An expandable cage for maintain the position of adjacent vertebrae includes a cage top, a cage bottom, and a plurality of shims. The cage top is adapted for contacting a bottom surface of the upper of the adjacent vertebrae, and the cage bottom is adapted for contacting an upper surface of the lower of the adjacent vertebrae. The plurality of shims are adapted for insertion between the cage top and cage bottom to expand the cage. The shims include a proximal end having a bone graft distribution feature configured such that when bone graft material is introduced to the site of the expandable cage, the bone graft material is separated at the bone graft distribution feature and distributed to either side of the cage.
