title: Safety and Accuracy of Freehand Versus Navigated Iliac Screws: Results From 222 Screw Placements.
abstract: METHODS
  Retrospective review.
  
  
  OBJECTIVE
  To compare the safety and accuracy of the freehand technique versus stereotactic navigation for placement of iliac screws.
  
  
  BACKGROUND
  Iliac screw fixation is often used to augment lumbosacral reconstruction in advanced spine disease to increase the likelihood of successful arthrodesis. Iliac screws can be placed with image guidance, using either intraoperative fluoroscopy or computed tomography (CT) to guide navigation. However, these imaging modalities add radiation exposure and can disrupt workflow. The freehand technique is an alternative strategy that decreases radiation exposure and workflow disruption but may compromise safety and accuracy.
  
  
  METHODS
  A retrospective review was performed for a consecutive series of adult patients with degenerative spine conditions who underwent posterior reconstruction with iliac screw placement between 2011 and 2016. Clinical and radiographic data were collected and analyzed. The accuracy of iliac screw placement was determined with either intraoperative/postoperative CT imaging or anteroposterior/lateral radiography when CT was not performed.
  
  
  RESULTS
  Bilateral iliac screws were placed in all 111 patients, for a total of 222 iliac screws. Eighty screws were placed with the freehand technique and 142 with the intraoperative navigation technique. CT imaging was used to assess placement accuracy of 124 screws (46 freehand [37%], 78 navigated [63%]). Accuracy was similar for the freehand group (89%, 41/46) and the navigated group (96%, 75/78) (P = 0.12). For patients without intraoperative/postoperative CT imaging, radiography was used to assess placement accuracy of 98 screws (34 freehand, 64 navigated) and the placement accuracy rate for the freehand group (100%, 34/34) was comparable to that for the navigated group (98%, 63/64) (P = 0.46). No complications attributable to iliac screw placement occurred in either group.
  
  
  CONCLUSIONS
  Overall, there was no difference in the safety and accuracy between the freehand and navigated techniques.
  
  
  METHODS
  4.
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ.
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Hlubek
authors.forename: Kaith K
authors.initials: KK
authors.lastname: Almefty
authors.forename: David S
authors.initials: DS
authors.lastname: Xu
authors.forename: Jay D
authors.initials: JD
authors.lastname: Turner
authors.forename: Udaya Kumar
authors.initials: UK
authors.lastname: Kakarla
mesh_terms: D000328:Adult; D000368:Aged; D001863:Bone Screws / Q000009:adverse effects / Q000592:standards*; D005260:Female; D006801:Humans; D007085:Ilium / Q000000981:diagnostic imaging / Q000601:surgery*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods / Q000592:standards*; D013238:Stereotaxic Techniques; D014057:Tomography, X-Ray Computed / Q000379:methods