Block vertebra

Block vertebra is a type of vertebral anomaly where there is a failure of separation of two or more adjacent vertebral bodies. It is an anatomic variant.

Pathology

In a block vertebra, there is partial or complete fusion of adjacent vertebral bodies.

Associations

• 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

Radiographic features

• 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 ⁴