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J Spinal Disord Tech. 2013 Jul 26. [Epub ahead of print]

Reliability and Usefulness of Intraoperative Three-Dimensional Imaging by Mobile C-Arm With Flat-Panel Detector.

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  • 1Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.



Reliability and agreement study OBJECTIVE:: To assess the reliability of intraoperative three-dimensional imaging with a mobile C-arm (3D C-arm) equipped with a flat-panel detector.


Pedicle screws are widely used in spinal surgery. Postoperative computed tomography (CT) is the most reliable method to detect screw misplacement. Recent advances in imaging devices have enabled surgeons to acquire three-dimensional images of the spine during surgery. However, the reliability of these imaging devices is not known.


Two hundred three screws were used in 22 consecutive patients who underwent surgery for scoliosis. Screw position was read twice with a 3D C-arm and twice with CT in a blinded manner by 2 independent observers. Screw positions were classified into 4 categories at every 2 mm and then into 2 simpler categories of acceptable or unacceptable. The degree of agreement regarding screw positions between the double readings was evaluated by kappa value. With unanimous agreement between 2 observers regarding postoperative CT readings considered the gold standard, the sensitivity of the 3D C-arm for determining screw misplacement was calculated.


A total 804 readings were performed. For the 4-category classification, the mean kappa value for the 2 interobserver readings was 0.52 for the 3D C-arm and 0.46 for CT. For the 2-category classification, the mean kappa value for the 2 interobserver readings was 0.80 for the 3D C-arm and 0.66 for CT. The sensitivity, specificity, positive predictive value, and negative predictive value of intraoperative imaging with the 3D C-arm were 70%, 95%, 44%, and 98%, respectively. With respect to screws with perforation ≥4 mm, the sensitivity was 83%. No revision surgery was performed.


Intraoperative imaging with a 3D C-arm was reliable for detecting screw misplacement and helpful in decreasing the rate of revision surgery for screw misplacement.

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