AU2007223928B2

AU2007223928B2 - System and method for dynamic stabilization of the spine

Info

Publication number: AU2007223928B2
Application number: AU2007223928A
Authority: AU
Inventors: Alan Lombardo; Armin Studer
Original assignee: Blackstone Medical Inc
Current assignee: Orthofix Spinal Implants Inc
Priority date: 2006-03-08
Filing date: 2007-03-08
Publication date: 2011-09-29
Anticipated expiration: 2027-03-08
Also published as: WO2007103404A2; WO2007103404A3; AU2007223928A1; AU2007223928C1; JP2009528896A; JP4933567B2; EP1991173A2

Abstract

A method and device are for dynamically stabilizing a spine using a dynamic spine stabilizer. The dynamic spine stabilizer includes a plurality of rods arranged in series and a flexible member arranged between adjacent rods. The flexible member includes a sheath, e.g., a woven sheath. Each end of the sheath is connected to a respective end of the adjacent rods. An elastomeric plug is arranged in a lumen of the sheath and disposed between ends of adjacent rods.

Description

WO 2007/103404 PCT/US2007/005757 SYSTEM AND METHOD FOR DYNAMIC STABILIZATION OF THE SPINE INCORPORATION BY REFERENCE U.S. Provisional Patent Application Serial No. 60/780,903 is expressly incorporated herein in its entirety by reference thereto. 5 FIELD OF THE INVENTION The present invention relates generally to spine stabilizers. More particularly, the present invention relates to a system and method for dynamic stabilization of the spine. BACKGROUND INFORMATION Apparatuses for treating spinal disorders typically include a pair of implantable rods 10 for mounting on either side of the spinal column. Anchors in the form of hooks or screws, e.g., pedicle screws, are provided along each rod for anchoring to selected vertebrae. Once installed, the anchors are rigidly locked to the associated rod. The implantable rods typically have limited flexibility. SUMMARY 15 According to an example embodiment of the present invention, a dynamic spine stabilizer includes: two or more of rods arranged in series and a flexible member arranged between adjacent rods. The flexible member includes a sheath (e.g., a woven sheath) and an elastomeric plug. Each end of the sheath is connected to a respective end of the adjacent rods. The elastomeric plug is arranged in a lumen of the sheath and disposed between ends of 20 adjacent rods. The elastomeric plug may be floatingly arranged between ends of adjacent rods or it may be secured to ends of the adjacent rods. Further, the elastomeric plug may be made of polycarbonate-urethane and/or it may have a barrel shape. The sheath may be a wire netting tube. The wire netting tube may be made of 25 titanium. The elastomeric plug may be configured to provide resistance to the respective ends of the adjacent rods during compressive loading and it may limit constriction of the sheath during tension loading. 1 WO 2007/103404 PCT/US2007/005757 Rings may be attached to each end of the sheath and a compression collar may attach each ring to an end of a respective rod. At least one end of a rod may include a collar attachment structure and the compression collar may be attached to the collar attachment structure. 5 At least one end of a rod may include an externally tapered lock interface surface and an end portion of the sheath may extend over the tapered lock interface surface and be secured to the end of the rod by an internally tapered collar. The tapers may be oriented inwardly or outwardly. The dynamic spine stabilizer may include at least one sleeve extending over a portion 10 of the flexible member and movably attached to a pair of rods. The sleeve may include inner surfaces configured to contact raised surfaces of the rods. The sleeve may also include two mating portions. The dynamic spine stabilizer may include a plurality of anchor members each anchor member attached to a spine; each rod may be attached to a respective anchor member. The 15 anchor members may include pedicle screws. According to an example embodiment of the present invention, a dynamic spine stabilizer assembly may include a dynamic spine stabilizer as described above and a plurality of anchor members. Each anchor member may be attachable to a spine and to a rod. According to an example embodiment of the present invention, a method for 20 dynamically stabilizing a spine includes attaching anchor members to respective vertebra and attaching a dynamic spine stabilizer assembly to the anchor members, the dynamic spine stabilizer assembly having a plurality of rods arranged in series and a flexible member arranged between adjacent pairs of rods, the flexible member including a sheath (e.g., a woven sheath), each end of the sheath connected to a respective end of the adjacent rods, and 25 an elastomeric plug arranged in a lumen of the sheath and disposed between ends of adjacent rods, each rod attached to a respective anchor member. The method may further include movably attaching at least one sleeve to a pair of the rods, the sleeve extending over a portion of the flexible member. BRIEF DESCRIPTION OF THE DRAWINGS 30 Figure 1 shows a perspective view of a dynamic spine stabilizer according to an example embodiment of the present invention. 