Traumatic spondylolisthesis of the axis: Hangman's fracture.

Traumatic spondylolisthesis of the axis is classified either as Type 1, an undisplaced fracture involving the posterior elements only, or Type 2, a displaced fracture involving the posterior elements plus the anterior structures. This classification is the basis of a rational treatment program. Neurologically, not one in a series of 42 patients was made worse by the proposed program of treatment. All fractures healed per primam without operative intervention. There was no evidence of late instability. The incidence of spinal cord and nerve root involvement was low although the incidence of associated trauma, particularly head trauma, was extremely high.