Fusion is a surgical technique in which one or more of the vertebrae of the spine are united together (“fused”) so that motion no longer occurs between them. The concept of fusion is similar to that of welding in industry. Spinal fusion surgery, however, does not weld the vertebrae immediately during surgery. Rather, bone grafts are placed around the spine during surgery. The body then heals the grafts over several months – similar to healing a fracture – which joins, or “welds,” the vertebrae together. There are many potential reasons for a surgeon to consider fusing the vertebrae. These include: treatment of a fractured (broken) vertebra; correction of deformity (spinal curves or slippages); elimination of pain from painful motion; treatment of instability; and treatment of some cervical disc herniations.