summary Traumatic spondylolisthesis of the axis, also known as a Hangman's fracture, is a traumatic fracture of the bilateral pars interarticularis of C2 Diagnosis is made with CT of the cervical spine Treatment may be C-collar immobilization, halo immobilization, or surgical stabilization depending on displacement, angulation, and fracture stability Etiology Mechanism hyperextension leads to fracture of the pars secondary flexion tears PLL and disc, allowing subluxation Associated injuries 30% have concomitant C-spine fracture Presentation Symptoms neck pain Physical exam patients are usually neurologically intact Imaging Radiographs flexion and extension views show subluxation CT study of choice to delineate fracture pattern MRA consider if suspicious of a vascular injury to the vertebral artery Classification Levine and Edwards Classification (Based on Mechanism of Injury) Mechanism Characteristics Treatment Type I Axial compression and hyperextension <3 mm horizontal displacement of C2-3 No angulation C2-3 disc remains intact Stable fracture pattern Rigid collar x4-6 weeks Type II Hyperextension and axial load, followed by rebound flexion >3 mm of horizontal displacement Significant angulation Vertical fracture line C2-3 disc and PLL are disrupted Unstable fracture pattern If <5 mm displacement, reduction with traction then halo immobilization x6-12 weeks If >5 mm displacement, surgery or prolonged traction Usually heal despite displacement (autofuse C2 on C3) Type IIA Flexion-distraction No horizontal displacement Horizontal fracture line Significant angulation Avoid traction in type IIA Reduction with gentle axial load + hyperextension, then compression halo immobilization for 6-12 weeks Type III Flexion-distraction, followed by hyperextension Type I fracture with associated bilateral C2-3 facet dislocation Rare injury pattern Surgical reduction of facet dislocation followed by stabilization required Treatment Nonoperative rigid cervical collar x4-6 weeks indications type I fractures (<3 mm horizontal displacement) closed reduction followed by halo immobilization for 8-12 weeks indications type II with 3-5 mm displacement type IIA reduction technique type II use axial traction combined + extension type IIA use hyperextension (avoid axial traction in type IIA) Operative reduction with surgical stabilization indications type II with >5 mm displacement and severe angulation type III (facet dislocations) technique anterior C2-3 interbody fusion posterior C1-3 fusion bilateral C2 pars screw osteosynthesis