Spondylolistesis is a condition of the spine where a vertebrae (spinal bone) displace either forward or backward compared to the vertebra above or below it.
If an upper vertebrae slips forward over a lower one, it is called anterolisthesis. If the slippage is backward, it is called retrolisthesis.
Spondylolisthesis can lead to deformities in the spine as well as narrowing of the central spinal canal or compression of nerve roots. When the spinal canal is affected by this narrowing, the diagnosis is called central spinal stenosis.
When the nerve roots are compressed, the diagnosis is called foraminal stenosis (the foramen is the hole where the nerve roots exit).
For information on the causes of spondylolisthesis, click here.