• Neil Duggal, Robert H Chamberlain, Luis E Perez-Garza, Adolfo Espinoza-Larios, Volker K H Sonntag, and Neil R Crawford.
• London Health Sciences Centre, London, Ontario.
• Spine. 2007 Jan 15;32(2):182-7.

Study DesignIn vitro biomechanical flexibility experiment studying 5 sequential conditions.ObjectiveTo determine the biomechanical differences among 3 fixation techniques after a simulated hangman's fracture.Summary Of Background DataType II hangman's fractures are often treated surgically with a C2-C3 anterior cervical discectomy, fusion, and plating. Other techniques include direct fixation with C2 pars interarticularis screws or posterior C2-C3 fixation connecting C2 pars screws to C3 lateral mass screws.MethodsSeven cadaveric specimens (Oc-C4) were tested intact, after a simulated hangman's fracture, and after each fixation technique. Flexion, extension, lateral bending, and axial rotation were induced using nonconstraining torques while recording angular motions stereophotogrammetrically.ResultsDirect screw fixation reduced motion an average of 61% +/- 13% during lateral bending and axial rotation compared to the injured state (P < 0.007). However, instability remained during flexion and extension. Posterior C2-C3 rod fixation provided significantly greater rigidity than anterior plate fixation during lateral bending (P < 0.008) and axial rotation (P < 0.04).ConclusionsDirect fixation of the pars ineffectively limits flexion and extension after a Type II hangman's fracture. If pars screw fixation can be achieved, posterior C2-C3 fixation more effectively stabilizes a hangman's fracture than anterior cervical plating.

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