Accuracy Of Upper Cervical Pedicle Screw Installation For Traumatic Atlantoaxial Instability: A Comparison Between O-arm Combined With Infrared Rays Navigation And Free-hand Technique

Objective: To compare the accuracy of upper cervical pedicle screw installation between O-arm combined with infrared rays navigation and free-hand technique in the treatment of traumatic atlantoaxial instability.Methods: A retrospective review was conducted on 50 patients with traumatic atlantoaxial instability treated with upper pedicle screw fixation.The patients were divided into O-arm navigation group and free-hand group.The O-arm navigation group consisted of 29 patients underwent upper cervical pedicle screw installation assisted with O-arm navigation from January 2016 to February 2018,and the free-hand group consisted of21 patients underwent upper cervical pedicle screw installation from January 2010 to December 2015.All patients accepted postoperative CT scanning and multiple-planer reconstruction to evaluate the position of upper cervical pedicle screw.And the accuracy was classified into four grades according to Neo’s classification criterion: grade 0,no deviation,the screw was contained in the pedicle;grade 1,deviation less than 2 mm;grade2,deviation more than 2mm and less than 4 mm;grade 3,deviation more than 4 mm.The relevant parameters of two groups were recorded and the accuracy was compared.Results: All operations were completed successfully,no complications of spinal cord or vertebral artery injury related to pedicle screw were observed in the two groups.During the O-arm navigation group,76 upper cervical pedicle screws were implanted in29 patients(25 C1 pedicle screws and 51 C2 pedicle screws),including 69 screws with grade 0(90.8%),7 screws with grade 1(9.2%),no screw was grade 2 or grade 3.And among the 21 patients in the free-hand group,61 upper cervical pedicle screws were placed(22 C1 pedicle screws and 39 C2 pedicle screws),including 48 screws with grade 0(78.7%),8 screws with grade 1(13.1%),3 screws with grade 2(4.9%),2 screws with grade3(3.3%).There was no statistical significance of the accuracy distribution of upper cervical pedicle screw between the two groups(P=0.035),however,the accuracy of grade 0 pedicle screw insertion was higher in O-arm navigation group than that in the free-hand group(P=0.046).Conclusion: Compared with the traditional free-hand technique to deal with traumatic atlantoaxial instability,O-arm navigation could significantly improve the accuracy of upper pedicle screw installation.