Application of the pedicle screw in the subaxial cervical spine

OBJECTIVE: To research the clinical application of lower cervical pedicle screw fixation procedure. METHODS: From September 2011 to July 2013,32 patients underwent posterior pedicle screw-rod system fixation were retrospective analyzed includinig 20 males and 12 females with an average age of 56.4 years old ranging from 21 to 78 years. Among them, 10 patients were traumatic cervical spinal injury, 9 patients were cervical spinal canal tumors, 7 cases were posterior longitudinal ligament ossification of cervical vertebrae, 6 cases were multiple segmental cervical spondylopathy. Preoperatively, X-ray, computed tomography, magnetic resonance imaging and magnetic resonance angiography of the vertebral artery were performed in all patients. After the operation and during the follow-up,X-ray and computed tomography were performed to confirm the pedicle screw position. The accuracy of the pedicle screw placement was evaluated by 4 grades classification from Lee. The spinal cord function was assessed by ASIA impairment scale for traumatic patients and JOA score for non traumatic patients. RESULTS: Totally 144 pedicle screws performed on 32 patients from C3 to C7 involving 132 screws of grade 0,5 screws of grade 1,5 of screws grade 2 and 2 screws of grade 3 according to postoperative CT. There were 12 screws penetrating the pedicle cortex including 8 screws at lateral,2 screws at caudal, 1 screw at medial and 1 screw at cranial. The follow-up time was 12 to 33 months with an average of (21.0±1.5) months. The spinal cord function was not improved in 6 complete cervical spinal cord injury patients,but their paraplegic level descended 1 to 3 segments. Four incomplete cervical spinal cord injury patients' ASIA impairment scale was increased by 1 to 2 grades in average. The JOA score of 22 atraumatic patients increased from preoperative 11.5±0.8 to 15.9±0.6 of postoperative at 6 months (P<0.01). There were no screw loosening,screw pullout and screw-rod breakage. CONCLUSION: The lower cervical pedicle screw fixation can provide excellent 3D stability of the vertebral column. The operation risk and Complication could be minimized by adequate preoperative evaluation for appropriate cases and individual pedicle screw placement. It deserved the clinical expansion.