CT Scan Gives Insider View of Spinal Fusion

Interbody fusion: It can’t send you to the moon or split an atom. But it can do something better–reduce back pain. Spinal fusion for back pain can now be done with mesh cages inserted between the vertebrae. The cages are usually filled with bone chips or bone substitute. This bone graft causes more bone cells to grow, connecting the bone above with the one below. This is called interbody fusion.

But doctors don’t have a reliable way to tell if the bone graft is healing without opening up the patient and getting a look. In this study, researchers compared X-ray results with computed tomography (CT) scans. The CT scan is a special type of X-ray that lets doctors see “slices” of bone tissue. The machine uses a computer and X-rays to create these slices. The imaging studies were done six months after the surgery.

The authors found bone growth in 95 percent of cases with CT scan. The same patients viewed by X-ray showed bone growth in only four percent of the cases. Likewise, CT scan showed bridges of bone forming around the cages in 90 percent of the patients. In those same patients X-rays showed bone bridges only eight percent of the time.

Without a good solid spinal fusion, patients can develop movement at the fusion site. This condition is called a pseudoarthrosis. Loose cages can also occur. Finding these problems early can help plan further treatment and shorten the follow-up time.

The results of this study show that CT scans are much better than X-rays for evaluating spinal fusion with cages. The CT scan also showed new bone growth outside and around the cages when no bone graft was used to help it along.