A new study published in the Journal of Spinal Disorders and Techniques examines whether CT scans overestimated fusion rates after anterior cervical discectomy and fusion.
The researchers examined 22 patients after ACDF — cortical allograft with anterior plates — with 34 levels fused. The patients had CT scans and dynamic X-rays at three, six and 12 months after surgery. There were four surgeons blinded to the time the images were taken determining fusion status.
Here are six findings from the study:
1. At each time point, the CT scans showed higher rates of fusion than the X-ray:
• Three months: 26 percent for X-ray, 79 percent for CT scan
• Six months: 41 percent for X-ray, 79 percent for CT scan
• 12 months: 65 percent for X-ray, 91 percent for CT scan
2. The predicted fusion rate at each time point was significantly different and at three months, 41 percent of the levels the CT scan criteria determined were fused demonstrated greater than 1 mm motion on the dynamic X-rays.
3. Six months after surgery, 33 percent of the levels the CT scan showed fused had a persistent motion of 1 mm or greater.
4. One year after surgery, 23 percent of the levels the CT scan said were fused showed persistent motion.
5. After examining the results, the researchers concluded, "CT scans may overestimate the fusion rate during the early stages of ACDF healing with cortical allograft, and that CT scans alone may not accurately determine fusion status."
6. The researchers recommend dynamic information to determine reliable fusion with a flexion-extension X-ray in association with high-resolution static information from the CT scan.