Values of color Doppler ultrasound in observing vertebral artery during lateral “in-out-in” axis pedicle screw placement

English Keywords:Color Doppler ultrasound  Axis pedicle  Screw  Vertebral artery  Atlantoaxial

English Abstract:

  【Abstract】 Objectives: To analyze the clinical effect of color Doppler ultrasound in observing vertebral artery before and after the placement of lateral "in-out-in" axis pedicle screw in posterior occipitocervical surgery for atlantoaxial dislocation or instability. Methods: The data of 47 patients with atlantoaxial dislocation or instability treated with lateral “in-out-in” axis pedicle screw fixation in posterior occipitocervical surgery from January 2016 to January 2022 were retrospectively analyzed. There were 30 males and 17 females, aged 21-68 years, with an average age of 42.2±18.9 years. Unilateral axis pedicle stenosis in 40 cases and bilateral stenosis in 7 cases. In the observation group, 23 cases underwent screw placement with color Doppler ultrasound monitoring the morphology of vertebral artery and measuring its diameter at 3 time points of after exposure, screw path preparation and screw placement, and the final screw placement length was determined according to the change of vertebral artery diameters. In the control group, 24 cases were implanted with lateral "in-out-in" axis pedicle screw according to bleeding and experience. Perioperative complications were recorded, and the operative time and intraoperative blood loss were compared between the two groups. All the patients were followed up for 6-24 months, with an average of 11 months. X-ray, CTA and MRI were performed before and at 5d after operation to observe the internal fixation and vertebral artery. X-ray and CT examinations were performed at 3, 6 and 12 months after operation to observe the bone graft fusion. The Japanese Orthopaedic Association(JOA) scores before operation, at 5d after operation and the last follow-up were compared to evaluate the clinical efficacy. Results: The operation of the two groups was successfully completed. In the observation group, the diameter of one side of the vertebral artery in 1 case was significantly reduced after the preparation of the screw path, and a short screw was used for fixation. The diameters of the remaining vertebral artery were 3.15±0.61mm, 3.09±0.72mm, 3.21±0.57mm at the three time points, respectively, with no significant difference(P>0.05). The operative time of the observation group and control group were 199.1±52.4(138-257)min and 182.2±41.5(129-231)min, respectively; The amount of bleeding in the observation group and control group were 401.2±185.3(210-650)mL and 415.3±201.7(230-660)mL, respectively, and there was no significant difference between the two groups(P>0.05). Postoperative CTA found that 1 case of the control group had one side of the vertebral artery compressed by pedicle screw without clinical symptoms and complications such as spinal cord injury. CT examination at 6 months after operation showed bone graft fusion and no internal fixation loosening or displacement. The JOA scores of the observation group at 5d after operation and the last follow-up were 13.1±2.1 and 14.2±1.9, respectively, which were significantly improved compared with before operation(7.8±1.9)(P<0.05). The JOA scores of the control group were 12.9±1.7 and 13.8±2.2, respectively, which were significantly improved compared with before operation(8.1±2.5)(P<0.05). There was no significant difference in JOA score between the two groups at each time point(P>0.05). Conclusions: The use of color Doppler ultrasound to observe the vertebral artery during the placement of lateral "in-out-in" axis pedicle screws in posterior occipitocervical surgery can observe the shape and diameter of vertebral artery without increasing surgical trauma.