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.