BIOMECHANICAL EVALUATION OF CERVICAL-SPINE STABILIZATION METHODS USING A PORCINE MODEL

Study Design. The biomechanical stability of three different methods o f cervical spine stabilization was evaluated in a porcine model. Speci mens were tested in flexion, extension, and axial rotation. Objectives . Our goal was to determine if posterior lateral mass plating after an terior reconstruction provided more stability compared with unicortica l or bicortical anterior plate fixation after a simulated corpectomy. Methods. Twenty-one porcine cervical spines were destabilized with a o ne-level cervical corpectomy and reconstructed with an anterior methac rylate graft. Each construct was stabilized with either an AO Morscher plate system with unicortical, self-locking screws; a Caspar plate wi th bicortical screws; or two posterior lateral mass plates. Testing wi th cyclic loads was performed on an MTS machine in flexion, extension, and axial rotation. Results. There was no statistical difference betw een the two anterior forms of fixation in flexion, extension, or axial rotation. Posterior lateral mass plating was significantly more stabl e than either anterior construct. Screw loosening was seen most freque ntly with bicortical Caspar plating. Conclusions. After a single-level cervical corpectomy and idealized grafting, all three surgical constr ucts provided stability equal to or greater than the intact condit tio n in flexion extension, and axial rotation. In unstable cervical spine injury patterns involving anterior disruption, this study supports th e use of anterior grafting combined with posterior lateral mass platin g to achieve maximum stability.