2 WO 2007/103404 PCT/US2007/005757 Figure 2 shows a side view of the device shown in Figure 1 and includes a partial cross-sectional view. Figure 3 shows a perspective view of the device shown in Figures 1 and 2 with a sleeve in accordance with a non-limiting embodiment of the invention. 5 Figure 4 shows a side view of the device shown in Figure 3 and includes a partial cross-sectional view. Figure 5 shows a side view of a dynamic spine stabilizer assembly including the device shown in Figures 1 and 2 mounted to two pedicle screws. Figure 6 shows a portion of a wire netting tube of a flexible member in accordance 10 with the present invention. Figure 7 shows a surface of the wire netting tube shown in Figure 6 where the wire netting tube is not subject to significant external forces. Figure 8 shows a surface of the wire netting tube shown in Figure 6 where the wire netting tube is under compression. 15 Figure 9 shows a surface of the wire netting tube shown in Figure 6 where the wire netting tube is under tension. Figure 10 shows a perspective view of a dynamic spine stabilizer assembly with a taper collar interface in accordance with a non-limiting embodiment of the invention. Figure 11 shows a side view of the device shown in Figure 10. 20 Figure 12 shows a cross-sectional view taken along lines XII-XII in Figure 11. Figure 13 shows an enlarged cross-sectional view taken along line XIII in Figure 12. Figure 14 shows an exploded perspective view of the device shown in Figures 1 and 2 with weld rings 'and compression collars. Figure 15 shows a side view of the device shown in Figure 14. 25 Figure 16 shows a cross-sectional view taken along lines XVI-XVI in Figure 15. Figure 17 shows an enlarged cross-sectional view taken along line XVII in Figure 16. 3 WO 2007/103404 PCT/US2007/005757 Figure 18 shows an elastomeric plug according to an embodiment of the present invention. Figure 19 shows a dynamic spine stabilizer assembly according to an example embodiment of the present invention. 5 Figure 20 shows a front view of a dynamic spine stabilizer assembly according to an example embodiment of the present invention. Figure 21 shows a cross-sectional view of a sleeve in accordance with a non-limiting embodiment of the invention. Figure 22 shows a plan view of the sleeve shown in Figure 21. 10 Figure 23 shows a cross-sectional view of the device shown in Figure 20 with the sleeve shown in Figure 21 attached thereto. Figure 24 shows a side elevation view of a dynamic spine stabilizer assembly with a spiral-type configuration in accordance with a non-limiting embodiment of the invention. Figure 25 shows a perspective view of the device shown in Figure 24. 15 Figure 26 to 28 show example embodiments of the present invention featuring a rolled structure-type flexible member. DETAILED DESCRIPTION Like reference characters denote like parts in the drawings. Figures land 2 show a dynamic spine stabilizer 10 for helping to dynamically 20 stabilize a spine. The dynamic spine stabilizer includes a plurality of rods 12 and a flexible member 14. The rods 12 may include any elongated structures. Such an elongated structure may be solid or hollow and may have any desired cross-section (e.g., circular, oval, square, rectangular, etc.). The rods 12 are arranged in series, and the flexible member 14 is arranged between adjacent rods 12. The flexible member 14 includes a woven sheath 16 and an 25 elastomeric plug 18. Each end 20 of the woven sheath 16 is connected to a respective end 22 of adjacent rods 12. Ends 20 of the woven sheath may be connected to respective ends 22 of adjacent rods 12 by any suitable secure attachment (e.g., crimping, adhesives, welding, etc.). Woven sheath 16 is made of a biocompatible material and may be a weave, netting or other configuration providing a sheath structure. The elastomeric plug 18 is arranged in a lumen 24 4 WO 2007/103404 PCT/US2007/005757 (as shown, e.g., in Figure 5) of woven sheath 16 and disposed between ends 22 of adjacent rods 12. Elastomeric plug 18 provides resistance to respective ends 22 of adjacent rods 12 during compressive loading and limits constriction of woven sheath 16 during tensile loading. 