Which statement is true about iatrogenic spondylolisthesis?

• A. It is typically seen at adjacent segments to a fusion
• B. It occurs only at the fused segment
• C. It never progresses
• D. It occurs only in the cervical spine

Answer: (A)

When a spinal fusion is done, the fused levels stop moving, so the adjacent level has to accommodate more motion and greater stress. This shift in biomechanics accelerates degeneration at that nearby segment, making it susceptible to slipping forward relative to the level below — iatrogenic spondylolisthesis. Because the problem stems from the adjacent level taking on the excess load, it’s typically seen at the segment next to the fusion rather than at the fused segment itself.

It’s not limited to a single region, either; while the lumbar spine is a common site, the phenomenon can occur in other regions, including the cervical spine. It can also progress over time as degeneration advances.