• Virginie Cordemans, Ludovic Kaminski, Xavier Banse, Bernard G Francq, and Olivier Cartiaux.
• Neuro Musculo Skeletal Lab (NMSK), Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Avenue Mounier 53, Box B1.53.07, 1200, Brussels, Belgium. virginie.cordemans@uclouvain.be.
• Eur Spine J. 2017 Nov 1; 26 (11): 2906-2916.

PurposeThe goal of this study was to compare the accuracy of a novel intraoperative cone beam computed tomography (CBCT) imaging technique with that of conventional computed tomography (CT) scans for assessment of pedicle screw placement and breach detection.MethodsThree hundred and forty-eight pedicle screws were inserted in 58 patients between October 2013 and March 2016. All patients had an intraoperative CBCT scan and a conventional CT scan to verify the placement of the screws. The CBCT and CT images were reviewed by two surgeons to assess the accuracy of screw placement and detect pedicle breaches using two established classification systems. Agreement on screw placement between intraoperative CBCT and postoperative CT was assessed using Kappa and Gwet's coefficients. Using CT scanning as the gold standard, the sensitivity, specificity, positive predictive value, and negative predictive value were calculated to determine the ability of CBCT imaging to accurately evaluate screw placement.ResultsThe Kappa coefficient was 0.78 using the Gertzbein classification and 0.80 using the Heary classification, indicating a substantial agreement between the intraoperative CBCT and postoperative CT images. Gwet's coefficient was 0.94 for both classifications, indicating almost perfect agreement. The sensitivity, specificity, positive predictive value and negative predictive value of the CBCT images were 77, 98, 86, and 96%, respectively, for the Gertzbein classification and 79, 98, 88, and 96%, respectively, for the Heary classification.ConclusionsIntraoperative CBCT provides accurate assessment of pedicle screw placement and enables intraoperative repositioning of misplaced screws. This technique may make postoperative CT imaging unnecessary.

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