5 That is, during compression, ends 22 of rods 12 are in contact with respective ends of plug 18 such that plug 18 exerts a resistive force outwardly on rods 12. Thus, during compression, plug 18 functions as a bumper, buffer or stop. The weave of woven sheath 16 may also provide resistance to compressive loading. The general shape and material characteristics of plug 18 and woven sheath 16 provide for a desired interaction and responsiveness to 10 compressive and tensile loading. For example, when plug 18 is compressed it may be bound by woven sheath 16. Furthermore, as set forth above, during tensile loading plug 18 may limit constriction of woven sheath 16. That is, during tension, the weave of woven sheath 16 permits woven sheath 16 to neck down or radially restrict against an outer periphery of plug 18 thereby exerting a resistive force against tension applied to rods 12, even though plug 18 15 itself, as described above, maybe unattached to ends 22 of rod 12. As mentioned above, elastomeric plug 18 may be floatingly arranged between ends 22 of adjacent rods 12 (as shown, e.g., in Figure 5), or it may be secured to one or both ends 22 of adjacent rods 12. Elastomeric plug 18 may have a generally barrel shape and may be made of polycarbonate urethane (PCU). Elastomeric plug 18 may, however, be provided in other shapes 20 (cylindrical, tubular, rectangular, etc.) and other biocompatible materials with deformable properties. The physical properties of plug 18 and woven sheath 16 may altered to achieve a desired reaction to tensile, compressive and/or bending forces. The above described characteristics of woven sheath 16 are not limited in application to woven sheaths but include alternate sheath structures with similar properties (e.g., tubing, composite material sheaths, 25 etc.). Figures 3 and 4 show dynamic spine stabilizer 10 with a sleeve 24. Sleeve 24 is removably attached to dynamic spine stabilizer 10. Sleeve 24 spans between ends 22 of rods 12 and renders dynamic spine stabilizer 10 substantially inflexible to bending forces while maintaining flexibility with respect to axial loads. Removal of sleeve 24 renders dynamic 30 spine stabilizer 10 flexible to bending forces. Sleeve 24 includes inner surfaces 26 configured to contact raised surfaces 28 of rods 12. Thus, a range of motion of sleeve 24 may be defined by the interaction of inner surfaces 26 with raised surfaces 28 of rods 12. Accordingly, sleeve 24 may also be utilized to limit the elastic properties of flexible member 14 when it is subjected to tensile loads. Sleeve 24 may include two mating portions 30 and 5s WO 2007/103404 PCT/US2007/005757 32 that thread together. Mating portions 30 and 32 may also be connected by other connection structures such as an interference fit, snaps, etc. Figure 5 shows a dynamic spine stabilizer assembly 2 including a dynamic spine stabilizer 10 mounted to two pedicle screws 34. Pedicle screws 34 include a screw 36, heads 5 38 and set screws 40. The dynamic spine stabilizer 10 is mounted to pedicle screws 34 at rods 12 and secured with set screws 40. Screws 36 are attached to the spine. Alternatively, or in combination with pedicle screws 34, other anchor members may be utilized (e.g., hooks, etc.). The flexible member 14 is attached to the respective adjacent rods 12 by crimping a portion of the end of rods 12 to the flexible member. Alternatively, a separate member may 10 be attached to the ends of rods 12 and be crimped or otherwise secured (e.g., welding, adhesives, etc.) to flexible member 14. Also, flexible member 14 may be directly secured to the ends of rods 12 by an adhesive, welding, etc. Figures 6 to 9 show a portion of a wire netting tube 70 of a flexible member that is usable as the woven sheath 16 shown in Figures 1 and 2. Figure 6 generally shows a section 15 of the wire netting tube 70. Figure 7 shows a surface of the wire netting tube 70 shown in Figure 6 where the wire netting tube 70 is not subject to significant external forces. Figure 8 shows a surface of the wire netting tube 70 shown in Figure 6 where the wire netting tube 70 is under compression. Figure 9 shows a surface of the wire netting tube 70 shown in Figure 6 where the wire netting tube is under tension. 20 Figures 10 to 13 show dynamic spine stabilizer 10 with a taper collar interface 42. The ends 22 of rods 12 include an externally tapered lock interface surface 44. End portions 46 of sheath 50 extend over tapered lock interface surfaces 44 and are secured to ends 22 of rods 12 by internally tapered collars 48. The tapered surfaces may also be provided opposite to the direction shown and may alternate directions. Sheath 50 may be a weave, netting, 25 tubular member or other configuration providing a sheath like structure. Figures 14 to 17 show dynamic spine stabilizer 10 with weld rings 54 and compression collars 52. Weld rings 54 are welded to ends 56 of woven sheath 16. Compression collars 52 attach weld rings 54 to ends 22 of rods 12. Ends 22 of rods 12 include collar attachment structures 58. Compression collars 52 are attached to the collar 30 attachment structures 58. Weld rings 54 may be part of weld ring sub-assemblies. Although weld rings 54 are shown, alternative fastening mechanisms may be employed to secure ends 56 of woven sheath 16 to ends 22 of rods 12 (e.g., fastening rings, crimping, adhesives, etc. may be used alone or in combination). 