title: Iliac screw fixation using computer-assisted computer tomographic image guidance:  technical note.
abstract: BACKGROUND
  Iliac screw fixation is a powerful tool used by spine surgeons to achieve fusion across the lumbosacral junction for a number of indications, including deformity, tumor, and pseudarthrosis. Complications associated with screw placement are related to blind trajectory selection and excessive soft tissue dissection.
  
  
  OBJECTIVE
  To describe the technique of iliac screw fixation using computed tomographic (CT)-based image guidance.
  
  
  METHODS
  Intraoperative registration and verification of anatomic landmarks are performed with the use of a preoperatively acquired CT of the lumbosacral spine. With the navigation probe, the ideal starting point for screw placement is selected while visualizing the intended trajectory and target on a computer screen. Once the starting point is selected and marked with a burr, a drill guide is docked within this point and the navigation probe re-inserted, confirming the trajectory. The probe is then removed and the high-speed drill reinserted within the drill guide. Drilling is performed to a depth measured on the computer screen and a screw is placed.
  
  
  RESULTS
  Confirmation of accurate placement of iliac screws can be performed with standard radiographs.
  
  
  CONCLUSIONS
  CT-guided navigation allows for 3-dimensional visualization of the pelvis and minimizes complications associated with soft-tissue dissection and breach of the ilium during screw placement.
authors.affiliation: Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA. shin.john@mgh.harvard.edu
authors.forename: John H
authors.initials: JH
authors.lastname: Shin
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hoh
authors.forename: Iain H
authors.initials: IH
authors.lastname: Kalfas
mesh_terms: D001863:Bone Screws / Q000592:standards*; D006801:Humans; D007085:Ilium / Q000033:anatomy & histology / Q000601:surgery*; D007431:Intraoperative Complications / Q000209:etiology / Q000517:prevention & control; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000601:surgery; D038361:Neuronavigation / Q000379:methods; D010388:Pelvis / Q000033:anatomy & histology / Q000601:surgery; D012447:Sacrum / Q000033:anatomy & histology / Q000601:surgery; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*