title: Usefulness of navigated O-arm(®) in a teaching center for spinal trauma.
abstract: BACKGROUND
  There is a relatively high incidence of screw misplacement during spinal instrumentation due to distortion of normal anatomy following spinal trauma.
  
  
  OBJECTIVE
  To evaluate and share the initial experience with the use of neuro-navigated 3D O-arm(®) (Medtronic, USA) as compared to traditional 2D fluoroscopy in atrauma center in India.
  
  
  METHODS
  In this retrospective study, consecutive patients of spinal injury who underwent screw fixation under O-arm guidance over nine-month period (July 2010 till March 2011) were evaluated for accuracy of screw placement. An equal number of consecutive patients prior to March 2011 who underwent screw fixation in 2D fluoroscopy were included for comparison. Patient demographics and radiology were reviewed and spinal injury was assessed using the ASIA grading in both the groups. Screw placement was assessed by postoperative CT scans of the relevant spine and accuracy of screw placement and breach of the medial or lateral cortex of the pedicle were recorded for each case.
  
  
  RESULTS
  In the O-arm group, there were 57 patients in whom 210 screws were inserted. None of the patients had screw mal-placement. In 2D fluoroscopy group, 57 patients had 268 screws insertions. 10 (3.73%) screws were found to be malpositioned in the postoperative CT scans (8 in thoracic spine and 2 in odontoid fractures). The malposition rate was highly significant in 2D fluoroscopy thoracolumbar (P = 0.0015) subgroup. One patient had neurological deterioration and three patients required repositioning of the screws.
  
  
  CONCLUSIONS
  In a teaching center with multiple surgeons, the O-arm(®) imaging ensures accurate placement of screws as compared to traditional 2D fluoroscopy.
authors.affiliation: Department of Neurosurgery, JPN Apex Trauma Centre, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Agrawal
keywords: 3D intraoperative imaging; O-arm; complication; screw; spine; trauma