Vertebral body squaring (differential)
Vertebral body squaring refers to the loss of normal concavity of the anterior border. It is seen in a variety of conditions including:
Ankylosing spondylitis is the most common cause of vertebral body squaring. It usually involves multiple levels and typically begins in the lumbar spine. Vertebral body squaring occurs after the shiny corner sign/Romanus lesion and precedes bamboo spine.
Paget disease of bone
Paget disease of bone can result in squaring of the vertebral bodies although it usually involves individual vertebrae and is associated with other signs typical of the condition, e.g. bony expansion, trabeculation and cortical thickening.
There are many inflammatory arthritides, but while vertebral body squaring can occur it is an uncommon manifestation of these conditions. Examples include:
Down syndrome may result in vertebral body squaring, but it is not a classical finding.
Block vertebra (congenital fusion)