This page contains information about Spondylolisthesis and Treatment. Spondylolisthesis is a spinal condition when one vertebra slips forward over another vertebra. Depending upon where in the spine the slip occurs, the type of condition can be considered Degenerative Spondylolisthesis or Isthmic Spondylolisthesis. Because of the length of information of these pages, you can read more detail on their respective pages. These slips are all classified using the Meyerding Grading System which is based on the percentage that one vertebral body has slipped forward over the vertebral body. A Grade I slip is considered the most mild, while a Grade V slip represents the vertebral body has completely slipping off the body below (called spondyloptosis).