I had a lumbar fusion 10 years ago. My doctor says that I have adjacent segment disease. What does that mean.

According to a recent literature review, 34 percent of patients who had fusion of the lumbar spine developed adjacent segment disease. In the literature reviewed, the rate ranged from 5 percent to 100 percent of patients. Adjacent segment disease is progressive degeneration of the spine either above or below the fusion level at a rate greater than would be expected. It is asymptomatic. Adjacent segment disease shows progressive degeneration and is symptomatic, causing symptoms which correlate with the segment involved.