Developmental spondylolisthesis is further divided into two types, both with lysis and elongation: low dysplastic and high dysplastic, depending on the severity of the bony dysplastic changes present on the L5 and S1 vertebrae and on the risk of slip progression.

Succesful management of a giant anterior sacral meningocele associated with low-dysplastic spondylolisthesis from single posterior approach: case report ¹⁾.