Comparison of Three Different Techniques in Cervical Transpedicular Screw Insertion

ABSTRACT

OBJECTIVE: This is a cadaver study to assess the accuracy of three cervical screw insertion techniques: the blind technique (Group I), the laminotomy technique (Group II), and the funnel technique (Group III). METHODS: Ten human cadavers embalmed with formaldehyde were prepared. After exposing the spinous processes, the laminas and the lateral masses, titanium alloy transpedicular screws were inserted from C3 to C7. A total of 100 pedicles were ramdomly assigned to one of three techniques (the blind technique: 31 screws, the laminotomy technique: 51 screws, the funnel technique: 18 screws). Axial computed tomography with 1-mm slices, and sagittal and coronal reformation were performed to identify the accuracy of the screw insertion and the anatomic relationships. RESULTS: In Group I, 9 screws (29%) were either contained within or penetrated less than 1mm, which were rated as successful. In Group II, 24 screws (47%) were successful. In Group III, 16 screws (89%) were successful. In the multiple comparison, there was a statistically significant difference between Groups I and III and between Groups II and III (chi-square test and Bonfenoni test). CONCLUSION: The funnel technique can help a surgeon's understanding about the cervical pedicle more precisely than the other two techniques. The funnel technique is less dependent on lateral soft tissue retraction state.