In a block vertebra, there is partial or complete fusion of adjacent vertebral bodies.
- hemivertebrae/absent vertebra above or below block level and with posterior element fusion
- fusion of multiple cervical vertebral bodies is also seen in Klippel-Feil syndrome
- VACTERL association
- combined vertebrae may be of normal height, short, or tall
- disc space is frequently rudimentary or absent
- the "wasp-waist sign" may be seen in congenital block vertebrae