Piezoelectric spinal implant assembly having endplates with non-planar surfaces

A kit for a spinal implant assembly comprising:

• a first endplate having a first non-planar inner surface;
• a second endplate having a second non-planar inner surface;
• at least one fastener to attach the first endplate and the second endplate to one another;
• and
• a layer including a piezoelectric material (piezoelectric layer), wherein the piezoelectric layer is configured to have, in the spinal implant assembly, a non-planar upper surface facing toward the first non-planar inner surface and a non-planar lower surface facing toward the second non-planar inner surface, and wherein the first non-planar inner surface and the second non-planar inner surface are configured to define, in the spinal implant assembly, a vertically biased interface.

A method to make a kit for a spinal implant assembly, the method comprising:

• providing a first endplate having a first non-planar inner surface;
• providing a second endplate having a second non-planar inner surface;
• providing at least one fastener to attach the first endplate and the second endplate to one another;
• and
• providing a layer including a piezoelectric material (piezoelectric layer), wherein the piezoelectric layer is configured to have, in the spinal implant assembly, a non-planar upper surface facing toward the first non-planar inner surface and a non-planar lower surface facing toward the second non-planar inner surface, and wherein the first non-planar inner surface and the second non-planar inner surface are configured to define, in the spinal implant assembly, a vertically biased interface.