Spinal interbody cage comprising a bulk interbody cage, a top face, a bottom face, pillars, and slots

1. A spinal interbody cage comprising:

(a) a bulk interbody cage;

(b) a top face being a top exterior surface of the bulk interbody cage and having a top central opening;

(c) a bottom face being a bottom exterior surface of the bulk interbody cage and having a bottom central opening;

(d) pillars for contacting vertebral bodies, the pillars being distributed on the top face, around the top central opening, and extending distally therefrom, and being distributed on the bottom face, around the bottom central opening, and extending distally therefrom, across areas of at least 25 mm 2 of each of the top face and the bottom face, respectively, each pillar being integral to the bulk interbody cage, having a distal end, having a transverse area of (100×100) to (2,000×2,000) μm 2 , and having a height of 100 to 2,500 μm; and

(e) slots to be occupied by bone of the vertebral bodies and/or by bone of a bone graft, the slots being defined by the pillars, the slots intersecting between the pillars such that each of the slots intersects at least one of the other slots, and each slot having a width of 100 to 2,500 μm as measured along the shortest distance between adjacent pillars; wherein:

the spinal interbody cage has a Young's modulus of elasticity of at least 3 GPa, and has a ratio of (i) the sum of the volumes of the slots to (ii) the sum of the volumes of the pillars and the volumes of the slots of 0.40:1 to 0.90:1; and

each pillar has at least two adjacent lateral sides that face adjacent pillars.

2. The spinal interbody cage of claim 1 , wherein the spinal interbody cage is made of one or more materials selected from implantable-grade polyaryletherketone that is essentially unfilled, implantable-grade polyetheretherketone, implantable-grade polyetherketoneketone, titanium, stainless steel, cobalt-chromium alloy, titanium alloy, Ti-6Al-4V titanium alloy, Ti-6Al-7Nb titanium alloy, ceramic material, silicon nitride (Si3N4), implantable-grade composite material, implantable-grade polyaryletherketone with filler, implantable-grade polyetheretherketone with filler, implantable-grade polyetheretherketone with carbon fiber, or implantable-grade polyetheretherketone with hydroxyapatite.

3. The spinal interbody cage of claim 1 , wherein the spinal interbody cage is made of one or more other hard tissues selected from human hard tissue, animal hard tissue, autologous hard tissue, allogenic hard tissue, xenogeneic hard tissue, human cartilage, animal cartilage, human bone, animal bone, cadaver bone, or cortical allograft.

4. The spinal interbody cage of claim 1 , wherein the spinal interbody cage has a parallel profile.

5. The spinal interbody cage of claim 1 , wherein the spinal interbody cage has a lordotic profile.

6. The spinal interbody cage of claim 1 , wherein the spinal interbody cage has a domed profile.

7. The spinal interbody cage of claim 1 , wherein the transverse area of each pillar is (250×250)μm 2 to (1,000×1,000)μm 2 .

8. The spinal interbody cage of claim 1 , wherein the height of each pillar is 300 to 1,000 μm.

9. The spinal interbody cage of claim 1 , wherein the width of each slot is 150 to 1,000 μm.

10. The spinal interbody cage of claim 1 , wherein the bulk interbody cage is non-porous.

11. The spinal interbody cage of claim 1 , wherein the pillars are non-porous.

12. The spinal interbody cage of claim 1 , wherein:

one or more pillars have dimensions that differ from those of other pillars, such that the transverse areas and/or heights, and thus volumes, of the one or more pillars differ from those of the other pillars; and

the spinal interbody cage provides an endplate profile based on the heights of the one or more pillars differing from those of the other pillars, and the spinal interbody cage having a parallel height.

13. The spinal interbody cage of claim 1 , wherein the pillars are distributed and dimensioned to provide immediate micro-subsidence following implantation in a patient, between adjacent vertebral bodies, thereby providing post-operative interdigitated fixation and stability.

14. The spinal interbody cage of claim 1 , wherein the spinal interbody cage comprises at least one lateral exterior surface comprising lateral exterior surface pillars extending therefrom.

15. The spinal interbody cage of claim 1 , wherein the spinal interbody cage comprises at least one interior surface comprising interior surface pillars extending therefrom.

16. The spinal interbody cage of claim 15 , wherein one or more of the interior surface pillars have heights that differ from those of other interior surface pillars.

17. The spinal interbody cage of claim 1 , wherein the pillars comprise, at their distal ends, a roughened surface.

18. The spinal interbody cage of claim 1 , wherein the transverse area of one or more of the pillars increases distally.

19. The spinal interbody cage of claim 1 , wherein the transverse area of one or more of the pillars is substantially constant along the vertical axis along which the one or more pillars extend distally.

20. The spinal interbody cage of claim 1 , wherein the spinal interbody cage is selected from the group consisting of an anterior lumbar interbody fusion (ALIF) spinal interbody cage, a posterior lumbar interbody fusion (PLIF) spinal interbody cage, a lateral spinal interbody cage, a direct lateral interbody fusion (DLIF) spinal interbody cage, a transforaminal lumbar interbody fusion (TLIF) spinal interbody cage, an extreme lateral interbody fusion (XLIF) spinal interbody cage, and a cervical spinal interbody cage.