Spinous process implants and associated methods
The present invention provides spinous process implant and associated methods. In one aspect of the invention the implant limits the maximum spacing between the spinous processes. In another aspect of the invention, a spacer has at least one transverse opening to facilitate tissue in-growth. In another aspect of the invention, an implant includes a spacer and separate extensions engageable with the spacer. The spacer is provided in a variety of lengths and superior to inferior surface spacings. In another aspect of the invention, an implant includes a spacer and a cerclage element offset from the midline of the spacer in use so that the spacer defines a fulcrum and the cerclage element is operative to impart a moment to the vertebrae about the spacer. In another aspect of the invention, instrumentation for inserting the implant is provided. In other aspects of the invention, methods for treating spine disease are provided.
1. An implant for placement between spinous processes of adjacent vertebrae of a spine, the implant comprising:
a cylindrical hollow spacer with a first end, a second end, and a longitudinal axis extending from the first end to the second end, the spacer comprising superior and inferior surfaces operable to abut the spinous processes and maintain minimum spacing between spinous processes, the spacer comprising at least one channel running along a length of the spacer aligned with the longitudinal axis and exposing an inner portion of the cylindrical hollow spacer to facilitate tissue in-growth into the cylindrical hollow spacer;
a first extension integral with and projecting from the first end of the spacer transverse to the longitudinal axis to lie generally alongside the spinous processes of adjacent vertebrae; and
a second extension opposing the first extension, the second extension defining an aperture that comprises at least one tab member adapted to directly engage the at least one channel of the spacer, the second extension being translatable over the spacer from the spacer second end towards the first extension;
wherein at least one of the first and second extensions further comprise at least one fastener adapted to engage the spinous processes to fix the implant to the spinous processes.
2. The implant of claim 1 , wherein the first extension comprises the at least one fastener adapted to engage at least one of the spinous processes to fix the spacer to the spinous processes.
3. The implant of claim 1 , wherein the spacer and first extension comprise a first relatively softer material and the fastener comprises a second relatively harder material.
4. The implant of claim 1 , wherein the second extension comprises the at least one fastener adapted to engage at least one of the spinous processes to fix the spacer to the spinous processes.
5. The implant of claim 1 , wherein the at least one fastener comprises a plurality of fasteners on both of the first and second extensions, wherein the fastener on the first extension is adapted to be offset relative to the fastener on the second extension when the fasteners are engaged with the spinous processes.
6. The implant of claim 1 , wherein the at least one fastener is adjustable angularly relative to the extension to which it is attached such that the at least one fastener is non-normal to the extension.
7. The implant of claim 1 , wherein the at least one fastener is adjustable to vary the distance it extends from the extension to which the at least one fastener is attached.
8. The implant of claim 1 , wherein the at least one fastener is removable from the extension to which it is attached.
9. The implant of claim 1 , wherein the at least one fastener comprises a plurality of fasteners connected together at a common base, the common base being removably engageable with the extension to which it is attached.
10. The implant of claim 1 , wherein the first extension has a first portion extending superiorly and a second portion extending inferiorly, the superior and inferior portions being offset anteriorly-posteriorly relative to one another to allow the extensions of multiple implants placed in adjacent interspinous spaces to be able to interleave.
11. The implant of claim 1 , wherein the spacer comprises an anterior side between the superior and inferior surfaces facing anteriorly when the superior and inferior surfaces are abutting the spinous processes, the spacer having anteriorly facing chamfers at its first and second ends.
12. The implant of claim 1 , wherein the superior and inferior surfaces of the spacer have a midline and the first extension is offset posteriorly of the midline so that the spacer is positioned relatively more anteriorly and the first extension is positioned relatively more posteriorly.
13. An implant for placement between spinous processes of adjacent vertebrae of a spine, the implant comprising:
a cylindrical hollow spacer having a first end, a second end, and a longitudinal axis extending from the first end to the second end, the spacer comprising superior and inferior outer surfaces adapted to abut the spinous processes, the spacer comprising at least one channel running along a length of the spacer aligned with the longitudinal axis and exposing an inner portion of the cylindrical hollow spacer to facilitate tissue in-growth into the cylindrical hollow spacer and at least one transverse opening disposed in at least one of the superior and inferior outer surfaces to further facilitate tissue in-growth into the hollow spacer;
a first extension extending outwardly from the spacer transverse to the longitudinal axis to lie generally alongside and be fixedly coupleable to at least one spinous process; and
a second extension opposing the first extension, the second extension defining an aperture that comprises at least one protrusion adapted to engage the at least one channel of the spacer, the second extension being axially translatable over at least a portion of the superior and inferior surfaces of the spacer to fix the spacer between adjacent spinous processes.
14. The implant of claim 13 , wherein the first extension comprises the at least one fastener adapted to engage at least one of the spinous processes to fix the spacer to the spinous processes.
15. The implant of claim 13 , wherein the spacer and first extension comprise a first relatively softer material and the fastener comprises a second relatively harder material.
16. The implant of claim 13 , wherein the second extension comprises the at least one fastener adapted to engage at least one of the spinous processes to fix the spacer to the spinous processes.
17. The implant of claim 13 , wherein the at least one fastener comprises a plurality of fasteners on both of the first and second extensions, wherein the fastener on the first extension is adapted to be offset relative to the fastener on the second extension when the fasteners are engaged with the spinous processes.
18. The implant of claim 13 , wherein the first extension has a first portion extending superiorly and a second portion extending inferiorly, the superior and inferior portions being offset anteriorly-posteriorly relative to one another allowing the extensions of multiple implants placed in adjacent interspinous spaces to be able to interleave.
19. The implant of claim 13 , wherein the spacer comprises an anterior side between the superior and inferior surfaces facing anteriorly when the superior and inferior surfaces are abutting the spinous processes, the spacer having anteriorly facing chamfers at its first and second ends.
20. The implant of claim 13 , wherein the superior and inferior surfaces of the spacer have a midline and the first extension is offset posteriorly of the midline so that the spacer is positioned relatively more anteriorly and the first extension is positioned relatively more posteriorly.