Implant with compliant layer

1. An intervertebral spacer comprising:

an upper layer having a first exterior surface and a first interior surface;

a lower layer having a second exterior surface and a second interior surface;

a non-planar compliant layer substantially disposed between the first interior surface of the upper layer and the second interior surface of the lower layer,

wherein the first interior surface of the upper layer and the second interior surface of the lower layer each have a predetermined complementary shape to receive the non-planar compliant layer,

wherein the non-planar compliant layer includes a u-shaped portion along a cross-section thereof, and a leading portion and a trailing portion on opposite sides of the u-shaped portion, the leading portion and the trailing portion each having a planar inclined surface having its highest location most proximate the u-shaped portion and its lowest location farthest from the u-shaped portion, the first interior surface and the second interior surface each defining a corresponding leading portion and a trailing portion;

wherein the upper layer and lower layer comprise a first biocompatible material, and

wherein the non-planar compliant layer comprises a second biocompatible material that is more yielding than the first biocompatible material;

wherein the u-shaped portion comprises at least one island portion that is disposed within a recessed area of the lower layer, wherein the first interior surface includes a complementary protrusion that is received within the at least one island portion.

2. The intervertebral spacer of claim 1 , wherein the non-planar compliant layer includes an other u-shaped portion along a cross-section thereof.

3. The intervertebral spacer of claim 1 , wherein the intervertebral spacer is one of an oval-shaped, kidney-shaped, rectangular or trapezoidal shaped.

4. The intervertebral spacer of claim 1 , wherein the intervertebral spacer comprises two sections for placement from a posterior side of a body.

5. The intervertebral spacer of claim 1 , wherein the non-planar compliant layer comprises one of polyurethane, silicone, co-polymers of polyurethane, co-polymers of silicone, polyolefin, a foamed material, a material that cures in situ or that hardens over time, and polymer fibers formed as a woven structure.

6. The intervertebral spacer of claim 1 , wherein the upper layer and lower layer comprise one of cobalt chrome, steel, titanium, titanium alloy, tantalum, zirconium, nitinol, alumina, zirconia, mixtures of alumina and zirconia, silicon nitride, Polyaryletherketone (PAEK), Polyether ether ketone (PEEK), polyether ketone ketone (PEKK), Poly Ether Ketone (PEK), polyether ketone ether ketone ketone (PEKEKK), Poly methyl methacrylate (PMMA), a carbon reinforced PAEK, or polyethylene.

7. An intervertebral spacer comprising:

an upper layer having a first exterior surface and a first interior surface;

a lower layer having a second exterior surface and a second interior surface;

a non-planar compliant layer substantially disposed between and engaging at least a portion of the upper layer and at least a portion of the lower layer, the non-planar compliant layer including a u-shaped portion along a cross-section thereof, and a leading portion and a trailing portion on opposite sides of the u-shaped portion, the leading portion and the trailing portion each having a planar inclined surface having its highest location most proximate the u-shaped portion and its lowest location farthest from the u-shaped portion, the upper layer and the lower layer each defining a corresponding leading and trailing portion;

wherein engagement of the non-planar compliant layer with the at least a portion of the upper layer and the at least a portion of the lower layer provides resistance to shear forces that act on the intervertebral spacer, and

wherein the upper layer and lower layer comprise a first biocompatible material, and

wherein the non-planar compliant layer comprises a second biocompatible material;

wherein the u-shaped portion comprises at least one island portion that is disposed within a recessed area of the lower layer, wherein the first interior surface includes a complementary protrusion that is received within the at least one island portion;

wherein the second biocompatible material is more yielding than the first biocompatible material.

8. The intervertebral spacer of claim 7 , wherein the upper layer, the non-planar compliant layer and the lower layer define a pre-assembled unit having a geometrical shape.

9. The intervertebral spacer of claim 8 , wherein the intervertebral spacer is one of an oval-shaped, kidney-shaped, rectangular or trapezoidal shaped.

10. The intervertebral spacer of claim 8 , wherein the intervertebral spacer comprises two sections for placement from a posterior side of a body.

11. The intervertebral spacer of claim 7 , wherein the non-planar compliant layer comprises one of polyurethane, silicone, co-polymers of polyurethane, co-polymers of silicone, polyolefin, a foamed material, a material that cures in situ or that hardens over time, and polymer fibers formed as a woven structure.

12. The intervertebral spacer of claim 7 , wherein the upper layer and lower layer comprise one of cobalt chrome, steel, titanium, titanium alloy, tantalum, zirconium, niobium, nitinol, alumina, zirconia, mixtures of alumina and zirconia, silicon nitride, Polyaryletherketone (PAEK), Polyether ether ketone (PEEK), polyether ketone ketone (PEKK), Poly Ether Ketone (PEK), polyether ketone ether ketone ketone (PEKEKK), Poly methyl methacrylate (PMMA), a carbon reinforced PAEK, or polyethylene.

13. A multilayer intervertebral spacer, comprising:

a lower layer having a first engagement region having a first exterior surface and a first interior surface;

an upper layer having a second engagement region having a second exterior surface and a second interior surface;

at least one intermediate compliant non-planar layer having a portion thereof extending outside a lateral plane of the intervertebral spacer in which the at least one intermediate non-planar layer is disposed, the at least one intermediate layer engaging the first engagement region and the second engagement region, the at least one intermediate compliant non-planar layer including a u-shaped portion along a cross-section thereof, and a leading portion and a trailing portion on opposite sides of the u-shaped portion, the leading portion and the trailing portion each having a planar inclined surface having its highest location most proximate the u-shaped portion and its highest location farthest from the u-shaped portion, the upper layer and the lower layer each defining a corresponding leading and trailing portion;

wherein the at least one intermediate non-planar layer comprises a biocompatible material that is more yielding than that of the lower layer and the upper layer;

wherein the u-shaped portion comprises at least one island portion that is disposed within a recessed area of the lower layer, wherein the first interior surface includes a complementary protrusion that is received within the at least one island portion.

14. The multilayer intervertebral spacer of claim 13 , wherein the intervertebral spacer is one of an oval-shaped, kidney-shaped, rectangular or trapezoidal shaped.

15. The multilayer intervertebral spacer of claim 13 , wherein the at least one intermediate non-planar compliant layer comprises one of polyurethane, silicone, co-polymers of polyurethane, co-polymers of silicone, polyolefin, a foamed material, a material that cures in situ or that hardens over time, and polymer fibers formed as a woven structure.

16. The multilayer intervertebral spacer of claim 13 , wherein the upper layer and lower layer comprise one of cobalt chrome, steel, titanium, titanium alloy, tantalum, zirconium, nitinol, alumina, zirconia, mixtures of alumina and zirconia, silicon nitride, Polyaryletherketone (PAEK), Polyether ether ketone (PEEK), polyether ketone ketone (PEKK), Poly Ether Ketone (PEK), polyether ketone ether ketone ketone (PEKEKK), Poly methyl methacrylate (PMMA), a carbon reinforced PAEK, or polyethylene.