A fusion is a procedure that is done to “fuse” two or more spinal bones (vertebral bodies) together to stop motion between them.
This is done for several reasons including painful instability (spondylolisthesis), where the bones are moving relative to each other in an abnormal way, or for painful worn out discs. Usually bone graft, what I like to call “seed bone”, is used to connect or fuse the two or more bones together. There are several sources of bone graft, including your own bone, donor bone and man-made materials. I will explain the advantages and disadvantages of these choices if fusion is recommended.
Essentially, we are tricking your body into thinking that there is a broken bone, which it then heals, or fuses together. In most cases, screws and/or hooks, connected to rods are used to hold the bones and prevent motion so that they may fuse. This is the same principle as applying a clamp to an item you are gluing together. In this case, the bone graft is the glue and the screws and rods are the clamp. Although a clamp is removed after the glue has set, we don’t typically go back in to remove the screws and rods. They are inert, biocompatible metals that are not rejected by the body and you can have them in your spine forever. Often fusion is performed at the same time as laminectomy.