A limbus vertebra is a well-corticated unfused secondary ossification center of the vertebral body

A limbus vertebra is a well-corticated unfused secondary ossification center of the vertebral body, usually of its anterosuperior corner, that occurs secondary to herniation of the nucleus pulposus through the vertebral body endplate beneath the ring apophysis (see ossification of the vertebrae). These are closely related to Schmorl nodes and should not be confused with limbus fractures or infection.

Their formation occurs before the age of 18 years, but often they are seen in older adults.

Anterior limbus vertebrae are generally asymptomatic and are detected incidentally. Posterior limbus vertebrae are far less common but have been reported to cause nerve compression.

A limbus vertebra of the anterosuperior corner of a single vertebral body in the mid lumbar spine is the most common presentation. The anteroinferior and posteroinferior corners are seen far less frequently. Occasionally it may be seen in the thoracic spine.

Usually, radiography with or without CT or MRI is sufficient for diagnosis. Initially, the etiology was confirmed with discography where contrast extends into the intraosseous herniation of the nucleus pulposus.

The term limbus is a direct borrowing from the Latin word meaning fringe, as in the edge of something, or hem. Interestingly, limbus vertebra was first described by Schmorl in 1927 .

Differential diagnosis

Consider

_intercalary bone: ossification is in the anterior annular fibers of an intervertebral disc

_acute fractures: should have an adjacent perivertebral hematoma

limbus fracture

teardrop fracture (cervical spine)

_degenerative disease of the spine

_infection: adjacent cortical loss and soft tissue mass