Intervertebral implant for transforaminal posterior lumbar interbody fusion procedure

• US 20030139813A1
• Filed: 11/13/2002
• Published: 07/24/2003
• Est. Priority Date: 05/03/2001
• Status: Active Grant

• Current Assignee: Depuy Synthes Products Incorporated (Johnson & Johnson)
• Original Assignee: Synthes USA LLC (Johnson & Johnson), Synthes AG Chur
• Inventors: Messerli, Dominique, Gerber, David, Paul, David, Kobayashi, Kenneth Isamu
• Granted Patent: US 6,974,480 B2
• Time in Patent Office: Days
• US Class Current: 623/17.11
• CPC Class Codes: A61B 17/1604 Chisels; Rongeurs; Punches; Stamps
• CPC Class Codes: A61B 17/1659 Surgical rasps, files, planes, or scrapers
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• 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 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2/4684 Trial or dummy 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 2002/3008 radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30383 made by laterally inserting a protrusion, e.g. a rib into a complementarily-shaped groove
• CPC Class Codes: A61F 2002/30492 using a locking pin
• 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 2002/30593 hollow
• CPC Class Codes: A61F 2002/30594 slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• CPC Class Codes: A61F 2002/30599 stackable
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30785 parallel
• CPC Class Codes: A61F 2002/30787 : inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/30797 : internally-threaded
• CPC Class Codes: A61F 2002/30843 : Pyramidally-shaped
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/30975 : made of two halves
• CPC Class Codes: A61F 2002/4628 : with linear motion along or rotating motion about an axis transverse to the instrument axis or to the implantation direction, e.g. clamping
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2230/0015 : Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2250/0006 : for adjusting angular orientation
• CPC Class Codes: A61F 2250/0063 : Nested prosthetic parts
• CPC Class Codes: A61F 2250/0098 : radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00359 : Bone or bony tissue

Abstract

An intervertebral implant for fusing vertebrae is disclosed. The implant has a body with curved, substantially parallel posterior and anterior faces separated by two narrow implant ends, superior and inferior faces having a plurality of undulating surfaces for contacting upper and lower vertebral endplates, and at least one depression in the anterior or posterior face for engagement by an insertion tool, at least two vertical through-channels extending through the implant from the superior face to the inferior face, a chamfer on the superior and inferior surfaces at one of the narrow implant ends, and a beveled edge along a perimeter of the superior and inferior faces. The arcuate implant configuration and the chamfers on the superior and inferior faces at the narrow end facilitate insertion of the implant from a transforaminal approach into a symmetric position about the midline of the spine so that a single implant provides balanced support to the spinal column. The implant may include radiopaque markers extending through the thickness of the implant to indicate the location and size of the implant. The implant may be formed of a plurality of interconnecting bodies assembled to form a single unit. An implantation kit and method are also disclosed.

Claims

1. An intervertebral implant for posterior insertion via a transforaminal window comprising:

curved, substantially parallel posterior and anterior faces, the posterior and anterior faces extending along a longitudinal axis of the implant;

a pair of convex narrow ends separating the posterior and anterior faces;

superior and inferior faces for contacting upper and lower vertebral endplates, the superior and inferior faces defining a thickness of the implant;

at least one depression in the anterior or posterior face for engagement by an insertion tool;

at least two vertical through-channels extending through the implant from the superior face to the inferior face, each vertical through-channel having a width and walls on posterior and anterior sides of the width; and

a chamfer on the superior and inferior faces at one of the convex narrow ends to facilitate implant insertion.

2. The implant of claim 1, wherein a first convex narrow end is configured and adapted to be inserted first into an affected disc space before a second convex narrow end, and the chamfer is at the first convex narrow end.

3. The implant of claim 2, further comprising a beveled edge along a perimeter of the superior and inferior faces.

4. The implant of claim 3, further comprising at least two anterior-posterior horizontal through-channels extending through the implant from the posterior face to the anterior face.

5. The implant of claim 4, further comprising at least one lateral horizontal through-channel extending through the implant from at least one of the convex narrows ends to an adjacent anterior-posterior horizontal through channel.

