Articulated expandable spinal fusion cage system

• US 6,454,807 B1
• Filed: 11/30/2000
• Issued: 09/24/2002
• Est. Priority Date: 11/30/2000
• Status: Expired due to Fees

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Roger P. Jackson
• Inventors: Jackson, Roger P.
• Primary Examiner(s): Willse, David H.
• Assistant Examiner(s): GHERBI, SUZETTE JAIME J
• Application Number:
  US09/726,724
• Time in Patent Office: 663 Days
• Field of Search: 623/17.11, 623/17.15, 623/17.16
• US Class Current: 623/17.15
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• 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 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• 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 2002/30362 with possibility of relative movement between the protrusion and the recess
• CPC Class Codes: A61F 2002/30392 Rotation
• CPC Class Codes: A61F 2002/30507 using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30517 using a locking plate
• CPC Class Codes: A61F 2002/30538 for adjusting angular orientation
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30777 Oblong apertures
• CPC Class Codes: A61F 2002/30904 serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/448 comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2250/0006 for adjusting angular orientation
• CPC Class Codes: A61F 2310/00017 Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00131 Tantalum or Ta-based alloys

Abstract

An apparatus and method for implanting an articulated spinal fusion cage into the intervertebral space and adjusting the cage in situ to support the adjacent vertebrae in a normal curved alignment. The invention provides a greatly improved modular cage system having a base unit with a pair of sockets for receiving the ends of a pair of legs. The sockets permit pivotal movement of the legs about a posterior fulcrum from a closed, parallel insertion position to an anteriorly open, wedge-shaped orientation. The base has a threaded bore for receiving a driver, which is operable to urge the anterior ends of the legs apart as well as to support the front of the installed fusion cage. Interchangeable drivers are provided having various sized tips. The interior end surface of each leg unit includes a driver-receiving groove for providing torsional stability. Alternatively, a pair of pins and bores are provided on the inner surfaces of the opposed ends for receiving a driver tip. In certain embodiments the base is of integral construction with one of the legs, and includes a socket for receiving a pivot end of the second leg.

Claims

1. An apparatus for positioning between adjacent vertebrae and comprising:

a) a fusion cage having a first leg and a second leg, each leg having a first end, a second end and a support surface therebetween, said first ends being expandably coupled, said cage being implantable between adjacent vertebrae with said support surfaces of said legs engaging said vertebrae;

b) said second leg including a bore and a socket for receiving said first leg second end and permitting pivotal movement within said socket; and

c) a driver received within said bore and operable for urging said first ends apart and pivoting said second end for moving said first support surface of said fusion cage to form a selected angle.

2. The apparatus according to claim 1, wherein:

a) said first end of said first leg includes a pair of spaced pins;

b) said first end of said second leg includes a pair of spaced bores for receiving said pins; and

c) said driver is received between said pins when said first ends are urged apart.

3. The apparatus according to claim 1, wherein:

a) said first ends of said first and second legs include opposed bearing surfaces; and

b) said bearing surfaces each include an axial groove for receiving said driver when said first ends are urged apart.

4. The apparatus according to claim 1, wherein:

a) said bore and said driver are threaded for mating reception of said driver within said bore.

5. The apparatus according to claim 1, wherein:

a) said driver is selected from a plurality of drivers; and

b) each driver includes a tip sized to form said apparatus into a different predetermined angle.

6. An apparatus for positioning between adjacent vertebrae and comprising:

a) a fusion cage having a pair of legs, each leg having a first end, a second end and a support surface therebetween, said first ends being expandably coupled, said cage being implantable between adjacent vertebrae with said support surfaces of said legs engaging said vertebrae;

b) a base having a threaded bore and a pair of sockets for receiving said leg ends and permitting pivotal movement within said sockets; and

c) a driver received within said bore and operable for urging said first ends apart and pivoting said second ends for moving said support surfaces of said fusion cage to form a selected angle.

7. The apparatus according to claim 6, wherein:

a) said first end of one of said legs includes a pair of spaced pins;

b) said first end of the other of said legs includes a pair of spaced bores for receiving said pins; and

c) said driver is received between said pins when said first ends are urged apart.

8. The apparatus according to claim 6, wherein:

a) said first ends of said legs each include opposed bearing surfaces; and

b) said bearing surfaces each include an axial groove for receiving said driver when said first ends are urged apart.

