Spondylolisthesis is a condition in which a vertebra slips forward on the vertebra below it.
It normally occurs in the lumbar vertebra, most often at the level between the fifth lumbar vertebra and the first sacral vertebra. Spondylolisthesis may occur as the result of a congenital defect in the fifth lumbar vertebra, stress fractures , and traumatic fractures. Spondylolisthesis may occasionally be associated with bone diseases. Spondylolisthesis may vary from mild to severe. Symptoms may include lower back pain and pain in the thighs and buttocks, stiffness, muscle tightness, and tenderness in the slipped area.