Fracture types of axis, C2 by Effendi, modified by Levine & Edwards

The classification of fractures of axis was introduced by Effendi et al. and later modified by Lewine and Edwards. With further two types added (IA and IIA), the modified classification has five types.

Type Description
Type I fracture of the pedicles, intervertebral disc C2/3 is intact, dislocation ≤3mm without angulation
Type IA fracture lines on each side are not parallel, fracture line may involve foramen transversarium on one side
Type II fracture of the pedicles with dislocation >3mm and/or angulation, involvement of the intervertebral disc C2/3
Type IIA oblique fracture - commonly anterior-inferior to posterior-superior with little subluxation but more angulation
Type III type II and luxation of vertebral joints C2/3 - posterior arch is free floating


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