POSTERIOR EXPANDABLE FUSION CAGE

• US 20020068976A1
• Filed: 12/04/2000
• Published: 06/06/2002
• Est. Priority Date: 12/04/2000
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Roger P. Jackson
• Inventors: Jackson, Roger P.
• Granted Patent: US 6,443,989 B1
• 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 2002/30507 using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30538 for adjusting angular orientation
• CPC Class Codes: A61F 2002/30556 for adjusting thickness
• 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 2002/30904 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 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 or distal 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 an anterior wedge portion that engages the anterior ends of the walls and forces the walls apart as the expansion member is screwed into the body. A surface engages the expansion member after expansion and supports the walls during usage. 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 head thereof.

Claims

1. A posterior 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 rear wall having a threaded bore, said upper and lower walls having a non-expanded configuration;

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

c) an elongate expansion member;

said expansion member being threaded and being operably threadedly received in said rear wall bore;

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

2. The device according to claim 1 wherein:

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

b) said wedge is cylindrical shaped and is coaxial with said axis of rotation.

3. The device according to claim 1 wherein:

a) said expansion member includes a support surface adjacent and anterior of said mating region.

4. The device according to claim 3 wherein:

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

including in a set a second expansion member such that said first and second expansion members have cylindrical 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 has a threaded region near a posterior end thereof that is screwable into a thread in said rear wall bore;

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

said head including said wedge in the shape of a cylinder;

said body including a supporting surface anterior of said mating region 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 engages said upper and lower wall wedge mating regions and vertically spreads the anterior ends of said upper and lower walls while said walls hinge at a posterior end thereof and, thereafter said support surface engages and supports anterior ends of 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 limit advancement of said expansion member into said body and to position said expansion member in said body.

7. The device according to claim 6 wherein:

a) said stop is adjacent and posterior to said threaded region of said expansion member and has a greater diameter than said threaded region.

8. The device according to claim 1 wherein:

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

9. 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.

10. 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.

11. The device according to claim 1 wherein:

a) said upper and lower walls each include an anterior pair of spaced feet that respectively engage and rest against feet of the opposite wall when in the non-expanded configuration.

12. The device according to claim 1 wherein:

a) when fully inverted, said expansion member extends longitudinally through said body from a posterior end thereof in said threaded bore to near an anterior end thereof.

15. The cage according to claim 14 wherein:

a) said kit includes a non-expansion plug.

16. The cage according to claim 15 wherein:

a) at least one of said non-expansion plug and expansion members includes a threaded region for being threaded into a bore in a rear wall of said cage and said threaded region includes a passageway therethrough to allow insertion of matrix material into said cage after installation of said one of said non-expansion plug and expansion members.

13. In an expandable posterior interbody fusion cage;

the improvement comprising;

a) said cage having a U-shaped body having upper and lower walls each with anterior mating regions near an anterior end thereof; and

b) an elongate expansion member that is threadedly received in said body;

said expansion member having a head with an anterior wedge for operably engaging said body mating regions and expanding an anterior end of said cage as said expansion member advances into said body.

14. In a posterior 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.