, or composite material.
7. The flexible connection unit of claim 1 wherein the connection unit is configured in the profile of a cylindrical rod.
8. The flexible connection unit of claim 1 wherein the spacer is made of a material comprising metal, metal alloy, organic polymer, naturally occurring resin, thermoplastic or composite material.
9. The flexible connection unit of claim 1 wherein the ring element is made of a material comprising metal, metal alloy or composite material.
10. The flexible connection unit of claim 1 wherein the flexible member comprises a flexible wire or bundle of wires.
11. The flexible connection unit of claim 6 wherein the resilient element comprises elastomeric cladding.
12. The flexible connection unit of claim 1 wherein the first and second end portions of the longitudinal member, the ring element and the flexible member each are made of a material comprising metal or metal alloy.
13. The flexible connection unit of claim 12 wherein the resilient element comprises elastomeric cladding.
14. The flexible connection unit of claim 1 wherein the flexible member is positioned axially through the spacer and at least a portion of the first or second end portions.
15. The flexible connection unit of claim 1 wherein the resilient element is concentric with the flexible member.
16. The flexible connection unit of claim 1 wherein the flexible member is eccentrically located in an axial cavity of the at least one spacer.
17. The flexible connection unit of claim 1 wherein the flexible member is physically separated from both the first end portion and the second end portion.
18. The flexible connection unit of claim 17 wherein the flexible member is surrounded with an elastomer.
19. The flexible connection unit of claim 18 wherein the flexible member is formed of at least one wire and the at least one wire is axially slidable within a pre-formed extruded elastomer.
20. The flexible connection unit of claim 1 wherein the flexible member is in contact with at least one of the first and second end portions.
21. The flexible connection unit of claim 1 wherein the flexible member is fixed with respect to at least one of the first and second end portions.
22. The flexible connection unit of claim 1 wherein the flexible member is fixed at both the first end portion and the second end portion.
23. The flexible connection unit of claim 1 wherein the ring element circumferentially surrounds the resilient element.
24. The flexible connection unit of claim 1 wherein the spacer comprises a plurality of ring elements and the resilient element comprises an elastomer.
25. The flexible connection unit of claim 9 wherein the resilient element is polycarbonate urethane.
26. The flexible connection unit of claim 1 , wherein the resilient element is configured to abut the first and second end portions of the longitudinal member such that the resilient element is at least partially disposed within a cavity of the first or second end.
27. The flexible connection unit of claim 1 , wherein the resilient element is configured to abut the first and second end portions of the longitudinal member such that the first or second end portion is at least partially disposed within a cavity of the resilient member.