Spinal fusion is a surgical procedure that stabilizes two adjoining vertebrae---the bones of the spinal column---by joining them together. The surgeon places a bone graft between the affected vertebrae and the healing process fuses the bones together, explains the North American Spine Society. The graft material may come from the patient's own hip or pelvis, a bone bank donor, or a synthetic bone substitute currently under development. Spinal fusion is most often used to relieve back or neck pain caused by deformities or injuries of the spine. In many cases, patients have tried nonsurgical treatment before spinal fusion is considered.
Fractured Vertebrae
Spinal fusion is the treatment of choice for some fractures of one or more vertebrae, which are the bones that surround the spinal cord. The most frequent cause of fractured vertebrae is osteoporosis, a weakening of the bones that often occurs in older women, but automobile accidents and falls also cause this type of injury, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Spinal fusion is primarily indicated when the patient's fracture has caused damage or irritation to the spinal cord or nerves. Spondylolisthesis---a vertebra that has slipped forward because of a hairline fracture---is also an indication for spinal fusion.
Instability
Instability---excessive motion of the vertebrae---can cause pain and nerve irritation. Most orthopedic surgeons agree that instability is an indication for spinal fusion although the definition of instability is in dispute, according to the North American Spine Society. Spinal fusion in cases of significant back pain that is not related to unstable vertebrae is more controversial because it is difficult to locate the source of the pain. In those cases, all efforts should be made to treat the pain nonsurgically before spinal fusion is considered.
Spinal Stenosis
The spinal cord runs through the spinal canal, the opening in the middle of the vertebrae. When the spinal canal becomes narrowed by osteoarthritis---a condition called spinal stenosis---the nerves are compressed and an individual experiences pain in the back and legs. The person may lose bowel and bladder control and have difficulty walking as a result. Spinal fusion may be required to relieve the compression on the nerves, according to the North American Spine Society.
Degenerative Disk Disease
When the fluid-filled disks that act as shock absorbers between the vertebrae are damaged through injury or wear and tear, the resulting bone-on-bone motion causes pain and sometimes nerve irritation. Removing the disk, called a laminectomy, and fusing the affected vertebrae to stabilize them may relieve the patient's pain. However, the procedure is only 60 to 70 percent successful and should be used only if other treatment has failed, according to NIAMS. Another option, replacing the damaged disk with an artificial disk, usually requires fusion if the cervical, or neck, vertebrae are involved.
Spinal Deformities
Abnormal curvature of the back---scoliosis and kyphosis---is most common in teenagers but can also affect adults and children. These abnormalities cause varying degrees of pain, disability and deformity. Depending on the patient's age and the severity of the curvature, either a brace or a spinal fusion may be indicated to straighten the spine, according to the Cleveland Clinic.
