Spondylolisthesis is a spinal condition that occurs when one of the vertebrae in your spinal column moves out of place, moving off the vertebra below it. In other words, it means slipping of one vertebra out of place from the vertebrae below. This can cause back pain and /or leg pain. This condition can become very painful for the patient. It can put pressure on the nerves in the patient’s back. This can create lower back pain and pain in the patient’s legs. In some cases, it can cause the patient to lose control over his or her bladder or bowel. If this occurs, the patient should get medical help right away.