Spinal Interbody Implants

1 . A spinal interbody implant comprising:

an outer portion having a first porosity; and

an inner portion extending from a first end of the implant to a second end of the implant, the inner portion peripherally surrounded by the outer portion and having a plurality of channels extending therethrough and a second porosity greater than the first porosity,

wherein the outer portion defines a hollow space therewithin having a size greater than a size of a space defined by each of the plurality of channels, the hollow space at least partially enclosed on all sides by the outer portion.

2 . The spinal interbody implant of claim 1 , wherein the first end of the implant is a top of the implant and the second end of the implant is a bottom of the implant, the top and bottom of the implant configured to abut vertebral bodies when implanted.

3 . The spinal interbody implant of claim 1 , wherein an entire circumference of the inner portion is surrounded by the outer portion.

4 . The spinal interbody implant of claim 1 , wherein a top surface of the outer portion is coplanar with a top surface of the inner portion and wherein a bottom surface of the outer portion is coplanar with a bottom surface of the inner portion.

5 . The spinal interbody implant of claim 1 , wherein the outer portion defines a plurality of channels extending therethrough from a first end of the outer portion to a second opposing end of the outer portion.

6 . The spinal interbody implant of claim 1 , wherein each channel includes at least one strut at least partially disposed within the channel and extending a length equal to a length of the channel.

7 . The spinal interbody implant of claim 1 , wherein the hollow space circumferentially surrounds an entire circumference of the inner portion.

8 . The spinal interbody implant of claim 1 , wherein the hollow space is enclosed between a top surface of the outer portion, a bottom surface of the outer portion, an outer surface of the outer portion, and an inner surface of the outer portion.

9 . The spinal interbody implant of claim 1 , wherein the plurality of channels extend linearly through the inner portion.

10 . A spinal interbody implant comprising:

an outer portion forming a first part of a top surface of the implant;

an inner portion disposed within the outer portion, the inner portion forming a second part of the top surface of the implant; and

a first channel extending through the outer portion and the inner portion, a first end of the first channel being on a lateral surface of the implant and a second end of the first channel opposite the first end being on the top surface or a bottom surface of the implant,

wherein the inner portion is more porous than the outer portion.

11 . The spinal interbody implant of claim 10 , wherein the first end of the first channel is in the outer portion and the second end of the first channel is in the inner portion.

12 . The spinal interbody implant of claim 10 , wherein the inner portion includes an inner surface defining a central opening.

13 . The spinal interbody implant of claim 12 , further comprising a second channel that extends from a first end on the inner surface of the inner portion to a second end on the top surface or the bottom surface of the implant.

14 . The spinal interbody implant of claim 10 , wherein the first channel has a length that is less than half of a distance between the top surface of the implant and the bottom surface of the implant.

15 . The spinal interbody implant of claim 10 , wherein the outer portion and the inner portion are one of titanium or a titanium alloy.

16 . An implant comprising:

an outer shell including a first endplate surface and a second endplate surface, the first endplate surface and the second endplate surface being separated by a lateral wall of the outer shell;

a fill material disposed within the outer shell, the fill material including a first layer and a second layer enclosing the first layer, the first layer having a first porosity and the second layer having a second porosity less than the first porosity

a first plurality of channels extending through the outer shell and the fill material with opposite ends at an outer surface of the lateral wall, the first plurality of channels being at a first distance from the first endplate surface; and

a second plurality of channels each being at a second distance from the first endplate surface, the second distance being less than the first distance,

wherein the fill material is more porous than the outer shell.

17 . The spinal interbody implant of claim 16 , wherein the second layer of the fill material circumferentially surrounds an entirety of the first layer of the fill material, and wherein the outer shell circumferentially surrounds an entirety of the fill material.

18 . The spinal interbody implant of claim 17 , wherein the first porosity is between 55% and 65% and the second porosity is between 20% and 50%.

19 . The spinal interbody implant of claim 16 , wherein the second plurality of channels each has a length no greater than a thickness of the lateral wall.

20 . The spinal interbody implant of claim 16 , further comprising a plurality of teeth extending from the outer shell.