Os odonteideum is a seperate odontoid process from the body of the axis. It is the most common anomaly of the odontoid process. The etiology of os odontoideum remains controversial, although there is emerging consensus on both traumatic etiology and a congenital source. Patients with this condition can be asymptomatic or present with a wide range of neurological dysfunctions. It may cause cervical instability, atlantoaxial dislocation and myelopathy. This anomaly can mimic Type-I and II odontoid fractures. Accurate diagnosis is mandatory to prevent treatment failures. There is a role for conservative treatment of an asymptomatic incidentally found, radiologically stable, and non-compressive os odontoideum. However, surgical treatment has a definitive role in symptomatic cases.

In this study, the case is presented of a 31 year- old male patient with neck pain who was diagnosed with incidental os odontoideum. The diagnosis of acute odontoid fracture was discarded in this case as the radiological findings were of a characteristic cortex with smooth contours, and there was no history of recent trauma, sclerosis or hypertrophy of the anterior tubercle of the atlas.

Keywords: Os odontoideum, congenital anomaly, cervical instability