Clinical accuracy of 3D fluoroscopy-assisted cervical pedicle screw insertion.

Abstract

Cervical pedicle screw (PS) misplacement leads to injury of the spinal cord, nerve root, and vertebral artery. Recently, several investigators reported on the usefulness of a spinal navigation system that improves the accuracy of PS insertion. In this study, the authors assessed the accuracy of cervical pedicle, lateral mass, and odontoid screw insertions placed using a 3D fluoroscopy navigation system, the Iso-C3D unit. In this prospective analysis of the authors' initial 50 cases of 3D fluoroscopy-assisted cervical screw insertion, the authors inserted 176 PSs, 58 lateral mass screws, and 5 odontoid screws into the C1-7 vertebrae. They placed screws using intraoperative acquisition of data by the isocentric C-arm fluoroscope and a computer navigation system. They obtained postoperative fine-cut CT scans in all patients and assessed the accuracy of screw insertion. A PS (>or= 3.5 mm) could be inserted into 24 (63%) of 38 pedicles at the level of C-3, 18 (53%) of 34 pedicles at C-4, 30 (65%) of 46 at C-5, 33 (80%) of 41 at C-6, and 43 (100%) of 43 at C-7. Of 176 PSs inserted into vertebrae between C-2 and C-7, 171 screws (97.2%) were classified as Grade 1 (no pedicle perforation), and 5 screws (2.8%) were classified as Grade 2 (screw perforation of the cortex by up to 2 mm). Clinically significant screw deviation in the present study was considered Grade 3 (screw perforation of the cortex by > 2 mm), and this occurred in 0% of the placements. In this study, the authors were able to correctly insert cervical PSs using the 3D fluoroscopy and navigation system.