Fusion is the process of joining bones with bone grafts, adding bone graft or bone graft substitute to an area of the spine to set up a biological response that causes the bone to grow between the two vertebral elements and thereby stop the motion at that segment. The fusion process essentially "tricks" the body into thinking it has a fracture.

Anterior thoracic fusion is performed from the front of the mid-back region and is used in the treatment of scoliosis, kyphosis, tumors, instability, fracture, or degenerative disc disease.

The General Procedure:

1. Surgical approach
• The skin incision is made in the side of the chest.
• The space between the ribs is entered.
• The lungs and great vessels are retracted off of the spine.
• This part of the procedure is often performed by a thoracic surgeon.


2. Disc removal
• A needle is then inserted into the disc space and an x-ray is done to confirm that the surgeon is at the correct level of the spine.
• After the correct disc space has been identified on x-ray, the disc is then removed by first cutting the outer annulus fibrosis (fibrous ring around the disc) and removing the nucleus pulposus (the soft inner core of the disc).
• Dissection is carried out from the front to back of the disc. Part of the rib head may need to be resected to allow complete disc removal.


3. Preparation of the fusion bed
• After the disc is removed, a space remains between the vertebral bodies.
• Disc space shavers and spacers may be used to template the height, width, and depth of bone graft that is needed.
• The surfaces of the vertebral bodies are meticulously prepared for bone graft by burring any irregularities. This allows surface area for the ingrowth of bone.


4. Bone graft and fusion
• Since it is desirable to maintain the height of the disc space, a ‘structural’ piece of bone may be used in the lower thoracic spine if necessary.
• Bone graft is often obtained from the pelvis (the iliac crest). Alternatively, allograft and/or bone graft substitutes and extenders can be used.
• Next, the bone graft material is placed in the disc space.

However, a solid fusion is not always achieved. There are a few factors that patients can control that are important in determining whether or not a fusion grows in solidly, including:

• Smoking cessation. It is generally advisable to quit smoking prior to a spinal fusion procedure, as nicotine is a direct toxin to bone graft and will prevent the bone from forming.
• Limited motion. Bone forms better if motion is limited, so patients are often advised to avoid bending, lifting, and twisting for up to three months after spinal fusion surgery depending on the amount of instability.