6. The implant of claim 3, further comprising a plurality of bone-engaging undulating surfaces on the superior and inferior faces.

7. The implant of claim 6, wherein the undulating surfaces are teeth.

8. The implant of claim 3, wherein the walls on the posterior and anterior sides of the width of the vertical through-channels have a thickness greater than the width of the vertical through channels.

9. The implant of claim 8, wherein the width of the vertical through-channels in the anterior-posterior direction is approximately 3.0 mm and the thickness of the walls on the posterior and anterior sides of the vertical through-channels is approximately 3.5 mm.

10. The implant of claim 3, wherein the superior and inferior faces are convex.

11. The implant of claim 10, wherein the thickness of the implant between the superior and inferior faces is greatest at a mid-section between the narrow ends of the implant and the thickness tapers toward the narrow ends.

12. The implant of claim 3, wherein the implant is formed of polyaryl ether ketone (PAEK).

13. The implant of claim 3, wherein the implant is formed of polyether ether ketone (PEEK), polyether ketone ketone (PEKK), or titanium

14. The implant of claim 1, further comprising one or more radiopaque markers extending substantially through the thickness of the implant.

15. The implant of claim 14, wherein the radiopaque markers indicate a size of the implant.

16. The implant of claim 1, wherein the implant is formed of a plurality of interconnecting bodies assembled to form a single unit.

17. The implant of claim 16, further comprising at least one pin extending through an opening in the plurality of bodies to hold the bodies together as a single unit.

18. The implant of claim 17, wherein the plurality of bodies have mating interlocking surfaces that aid in holding the bodies together as a single unit.

19. A kit for implanting an intervertebral implant into an affected disc space of a patient via a posterior approach through a transforaminal window comprising:

an implant having curved, substantially parallel posterior and anterior faces separated by a pair of convex narrow ends, superior and inferior faces for contacting upper and lower vertebral endplates, at least one depression in the anterior or posterior face for engagement by an insertion tool, at least two vertical through-channels extending through the implant from the superior face to the inferior face, each vertical through-channel having a width and adjacent walls on a posterior side of the vertical through-channel and an anterior side of the vertical through channel, and a chamfer on the superior and inferior faces at one of the convex narrow ends; and

an insertion tool for holding the implant during insertion,

wherein the arcuate implant configuration and the chamfer at the convex narrow end facilitate insertion of the implant via the transforaminal window.

20. The kit of claim 19, wherein the implant includes a first convex narrow end configured and adapted to be inserted first into an affected disc space before a second convex narrow end, and the chamfer is at the first convex narrow end.

21. The kit of claim 20, wherein the implant further comprises a beveled edge along a perimeter of the superior and inferior faces.

22. The kit of claim 21, wherein the implant includes at least two anterior-posterior horizontal through-channels extending through the implant from the posterior face to the anterior face.

23. The kit of claim 22, wherein the implant includes at least one lateral horizontal through-channel extending through the implant from at least one of the convex narrows ends to an adjacent anterior-posterior horizontal through channel.

24. The kit of claim 21, wherein the walls on the posterior and anterior sides of the width of the vertical through-channels of the implant have a thickness greater than the width of the vertical through channels.

25. The kit of claim 21, wherein the implant further comprises one or more radiopaque markers extending substantially through a thickness of the implant.

26. The kit of claim 25, wherein the radiopaque markers of the implant indicate a size of the implant.

27. The kit of claim 19, further comprising an angled impactor for properly positioning the implant within the affected disc space.

28. The kit of claim 19, wherein the insertion tool is angled to facilitate proper positioning of the implant within the affected disc space.

29. The kit of claim 19, further comprising at least one angled curette for removing disc material from the affected disc space.

30. The kit of claim 19, further comprising at least one trial-fit spacer for estimating the size of the implant to be inserted into the affected disc space.

31. The kit of claim 19, further comprising a guide to assist in positioning the implant behind the dura wherein the guide has a curved arm designed and configured to cooperate with the curved anterior face of the implant to facilitate proper positioning of the implant about the midline of the spine anterior to the dura or cauda equina.

