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Spine
intermediate
X-Type

Os Odontoideum - Diagnosis, Classification, and Surgical Indications

Cervical Spine Disorders

A 14-year-old boy with Down syndrome is evaluated prior to participating in Special Olympics. Cervical spine radiographs show a smooth, rounded ossicle separated from a hypoplastic dens, located in the normal odontoid position. Flexion-extension views demonstrate an atlantodens interval (ADI) of 6mm in flexion, reducing to 2mm in extension. He has no neurologic symptoms. The spine surgeon discusses the diagnosis and management options with the family. Regarding os odontoideum:

Mark each as TRUE or FALSE

A

Os odontoideum is a smooth, rounded ossicle separate from a hypoplastic dens; it may be orthotopic (...

B

The etiology is debated but current evidence favors an acquired origin from unrecognized childhood d...

C

All patients with os odontoideum are symptomatic and require immediate surgical fusion regardless of...

D

Atlantoaxial instability with ADI greater than 3mm in adults or greater than 5mm in children on flex...

E

Associated conditions include Down syndrome, Klippel-Feil syndrome, Morquio syndrome, and spondyloep...

Answer the questions to see explanations

Click T (True) or F (False) for each option