Expandable interbody device

There is disclosed an expandable interbody device for placement between adjacent vertebrae comprising: an upper structure comprising an upper proximal angled surface and an upper distal angled surface; a lower structure comprising a lower proximal angled surface and a lower distal angled surface, the lower structure configured to slideably couple with the upper structure; and a screw mechanism between the upper structure and the lower structure, the screw mechanism comprising: a proximal section comprising a proximal frustoconical surface; a distal section comprising a distal frustoconical surface; and a coupler comprising a proximal side configured to engage the proximal section and a distal side configured to engage the distal section, wherein the proximal section and the distal section are configured to rotate to change a distance between the upper structure and the lower structure from a first distance to a second distance, wherein the proximal frustoconical surface is configured to exert a force on the upper proximal angled surface and the lower proximal angled surface, and the distal frustoconical surface is configured to exert a force on the upper distal angled surface and the lower distal angled surface to move the upper structure and the lower structure such that the distance therebetween changes from the first distance to the second distance, and wherein the coupler further comprises at least one anti rotational feature configured to engage the upper structure or lower structure to prevent the coupler from rotating when the proximal section and the distal section are rotated.