Selectively Expanding Spine Cage, Hydraulically Controllable In Three Dimensions For Enhanced Spinal Fusion

• US 20110270398A1
• Filed: 07/14/2011
• Published: 11/03/2011
• Est. Priority Date: 09/26/2005
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Coalign Innovations Inc. (Stryker Corporation)
• Inventors: Pretti, Rudy, Grotz, Thomas
• Granted Patent: US 8,454,695 B2
• Time in Patent Office: Days
• US Class Current: 623/17.12
• CPC Class Codes: A61F 2/30771 applied in original prostheses, e.g. holes or grooves
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• CPC Class Codes: A61F 2/4601 for introducing bone substitute, for implanting bone graft implants or for compacting them in the bone cavity
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2/484 Fluid means, i.e. hydraulic or pneumatic
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30538 for adjusting angular orientation
• CPC Class Codes: A61F 2002/3055 for adjusting length
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30579 with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30583 filled with hardenable fluid, e.g. curable in-situ
• CPC Class Codes: A61F 2002/30589 Sealing means
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30617 Visible markings for adjusting, locating or measuring
• CPC Class Codes: A61F 2002/30772 Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2002/4627 : with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2002/4629 : connected to the endoprosthesis or implant via a threaded connection
• CPC Class Codes: A61F 2002/4666 : for measuring force, pressure or mechanical tension
• CPC Class Codes: A61F 2210/0085 : hardenable in situ, e.g. epoxy resins
• CPC Class Codes: A61F 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2230/0015 : Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0006 : for adjusting angular orientation
• CPC Class Codes: A61F 2250/0097 : Visible markings, e.g. indicia
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

A selectively expanding spine cage has a minimized diameter in its unexpanded state that is smaller than the diameter of the neuroforamen through which it passes in the distracted spine. The cage conformably engages between the endplates of the adjacent vertebrae to effectively distract the anterior disc space, stabilize the motion segments and eliminate pathologic spine motion. Angular deformities can be corrected, and natural curvatures restored and maintained. The cage enhances spinal arthrodesis by creating a rigid spine segment, or if filled with compressible substances, the cage can be used for motion preservation between vertebral bodies. Expanding selectively (anteriorly, along the vertical axis of the spine) rather than uniformly, the cage height increases and holds the vertebrae with fixation forces greater than adjacent bone and soft tissue failure forces in natural lordosis. Stability is thus achieved immediately, enabling patient function by eliminating painful motion. The cage shape intends to rest proximate to the anterior column cortices securing the desired spread and fixation, allowing for bone graft in, around, and through the implant for arthrodesis whereas for arthroplasty it fixes to endpoints but cushions the spine naturally.

Claims

1. An apparatus for providing spinal correction in three dimensions, comprising:

a selectively expanding spinal implant for insertion between first and second vertebrae of a patient, said spinal implant comprising;

a cylinder block comprising a body configured for engaging a first vertebra and defining two or more slave cylinders; and

corresponding slave pistons received in said slave cylinders and having a corrective bone engaging surface for extending against a second vertebra.

2. The apparatus of claim 1, further comprising a master cylinder located away from the patient and communicating hydraulically with the slave cylinders to operate said pistons to impart a desired spinal correction.

3. The apparatus of claim 2, wherein said master cylinder communicates independently with each slave cylinder for independently operating a corresponding slave piston to impart a desired anterior/posterior spinal correction and for operating the pistons differentially for imparting desired lateral, right/left spinal correction.

4. The apparatus of claim 1, further comprising an incompressible fluid disposed within said cylinders for extending said pistons.

5. The apparatus of claim 4, wherein the said pistons are lockable in an extended position at a desired spinal correction.

6. The apparatus of claim 5, wherein:

the incompressible fluid comprises a curable polymer having a fluid state for providing hydraulic communication of mechanical force from said master cylinder to said slave cylinders to elevate said pistons to a position that provides the desired spinal correction; and

said polymer cures to a solid state to lock said pistons at said desired correction.

7. The apparatus of claim 1, wherein the cylinder block defines a central cavity for receiving osteoconductive material, the central cavity opening to an intervertebral space between the first and second vertebrae.

8. The apparatus of claim 7, wherein the central cavity extends through the cylinder block and the bone engaging surface.

9. The apparatus of claim 7, wherein said cylinder block further defines a bone graft infusion port communicating with the central cavity, said port coupled through a conduit with an input port connectable to a source of bone graft material for infusion of said bone graft material into the intervertebral space.

