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Odontoid Fracture

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Other Names

  • Odontoid Process Fracture
  • C2 Fracture
  • Dens Fracture
  • Axis Fracture



  • Account for 9-15% of adult cervical spine fractures[1]
  • Most common fracture of Axis (need citation)
  • Bimodal distribution: young males, elderly females (need citation)


  • Typically associated with high energy trauma
  • Displacement can be due to hyperflexion (anterior) or hyperextension (posterior)
    • Anterior: due to failure of transverse ligament and/or atlanto-axial instability
    • Posterior: direct impact from anterior arch during extension


  • C2 (Axis)
    • Composed of odontoid process and body
    • Articulates with C1 and C3
    • Stabilized by transverse, apical and alar ligaments

Associated Injuries

  • Up to 34% of odontoid fractures have additional cervical spine injuries[2]
  • Os Odontoideum
    • Looks like a Type II odontoid fracture
    • Etiology: failure of fusion during childhood or old traumatic process

Risk Factors

  • Unknown

Differential Diagnosis

Clinical Features

  • General: Physical Exam Neck
  • History
    • History of trauma
    • Complains of neck pain, worse with movement
    • Can have dysphagia due to retropharyngeal hematoma
  • Physical Exam
    • Uncommon to have neuro deficits
  • Special Tests


Odontoid view cervical spine radiograph showing type 1 dens fracture with callous formation


  • Standard 3 view C spine films can be helpful
  • Open-mouth (odontoid view) can be diagnostic
  • Flexion-extension views to evaluate for occiptocervical stability


  • Gold standard for evaluating C-spine in the setting of trauma
  • Allows for better characterization of fracture patterns, displacement
  • Consider angiography


  • Indicated if any neurological deficits
  • Better evaluate soft tissues


Anderson and D'Alonzo Classification

  • Type I: Fracture is at the tip[3]
  • Type II: Base of dens
  • Type III: Body of C2

Grauer Classification of Type II Odontoid fractures

  • Type IIA: Nondisplaced/minimally displaced with no comminution
  • Type IIB: Displaced fracture with fracture line from anterosuperior to posteroinferior
  • Type IIC: Fracture from anteroinferior to posterosuperior, or with significant comminution.



  • Associated with a high rate of morbidity and mortality
    • Increases significantly in elderly patients
  • Type I: Excellent prognosis if uncomplicated[4]


  • Os Odontoideum
    • Observation
  • Type I
    • Generally non surgical management
    • Indications: Stable, no co-occurring injuries
    • Technique: Immobilize in rigid cervical collar
  • Type II
    • Indications: very controversial but IIA
    • Technique: halo vest or a nonrigid orthosis (cervical collar)
    • One study reported successful outcomes with non-surgical approach[5]
    • Koivikko et al: only 46% union rate with nonoperative management[6]
  • Type III
    • Indications: Stable/ non displaced
    • Technique: halo vest or a nonrigid orthosis (cervical collar)


  • Type II
    • Risk factors: age > 40, significant displacement (>5 mm), angulation (>11°), neuro deficits, comminution
    • Indications: risk factors above or failure of conservative management, although some surgeons recommend surgical management for call cases
    • Technique: atlantoaxial arthrodesis, occipitocervical fusion with C1 laminectomy

Rehab and Return to Play


  • Needs to be updated

Return to Play

  • Needs to be updated


  • Nonunion
    • Type II 26-85%<[4]
    • Type III 8%[7]
    • Can lead to chronic pain, parasthesias and myelopathy
  • Orthosis complications
    • Pin site loosening
    • Infection
    • Pressure sores
    • Limitation of respiratory function
    • Difficulty swallowing
  • Surgical
    • Respiratory complications
    • Loss of function, mobility, range of motion

See Also


  1. Vaccaro AR, Madigan L, Ehrler DM: Contemporary management of adult cervical odontoid fractures. Orthopedics 2000;23(10):1109-1115
  2. Green RA, Saifuddin A: Whole spine MRI in the assessment of acute vertebral body trauma. Skeletal Radiol 2004; 33(3):129-135
  3. Anderson LD, D'Alonzo RT: Fractures of the odontoid process of the axis. J Bone Joint Surg Am 1974;56(8):1663-1674
  4. 4.0 4.1 Julien TD, Frankel B, Traynelis VC, Ryken TC: Evidence-based analysis of odontoid fracture management. Neurosurg Focus 2000;8(6):e
  5. Müller EJ, Schwinnen I, Fischer K, Wick M, Muhr G: Non-rigid immobilisation of odontoid fractures. Eur Spine J 2003; 12(5):522-525
  6. Koivikko MP, Kiuru MJ, Koskinen SK, Myllynen P, Santavirta S, Kivisaari L: Factors associated with nonunion in conservatively-treated type-II fractures of the odontoid process. J Bone Joint Surg Br 2004;86(8):1146-1151
  7. Hsu, Wellington K., and Paul A. Anderson. "Odontoid fractures: update on management." JAAOS-Journal of the American Academy of Orthopaedic Surgeons 18.7 (2010): 383-394.
Created by:
John Kiel on 4 July 2019 09:27:42
Last edited:
6 October 2022 23:16:55