9. The apparatus according to claim 6, wherein:

a) said bore and said fastener are threaded for mating reception of said fastener within said bore.

10. The apparatus according to claim 6, wherein:

a) said driver is selected from a plurality of drivers; and

b) each driver includes a tip sized to form said apparatus into a different predetermined angle.

11. An apparatus for positioning between adjacent vertebrae and comprising:

a) a pair of fusion cages for implanting in side-by-side relationship between a pair of adjacent vertebrae;

b) each fusion cage having a pair of legs, each leg having a first end, a second end and a support surface therebetween, said first ends being expandably coupled;

c) each fusion cage having a base with a threaded bore and a pair of sockets for receiving said leg ends and permitting pivotal movement with said sockets; and

d) a threaded driver received within each of said bores and operable for urging said first ends apart and moving said support surfaces of said fusion cages to form a selected angle.

12. The apparatus according to claim 11, wherein:

a) said first end of each of said first legs includes a pair of spaced pins;

b) said first end of said second leg includes a pair of spaced bores for receiving said pins; and

c) said driver is received between said pins when said first ends are urged apart.

13. The apparatus according to claim 11, wherein:

a) said first ends of said first and second legs include opposed bearing surfaces; and

b) said bearing surfaces each include an axial groove for receiving said driver when said first ends are urged apart.

14. The apparatus according to claim 11, wherein:

a) each said driver is selected from a plurality of drivers; and

b) each driver includes a tip sized to form said fusion cage into a different predetermined angle.

15. A method of positioning and stabilizing adjacent vertebrae comprising the steps of:

a) providing a fusion cage having a pair of pivotally connected legs which can be selectively anteriorly expanded by relative pivoting of said legs to form a wedge;

b) implanting said fusion cage between a pair of adjacent vertebrae such that said legs respectively engage said adjacent vertebrae;

c) providing a threaded driver adapted for expanding the anterior portion of said cage to a predetermined angle by engagement of said driver with said legs; and

d) coupling said driver with said fusion cage and expanding said fusion cage to a predetermined angle to cause alignment of the adjacent vertebrae.

16. A method of positioning and stabilizing adjacent vertebrae comprising the steps of:

a) providing a fusion cage which can be selectively anteriorly expanded to form a wedge;

b) implanting said fusion cage between a pair of adjacent vertebrae;

c) providing a threaded driver adapted for expanding the anterior portion of said implant to a predetermined angle;

d) coupling said driver with said fusion cage and expanding said fusion cage to a predetermined angle to cause alignment of the adjacent vertebrae; and

e) wherein the step of providing a driver includes the step of providing a plurality of drivers of various sizes.

17. A method of positioning and stabilizing adjacent vertebrae comprising the steps of:

a) providing a fusion cage which can be selectively anteriorly expanded to form a wedge;

b) implanting said fusion cage between a pair of adjacent vertebrae;

c) providing a plurality of threaded drivers of various sizes, each adapted for expanding the anterior portion of said implant to a predetermined angle;

d) selecting the smallest driver;

e) coupling said driver with said fusion cage and anteriorly expanding said fusion cage; and

f) removing said driver and repeating steps (d) through (f) until said fusion cage is anteriorly expanded to a predetermined angle to cause alignment of the adjacent vertebrae.

18. A spinal fusion cage comprising:

a) a base having an opening therethrough;

b) a first leg and a second leg, each leg having a first end and a second end, said first leg pivotally connected at said first end to said base such that said second end of said first leg is pivotal toward and away from said second end of said second leg;

c) a plurality of drivers, each having a tip selectively insertable through said opening in said base such that said tip engages inwardly facing surfaces of said first and second legs proximate said second ends thereof to pivot said first leg relative to said second leg to a selected angle;

each of said plurality of drivers having a tip of a different size to vary the selected angle to which said first leg is pivoted relative to said second leg when said respective driver is inserted therebetween.

19. The spinal fusion cage as in claim 18 wherein:

a) said second leg is pivotally connected at said first end to said base.

20. The spinal fusion cage as in claim 18, wherein:

a) said opening through said base is threaded; and

b) each of said drivers includes a threaded shank which is removably securable within said threaded opening in said base.