Push-in interbody spinal fusion implants for use with self-locking screws
An apparatus including an interbody spinal fusion implant having a leading end, a trailing end, and a length therebetween, and opposed upper and lower portions adapted to contact each of the adjacent vertebral bodies. Each of the upper and lower portions having at least one opening adapted to communicate with one each of the adjacent vertebral bodies and to communicate with one another to permit for the growth of bone from vertebral body to adjacent vertebral body through the implant. Each of the upper and lower portions has at least one screw hole passing therethrough proximate the trailing end. The apparatus further includes bone screws adapted for placement through the screw holes of the upper and lower portions and into each of the adjacent vertebral bodies adjacent the disc space to be fused and into which the implant is adapted to be positioned.
1. An interbody spinal fusion implant for surgical implantation at least in part within a disc space between two adjacent vertebral bodies in a segment of a human spine, said implant comprising:
a leading end for entry into the spine, a trailing end opposite said leading end, a length from said leading end to said trailing end, a maximum width perpendicular to the length, and upper and lower exterior surfaces for contacting each of the adjacent vertebral bodies when positioned therein, said implant having a vertical plane passing through said upper and lower surfaces and passing through said leading and trailing ends, the vertical plane bisecting the maximum width of said implant, said trailing end of said implant having a maximum height from said lower surface to said upper surface, the maximum height being perpendicular to both the length and the maximum width of said implant, the maximum height of said trailing end of said implant being adapted to fit into an implantation site created in the spine, each of said upper and lower surfaces having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said openings in said upper and lower surfaces being in communication with one another and adapted to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant, said trailing end having four bone screw receiving holes, each of said bone screw receiving holes having a central longitudinal axis passing through said trailing end and one of said upper and lower surfaces, each of said bone screw receiving holes having a diameter and being threaded to receive a complementary thread of a self-locking bone screw, two of said four bone screw receiving holes being on a left side of the vertical plane, another two of said four bone screw receiving holes being on a right side of the vertical plane, the central longitudinal axes of two of said four bone screw receiving holes closest to the vertical plane passing through one of said upper and lower surfaces of said implant so that respective bone screws inserted through said bone screw receiving holes closest to the vertical plane will both engage a first of the adjacent vertebral bodies, the central longitudinal axes of two of said four bone screw receiving holes furthest away from the vertical plane passing through the other of said upper and lower surfaces of said implant so that respective bone screws inserted through said bone screw receiving holes furthest away from the vertical plane will both engage a second of the adjacent vertebral bodies, said two of said four bone screw receiving holes closest to the vertical plane being separated by a distance less than the diameter of one of said two of said four bone screw receiving holes closest to the vertical plane.
2. The implant of claim 1 , wherein a part of said implant is a non-resorbable plastic.
3. The implant of claim 1 , wherein a part of said implant is titanium.
4. The implant of claim 1 , wherein upper and lower surfaces are generally parallel to each other.
5. The implant of claim 1 , wherein said trailing end is taller than said leading end.
6. The implant of claim 1 , wherein the maximum width of said implant is greater than the maximum height of said trailing end.
7. The implant of claim 1 , wherein each bone screw receiving hole has a perimeter at said trailing end, the perimeter of each of said bone screw receiving holes extending along a majority of the maximum height of said trailing end.
8. The implant of claim 1 , wherein said upper and lower surfaces comprise a plurality of surface projections.
9. The implant of claim 1 , in combination with a self-locking bone screw having a leading end with a tip, a trailing end with a head, and a shaft from said tip to said head, said shaft having a first thread, said head having a second thread with a pitch different from a pitch of said first thread, said second thread being configured to engage said thread of one of said bone screw receiving holes.
10. The implant of claim 9 , wherein said bone screw is self-tapping.
11. The implant of claim 9 , wherein said bone screw includes a cutting flute.
12. The implant of claim 11 , wherein said cutting flute is configured to interrupt at least two turns of said first thread.
