Retrolisthesis, or backward slippage of a vertebra, is an uncommon joint dysfunction.
A vertebra is a small bony disc that makes the vertebrae, a series of small bones that form the backbone.
Each vertebra is separated by a cushion of intervertebral discs. These discs consist of an inner core called the nucleus pulposus. They’re held intact by a strong outer ring of ligament fibers called the annulus fibrosus.
Retrolisthesis occurs when a single vertebra slips and moves back along the intervertebral disc underneath or above it. It’s not the same as a dislocation. If the vertebra slips forward, it’s called spondylolisthesis.
There are three types of retrolistheses. They’re based on the displacement of the vertebra in relation to adjacent vertebra.
Complete retrolisthesis. One vertebra moves backward to both the spinal segments above and below.Partial retrolisthesis. One vertebra moves backward to a spinal segment either below or above. Stairstepped retrolisthesis. One vertebra moves backward to the body of a spinal segment located above, but ahead of the one below.Retrolistheses are typically found in the cervical spine (shoulder and neck region), lumbar region (lower back and pelvis), and thoracic spine (stomach region), although this is less common. Doctors measure the displacement in millimeters.