Spinous Process Screw Fixation: A Salvage Technique in Subaxial Cervical Spinal Instrumentation

Abstract

Objective: We sought to evaluate the feasibility and efficacy of spinous process screws in subaxial cervical fixation.

Methods: A retrospective study was conducted on 7 patients receiving posterior cervical instrumentation for subaxial fracture dislocation or atlantoaxial dislocation from 2014 to 2015. In addition, a biomechanical test was performed on 7 fresh-frozen cadaveric spine samples (from the occiput to C7) from healthy human subjects with no history of spinal trauma. And lastly, the potential trajectories of cervical spinous process screws of 100 adults were measured through axial computed tomography in order to establish the general rule for applicability of this technique.

Results: Rigid fixation and solid fusion were achieved in all 7 patients included in the study. Biomechanical test results revealed no significant difference between bilateral lateral mass screw fixation and the hybrid lateral mass and spinous process screw fixation constructs. Measurement of the potential trajectory suggested that spinous process screw fixation was a viable technique in the subaxial cervical spine in the general population.

Conclusions: The spinous process screw fixation technique in the subaxial cervical spine is a viable and effective salvage option for patients in whom conventional posterior fixations were not sufficient and salvage, supplementary techniques were required.

Keywords: Biomechanical test; Salvage fixation technique; Spinous process screw; Subaxial cervical spine.