Anderson and D'Alonzo classification of odontoid process fracture

The Anderson and D'Alonzo classification is the most commonly used classification of fractures of the odontoid process of C2.

Classification

  • type I
    • rare
    • fracture of the upper part of the odontoid peg (generally oblique)
    • above the level of the transverse band of the cruciform ligament
    • usually considered stable
  • type II
    • most common
    • transverse course fracture at the base of the odontoid
    • below the level of the transverse band of the cruciform ligament
    • unstable
    • high risk of non-union
  • type IIa
    • ​type II fractures with comminution at the odontoid base
    • Hadley 2 described this type of fracture which has a significantly increased risk of nonunion when treated non-operatively compared with classical type II fractures
    • represents 5-10% of type II fractures
  • type III
    • through the odontoid and into the lateral masses of C2
    • relatively stable if not excessively displaced
    • best prognosis for healing because of the larger surface area of the fracture

Another classification system is the Roy-Camille classification.

Fractures

Article information

rID: 41604
Synonyms or Alternate Spellings:
  • Anderson and D'Alonzo classification of odontoid process fractures

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Cases and figures

  • Figure 1
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  • Figure 2a: Anderson and D'Alonzo type 1
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  • Figure 2b: Anderson and D'Alonzo type 2
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  • Figure 2c: Anderson and D'Alonzo type 2a
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  • Figure 2d: Anderson and D'Alonzo type 3
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  • Case 1: type II
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  • Case 2: type III
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