Anatomical considerations for insertion of pedicular screw in cervicothoracic junction.

This study aimed to investigate the pedicle dimension and angulation in cervicothoracic junction (CTJ) using the findings of computed tomographic (CT) to help accurate insertion of pedicular screw. Forty three patients with high quality CT images of CTJ were evaluated. Pedicle width (PW), pedicle height (PH), pedicle axis length (PAL), transverse angle (TA) and sagittal angle (SA) were measured bilaterally from C6 to T2. Mean PW was 5.3 mm at C6, 6.2 mm at C7, 8.1 mm at T1 and 6.5 mm at T2. Males had larger pedicles than females. PH was greater than PW in all vertebrae. SA was relatively constant and around 15 degrees to horizontal plane. There was high variability of vertebral characteristics especially in PAL and TA. Small diameter screws must be used for pedicular fixation in CTJ. Because of high variability of pedicle morphometry, CT scan is recommended in all patients before instrumentation.