<unk>  can be classified as a form of spondylolisthesis, since spondylolisthesis is often defined in the literature as displacement in any direction. Yet, medical dictionaries usually define spondylolisthesis specifically as the forward or anterior displacement of a vertebra over the vertebra inferior to it (or the sacrum).<unk>  is also called retrospondylolisthesis.
Retrolisthesis
Spondylolisthesis
Disc protrusion
Back strain
Facet syndrome
Vertebral compression fracture
Discitis
Coccyx fracture