title: Volume slicing of cone-beam computed tomography images for navigation of percutaneous scaphoid fixation.
abstract: OBJECTIVE
  Percutaneous scaphoid fixation (PSF) is growing in popularity as a treatment option for non-displaced fractures. Success of this procedure demands high-precision screw placement, which can be difficult to achieve with standard 2D imaging. This study aimed to develop and test a system for computer-assisted navigation using volume slicing of 3D cone-beam computed tomography (CBCT).
  
  
  METHODS
  The navigated technique involved a distinctive workflow in which a 3D CBCT imager was calibrated preoperatively, circumventing the need for intraoperative patient-based registration. Intraoperatively, a 3D CBCT image was acquired for both preoperative planning and direct navigation using volume-rendered slices. An in vitro study was conducted to compare the navigated approach to two conventional fluoroscopic methods for volar PSF. The surgical goal was to insert a guide wire to maximize both length and central placement.
  
  
  RESULTS
  There was no significant difference in the mean central placement of guide wire, although the variance in central placement was significantly lower using VS navigation (P < 0.01). The lengths of the drill paths were significantly longer for the VS-navigated group compared with one 2D group (P < 0.1). Each navigated trial required only one drilling attempt and resulted in less radiation exposure than conventional C-arm (P < 0.01).
  
  
  CONCLUSIONS
  Volume-sliced navigation achieved a more repeatable and reliable central pin placement, with fewer drilling attempts than conventional 2D techniques. Volume-sliced navigation had a higher number of drill paths within the optimal zone maximizing both length of the path and depth from the surface.
authors.affiliation: Department of Mechanical Engineering, Queen's University, Kingston, ON, Canada. smith@me.queensu.ca
authors.forename: Erin J
authors.initials: EJ
authors.lastname: Smith
authors.forename: Hisham A
authors.initials: HA
authors.lastname: Al-Sanawi
authors.forename: Braden
authors.initials: B
authors.lastname: Gammon
authors.forename: Paul J
authors.initials: PJ
authors.lastname: St John
authors.forename: David R
authors.initials: DR
authors.lastname: Pichora
authors.forename: Randy E
authors.initials: RE
authors.lastname: Ellis
mesh_terms: D001858:Bone Nails; D001863:Bone Screws; D002138:Calibration; D054893:Cone-Beam Computed Tomography; D005593:Fracture Fixation, Internal / Q000379:methods*; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D021361:Scaphoid Bone / Q000000981:diagnostic imaging* / Q000601:surgery; D025321:Surgery, Computer-Assisted / Q000379:methods*