Anterior variable expandable fusion cage

• US 20020068977A1
• Filed: 12/05/2000
• Published: 06/06/2002
• Est. Priority Date: 12/05/2000
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Roger P. Jackson
• Inventors: Jackson, Roger P.
• Granted Patent: US 6,773,460 B2
• Time in Patent Office: Days
• 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 2/442 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 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• 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 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/30266 wedge-shaped parallelepipeds
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• 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 2002/30556 for adjusting thickness
• CPC Class Codes: A61F 2002/30579 with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30616 Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30774 internally-threaded
• CPC Class Codes: A61F 2002/30777 Oblong apertures
• CPC Class Codes: A61F 2002/30785 parallel
• CPC Class Codes: A61F 2002/30789 : perpendicular with respect to each other
• CPC Class Codes: A61F 2002/3079 : Stepped or enlarged apertures, e.g. having discrete diameter changes
• 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 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0006 : for adjusting angular orientation
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• 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

Abstract

An interbody device for use between a pair of adjacent vertebrae includes a body and at least one expansion member. The body has upper and lower walls that are joined by a rear wall that functions as a spring hinge. The walls have anterior ends that are supported in a non-expanded configuration by spaced feet that project out from the walls. The expansion member is elongate and has a threaded portion that is threadably received in the rear wall. Each expansion member also includes a head having a wedge portion that engages the anterior ends of the walls and forces the walls apart as the expansion member is screwed into the body. Preferably, the expansion member is only one of a plurality of expansion members found in a kit which vary with respect to the diameter of the expansion member head. Further, a support and connecting plate is preferably utilized subsequent to installation of the devices between vertebrae to connect the connected pair of the devices.

Claims

1. An anterior interbody device that is anteriorly variably expandable;

said device comprising;

a) a U-shaped body having an upper wall and a bottom wall hingeably joined by rear wall;

said body having a threaded bore, said upper and lower walls having a non-spaced configuration wherein anterior ends of said upper and lower walls are in close proximity to each other;

b) said upper and lower walls each having an anterior wedge mating receiver that face each other;

c) an elongate expansion member;

said expansion member being threaded and being threadedly received in said body bore;

d) said expansion member having an anterior wedge surface that is sized, shaped and positioned to engage said upper and lower anterior wedge mating receivers as said expansion member is threadedly advanced into said body bore, such that anterior ends of upper and lower walls are placed in a spaced configuration wherein said upper and lower walls become spaced greater than said non-spaced configuration.

2. The device according to claim 1 wherein:

a) said expansion member has an axis of rotation; and

b) said wedge surface has a truncated coaxial shape and is coaxial with said axis of rotation.

3. The device according to claim 1 wherein:

a) said expansion member includes a support surface anterior of said wedge surface; and

b) said support surface being cylindrical in shape.

4. The device according to claim 3 wherein:

a) said expansion member is a first expansion member; and

including in a second expansion member such that said first and second expansion members have support surfaces of different diameters so that said first and second expansion members can be selectively individually used with said body to produce different degrees of expansion of the anterior end of said body.

5. The device according to claim 1 wherein:

a) said expansion member has an axis of rotation;

b) said expansion member having a threaded region near a posterior end thereof that is mateable with said body bore;

c) said expansion member having a head near an anterior end thereof;

said head including said wedge surface in the shape of a truncated cone;

said head including a cylindrical supporting surface anterior of said wedge surface that is sized, shaped and positioned to engage and support said upper and lower walls when said expansion member is fully inserted into said body;

so that as said expansion member is threadedly advanced into said body, said wedge surface engages said upper and lower wall wedge mating receivers and spreads the anterior ends of said upper and lower walls while hinging at a posterior end of said wall and, thereafter said support surface engages and supports said upper and lower walls in a preselected anterior spaced configuration.

6. The device according to claim 5 wherein:

a) said expansion member includes a stop located to position said expansion member in said body.

7. The device according to claim 6 wherein:

a) said stop is a region along said expansion member anterior of said threaded region and having a greater diameter than said threaded region.

8. The device according to claim 1 wherein:

a) said device is a first device; and

including

b) a second device; and

c) a connector for joining said first and second devices in close proximity to one another during use.

9. The device according to claim 8 wherein:

a) said connector is a plate sized and shaped to engage anterior portions of vertebrae between which the device is located during use to provide additional support to said vertebrae.

10. The device according to claim 1 wherein:

a) said expansion member is a first expansion member and including a second expansion member;

said body bore being a first bore and including a second bore spaced sideways with respect to said first bore;

said first and second expansion members being used together to expand an anterior end of said device.

11. The device according to claim 1 wherein:

a) said body is generally rectangular in cross-section.

12. The device according to claim 1 wherein:

a) said body is generally cylindrical in cross-section.

13. The device according to claim 1 wherein:

a) said upper and lower walls each include a window positioned to allow growth of bone therethrough during usage.

14. The device according to claim 1 wherein:

a) said upper and lower walls have anterior surfaces that engage when in a non-expanded configuration such that said device is adapted to be utilized alternatively as an expanded or non-expanded fusion cage.

15. The device according to claim 1 wherein:

a) said upper and lower walls each include an anterior pair of spaced feet that respectively engage feet of the opposite wall when in non-expanded configuration and which define an aperture therebetween for receiving said expansion member into said body.

16. The device according to claim 15 wherein:

a) said threaded bore is located in said device and during use of said expansion rear wall member;

said expansion member extends longitudinally through said body from anterior end thereof into said threaded bore.

17. The device according to claim 1 wherein:

a) said wedge mating receiver is an edge that is positioned perpendicular to and spaced from an axis or rotation of said expansion member.

18. In an expandable anterior interbody fusion cage;

the improvement comprising;

a) said cage having a U-shaped body having upper and lower walls each with anterior wedge mating receivers; and

b) an elongate expansion member that is threadedly received in said body and which has a head with an anterior wedge shaped surface for operably engaging said body wedge mating receivers and expanding an anterior end of said cage as said expansion member advances into said body.

19. In an expandable fusion cage;

the improvement comprising;

a) an expansion kit including at least a pair of interchangeable expansion members;

each of said expansion members being cooperatively mateable with said cage to provide a different degree of anterior expansion of said cage.