A cage for implanting in bone that has a first plate having a surface that contacts a first bone surface, a second plate having a surface that contacts a second bone surface, a intermediary plate that dynamically couples to the first plate and the second plate, an actuator that drives and causes the intermediary plate to move between the first plate and the second plate along a predetermined direction, and an anchor that attaches to the first plate and the second plate to engage the actuator to drive the actuator longitudinally along the predetermined direction.
