title: A spine frame for intra-operative fixation to increase accuracy in spinal navigation and robotics.
abstract: OBJECTIVE
  Intra-operative movements due to mechanical ventilation or manipulations are a limiting factor for accurate spinal navigation or robotic-assisted spinal surgery. The purpose of this study was to assess the accuracy of an intra-operative spinal fixation device in an experimental setup.
  
  
  METHODS
  We developed a fixation device, attached to the operating table, that combines soft tissue retraction with spinal process fixation. Using a lumbar spine cadaver, tightness of fixation was evaluated using two measurement systems. Accuracy measurements using changes in spatial co-ordinates of implanted reference markers were performed in three segments, following different manipulations of the spine. In addition, for intra-operative movements of the spine during mechanical ventilation, the range of motion was determined in 10 patients during lumbar interbody fusion.
  
  
  RESULTS
  The spine frame was easy to use and did not restrict screw insertion. Mean deviations of the markers' in all segments were measured at between 0.35 and 0.8 mm, following pedicle screw insertion and lateral traction. Intra-operative range of motion of the spine was measured with a mean value of 8.7 +/- 3.3 mm.
  
  
  CONCLUSIONS
  Using our spine frame, a rigid fixation following manipulation of the spine was demonstrated. By overcoming the intra-operative movement-dependent inaccuracy, safety in navigated spine surgery and robotic-assisted procedures might be improved.
authors.affiliation: Department of Neurosurgery, Charité, Virchow Medical Center, Universitätsmedizin of Berlin, Germany. uthomale@charite.de
authors.forename: Ulrich-W
authors.initials: UW
authors.lastname: Thomale
authors.forename: Marc
authors.initials: M
authors.lastname: Kneissler
authors.forename: Andreas
authors.initials: A
authors.lastname: Hein
authors.forename: Martin
authors.initials: M
authors.lastname: Maetzig
authors.forename: Stefan-Nikolaus
authors.initials: SN
authors.lastname: Kroppenstedt
authors.forename: Tim
authors.initials: T
authors.lastname: Lueth
authors.forename: Christian
authors.initials: C
authors.lastname: Woiciechowsky
mesh_terms: D000704:Analysis of Variance; D001863:Bone Screws; D002102:Cadaver; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D009038:Motion; D012371:Robotics / Q000295:instrumentation*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*; D025321:Surgery, Computer-Assisted; D014143:Traction