CASE 2211 Published on 20.11.2003

Posterior limbus vertebra: another cause of low back pain

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

Passomenos D

Patient

18 years, male

Categories
No Area of Interest ; Imaging Technique CT
Clinical History
Young male athlete presenting with low back pain.
Imaging Findings
The patient presenting with low back pain of 7 months' duration. He reported athletic activities during the previous 6 years.

Plain radiographs of the spine were obtained in two projections, and a small triangular osseous particle was noted on the posterior-inferior edge of the L5 vertebra. A subsequent CT scan revealed a slight posterior displacement of the apophyseal ring of the affected vertebra.
Discussion
The term 'limbus' denotes a small, unusual 'fracture' located on the inferior-posterior corner of a vertebral body (inferior vertebral endplate), usually in the lower lumbar spine. According to Schmorl and Kohler's study, lumbar vertebral ring apophyses, located at the margin of the superior and inferior vertebral endplates, first appear as a cartilaginous rim in childhood and tend to ossify completely with the vertebral body by the age of 18-25 years. Whether this separated triangular bone fragment is a true fracture of the posterior ring apophysis or a separation of the posterior vertebral rim, a number of different names describe this entity as a posterior marginal node, posterior bony avulsion, apophyseal ring fracture or epiphyseal dislocation.

Posterior vertebral rim fractures usually present with symptoms of low back pain and/or radiculopathy, most often in male adolescents (ratio 2:1) or young adults but they can also be incidentally found. Plain radiographs, especially lateral projections, can demostrate this abnormality in 40% of cases. However, CT gives a more complete picture of the morphological changes of the displaced bone fragment, and shows any associated disc herniation and spinal canal compromise. Extruded, degenerated disc material between the fragment and the inferior corner of the vertebra can only be verified by discography, an invasive diagnostic method. An extradural defect at the site of a limbus vertebra can also be demonstrared by myelography, where encroachment on the spinal canal may vary from mild to complete blockage. A fracture of the posterior cortex of the vertebral body has to be excluded in considering a diagnosis of posterior limbus vertebra.
Differential Diagnosis List
Posterior limbus L5 vertebra
Final Diagnosis
Posterior limbus L5 vertebra
Case information
URL: https://www.eurorad.org/case/2211
DOI: 10.1594/EURORAD/CASE.2211
ISSN: 1563-4086