Spondylolisthesis in children. Cause, natural history, and management.

Spondylolysis is the term used for a defect in the pars interarticularis of the vertebra. The term is from the Greek roots spondylos, meaning vertebra, and lysis, meaning break or defect. Spondylolisthesis is from spondylos and listhesis, meaning movement or slipping, and refers to the slipping forward of one vertebra on the next caudal vertebra. Spondylolisthesis was first described in 1782 by Herbiniaux, a Belgian obstetrician. Spondylolysis is most common at L5, and therefore a slip is most common at this level, with L5 slipping forward on S1. Even though this discussion is about spondylolisthesis, some discussion of spondylolysis is necessary, because this is the cause of the most common type of spondylolisthesis.