Bone fusion system

An intervertebral cage, comprising:

• two longitudinal bar pairs, each pair comprising an upper bar and a lower bar, wherein the longitudinal bar pairs are spaced from each other on opposite sides of a midline vertical plane of the cage;
• a spacer moveable in a direction along the midline vertical plane into a space between the longitudinal bar pairs to direct movement of at least a portion of the longitudinal bar pairs away from each other in a horizontal direction substantially perpendicular to the midline vertical plane of the cage;
• and
• a separator movable between the upper and lower bars of a longitudinal bar pair in a direction between at least a portion of the upper and lower bars of that longitudinal bar pair in a direction substantially parallel to the midline vertical plane of the cage, such that contact between a sloped front surface of the separator and at least one of the upper bar or lower bar of that longitudinal bar pair drives vertical movement between the upper and lower bar.