6 WO 2007/103404 PCT/US2007/005757 Figure 18 shows elastomeric plug 18 and Figure 19 shows dynamic spine stabilizer 10 with flexible member 14 attached to ends 22 of rods 12. Figures 20 to 23 show a dynamic spine stabilizer 100 according to an example embodiment of the present invention. Dynamic spine stabilizer 100 may be mounted to 5 pedicle screws in order to help dynamically stabilize the spine. Dynamic stabilizer assembly 100 includes a plurality of rods 112 and a flexible member 114. The rods 112 are arranged in series, and the flexible member 114 is arranged between adjacent rods 112. Additionally, a sleeve 124 may be removably attached to dynamic spine stabilizer 100 such that sleeve 124 spans the distance between rods 112 and renders dynamic spine stabilizer 100 substantially 10 inflexible. Removal of sleeve 124, or movement of sleeve 124 such that it does not span the entire distance between rods 112, will render dynamic spine stabilizer 100 flexible. Sleeve 124 may be held in place on dynamic spine stabilizer 100 via an interference fit (see region "A" where sleeve 124 meets rod 112) and/or via a threaded connection (see region "B" where sleeve 124 meets rod at threads 160A of sleeve 124 and threads 160B of rod 112). 15 Figures 24 and 25 show a dynamic spine stabilizer 200 according to an example embodiment of the present invention. Dynamic spine stabilizer 200 may be mounted to pedicle screws in order to help dynamically stabilize the spine. Dynamic stabilizer 200 includes a plurality of rods 212 and a flexible member 214. The rods 212 are arranged in series and the flexible member 214 is arranged between ends 222 of rods 212. The ends 222 20 of rods 212 are substantially inflexible. Flexible member 214 is integral with ends 222 of rods 212 and has a spiral-type configuration. Figure 26 to 28 show rolled structure flexible members 300 that can be used in a dynamic spine stabilizer in order to help dynamically stabilize the spine. Rolled structure flexible members 300 may be mounted directly to anchor members that are secured to the 25 spine or may be mounted between pairs of rods that are attached to the anchor members. Rolled structure flexible members 300 may be a rolled sheet metal structure. Rolled structure flexible members 300 are flexible (e.g., flexible in compression, flexible in tension and/or flexible in a "bending" motion). Rolled structure flexible members 300 may be thicker in the middle than at the ends. 30 A method for dynamically stabilizing the spine includes attaching anchor members, e.g., pedicle screws, to the spine and attaching a dynamic spine stabilizer, such as any of those described above, to the anchor members. The dynamic spine stabilizer assembly has a plurality of rods arranged in series and a flexible member arranged between adjacent pairs of rods. The flexible member includes a woven sheath and an elastomeric plug. Each end of 7 WO 2007/103404 PCT/US2007/005757 the woven sheath is connected to a respective end of the adjacent rods and the elastomeric plug is arranged in a lumen of the woven sheath and disposed between ends of adjacent rods. Additionally, the method may include movably attaching at least one sleeve to a pair of rods. The at least one sleeve extends over a portion of the at least one flexible member. 5 While a number of example embodiments of the present invention have been described, it is understood that these example embodiments are illustrative only, and not restrictive, and that many modifications would be apparent to those of ordinary skill in the art. For example, the assembly may be placed at any desired level of the spine and may have any number of adjacent rods. Further, the assembly may be used in conjunction with one or 10 more implants. Further still, the dynamic spine stabilizer assembly may be fixed axially and/or rotationally to anchor members. Further still, any of the component of the assembly may be provided in any desired size (e.g., in any desired custom size or in any desired size selected from a family of sizes, such as small, medium, large, etc.). Further still, one or more of the components may be made from any of the following materials: (a) any biocompatible 15 material; (b) a plastic; (c) a fiber; (d) a polymer; (e) a metal (a pure metal such as titanium and/or an alloy such as Ti-Al-Nb, Ti-6A1-4V, stainless steel, etc.); (f) any combination thereof and the elastomeric plug may be made of one or more materials with elastomeric properties. Further still, rather than a threaded screw, a hook or other mechanism may be used for attachment to bone. Further still, any interfacing portions (e.g., rods and pedicle 20 screw mounting mechanisms, etc.) may have one or more features for increasing friction at the interface. For example, any desired interface may have: a roughened or treated surface (e.g., via sandblasting or knurling), a threaded surface, a grooved surface, a ridged surface, a surface with protrusions, a surface with indentations, etc. Further still, the assembly may provide for dynamic flexibility (e.g., flexibility in compression, flexibility in tension and/or 25 flexibility in a "bending" motion, etc.) and/or dynamic motion damping (e.g., damping in compression, damping in tension and/or damping in connection with a "bending" motion, etc.). Further still, any steps described herein may be carried out in any desired order, and any desired steps may be added and/or deleted. 8