10. A selectively expandable spinal implant for insertion into between vertebrae of a patient, comprising:

a cylinder block defining at least first and second cylinders and comprising a base configured for resting on a first vertebrae;

at least first and second pistons respectively received in said at least first and second cylinders, said pistons being extendable to impart a desired spinal correction; and

a bone engaging plate attached to said pistons opposite said base for engaging a second vertebrae in response to extension of said pistons.

11. The spinal implant of claim 10, wherein the bone engaging plate is movably attached to said pistons to provide a corrective angle depending on relative expansion of the pistons.

12. The spinal implant of claim 10, wherein said pistons are independently, selectively hydraulically actuatable to impart a desired anterior/posterior spinal correction and wherein differential operation of the pistons with respect to one another imparts a desired lateral spinal correction.

13. The spinal implant of claim 10, wherein said pistons are lockable at the desired spinal correction.

14. The spinal implant of claim 13, further comprising a hydraulic fluid disposed in said cylinders, said hydraulic fluid comprising a polymer that cures to a solid state to lock the slave pistons immovably in place at a desired amount of spinal correction.

15. The spinal implant of claim 14, wherein said cylinder block and pistons comprise a biocompatible, substantially incompressible material for confining the curable polymer, wherein a desired amount of spinal correction imparted by the extended pistons is capable of withstanding compressive forces up to a structural failure limit of the cylinder block.

16. The spinal implant of claim 15, wherein the slave cylinder block and pistons comprise titanium or an alloy thereof.

17. The spinal implant of claim 15, wherein the slave cylinder block and pistons comprise stainless steel.

18. The spinal implant of claim 15, wherein the slave cylinder block and pistons comprise any of biodegradable and biologically active materials and polyarylethertherektone (PEEK) TM.

19. The apparatus of claim 15, wherein said implant can withstand compressive forces in a range from 8000-12,000 Newtons, or 3000 lbs and has a diameter substantially in a range of 0.8-1 cm in an unexpanded state to facilitate posterior insertion through a pedicle space.

20. The spinal implant of claim 10, said pistons are concurrently operable to provide medial/lateral adjustment of said patient'"'"'s spine for scoliosis with anterior/posterior adjustment of said patient'"'"'s spine to create natural lordosis, with relative anterior adjustment greater than posterior adjustment.

21. The apparatus of claim 10, wherein the cylinder block further defines a central cavity disposed between said cylinders for receiving osteoconductive material, the central cavity extending through said base and bone engaging plate to open to an intervertebral space between the first and second vertebrae.

22. An apparatus for providing spinal correction, comprising:

a selectively expandable spinal implant for insertion between vertebrae of a patient, said implant comprising;

a base member configured and dimensioned to engage a first vertebra;

at least two rigid cylinders carried by said base member;

at least first and second pistons respectively disposed in said cylinders, said pistons being configured to be rigidly fixed at an extended position;

a bone engaging member cooperating with pistons opposite the base member and configured and dimensioned to engage a second vertebra.

23. The apparatus of claim 22, wherein the bone engaging member comprises a bone engaging plate moveably attached to the pistons to provide a corrective angle depending on relative extension of the pistons

24. The apparatus of claim 22, wherein the base member comprises a cylinder block defining said cylinders.

25. The apparatus of claim 22, wherein the implant further comprises a lordosis plate cooperating with the base member.

26. The apparatus of claim 29, wherein:

said cylinders are slave cylinders; and

the apparatus further comprises at least one master cylinder configured and dimensioned to be disposed away from the patient while communicating hydraulically with each said slave cylinder for extension of said cylinders.

27. The apparatus of claim 26, wherein:

said pistons are separately controllable via said at least one master cylinder

said bone engaging member is pivotably connected with said pistons to accommodate variations in height between said pistons.

28. The apparatus of claim 22, wherein the pistons are actuated by fluid applied to the cylinders.

29. The apparatus of claim 28, wherein fluid comprises a material that is curable to a solid state to rigidly fix the pistons.

30. The apparatus of claim 28, further comprising an insertion tool releasably engageable with said implant for positioning the implant between the vertebrae and delivering hydraulic fluid to the cylinders.

31. The apparatus of claim 30, wherein:

the base member defines passages for said hydraulic fluid and for osteoconductive material and an input port communicating therewith;

the insertion tool has an end configured and dimensioned to be secured to said insertion port; and

the insertion tool defines separate passages for hydraulic fluid and osteoconductive material that communicate with said input port passages respectively when the insertion tool is secured thereto.

32. The apparatus of claim 31, wherein said implant further comprises a central cavity disposed between said cylinders for receiving the osteoconductive material, the central cavity extending through said base member and bone engaging member to open to an intervertebral space between the vertebrae, said central cavity communicating with said passage for osteoconductive material defined by the base member for infusion of said material into the intervertebral space.