Kinematics of the cervical spine: effects of multiple total laminectomy and facet wiring.

The effect of multiple-level total laminectomies followed by stabilization on the load-deformation behavior of the cervical spine is described. Fresh human ligamentous cervical spines (C2-T2) were potted and clinically relevant load types applied via a loading frame attached to the C-2 vertebra of the specimen. A set of three infrared light-emitting diodes (LEDs) were attached rigidly to each of five vertebrae (C3-7) to record their spatial locations after each load step application, using a Selspot II system. The specimen was tested again after total laminectomy performed on C5. The supraspinous, interspinous, and flavum ligaments between the C4-5 and C5-6 motion segments were cut; thereafter, the vertebral arch was removed. The specimen testing was resumed after inducing injury at C-6 in a similar fashion. The specimen was stabilized, using a facet wiring construct, across the C4-7 segment before testing for the final time. The load-deformation data of the injured and stabilized tests were normalized with regard to the corresponding results of the intact test. In flexion-extension mode, an increase in motion of about 10% after laminectomies was observed. Facet wiring was found to be an effective technique to stabilize injured cervical spines (approximately equal to 80% reduction in motion, compared with intact spines, was observed.