The Biomechanical Response of the Lower Cervical Spine Post Laminectomy: Geometrically-Parametric Patient-Specific Finite Element Analyses

Purpose: This study aimed to investigate the biomechanical impact of laminectomy on cervical intersegmental motion and load sharing using a parametric patient-specific finite element (FE) model towards providing clinicians with a viable quantitative tool for informed decision-making and improved surgical planning. Methods: Ten subject-specific nonlinear osteo-ligamentous cervical spine (C3–C7) FE models were developed using X-ray image-based algorithms. The models were used to evaluate the effect of laminectomy on lower cervical spine biomechanics for two-level (C3–C4) and three-level (C3–C5) laminectomy procedures. Results: The average cervical spine ranges of motion (ROM) for the pre-op models were 24.09 (± 8.65), 18.08 (± 7.48), 27.86 (± 6.82), and 33.18 (± 10.81) degrees, during flexion, extension, lateral bending, and axial rotation, respectively, in alignment with the literature. Post laminectomy increased the intersegmental ROM, disc stress, and intradiscal pressure at the upper cervical levels during sagittal plane motion and axial rotation, while the lower levels experienced the opposite trend, as compared with intact models. No significant changes were observed in facet joint forces after surgery. Conclusions: The current study used a parametric personalized FE modeling technique as a practical, clinically-applicable approach to predict cervical spine biomechanics post-surgical laminectomy. Altered biomechanical responses, both in terms of kinematics and kinetics, were observed, although more pronounced in models with fewer levels of laminectomy. Overall, a higher degree of motion compensation was observed at the higher levels of the cervical spine, regardless of the laminectomy level, which suggests increased spinal instability, potential risk of post-laminectomy kyphosis, and axial neck pain.