Os odontoideum: A comprehensive review

Sia Cho, Nathan A. Shlobin, Nader S. Dahdaleh*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review


Os odontoideum (OO) is a rare craniocervical anomaly that is characterized by a round ossicle separated from the C2 vertebral body. With a controversial etiology and unknown prevalence in the population, OO may be asymptomatic or present in patients with myelopathic and neurological symptoms. In this literature review, we aimed to investigate epidemiology, embryology, pathophysiology, clinical presentation, and the role of diagnostic radiography in OO. By providing an overview of different management strategies, surgical complications, and postoperative considerations for OO, our findings may guide neurosurgeons in providing proper diagnosis and treatment for OO patients. A literature review was conducted using the PubMed, EMBASE, and Scopus databases. A search using the query 'os odontoideum' yielded 4319 results, of which 112 articles were chosen and analyzed for insights on factors such as etiology, clinical presentation, and management of OO. The presentation of OO varies widely from asymptomatic cases to severe neurological deficits. Asymptomatic patients can be managed either conservatively or surgically, while symptomatic patients should undergo operative stabilization. Although multiple studies show different techniques for surgical management involving posterior fusion, the diversity of such cases illustrates how treatment must be tailored to the individual patient to prevent complications. Conflicting studies and the paucity of current literature on OO highlight poor comprehension of the condition. Further understanding of the natural history of OO is critical to form evidence-based guidelines for the management of OO patients. More large-center studies are thus needed to promote accurate management of OO patients with optimal outcomes.

Original languageEnglish (US)
Pages (from-to)256-264
Number of pages9
JournalJournal of Craniovertebral Junction and Spine
Issue number3
StatePublished - Jul 1 2022


  • Atlantoaxial instability
  • atlantoaxial subluxation
  • craniocervical junction
  • os odontoideum
  • screw fixation

ASJC Scopus subject areas

  • Clinical Neurology
  • Surgery


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