Implant having arcuate upper and lower bearing surfaces along a longitudinal axis

• US 20050038512A1
• Filed: 08/26/2004
• Published: 02/17/2005
• Est. Priority Date: 06/07/1995
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Michelson, Gary Karlin
• Granted Patent: US 7,789,914 B2
• Time in Patent Office: Days
• US Class Current: 623/17.110
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• 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 2/4611 of spinal prostheses
• 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 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30158 trapezoidal
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/3037 Translation along the common longitudinal axis, e.g. piston
• CPC Class Codes: A61F 2002/30398 Sliding
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30507 using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30556 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 2002/30599 : stackable
• CPC Class Codes: A61F 2002/30604 : modular
• 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 2002/30787 : inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/30789 : perpendicular with respect to each other
• CPC Class Codes: A61F 2002/30797 : internally-threaded
• CPC Class Codes: A61F 2002/30836 : knurled
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30843 : Pyramidally-shaped
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/3092 : having an open-celled or open-pored structure
• CPC Class Codes: A61F 2002/4485 : comprising three or more adjacent spinal implants
• CPC Class Codes: A61F 2002/449 : comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• CPC Class Codes: A61F 2002/4629 : connected to the endoprosthesis or implant via a threaded connection
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• 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 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0026 : trapezoidal
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• CPC Class Codes: A61F 2250/0063 : Nested prosthetic parts
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: Y10S 606/90 : Lumbar stabilizer
• CPC Class Codes: Y10S 606/907 : Composed of particular material or coated
• CPC Class Codes: Y10S 606/908 : Bioabsorbable material

Abstract

The present application is directed to interbody spinal fusion implants having a structural configuration that provides for the maintaining and creating of the normal anatomic angular relationship of two adjacent vertebrae of the spine to maintain and create spinal lordosis. The spinal fusion implants are sized to fit within the disc space created by the removal of disc material between two adjacent vertebrae and conform wholly or in part to the disc space created. The spinal fusion implants of the present invention have upper and lower surfaces that form a support structure for bearing against the end plates of the adjacent vertebrae. The upper and lower surfaces are disposed in a converging angular relationship to each other such that the implants have an overall “wedged-shape” in an elevational side view. The angular relationship of the upper and lower surfaces places and maintains the vertebrae adjacent to those surfaces in an angular relationship to each other, creating and maintaining the desired lordosis.

Claims

1. An implant for insertion between a first vertebra and a second vertebra, the first vertebra having a first cortical bone endplate and the second vertebra having a second cortical bone endplate, wherein the implant comprises:

a first terminal part defining a first bearing surface substantially planar and adapted to bear against the first cortical bone endplate and an opposite second bearing surface substantially planar and adapted to bear against the second cortical bone endplate;

a second terminal part opposite said first terminal part, said second terminal part defining a third bearing surface adapted to bear against the first cortical bone endplate, a fourth bearing surface adapted to bear against the second cortical bone endplate, and an insertion face extending arcuately from the third bearing surface to the fourth bearing surface, said third bearing surface and said fourth bearing surface include an anti-expulsion feature; and

an elongated body including a central portion extending from said first terminal part to said second terminal part, said body defining a longitudinal axis and having an upper bearing surface and a lower bearing surface, wherein the upper bearing surface and the lower bearing surface are arcuate along the longitudinal axis.

2. The implant of claim 1, wherein the body defines a cavity for receiving bone osteogenic material.

3. The implant of claim 2, wherein the upper bearing surface and the lower bearing surface each include at least one opening into the cavity and a continuous perimeter surface.

4. The implant of claim 1, wherein the first bearing surface and the second bearing surface include an anti-expulsion feature.

5. The implant of claim 4, wherein the anti-expulsion feature includes ridges transverse to the longitudinal axis.

6. The implant of claim 1, wherein the third and fourth bearing surfaces are curved.

7. The implant of claim 1, wherein the upper bearing surface and the lower bearing surface are adapted to engage a cancellous bone portion of the first and second vertebrae.

8. The implant of claim 1, wherein the upper bearing surface is configured to mate with the first cortical bone endplate and the lower bearing surface is configured to mate with the second cortical bone endplate.

9. An implant for insertion between a first vertebra and a second vertebra, the first vertebra having a generally vertically extending first peripheral wall and a first cortical bone endplate and the second vertebra having a generally vertically extending second peripheral wall and a second cortical bone endplate, wherein the implant comprises:

a first terminal part defining a first bearing surface adapted to bear against a portion of the cortical bone endplate proximate to the first peripheral wall and an opposite second bearing surface adapted to bear against a portion of the second cortical bone endplate proximate to the second peripheral wall;

an elongated body including a central part extending from said first terminal part, said central part defining a longitudinal axis and having an upper bearing surface and a lower bearing surface wherein the upper bearing surface and the lower bearing surface extend arcuately from the first terminal part in a direction substantially parallel to the longitudinal axis, terminating in a second terminal part opposite said first terminal part, said second terminal part including an anti-expulsion feature and having an insertion face extending from the upper bearing surface to the lower bearing surface wherein said insertion face consists of a curved surface, said curve extending from the upper bearing surface to the lower bearing surface.

10. The implant of claim 9, wherein the body defines a cavity for receiving bone osteogenic material.

11. The implant of claim 9, wherein the first bearing surface and the second bearing surface include at least one anti-expulsion feature.

12. The implant of claim 11, wherein the anti-expulsion feature includes a ridge transverse to the longitudinal axis.

13. The implant of claim 9, wherein the first bearing surface and the second bearing surface are substantially planar.

14. The implant of claim 9, wherein the second terminal part includes a third bearing surface provided to bear against a portion of the cortical bone endplate proximate to the first peripheral wall and an opposite fourth bearing surface adapted to bear against a portion of the second cortical bone endplate proximate to the second peripheral wall.

15. The implant of claim 14, wherein the third bearing surface and the fourth bearing, surface include anti-expulsion features.

16. The implant of claim 14, wherein the third and fourth bearing surface are curved.

17. The implant of claim 9, wherein the upper bearing surface and the lower bearing surface include openings into the cavity.

18. The implant of claim 10, wherein the upper bearing surface and the lower bearing surface are adapted to engage cancellous bone of the first and second vertebrae.