Analysis of Radiological Accuracy among Different Intraoperative Imaging Systems for Screw Fixation in Cervicothoracic Region

Aims: The aim of this study was to compare the accuracy of posterior subaxial cervicothoracic fixation using three different techniques: intraoperative computed tomography (iCT-AIRO) scanner-guided navigation, 3D (O-arm) based spinal navigation, and fluoroscopy based posterior stabilization.

Methods: In the period between March 2015 and November 2017, a total of 140 screws were implanted in 17 patients with cervicothoracic instability who underwent posterior fixation. Eight six screws were inserted with the use of the iCT-based spinal navigation (group A), 42 screws were implanted using the O-arm navigation system (group B), while 12 screws were inserted under the guidance of fluoroscopy (group C).

Screw positions were evaluated using postoperative CT scans according to the Neo et al (cervical pedicles) and Gertzbein and Robbins (thoracic) classifications. The screws in the cervical lateral mass were evaluated according to a new classification created by the authors. The assessment of the screw placement was retrospectively done and graded by an independent observer. Accurate positioning was defined then as screws that were correctly placed completely within the pedicle as well as screws with a breach of < 2 mm or screws that were correctly placed within the lateral mass as well as screws with incomplete perforation of the cortex.

Results: Intraoperative computed tomography-based navigation has permitted a more accurate intraoperative evaluation of the implanted screws and has allowed the immediate correction of misplaced screws. With the use of the iCT, the accuracy rate has reached 97.67% with a much better resolution of the imaged acquired, while with the O-arm navigation, the accuracy rate has reached 95.16%. In cervicothoracic posterior stabilizations done with the aid of fluoroscopy, the intraoperative accuracy was not determined and only a final accuracy rate was measured which reached 91.66%.

Conclusions: In subaxial cervicothoracic posterior fixation either with lateral mass or pedicle screws, the use of iCT-based spinal navigation has demonstrated higher accuracy rates as well as higher quality images allowing more accurate evaluation than with the O-arm-based spinal navigation or fluoroscopy-based systems.