Patent ID: 8771360

Claim:
A distractible intervertebral body fusion device adapted for implantation into, and fusion of, an intervertebral disc space of a patient, comprising; a first bearing surface; a second bearing surface; and at least one coaxial screw gear sleeve mechanism disposed between the first bearing surface and the second bearing surface, the coaxial screw gear sleeve mechanism including: a threaded post projecting inwardly from one of the first bearing surface and the second bearing surface; and a corresponding sleeve having a threaded interior surface surrounding and mating with the threaded post and a helically geared exterior surface; wherein selective rotation of the sleeve causes an expansion of the first bearing surface relative to the second bearing surface due to a telescoping expansion resulting from the sleeve translating relative to one of the first bearing surface and the second bearing surface simultaneously with the threaded post translating relative to the sleeve, such that the coaxial screw gear sleeve mechanism is adapted to support in-vivo loads between the first bearing surface and the second bearing surface to maintain a normal height of the disc space following implantation of the device into the intervertebral disc space and during a time fusion occurs between vertebral bodies of the intervertebral disc space of the patient.