Spinal fusion is a process by which two or more vertebrae are fused together with synthetic materials, bone grafts and other internal fixation devices in order to allow healing of the two vertebrae into a single solid bone. The surgery eliminates motion between vertebrae segments, which may be desirable when motion is the cause of significant pain. It also stops the progress of a spinal deformity such as scoliosis. A spinal fusion takes away some of the patient’s spinal flexibility. Most spinal fusions involve a very limited number (usually 1 or 2) of spinal segments and thus do not limit motion very much. In some cases, there is a conversion of fusion to artificial disc replacement.