title: Os odontoideum: etiology and surgical management.
abstract: OBJECTIVE
  Os odontoideum is an independent ossicle of variable size with smooth circumferential cortical margins separated from the foreshortened odontoid peg. The etiology of os odontoideum remains controversial, but there is now emerging consensus on the traumatic etiology of os odontoideum rather than a congenital source.
  
  
  RESULTS
  We reviewed the literature of os odontoideum. Patients with this condition can be asymptomatic or present with wide range of neurological dysfunctions. Although the diagnosis of os odontoideum can be made with plain x-rays, further imaging modalities including magnetic resonance imaging and computed tomography angiography have improved the preoperative planning.
  
  
  CONCLUSIONS
  There is a role for conservative treatment of an asymptomatic incidentally found, radiologically stable, and noncompressive os odontoideum. Conversely, surgery has a definite role in symptomatic cases. The main method of surgical treatment today is posterior decompression after reduction and fusion via independent C1 and C2 instrumentation. Irreducible, persistent anterior compression from os odontoideum can be approached by a transoral route with good results in experienced hands.
authors.affiliation: Toronto Western Hospital, University of Toronto, Toronto, ON, Canada.
authors.forename: Babak
authors.initials: B
authors.lastname: Arvin
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Fournier-Gosselin
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fehlings
mesh_terms: D001268:Atlanto-Axial Joint / Q000293:injuries / Q000473:pathology / Q000601:surgery*; D001915:Braces; D019299:Decompression, Surgical / Q000295:instrumentation / Q000379:methods; D003952:Diagnostic Imaging / Q000379:methods; D006801:Humans; D016268:Internal Fixators / Q000592:standards / Q000639:trends; D007593:Joint Instability / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D009809:Odontoid Process / Q000293:injuries / Q000473:pathology / Q000601:surgery*; D013117:Spinal Cord Compression / Q000503:physiopathology / Q000517:prevention & control / Q000601:surgery*; D016103:Spinal Fractures / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods