In spondylolisthesis, 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.