Variable stiffness support members

• US 7,875,059 B2
• Filed: 01/18/2007
• Issued: 01/25/2011
• Est. Priority Date: 01/18/2007
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Veldman, Michael S., Allard, Randall, Patterson, Christopher M.
• Primary Examiner(s): Robert; Eduardo C
• Assistant Examiner(s): Negrelli; Christina
• Application Number:
  US11/624,401
• Publication Number:
  US 20080177388A1
• Time in Patent Office: 1,468 Days
• Field of Search: 606246-279, 606300-321, 606/63, 623 1711- 1716, 623/23.32, 623 2344- 2347
• US Class Current: 606/261
• CPC Class Codes: A61B 17/7004 with a cross-section which varies along its length A61B17/7019 takes precedence
• CPC Class Codes: A61B 17/7031 made wholly or partly of flexible material
• CPC Class Codes: A61B 17/705 for linking adjacent ends of longitudinal elements
• CPC Class Codes: A61B 2017/00526 Methods of manufacturing

Abstract

Spinal support members having varying stiffnesses are disclosed. In one embodiment, an elongated spinal prosthetic includes a pair of curved elongated portions. The portions are formed of materials having different stiffness characteristics such that the stiffness of the prosthetic varies along its length. In another embodiment, an elongated spinal implant includes a pair of threadedly engaged elongated sections. The first section is formed of a first material having a first rigidity. The second section has an inner portion formed of the first material and an outer portion formed of a second material. The second material is less rigid than the first material. In another embodiment, a modular spinal rod is provided. The modular spinal rod includes a pair of connectable rod portions with different stiffness characteristics. In yet another embodiment, a kit for a modular spinal rod includes a plurality of connectable modular rod portions having different stiffness characteristics.

Claims

1. An elongated spinal prosthetic comprising:

a first elongated portion having a male connection mechanism extending from one end, the first elongated portion having a first outer surface formed of a first material having a first rigidity, wherein the first outer surface has a first cylindrical profile along a majority of its length, the first cylindrical profile having a first diameter; and

a second elongated portion having a female connection mechanism for receiving the male connection mechanism of the first elongated portion to fixedly connect the first and second elongated portions, the second elongated portion having a second outer surface formed of a second material different from the first material, the second material having a second rigidity less than the first rigidity of the first material,

wherein the second outer surface has a second cylindrical profile along a majority of its length, the second cylindrical profile having a second diameter, the second diameter being substantially equal to the first diameter such that when the first and second elongated portions are connected via the male and female connection mechanisms the elongated spinal prosthetic has a substantially constant cylindrical profile along a majority of its length,

wherein a majority of the first elongated portion is formed of the first material and wherein a majority of the second elongated portion is formed of the second material,

wherein the first material is a metal and the second material is a polymer,

wherein the first elongated portion is curved along its length,

wherein a thickness of the male connection mechanism is varied along its length, and

wherein the thickness of the male connection mechanism is tapered along its length.

2. The elongated spinal prosthetic of claim 1 wherein the first material is selected from the group of metals consisting of titanium alloys, cobalt-chromium alloys, nickel titanium alloys, and stainless steel alloys, and the second material is PEEK.

3. The elongated spinal prosthetic of claim 1 wherein the male connection mechanism extends within the second elongated portion along a majority of the length of the second elongated portion.

4. The elongated spinal prosthetic of claim 1 wherein the thickness of male connection mechanism decreases and increases along its length.

5. The elongated spinal prosthetic of claim 1 wherein the radii of curvature for the first and second elongated portions are substantially equal such that the elongated spinal prosthetic has a substantially continuous radius of curvature along its length.

6. The elongated spinal prosthetic of claim 1 further comprising a sleeve member positioned around the first and second elongated portions adjacent a junction between the first and second outer surfaces.

7. The elongated spinal prosthetic of claim 6 wherein the sleeve member comprises a clamp.

8. The elongated spinal prosthetic of claim 1 further comprising an end cap adapted to engage at least one end of at least one of the first and second elongated portions.

9. The elongated spinal prosthetic of claim 1 wherein the second elongated portion is molded over the first elongated portion.

10. The elongated spinal prosthetic of claim 1, wherein the radius of curvature for the first elongated portion is different from the radius of curvature for the second elongated portion such that the elongated spinal prosthetic has a varying radius of curvature along its length.

11. The elongated spinal prosthetic of claim 10 wherein the radius of curvature for the first elongated portion is curved in a direction substantially opposite the radius of curvature for the second elongated portion when the first and second portions are connected.

12. An elongated spinal prosthetic comprising:

a first elongated portion having a male connection mechanism extending from one end, the first elongated portion having a first outer surface formed of a first material having a first rigidity, wherein the first outer surface has a first cylindrical profile along a majority of its length, the first cylindrical profile having a first diameter; and

a second elongated portion having a female connection mechanism for receiving the male connection mechanism of the first elongated portion to fixedly connect the first and second elongated portions, the second elongated portion having a second outer surface formed of a second material different from the first material, the second material having a second rigidity less than the first rigidity of the first material,

wherein the second outer surface has a second cylindrical profile along a majority of its length, the second cylindrical profile having a second diameter, the second diameter being substantially equal to the first diameter such that when the first and second elongated portions are connected via the male and female connection mechanisms the elongated spinal prosthetic has a substantially constant cylindrical profile along a majority of its length,

wherein a majority of the first elongated portion is formed of the first material and wherein a majority of the second elongated portion is formed of the second material,

wherein the first material is a metal and the second material is a polymer,

wherein the first elongated portion is curved along its length,

wherein the second elongated portion is curved along its length, and

wherein the radius of curvature for the first elongated portion is different from the radius of curvature for the second elongated portion such that the elongated spinal prosthetic has a varying radius of curvature along its length.

13. The elongated spinal prosthetic of claim 12 wherein a thickness of the male connection mechanism is varied along its length.

14. The elongated spinal prosthetic of claim 13 wherein the thickness of the male connection mechanism is tapered along its length.

15. The elongated spinal prosthetic of claim 13 wherein the thickness of the male connection mechanism is stepped along its length.

16. The elongated spinal prosthetic of claim 12 wherein the radius of curvature for the first elongated portion is curved in a direction substantially opposite the radius of curvature for the second elongated portion when the first and second portions are connected.

17. The elongated spinal prosthetic of claim 12 further comprising a sleeve member positioned around the first and second elongated portions adjacent a junction between the first and second outer surfaces.

18. The elongated spinal prosthetic of claim 17 wherein the sleeve member comprises a clamp.

19. The elongated spinal prosthetic of claim 12 further comprising an end cap adapted to engage at least one end of at least one of the first and second elongated portions.

20. The elongated spinal prosthetic of claim 12 wherein the second elongated portion is molded over the first elongated portion.

21. The elongated spinal prosthetic of claim 12 wherein the first material is selected from the group of metals consisting of titanium alloys, cobalt-chromium alloys, nickel titanium alloys, and stainless steel alloys, and the second material is PEEK.