Evaluation of rigid, semi-rigid, and dynamic stabilization of the cervical spine

Laminectomy following rigid or semi-rigid rod and screw stabilization is one of the most common approaches in treating spinal stenosis in the cervical region. Fusion-related problems such as altering the motion pattern and degenerative changes in adjacent tissues have led to the development of dynamic rod and screw stabilizers. The present study has been conducted to investigate the effects of rigid, semi-rigid, and dynamic rod and screw systems on the biomechanical performance of the subaxial cervical spine. Using a validated finite element model of the intact subaxial cervical spine, laminectomy following lateral mass screw fixation was simulated at the C45 level. Operated models were stabilized using rigid, semi-rigid, and dynamic rod and screw systems, and the range of motions (ROMs) and facet joint contact forces (FJCFs) were assessed at the index level. The results of the simulations showed that the dynamic stabilizer provided better performance in restoring the intact model ROM in flexion, extension, lateral bending, and axial rotation up to 120%, 340% 60%, and 4.9%, respectively, when compared to other stabilizers. While rigid and semi-rigid stabilizers in all motions and the dynamic stabilizer only in axial rotation inhibited facet contact, the dynamic stabilizer restored 24% and 40% of the FJCFs in extension and lateral bending, respectively. This research will help understand the biomechanical performance of patients’ spine after post-laminectomy stabilizing surgery.