Expandable intervertebral cage

An expandable intervertebral cage device adapted to be implanted into an intervertebral disc space in a patient's body, comprising:

• a first base plate having a first outer bearing surface configured to interface with a first vertebra of the intervertebral disc space;
• a second base plate having a second outer bearing surface configured to interface with a second vertebra of the intervertebral disc space;
• only a single arm assembly extending between the first base plate and second base plate on each of a first side of the device and second side of the device, each arm assembly including only a pair of arms with a first arm of the pair of arms mechanically coupled to the first base plate and a second arm of the pair of arms mechanically coupled to the second base plate;
• and
• a screw device extending longitudinally between the first base plate and the second base plate, wherein rotation of the screw in a first direction causes the arm assemblies to expand and the rotation of the screw in a second direction causes the arm assemblies to contract, and wherein expansion of the arm assemblies causes the first base plate and the second base plate to be angled relative to one another.

A method comprising:

• providing an expandable intervertebral cage device, comprising:
• a first base plate having a first outer bearing surface;
• a second base plate having a second outer bearing surface;
• a proximal block mechanically coupled to the first base plate and the second base plate, wherein the proximal block comprises internal threading;
• a distal block comprising an internal passage;
• only two arm assemblies, wherein a first one of the two arm assemblies is arranged on a first side of the device and a second one of the two arm assemblies is arranged on a second side of the device, wherein each of the only two arm assemblies comprises:
• a first arm mechanically coupled to the first base plate and the distal block;
• and
• a second arm is mechanically coupled to the second base plate and the distal block;
• and
• a screw arranged partially within the internal threading of the proximal block and passing through the internal passage of the distal block, such that rotation of the screw relative to the proximal block causes a change in distance between the proximal block and the distal block, and a corresponding change in the spacing and lordosis of the device due to an expansion or contraction of the arm assemblies;
• and
• providing instructions for performing an intervertebral body fusion and distraction procedure with the expandable intervertebral cage device, the instructions comprising:
• inserting the expandable intervertebral cage device into an intervertebral disc space of a patient defined between adjacent vertebrae such that the first bearing surface interfaces with an end plate of a superior vertebra of the intervertebral disc space and the second bearing surface interfaces with an end plate of an inferior vertebra of the intervertebral disc space;
• expanding the device within the intervertebral disc space into an expanded configuration by rotating the screw relative to the proximal block;
• and
• leaving the device within the intervertebral disc space following insertion and expansion.