Claims

1. A dynamic spine stabilizer, comprising: rods arranged in series; and a flexible member arranged between adjacent rods, the flexible member including a sheath, each end of the sheath connected to a respective end of the adjacent rods, and an elastomeric plug arranged in a lumen of the sheath and disposed between ends of adjacent rods.

2. The stabilizer according to claim 1, wherein the elastomeric plug is floatingly arranged between ends of adjacent rods.

3. The stabilizer according to claim 1, wherein the elastomeric plug is secured to ends of adjacent rods.

4. The stabilizer according to claim 1, wherein the elastomeric plug is polycarbonate urethane.

5. The stabilizer according to claim 1, wherein the elastomeric plug has a barrel shape.

6. The stabilizer according to claim 1, wherein the sheath is a woven sheath.

7. The stabilizer according to claim 1, wherein the sheath is a wire netting tube.

8. The stabilizer according to claim 7, wherein the wire netting tube is made of titanium.

9. The stabilizer according to claim 1, wherein the elastomeric plug is configured to provide resistance to the respective ends of the adjacent rods during compressive loading and limit constriction of the sheath during tension loading.

10. The stabilizer according to claim 1, wherein a ring is attached to the end of the sheath and a compression collar attaches the ring to the respective end of the adjacent rod. 9 WO 2007/103404 PCT/US2007/005757

11. The stabilizer according to claim 10, wherein at least one end of a rod includes a collar attachment structure, the compression collar attached to the collar attachment structure.

12. The stabilizer according to claim 1, wherein at least one end of a rod includes an externally tapered lock interface surface, an end portion of the sheath extending over the tapered lock interface surface and secured to the end of the rod by an internally tapered collar.

13. The stabilizer according to claim 12, wherein the externally tapered lock interface surface and tapered collar are tapered outwardly.

14. The stabilizer according to claim 12, wherein the externally tapered lock interface surface and tapered collar are tapered inwardly.

15. The stabilizer according to claim 1, further comprising at least one sleeve extending over a portion of the flexible member and movably attached adjacent of rods.

16. The stabilizer according to claim 15, wherein the sleeve includes an inner surface configured to contact a raised surface of the rod.

17. The stabilizer according to claim 15, wherein the sleeve includes two mating portions.

18. A dynamic spine stabilizer assembly, comprising the dynamic spine stabilizer according to claim 1 and a plurality of anchor members, each anchor member attachable to a spine and to a rod.

19. The stabilizer assembly according to claim 18, wherein the anchor member is a pedicle screw.

20. A method for dynamically stabilizing a spine, comprising: attaching anchor members to the spine; and attaching a dynamic spine stabilizer to the anchor members, the dynamic spine stabilizer having a plurality of rods arranged in series and a flexible member arranged between adjacent rods, the flexible member including a sheath, the end of the sheath 10 WO 2007/103404 PCT/US2007/005757 connected to the respective end of the adjacent rod, and an elastomeric plug arranged in a lumen of the sheath and disposed between the ends of the adjacent rods, each rod attached to a respective anchor member.

21. The method according to claim 20, further comprising movably attaching at least one sleeve to a pair of the adjacent rods, the sleeve extending over the flexible member. 11