Comparing Accuracy of Cervical Pedicle Screw Placement between a Guidance System and Manual Manipulation: A Cadaver Study

BACKGROUND The aim of this study was to compare the accuracy of cervical pedicle screw placement between a three-dimensional guidance system and manual manipulation. MATERIAL AND METHODS Eighteen adult cadavers were randomized into group A (n=9) and group B (n=9). Ninety pedicle screws were placed into the C3-C7 under the guidance of a three-dimensional locator in group A, and 90 screws were inserted by manual manipulation in group B. The cervical spines were scanned using computed tomography (CT). Parallel and angular offsets of the screws were compared between the two placement methods. RESULTS In group A, 90% of the screws were within the pedicles and 10% breached the pedicle cortex. In group B, 55.6% were within the pedicle and 44.4% breached the pedicle cortex. Locator guidance showed significantly lower parallel and angular offsets in axial CT images (P<0.01), and significantly lower angular offset in sagittal CT images (P<0.01) than manual manipulation. CONCLUSIONS Locator guidance is superior to manual manipulation in accuracy of cervical screw placement. Locator guidance might provide better safety than manual manipulation in placing cervical screws.