The intervertebral discs function as shock absorbers for the spine. Sometimes these discs can degenerate, thin, or herniate. When this occurs, pressure from the two vertebrae coming in contact with each other can compress the nerves in the spine, resulting in debilitating back pain. In severe cases, repair of this disorder requires spinal fusion. This procedure involves creating a bone graft, which requires removal of the damaged disc and replacing it with bone.
The most common method for bone grafting is to use bone harvested from the patient's own body, such as from the iliac crest or hip bone. The new bone is inserted between the vertebrae where the disc has been removed. Specialized cells called osteocytes within the bone help fuse the vertebrae and new bone. Oftentimes an internal fixation rod is attached to the spine at the site of the graft to provide stabilization while the graft is healing.