Application of "in-out-in" multi-cortical C2 pedicle screw in posterior approach for atlantoaxial dislocation or instability

English Keywords:Axis  Pedicle screw  Atlantoaxial dislocation  Atlantoaxial instability

English Abstract:

  【Abstract】 Objectives: To investigate the clinical effect of "in-out-in" multi-cortical C2 pedicle screw placement for the treatment of atlantoaxial dislocation or instability. Methods: Twenty-six patients with atlantoaxial dislocation or instability were treated by posterior fusion and fixation with "in-out-in" multi-cortical C2 pedicle screw fixation from January 2014 to January 2016. There were 17 males, 9 females, aged 25-63 years(mean 43±9 years); unilateral high-riding vertebral artery was found in 10 cases, bilateral high-riding in 2 cases, unilateral axial pedicle dysplasia due to C2-3 congenital fusion was found in 12 cases, bilateral dysplasia in 2 cases. Patients presented with neck pain, VAS score of 1-6 points(average, 3.12±2.13) was noted; 23 cases presented with decreased neurofunction, the Japanese Orthopedic Association(JOA) score was 5-11 points(average of 7.9±2.1 points). X-ray, CT and MRI were performed before operation and 7 days, 3, 6, 12 months after operation. X-ray and CT examination were used to observe the fusion of bone grafts. VAS score and JOA score were compared at each time point. Results: The operation time was 125-215min(153.7±27.9min). The bleeding volume was 160-650ml(263.1±68.5ml). The "in-out-in" technology screw process suspended due to high bleeding and was changed to translaminar screws; no spinal cord or vascular injury and other serious complications was noted. All patients were followed up for 8-20 months(mean, 12±4 months). At 6 months postoperatively, bone graft fusion was obtained and there was no instrument failure. The VAS score was 1.13±0.72, 1.11±0.93, 1.09±0.78 and 1.07±0.81 points at 7 days, 3 months, 6 months and the final follow-up respectively, compared with preoperative ones, there existed significant differences(P＜0.05). The JOA score was 12.9±1.8, 13.4±2.3, 13.6±1.9 and 13.8±2.1 points at 7 days, 3 months, 6 months and the final follow-up respectively, compared with preoperative ones, there existed significant differences(P＜0.05).