Presentation
Motor vehicle accident.
Patient Data
Age: 25 years
Gender: Male
From the case:
Bipartite atlas
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Loss of the normal cervical lordosis. No fracture. Vertebral body height and intervertebral disc spaces are preserved. Atlantoaxial and atlantooccipital joints are unremarkable. No widening of the facet joints to suggest ligamentous instability. Incomplete posterior arch of C1 and incomplete fusion of the anterior arch of C1 representing a bipartite (split) atlas which is a normal variant. No prevertebral or paravertebral soft tissue swelling.
Case Discussion
The presence of both anterior arch and posterior arch fusion defects (which are usually in the midline) represent a rare anatomic variant termed bipartite (or split) atlas. It can mimic a Jefferson fracture.
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