• Hiroaki Nakashima, Kouji Sato, Toshihiro Ando, Hidefumi Inoh, and Hiroshi Nakamura.
• Department of Orthopedic Surgery, Chubu Rosai Hospital, Aichi, Japan. hirospine0527@yahoo.co.jp
• J Spinal Disord Tech. 2009 Oct 1;22(7):468-72.

Study DesignRetrospective clinical study to compare the percutaneous screw placement precision of isocentric C-arm (Iso-C) 3-dimensional fluoroscopy-navigated pedicle screw implantation and conventional fluoroscopy.ObjectiveThe purpose of this study was to evaluate the accuracy of clinical percutaneous pedicle screw placement (PPSP) using Iso-C 3-dimensional fluoroscopy navigation.Summary Of Background DataThe technique of PPSP recently has been applied to internal fixation for segmental lumbar instability as a form of minimally invasive spine surgery. The percutaneous insertion technique requires surgical skill and experience. The 3-dimensional fluoroscopy-based image-guidance navigation system has been proven to be effective in guiding accurate PPSP in the lumbar area of cadavers. However, there have been few clinical reports comparing the accuracy of Iso-C 3-dimensional fluoroscopy-navigated pedicle screw implantation and the conventional fluoroscopy method.MethodsHere, 300 percutaneous pedicle screws were evaluated; half of them were inserted under Iso-C 3-dimensional navigation and the others under fluoroscopy. The accuracy of pedicle screw placement was examined postoperatively using an axial 2-mm slice computed tomography. Screw malpositioning was classified either as exposed screw (<50% of the screw outside the pedicle) or perforated pedicle (>50% of the screw outside the pedicle boundaries).ResultsOf the 150 pedicle screws placed with Iso-C 3-dimensional fluoroscopy-based image-guide assistance, 11 (7.3%) were classified as exposed screws and 0 (0%) as perforated pedicle. Of the 150 pedicle screws inserted under fluoroscopy, 18 (12%) were classified as exposed screw and 5 (3.3%) as perforated pedicle. The difference in frequency of screw misplacement between the procedure using Iso-C 3-dimensional fluoroscopy-based image-guide assistance and that using fluoroscopy was statistically significant (P<0.05; chi test).ConclusionsThis study demonstrates the feasibility of placing percutaneous posterior lumbar pedicle screws with the assistance of Iso-C 3-dimensional navigation.

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