Individual protocol and clinical application of pedicle screw and plate internal fixation for the treatment of upper cervical disorders / 中国组织工程研究

ABSTRACT

BACKGROUND: The treatment of upper cervical spine disorders through a posterior pedicle fixation approach have been carried out in some domestic large hospitals, but this surgery is still considered as a difficulty of cervical spine surgery. In order to minimize the risk of surgery, the authors designed a program of individual operations, and combined with self-developed pedicle locating and directing speculum to determine precise intraoperative position of pedicle screws, and no report is found by searching related database in China.OBJECTIVE: To improve the one-time success rate of internal fixation screws, to investigate the biomechanical effect of the implant, to formulate a simple, practical, individual protocol for atiantoaxial pedicle screw-plate system based on related data. METHODS: A total of 31 patients were recruited from Department of Orthopaedics in the 251 Hospital of Chinese PLA, between January 2002 and September 2006. Under the guidance of self-made atlantoaxial locating and directing speculum, the entrance point and angle for screw insertion, as well as screw diameter and length were determined according to the results of X-ray and CT measurement. Atlas pedicle screw was inserted at left (19.93±1.32) mm, and right (19.16±1.3) mm; Atlas pedicle screw insertion angle to inside was left (23.72±2.09)°, and right (23.35±1.91)°; Atlas pedicle screw insertion angle to side of head was (9.00±1.20)°. Axis pedicle screw was inserted at left (13.14±0.82) mm, and right (13.85±0.79) mm; Axis pedicle screw insertion angle to inside was left (24.52±1.26)°, and right (20.42±1.42)°; Axis pedicle screw insertion angle to side of head was (25.00±3.00)°.RESULTS AND CONCLUSION: ①Totally 124 pedicle screws were implanted into 31 patients, and 122 screws were of one-time success. The precision rate was 98.39%. Two screws were secondly inserted because of cutting lateral cortical bone of pedicle for deviation of inward angle. ②Occipital neuralgia was found in 2 cases postoperatively and cured after one month of treatment;screws penetrated atlas left vertebral lateral wall in 2 cases, no spinal or vertebral artery injury was found. ③Radiographs showed that atlas was completely reduced in all patients, and apposition of dentoid process of axis fracture was good. CT films showed the screws a good location to the vertebrarterial spinal cord. ④The follow-up visit was averaged of 10.5 months. Bony fusion was found in all patients. No screw-plate breakage was found. No inflammatory or rejection reactions occurred.⑤By JOA scale, there were 16 cases of excellent, 12 cases of good, 2 cases of fine, and 1 case of poor. The excellent and good rate was 90%. It is suggested that the success rate of atlantoaxial pedicle screw-plate mplantation can be improved through a biomechanical angle.