An expandable intervertebral cage device includes a first base plate and a second base plate, a proximal block with internal threading that mechanically couples the first base plate and the second base plate, and a distal block comprising an internal passage. The device has exactly two arm assemblies, one on each side. Each arm assembly includes 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. A screw is arranged partially within the internal threading of the proximal block and passes 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.
