Electronic Thesis and Dissertation Repository


Master of Science




Chris bailey



The Effect of Fixation Plate Length on Spinal Instability Following Anterior Cervical Plate Fixation for the Repair of in Vitro Flexion-Distraction Injuries

Introduction: Anterior cervical decompression and fusion with a plate (ACDFP) is a commonly performed treatment following a traumatic injury to the subaxial cervical spine. The purpose of the presented work was to determine the biomechanical effect of plate length on cervical spine kinematic stability following ACDFP stabilization for a simulated traumatic injury.

Methods: Eleven fresh-frozen cadaveric C5-C6 and C6-C7 motion segments were examined in this study. To assess kinematics, flexibility testing was performed on each specimen using a spinal loading simulator. A testing protocol was designed to assess the kinematics of the following conditions: i) preinjury, ii) simulated soft tissue injury (both facet capsules, ½ of the ligamentum flavum, and 2/3 of the annulus were sectioned along with an induced rotation to a unilateral facet perch), iii) ACDFP with 22.5mm plate fixation, and iv) ACDFP with 32.5mm fixation. Kinematic range of motion (ROM) data was collected and analyzed for motions of flexion-extension, axial rotation, and lateral bending.

Results: The injury produced significantly greater motion than the pre-injury state; with the greatest increase in motion occurring for axial rotation. Both plates were successful in significantly reducing the ROM (for all motion types) below the injured condition and there were no significant differences in the change in ROM between the two plate sizes. Furthermore, in flexion-extension, both plates also significantly reduced the ROM below that of the intact condition.

Discussion and Conclusions: The results would suggest that the simulated injury was successful in generating spinal instability consistent with the intended injury. The position of the plate in the frontal plane is responsible for impeding the flexion-extension ROM below the motions experienced by the intact condition. Finally, there were no differences between plate sizes for any of the measured motions. Therefore, we advise the use of smallest plates suitable to avoid the theoretical risk of adjacent level degeneration.