Spondylolisthesis is a condition that occurs when one vertebra in the spinal column slides over the one below it. Damage to the bone or joints in a vertebra can cause this slippage. When the vertebra moves out of position, the spinal cord or nerve roots may be pinched causing symptoms of pain and other neurological dysfunction. Spondylolisthesis can also lead to deformities of the spine such as lordosis or kyphosis.