Abstract: Methods and apparatuses for promoting fusion of vertebrae are provided. The apparatuses comprise interconnecting plates that fixate vertebrae to each other and provide for a predetermined amount of subsidence where the fusion occurs. Allowing for this predetermined amount of subsidence increases bone to bone contact at the graft, which promotes fusion without having excessive settling of the two vertebrae onto the graft. The predetermined amount of subsidence is achieved by the placement of a plate spacer between each of two interconnecting plates when the plates are attached to the vertebrae. The plate spacer has a height equal to the maximum amount of subsidence desired. After affixing the plates to the vertebrae, the plate spacer is removed, leaving a space between the plates, which allows the vertebrae to subside by a distance equal to the height of the plate spacer.