To achieve a spinal fusion, a bone graft is used to promote two bones growing together into one. The patient's own bone will grow into and around the bone graft and incorporate the graft bone as its own. This process creates one continuous bone surface and eliminates motion at the fused joint. A small piece of bone is used to fuse a disc space and a longer so-called strut graft is used to bridge across multiple disc spaces, if a corpectomy has been performed.