What is the reason for having lumbar spinal fusion surgery?

Lumbar spinal fusion surgery (a surgery to join two or more spinal bones -- vertebrae -- so that they eventually grow into one solid bone) is usually done to correct instability of the spine. Arthritis, injuries, or simple wear and tear can cause some of the bones in your spine to slip or shift out of place. This abnormal bone movement can cause back pain. It can also pinch nerves, causing pain, numbness, or weakness in your legs. The leg pain is called sciatica or radiculopathy. The goal of spinal fusion is to stop abnormal movement and thus eliminate pain in your back and legs.