32. A method for implanting an intervertebral implant into an affected disc space of a patient comprising:

creating a transforaminal window from the posterior side of the spine;

inserting bone graft material into the affected disc space, the disc space having an anterior edge and a posterior edge;

providing an implant having curved, substantially parallel posterior and anterior faces separated by a pair of convex narrow ends, superior and inferior faces for contacting upper and lower vertebral endplates, at least one depression in the anterior or posterior face for engagement by an insertion tool, at least two vertical through-channels extending through the body from the superior face to the inferior face, each vertical through-channel having a width and walls on walls on posterior and anterior sides of the width, and a chamfer on the superior and inferior faces at one of the convex narrow ends;

adding bone graft material to the vertical through-channels of the implant;

inserting a first convex narrow end of the implant into the affected disc space via the transforaminal window with an insertion tool;

guiding the implant around the dura or cauda equina through the transforaminal window using the insertion tool; and

seating the implant in a portion of the disc space closer to the anterior edge of the disc space than the posterior edge of the disc space.

33. The method of claim 32, wherein the chamfer on the superior and inferior faces of the implant is at the first convex narrow end.

34. The method of claim 33, wherein the implant further comprises a beveled edge along a perimeter of the superior and inferior faces.

35. The method of claim 34, wherein the implant has at least two anterior-posterior horizontal through-channels extending through the body from the posterior face to the anterior face and the method further comprises adding bone graft material to the anterior-posterior horizontal through-channels of the implant.

36. The method of claim 35, wherein the implant includes at least one lateral horizontal through-channel extending through the implant from at least one of the convex narrows ends to an adjacent anterior-posterior horizontal through channel.

37. The method of claim 34, wherein the walls on the posterior and anterior sides of the width of the vertical through-channels of the implant have a thickness greater than the width of the vertical through channels.

38. The method of claim 32, further comprising positioning the implant symmetrically about the midline of the spine.

39. The method of claim 32, wherein the insertion tool is angled to facilitate insertion of the implant via the transforaminal window.

40. The method of claim 32, further comprising impacting the implant with an impactor tool to properly position the implant within the affected disc space.

41. The method of claim 40, wherein the impactor tool is angled to facilitate proper positioning of the implant within the affected disc space.

42. The method of claim of 32, further comprising using a curved guide to assist in locating the implant in the affected disc space anterior to the dura or cauda equina.

43. The method of claim 32, wherein the inserting and guiding steps further comprise, rotating the implant so that the anterior face of the implant faces anteriorly and moving the implant around the dura or cauda equina.

44. An intervertebral implant for maintaining a desired space between vertebral bodies comprising:

a convex anterior face, the anterior face shaped to match the shape of the anterior perimeter of the vertebrae;

a concave posterior face;

arcuate convex end faces connected between the posterior and anterior faces, the posterior and anterior faces being at least double the length of the end faces and the posterior and anterior faces each having at least one depression extending from one of the end faces toward the other end face configured and adapted to be engageable with an insertion tool; and

superior and inferior faces for contacting upper and lower vertebral end plates, the superior and inferior faces having teeth and defining a thickness of the implant,

at least two vertical through-channels extending through the body from the superior face to the inferior face, each vertical through-channel having a width and walls on anterior and posterior sides of the width, the walls on the anterior and posterior sides of the width of the vertical through-channels having a thickness greater than the width of the vertical through channels;

at least two anterior-posterior horizontal through-channels extending through the body from the posterior face to the anterior face;

a chamfer on the superior and inferior faces at one of the arcuate end faces;

a beveled edge along a perimeter of the superior and inferior faces; and

at least one radiopaque pin extending substantially through the thickness of the implant,

wherein the implant is configured and adapted to be inserted into the disc space through a transforaminal window formed in the posterior of the spinal column, the disc space having an anterior edge and a posterior edge, and positioned anterior to the dura or cauda equina between vertebral end plates closer to the anterior edge of the disc space than the posterior edge of the disc space to maintain balanced support about the midline of the spine.

45. The implant of claim 44, further comprising at least one lateral horizontal through-channel extending through the implant from at least one of the arcuate convex ends to an adjacent anterior-posterior horizontal through channel.