gms | German Medical Science

62nd Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Polish Society of Neurosurgeons (PNCH)

German Society of Neurosurgery (DGNC)

7 - 11 May 2011, Hamburg

Accuracy of image-guided spinal pedicle screw placement using intraoperative computed tomography-based navigation with automated referencing

Meeting Abstract

  • K.M. Scheufler - Department of Neurosurgery, Medical University Innsbruck, Austria
  • J. Franke - Department of Orthopedic Surgery, University Hospital Magdeburg, Germany
  • A. Eckardt - Department of Orthopedic Surgery, Hirslanden Klinik Birshof, Bale, Switzerland
  • H. Dohmen - Department of Neuropathology, University Hospital Zürich, Switzerland

Deutsche Gesellschaft für Neurochirurgie. Polnische Gesellschaft für Neurochirurgen. 62. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Polnischen Gesellschaft für Neurochirurgen (PNCH). Hamburg, 07.-11.05.2011. Düsseldorf: German Medical Science GMS Publishing House; 2011. DocDI.02.04

DOI: 10.3205/11dgnc109, URN: urn:nbn:de:0183-11dgnc1093

Published: April 28, 2011

© 2011 Scheufler et al.
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Outline

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Objective: To assess the accuracy of intraoperative computed tomography (iCT)-based spinal Navigation (iCT-N) for cervical, thoracic and lumbar transpedicular instrumentation.

Methods: 1044 screws (cervical: 138; thoracic: 314; lumbar: 460; sacral: 94; iliac: 38) were inserted in 82 patients (age range: 18–92 years). An automated single iCT registration was used for multisegmental instrumentation without additional fluoroscopic guidance. The reference frame was fixed to either a Mayfield-type clamp (for cervical pedicle screw insertion) or the L5 spinous process for thoracolumbosacropelvic fixation. Intraoperative navigation screenshots obtained during pedicle screw insertion were compared to post-instrumentation iCT or CT scans to assess reliability and accuracy of iCT-N. The degree of angular displacement of the final implant trajectory as compared to the navigated tool (i.e., virtual) trajectory was assessed in two planes. Final screw position was also graded according to established classification systems.

Results: Clinically significant screw misplacement or iCT-N failure mandating conversion to conventional technique did not occur. 99.3% of cervical screws were compliant with Neo classification grades 0 and 1 (0.7% grade 2). 97.8% of thoracic pedicle screws were assigned grades I-III of the Heary classification, with 2.2% grade IV placement. In the lumbar spine, 94.2% of screws were completely contained (Gertzbein classification grade 0), 4.7% displayed minor pedicle breaches <2 mm (grade 1), and 1.1% of lumbar screws deviated by >2<4 mm (grade 2). Accuracy of iCT-N progressively deteriorated with increasing distance from the spinal reference clamp, but allowed for safe instrumentation of up to 9 segments. With iCT-N, intraoperative fluoroscopy was avoided, completely eliminating staff radiation exposure.

Conclusions: Image guided spinal instrumentation using iCT-N with automated referencing allows for safe, highly accurate multilevel instrumentation of the cervical, thoracic and lumbosacral spine. ICT-N technique significantly reduces the need for re-registration in multilevel surgery, and may obviate the need for additional fluoroscopic surveillance. The radiation exposure to surgeon and staff may be greatly reduced or even eliminated.