title: Spinal intraoperative three-dimensional navigation: correlation between clinical and absolute engineering accuracy.
abstract: Spinal intraoperative computer-assisted navigation (CAN) may guide pedicle screw placement. Computer-assisted navigation techniques have been reported to reduce pedicle screw breach rates across all spinal levels. However, definitions of screw breach vary widely across studies, if reported at all. The absolute quantitative error of spinal navigation systems is theoretically a more precise and generalizable metric of navigation accuracy. It has also been computed variably and reported in less than a quarter of clinical studies of CAN-guided pedicle screw accuracy.
  
  
  
  This study aimed to characterize the correlation between clinical pedicle screw accuracy, based on postoperative imaging, and absolute quantitative navigation accuracy.
  
  
  
  This is a retrospective review of a prospectively collected cohort.
  
  
  
  We recruited 30 patients undergoing first-time posterior cervical-thoracic-lumbar-sacral instrumented fusion±decompression, guided by intraoperative three-dimensional CAN.
  
  
  
  Clinical or radiographic screw accuracy (Heary and 2 mm classifications) and absolute quantitative navigation accuracy (translational and angular error in axial and sagittal planes).
  
  
  
  We reviewed a prospectively collected series of 209 pedicle screws placed with CAN guidance. Each screw was graded clinically by multiple independent raters using the Heary and 2 mm classifications. Clinical grades were dichotomized per convention. The absolute accuracy of each screw was quantified by the translational and angular error in each of the axial and sagittal planes.
  
  
  
  Acceptable screw accuracy was achieved for significantly fewer screws based on 2 mm grade versus Heary grade (92.6% vs. 95.1%, p=.036), particularly in the lumbar spine. Inter-rater agreement was good for the Heary classification and moderate for the 2 mm grade, significantly greater among radiologists than surgeon raters. Mean absolute translational-angular accuracies were 1.75 mm-3.13° and 1.20 mm-3.64° in the axial and sagittal planes, respectively. There was no correlation between clinical and absolute navigation accuracy.
  
  
  
  Radiographic classifications of pedicle screw accuracy vary in sensitivity across spinal levels, as well as in inter-rater reliability. Correlation between clinical screw grade and absolute navigation accuracy is poor, as surgeons appear to compensate for navigation registration error. Future studies of navigation accuracy should report absolute translational and angular errors. Clinical screw grades based on postoperative imaging may be more reliable if performed in multiple by radiologist raters.
authors: Division of Neurosurgery, Department of Surgery, University of Toronto, 399 Bathurst St., Toronto, ON, M5T 2S8, Canada; Institute of Medical Science, School of Graduate Studies, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada; Biophotonics and Bioengineering Laboratory, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
authors: Daipayan
authors: D
authors: Guha
authors: Biophotonics and Bioengineering Laboratory, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada; Department of Biomedical Physics, Ryerson University, 350 Victoria St., Toronto, ON, M5B 2K3, Canada.
authors: Raphael
authors: R
authors: Jakubovic
authors: Biophotonics and Bioengineering Laboratory, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
authors: Shaurya
authors: S
authors: Gupta
authors: Division of Neurosurgery, Department of Surgery, University of Toronto, 399 Bathurst St., Toronto, ON, M5T 2S8, Canada; Institute of Medical Science, School of Graduate Studies, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
authors: Naif M
authors: NM
authors: Alotaibi
authors: Division of Neurosurgery, Department of Surgery, University of Toronto, 399 Bathurst St., Toronto, ON, M5T 2S8, Canada.
authors: David
authors: D
authors: Cadotte
authors: Division of Neurosurgery, Department of Surgery, University of Toronto, 399 Bathurst St., Toronto, ON, M5T 2S8, Canada.
authors: Leodante B
authors: LB
authors: da Costa
authors: JurongHealth, Ng Teng Fong General Hospital, 1 Jurong East Street, Singapore, 609606, Singapore.
authors: Rajeesh
authors: R
authors: George
authors: Division of Neuroradiology, Department of Medical Imaging, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
authors: Chris
authors: C
authors: Heyn
authors: Division of Neuroradiology, Department of Medical Imaging, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
authors: Peter
authors: P
authors: Howard
authors: Department of Medical Imaging, University of Toronto, 263 McCaul St., Toronto, ON, M5T 1W7, Canada.
authors: Anish
authors: A
authors: Kapadia
authors: Department of Medical Imaging, University of Toronto, 263 McCaul St., Toronto, ON, M5T 1W7, Canada.
authors: Jesse M
authors: JM
authors: Klostranec
authors: Division of Neurosurgery, Department of Surgery, University of Toronto, 399 Bathurst St., Toronto, ON, M5T 2S8, Canada.
authors: Nicolas
authors: N
authors: Phan
authors: JurongHealth, Ng Teng Fong General Hospital, 1 Jurong East Street, Singapore, 609606, Singapore.
authors: Gamaliel
authors: G
authors: Tan
authors: Division of Neurosurgery, Department of Surgery, University of Toronto, 399 Bathurst St., Toronto, ON, M5T 2S8, Canada.
authors: Todd G
authors: TG
authors: Mainprize
authors: Division of Orthopedic Surgery, Department of Surgery, University of Toronto, 149 College St., Toronto, ON, M5T 1P5, Canada.
authors: Albert
authors: A
authors: Yee
authors: Division of Neurosurgery, Department of Surgery, University of Toronto, 399 Bathurst St., Toronto, ON, M5T 2S8, Canada; Institute of Medical Science, School of Graduate Studies, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada; Biophotonics and Bioengineering Laboratory, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada; Department of Electrical and Computer Engineering, Ryerson University, 350 Victoria St., Toronto, ON, M5B 2K3, Canada. Electronic address: Victor.Yang@sunnybrook.ca.
authors: Victor X D
authors: VX
authors: Yang
mesh_terms: D000328:Adult; D000368:Aged; D019299:Decompression, Surgical / Q000009:adverse effects / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery; D008875:Middle Aged; D065289:Pedicle Screws / Q000009:adverse effects / Q000592:standards*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012447:Sacrum / Q000601:surgery; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods* / Q000592:standards; D025321:Surgery, Computer-Assisted / Q000009:adverse effects / Q000379:methods* / Q000592:standards; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Frameless stereotaxy; Image guidance; Intraoperative navigation; Pedicle screw; Registration; Target registration error