Degenerative Spondylolisthesis (Degenerative Spondylolysthesis) is a condition that normally occurs in the lower back but can occur also in the neck. All vertebrae stack up on each other. What holds them together in alignment is the disc and the paired facets in back. The facets are the “doorstops” of the back and neck. When the facets are intact, they hold the spine in alignment. When they wear out, the vertebra on top can slide forward on the vertebra below. This can cause instability- a feeling that the back or neck will give out with certain movements. The slip can also cause stenosis, a narrowing of the spinal canal which can lead to a compression of the nerves of the canal.