Anatomical and morphometric studies in posterior cervical spinal screw-plate systems.

To study potential risks for complications in posterior articular pillar plate fixation, screw-plate systems of Roy-Camille, Louis, and Magerl were implanted into the cervical spines of cadavers under authentic operation theater conditions and in vitro into isolated spine specimens according to the inaugurators' recommendations with regard to plate and screw positioning. We compared these systems with the method of our preference, using the small AO compression plate and monitoring each screw insertion fluoroscopically. The screws were directed toward the projection of the pedicles, and their length was measured individually. Radiographic analysis of the specimens and cryoplaning after implant removal and casting of the screw-plate cavities showed significant differences of the four systems with respect to effective screw length, possible and desirable screw trajectories, and risk for injuries of the facet joints, foraminal neurovascular elements, and vertebral artery, as well as mechanical conflict of the plate with adjacent facet joints.