title: Percutaneous antegrade scaphoid screw placement: a feasibility and accuracy analysis of a novel electromagnetic navigation technique versus a standard fluoroscopic method.
abstract: BACKGROUND
  Central screw positioning in the scaphoid provides biomechanical advantages.
  
  
  METHODS
  A prospective randomized study of six fluoroscopically guided and six electromagnetically navigated screw (ENS) placements was performed on human cadavers. Accuracy of screw position was determined. Intraoperative fluoroscopy exposure times, readjustments of drilling directions, complete restarts and complications were documented.
  
  
  RESULTS
  The ENS method provided a mean time benefit of 7.34 min compared with the standard method and the mean screw length ratio (SLR coronar: ENS 0.96 ± 0.04 mm, SFF: 0.92 ± 0.04 mm, P = 0.065; SLR sagittal: ENS 0.98 ± 0.02 mm, SFF: 0.91 ± 0.04 mm, P = 0.009) and the screw axis deviation angle (AD coronar: ENS 3.33 ± 2.34°, SFF: 10.33 ± 2.58°, P = 0.002; AD sagittal: ENS 2.83 ± 0.98°, SFF: 11.00 ± 6.16°, P = 0.002) were lower. Using the electromagnetic navigation procedure no drilling readjustments or restarts were required, no cortical breach occurred.
  
  
  CONCLUSIONS
  Compared with the standard fluoroscopic technique, the ENS method used in this study showed higher accuracy, less complications, required less operation and radiation exposure time.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Medical Center, Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Hoffmann
authors.forename: O D
authors.initials: OD
authors.lastname: Reinsch
authors.forename: J P
authors.initials: JP
authors.lastname: Petersen
authors.forename: M
authors.initials: M
authors.lastname: Schröder
authors.forename: M
authors.initials: M
authors.lastname: Priemel
authors.forename: A S
authors.initials: AS
authors.lastname: Spiro
authors.forename: J M
authors.initials: JM
authors.lastname: Rueger
authors.forename: S
authors.initials: S
authors.lastname: Yarar
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D055590:Electromagnetic Phenomena; D005240:Feasibility Studies; D005471:Fluoroscopy; D005592:Fracture Fixation / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional; D011446:Prospective Studies; D011897:Random Allocation; D065287:Robotic Surgical Procedures; D021361:Scaphoid Bone / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery*; D025321:Surgery, Computer-Assisted
keywords: electromagnetic navigation; fluoroscopy-free; minimal-invasive; scaphoid fracture