Spondylolisthesis

Spondylolisthesis / SPON-dill-oh-lis-THEE-sis is the forward or anterior displacement of one vertebra over another, and commonly involving the fifth lumbar vertebra.Backward displacement is referred to as retrolisthesis. When occurring in conjunction with scoliosis, the shortened term “olisthesis,” may sometimes be used instead.
Spondylolisthesis is a condition in which one bone in your back (vertebra) slides forward over the bone below it.

  It most often occurs in the lower spine (lumbosacral area). In some cases, this may lead to your spinal cord or nerve roots being squeezed. This can cause back pain and numbness or weakness in one or both legs. In rare cases, it can also lead to losing control over your bladder or bowels. See a doctor right away if you begin losing bladder or bowel control.
Sometimes when a vertebra slips out of place, you may have no symptoms at all or no symptoms until years later. Then, you may have pain in your low back or buttock. Muscles in your leg may feel tight or weak. You may even limp.

What causes Spondylolisthesis?

The bones in your spine come together at several small joints that keep the bones lined up while still allowing them to move. Spondylolisthesis is caused by a problem with one or more of these small joints that allows one bone to move out of line.