Intervertebral spacers with side wall accessible interior cavity

1. An interbody fusion spacer, comprising:

an elongated body having a first end wall, an opposite second end wall, and a side wall extending between said first and second end walls, said elongated body defining an outer surface and an interior chamber for receiving an osteogenic material, said side wall defining a main side wall opening in communication with said interior chamber, said main side wall opening sized and configured for loading said osteogenic material into said interior chamber, said side wall defining a plurality of secondary side wall openings extending from said outer surface and in communication with said interior chamber for bone ingrowth into said interior chamber;

wherein said elongated body comprises a generally cylindrical body having a length extending from said first end wall to said second end wall and wherein said generally cylindrical body is externally threaded along said length;

wherein said outer surface of said generally cylindrical body comprises an outer circumferential surface defining an outer circumference, said outer circumferential surface defining an external outer surface profile in the shape of an arc of a circle extending no less than 180 degrees about said outer circumference and extending along said length of said body from said first end wall to said second end wall; and

wherein said main side wall opening extends over at least about 20% of the outer circumference of said body and extends along at least about 50% of said length of said body to provide said main side wall opening with a size sufficient for loading said osteogenic material into said interior chamber.

2. The interbody fusion spacer of claim 1 , wherein said main side wall opening extends along at least about 80% of the overall length of said body.

3. The interbody fusion spacer of claim 2 , wherein said main side wall opening extends substantially entirely along the overall length of said body.

4. The interbody fusion spacer of claim 1 , wherein said main side wall opening extends along at least about 40% of the outer circumference of said body.

5. The interbody fusion spacer of claim 1 , wherein said plurality of secondary bone ingrowth openings are sized smaller than said main side wall opening.

6. The interbody fusion spacer of claim 1 , wherein at least one of said first and second end walls defines a tool engaging hole for receiving a driving tool for implanting the interbody fusion spacer into an intervertebral space.

7. The interbody fusion spacer of claim 1 , wherein said side wall defines a side wall discontinuity, said main side wall opening defined in said side wall discontinuity.

8. The interbody fusion spacer of claim 1 , wherein each of said first and second end walls includes an end wall discontinuity defining a concave surface sized and configured for nesting with an adjacent interbody fusion spacer.

9. The interbody fusion spacer of claim 1 , wherein said side wall of said elongated body defines a discontinuity circumferentially interrupting said outer circumferential surface, said discontinuity defining said main side wall opening.

10. The interbody fusion spacer of claim 9 , wherein said discontinuity extends across said first and second end walls.

11. The interbody fusion spacer of claim 10 , wherein said discontinuity has a concave configuration.

12. The interbody fusion spacer of claim 9 , wherein said plurality of secondary bone ingrowth openings are sized smaller than said main side wall opening.

13. The interbody fusion spacer of claim 1 , wherein said external outer surface profile of said outer circumferential surface extends no less than 216 degrees about said outer circumference.

14. An interbody fusion spacer, comprising:

a generally cylindrical elongated body having opposite first and second end walls and a side wall having a length extending from said first end wall to said second end wall and wherein said generally cylindrical elongated body is externally threaded along said length, said first and second end walls integral with said side wall to provide said elongated body as a unitary, single-piece structure, said elongated body defining an outer surface and an interior chamber for receiving an osteogenic material, said side wall defining a main side wall opening in communication with said interior chamber, said side wall defining a plurality of secondary side wall openings sized smaller than said main side wall opening and extending from said outer surface and in communication with said interior chamber to provide for bone ingrowth into said interior chamber; and

wherein said outer surface of said generally cylindrical elongated body comprises an outer circumferential surface defining an outer circumference, said outer circumferential surface defining an external outer surface profile in the shape of an arc of a circle extending no less than 180 degrees about said outer circumference and extending along said length of said body from said first end wall to said second end wall; and

wherein said main side wall opening is sized to extend over at least about 20% of said outer circumference of said body and along at least about 50% of said length of said elongated body to provide said side wall opening with a size sufficient for loading said osteogenic material into said interior chamber.

15. The interbody fusion spacer of claim 14 , wherein said main side wall opening extends substantially entirely along the overall length of said elongated body.

16. The interbody fusion spacer of claim 14 , wherein said main side wall opening extends along at least about 40% of the outer circumference of said elongated body.

17. The interbody fusion spacer of claim 14 , wherein said side wall of said elongated body defines a discontinuity circumferentially interrupting said outer circumference, said discontinuity defining said main side wall opening.

18. The interbody fusion spacer of claim 17 , wherein said discontinuity extends across said first and second end walls; and

wherein said discontinuity has a concave configuration.

19. The interbody fusion spacer of claim 14 , wherein said external outer surface profile of said outer circumferential surface extends no less than 216 degrees about said outer circumference.

20. An interbody fusion implant system, comprising:

a first interbody fusion spacer including an elongated body having a first end wall, an opposite second end wall, and a side wall extending between said first and second end walls, said elongated body defining an outer surface and an interior chamber for receiving an osteogenic material, said side wall defining a main side wall opening in communication with said interior chamber, said main side wall opening sized and configured for loading said osteogenic material into said interior chamber, said side wall defining a plurality of secondary side wall openings extending from said outer surface and in communication with said interior chamber for bone ingrowth into said interior chamber;

wherein said elongated body comprises a generally cylindrical body;

wherein said outer surface of said generally cylindrical body comprises an outer circumferential surface defining an outer circumference; and

wherein said main side wall opening extends over at least about 20% of the outer circumference of said body and extends along at least about 50% of an overall length of said body to provide said main side wall opening with a size sufficient for loading said osteogenic material into said interior chamber; and

a second interbody fusion spacer having a second elongated body, said second elongated body having a third end wall, a fourth end wall, a second side wall extending between said third and fourth end walls, said second interbody fusion spacer nested within a concave discontinuity in said first interbody fusion spacer.

21. The interbody fusion implant system of claim 20 , wherein said second elongated body of said second interbody fusion spacer is generally cylindrical in shape and has an outer circumferential surface defining an outer circumference; and

wherein said second elongated body includes a main side wall opening in communication with an interior chamber, said main side wall opening in said second elongated body is sized to extend over at least about 20% of the outer circumference of said second elongated body and along at least about 50% of an overall length of said second elongated body to provide said main side wall opening in said second elongated body with a size sufficient for loading said osteogenic material into said interior chamber of said second elongated body.

22. The interbody fusion implant system of claim 21 , wherein said main side wall opening in said second elongated body is sized to extend substantially entirely along the overall length of said second elongated body.

23. The interbody fusion implant system of claim 21 , wherein said main side wall opening in said second elongated body is sized to extend along at least about 40% of the outer circumference of said second elongated body.

24. The interbody fusion implant system of claim 20 , wherein said first and second end walls are non-removably fixed to said side wall; and

wherein said third and fourth end walls are non-removably fixed to said second side wall.

25. The interbody fusion implant system of claim 20 , wherein said first and second end walls are integral with said side wall to provide said elongated body as a first unitary, single-piece structure; and

wherein said third and fourth end walls integral with said second side wall to provide said second elongated body as a second unitary, single-piece structure.