13. The implant of claim 9 , wherein bone screw comprises titanium.
14. The implant of claim 9 , wherein said bone screw has a length in the range of 12 to 16 mm.
15. The implant of claim 9 , wherein said first thread of said bone screw has an outer locus that is generally cylindrical.
16. The implant of claim 9 , wherein said shaft of said bone screw has a root diameter that is generally cylindrical.
17. The implant of claim 1 , wherein the central longitudinal axis of each of said bone screw receiving holes is non-parallel to the vertical plane.
18. An interbody spinal fusion implant for surgical implantation at least in part within a disc space between two adjacent vertebral bodies in a segment of a human spine, said implant comprising:
a leading end for entry into the spine, a trailing end opposite said leading end, a length from said leading end to said trailing end, a maximum width perpendicular to the length, and upper and lower exterior surfaces for contacting each of the adjacent vertebral bodies when positioned therein, said trailing end of said implant having a maximum height from said lower surface to said upper surface, the maximum height being perpendicular to both the length and the width of said implant, the maximum height of said trailing end of said implant being adapted to fit into an implantation site created in the spine, said implant having a horizontal plane passing through said leading and trailing ends, the horizontal plane bisecting the maximum height of said trailing end, said implant having a vertical plane passing through said upper and lower surfaces and passing through said leading and trailing ends, the vertical plane bisecting the maximum width of said implant, each of said upper and lower surfaces having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said openings in said upper and lower surfaces being in communication with one another and adapted to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant, said trailing end having four bone screw receiving holes, said implant being configured so that the vertical plane does not pass through any bone screw receiving hole in said trailing end, each of said bone screw receiving holes having a central longitudinal axis passing through said trailing end and one of said upper and lower surfaces, each of said bone screw receiving holes being threaded to receive a complementary thread of a self-locking bone screw, said four bone screw receiving holes each having an exit at said trailing end, a portion of said exit of each of said four bone screw receiving holes intersecting the horizontal plane, said four bone screw receiving holes forming an inner pair of bone screw receiving holes and an outer pair of bone screw receiving holes, the central longitudinal axes of said inner pair of bone screw receiving holes passing through one of said upper and lower surfaces of said implant so that respective bone screws inserted through said inner pair of bone screw receiving holes will both engage a first of the adjacent vertebral bodies, the central longitudinal axes of said outer pair of bone screw receiving holes passing through the other of said upper and lower surfaces of said implant so that respective bone screws inserted through said outer pair of bone screw receiving holes will both engage a second of the adjacent vertebral bodies.
19. The implant of claim 18 , wherein a part of said implant is a non-resorbable plastic.
20. The implant of claim 18 , wherein a part of said implant is titanium.
21. The implant of claim 18 , wherein upper and lower surfaces are generally parallel to each other.
22. The implant of claim 18 , wherein said trailing end is taller than said leading end.
23. The implant of claim 18 , wherein the maximum width of said implant is greater than the maximum height of said trailing end.
24. The implant of claim 18 , wherein each bone screw receiving hole has a perimeter at said trailing end, the perimeter of each of said bone screw receiving holes extending along a majority of the maximum height of said trailing end.
25. The implant of claim 18 , in combination with a self-locking bone screw having a leading end with a tip, a trailing end with a head, and a shaft from said tip to said head, said shaft having a first thread, said head having a second thread with a pitch different from a pitch of said first thread, said second thread being configured to engage said thread of one of said bone screw receiving holes.
26. The implant of claim 25 , wherein said bone screw includes a cutting flute.
27. The implant of claim 26 , wherein said cutting flute is configured to interrupt at least two turns of said first thread.
28. The implant of claim 25 , wherein said bone screw has a length in the range of 12 to 16 mm.
29. The implant of claim 18 , wherein said implant includes a left side connecting said leading end to said trailing end, and a right side connecting said leading end to said trailing end, said leading end extending from said left side to said right side and through the vertical plane.
30. The implant of claim 18 , wherein said trailing end consists of only four bone screw receiving holes.