Spinal Fusion Health Article

Definition

Spinal fusion is a procedure that promotes the fusing, or growing together, of two or more vertebrae in the spine.

Purpose

Spinal fusion is performed to:

• Straighten a spine deformed by scoliosis, neuromuscular disease, cerebral palsy, or other disorder.
• Prevent further deformation.
• Support a spine weakened by infection or tumor.
• Reduce or prevent pain from pinched or injured nerves.
• Compensate for injured vertebrae or disks.

The goal of spinal fusion is to unite two or more vertebrae to prevent them from moving independently of each other. This may be done to improve posture, increase ability to ventilate the lungs, prevent pain, or treat spinal instability and reduce the risk of nerve damage.

Demographics

According to the American Academy of Orthopaedic Surgeons, approximately a quarter-million spinal fusions are performed each year, half on the upper and half on the lower spine.

Spinal anatomy

The spine is a series of individual bones called vertebrae, separated by cartilaginous disks. The spine is composed of seven cervical (neck) vertebrae, 12 thoracic (chest) vertebrae, five lumbar (lower back) vertebrae, and the fused vertebrae in the sacrum and coccyx that help to form the hip region.

While the shapes of individual vertebrae differ among these regions, each is essentially a short hollow tube containing the bundle of nerves known as the spinal cord. Individual nerves, such as those carrying messages to the arms or legs, enter and exit the spinal cord through gaps between vertebrae.

The spinal disks act as shock absorbers, cushioning the spine, and preventing individual bones from contacting each other. Disks also help to hold the vertebrae together.

The weight of the upper body is transferred through the spine to the hips and the legs. The spine is held upright through the work of the back muscles, which are attached to the vertebrae.

While the normal spine has no side-to-side curve, it does have a series of front-to-back curves, giving it a gentle "S" shape. The spine curves in at the lumbar region, back out at the thoracic region, and back in at the cervical region.