IS Case 253: Type 2 dens fracture

Scott Cassar, MD


Imaging Sciences URMC 2008
Publication Date: 2009-05-26

History

Patient is a teenage girl status post-motor vehicle collision with injury to her head, face, and spine.

Findings

Dens fracture with a 3mm anterior displacement of the superior fragment.

Discussion

Odontoid fractures are the most common upper cervical spine fractures and they occur in injuries of forced hyperextension or hyperflexion of the head. They have been classified into three types.

Type 1 is an oblique avulsion fracture of the superolateral tip of the dens by the alar ligament which connects the dens to the occiput. This type is rare and considered stable. and must be distinguished from an os odontoideum which is a congenital non-union of a secondary ossification center. The os odontoideum will have well-corticated margins while acute fractures should have sharp radiolucent margins.

Type 2 is a transverse fracture at the base of the odontoid. This is the most common type and is unstable. Treatment is to wear an immobilization halovest for 3 months if the initial displacement is less than 5 mm, otherwise a surgical posterior antlanto axial arthrodesis should be performed. Type 2 dens fractures must be distinguished from an os odontoideum which is a congenital non-union of a secondary ossification center. The os odontoideum will have well-corticated margins while acute fractures should have sharp radiolucent margins.

Type 3 is a fracture of the superior portion of the C2 vertebral body which extends to one or both superior articular facets. This allows the atlas and occiput to move together and is also an unstable fracture. Typical treatment is an immobilization halovest for 3 months.

References

  1. Adam A, Dixon AK, Grainger RG, Allison DJ (Editors). Grainger & Allison's Diagnostic Radiology, 5th ed., Churchill Livingstone, 2008.
  2. Goetz CG (Editor). Textbook of Clinical Neurology, 3rd ed., Saunders, 2007. [MD Consult]
  3. Wheeless CR, III. Duke Orthopaedics presents Wheeless’ Textbook of Orthopaedics.http://www.wheelessonline.com/ortho/dens_fracture

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