Biomechanical evaluation of cervical spine instability after multiple level laminectomy

Four fresh human cervical spine specimens (C2-T1) were tested both intact and with C5-C6 laminectomies to evaluate the biomechanical effects of multiple level laminectomy. The loads applied to the specimens were physiological and clinically relevant motion patterns were simulated. The results showed that C5 vertical displacements increased by 83.33% in axial compression, 168.75% in flexion, 106.09% in extension, and 35.14% in left bending after C5-C6 laminectomies compared with intact specimens. The increased rates of C6 vertical displacements after laminectomy were slightly lower than C5. The anterior horizontal bulging of C5-6 discs increased by 29.69% in axial compression, 13.86% in flexion, 61.79% in extension, and 13.40% in left bending after laminectomy. The rotational angles of whole specimens had an increase of 15% after laminectomy. The strains in the anterior vertebral bodies and posterior laminae near the articular processes of C5 and C6 were increased significantly after laminectomy. The data indicated that multiple level laminectomy can lead to biomechanical instability of the cervical spine.