C-OnSite super( registered ) for intraoperative 3D control of pedicular screw positions

• Published in: Acta neurochirurgica 2014-09, Vol.156 (9), p.1799-1805
• Main Authors: Kantelhardt, Sven Rainer, Keric, Naureen, Conrad, Jens, Nimer, Amr, Woo, Raymund, Varich, Laura, Giese, Alf
• Format: Article
• Language: English
• ISSN: 0001-6268; 0942-0940
• DOI: 10.1007/s00701-014-2111-z

Background: Two-dimensional image guidance and navigation can help to reduce the number of misplaced pedicle screws, but do not completely prevent misplacement. This experimental, retrospective, non-inferiority study was designed to evaluate and compare the efficacy of a novel 3D imaging technique versus conventional postoperative CT-scan, for intra-operative determination of pedicle screw position accuracy. Methods: The capacity of C-OnSite registered to intraoperatively assess screw placement was evaluated in 28 clinical cases and 23 deliberately misplaced screws in a cadaver model, and compared to placement accuracy determined by standard CT. The position of each implant, as viewed by both modalities, was graded by three neurosurgeons, one orthopaedic-surgeon and one radiologist. The intermodal variance determined the difference between CT- and C-OnSite registered results for each observer, while the inter-observer variance measured the difference between ratings of the same modality by different observers. Results: C-OnSite registered successfully assessed 120/138 screws (25/28 cases). Mean procedural fluoroscopy time was 132 plus or minus 51s, and 40 plus or minus 16s per C-OnSite registered scan. The average inter-modality variance was ,15 % with mismatches >1 degree between C-OnSite registered and the gold-standard imaging technique in only 2 % of the comparisons. Average inter-observer variances were about similar (12 % for CT and 18 % for C-OnSite registered ), with deviations of >1 degree reaching 1 % for CT and 3 % for C-OnSite registered . Individual variances between experienced only observers differed even less. Conclusions: C-OnSite registered is a feasible, reliable and intuitive means of intraoperatively visualizing pedicle screw positions and might render the majority of postoperative CTs superfluous. C-OnSite registered might help avoid re-operations for screw re-positioning.