Spinal Fusion with Instrumentation

What Is Spinal Fusion?

The spine is made up of a series of bones called “vertebrae”; between each vertebra are strong connective tissues called discs which hold one
vertebra to the next and act as cushions. The disc allows for movements of the vertebrae and lets people bend and rotate their neck and back. The
type and degree of motion varies between the different levels of the spine: cervical (neck), thoracic (chest) or lumbar (low back). The cervical spine
is a highly mobile region that permits movement in all directions. The thoracic spine is much more rigid because of the presence of ribs and is designed
to protect the heart and lungs. The lumbar spine allows mostly forward and backward bending movements (flexion and extension).

Fusion is a surgical technique in which one or more of the vertebrae of the spine are united together (“fused”) so that motion no longer
occurs between them. The concept of fusion is similar to that of welding in industry. Spinal fusion surgery, however, does not weld the
vertebrae during surgery. Rather, bone grafts are placed around the spine during surgery. The body then heals the grafts over several months
similar to healing a fracture—which joins, or “welds,” the vertebrae together.

When Is Fusion Needed?

Fusing the vertebrae may be considered for several reasons. These include: treatment of a fractured (broken) vertebra; correction
of deformity (spinal curves or slippages); elimination of pain from painful motion; treatment of instability; and treatment of some
cervical disc herniations.

One of the less controversial reasons to do spinal fusion is vertebral fracture. Although not all spinal fractures need surgery, some fractures
particularly those associated with spinal cord or nerve injury—generally require fusion as part of the surgical treatment.

Certain types of spinal deformity, such as scoliosis, are commonly treated with spinal fusion. Scoliosis is an “S” shaped curvature of the spine
that sometimes occurs in children and adolescents. Fusion is indicated for very large curves or for smaller curves that are getting worse.

When Is Fusion Needed?

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Sometimes a hairline fracture allows vertebrae to slip forward on top of each other. This condition is called spondylolisthesis (see North
American Spine Society brochure on Adult Isthmic Spondylolisthesis), and can be treated by fusion surgery.

Another condition that is treated by fusion surgery is actual or potential instability. Instability refers to abnormal or excessive motion between
two or more vertebrae. It is commonly believed that instability can either be a source of back or neck pain or cause potential irritation or damage
to adjacent nerves. Although there is some disagreement on the precise definition of instability, many surgeons agree that definite instability of
one or more segments of the spine is an indication for fusion.

Cervical disc herniations that require surgery usually need not only removal of the herniated disc (discectomy), but also fusion. With this procedure,
the disc is removed through an incision in the front of the neck (anteriorly) and a small piece of bone is inserted in place of the disc. Although
disc removal is commonly combined with fusion in the neck, this is not generally true in the low back (lumbar spine).

When Is Fusion Needed?

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Spinal fusion is sometimes considered in the treatment of a painful spinal condition without clear instability. A major obstacle to the successful
treatment of spine pain by fusion is the difficulty in accurately identifying the source of a patient’s pain. The theory is that pain can originate from
painful spinal motion, and fusing the vertebrae together to eliminate the motion will get rid of the pain. Unfortunately, current techniques to
precisely identify which of the many structures in the spine could be the source of a patient’s back or neck pain are not perfect. Because it can be
so hard to locate the source of pain, treatment of back or neck pain alone by spinal fusion is somewhat controversial. Fusion under these conditions
is usually viewed as a last resort and should be considered only after other conservative (nonsurgical) measures have failed.