title: [Computer-assisted screw placement into the posterior pelvic ring: assessment of different navigated procedures in a cadaver trial].
abstract: OBJECTIVE
  Computer-assisted procedures have recently been introduced for navigated iliosacral screw placement. Currently there are only few data available reflecting results and outcome of the different navigated procedures which may be used for this indication. We therefore evaluated the features of a new 3D image intensifier used for navigated iliosacral screw placement compared to 2D fluoroscopic and CT navigation.
  
  
  METHODS
  Twenty fixed human cadavers were used in this trial. Cannulated cancellous screws were percutaneously implanted in the supine position in four treatment groups. An optoelectronic system was used for the navigated procedures. Screw placement was postoperatively assessed by fluoroscopic 3D scan and CT. The target parameters of this investigation were practicability, precision as well as procedure and fluoroscopic time per screw.
  
  
  RESULTS
  All navigated procedures revealed a significant loss of time compared to non-navigated screw placement (2D: p<0.001, 3D: p>0.05, CT: p<0.001). Simultaneously a significant decrease of radiation exposure time was observed in the navigated groups (p<0.001 each). The misplacement rate was 20% in the non-navigated and the 2D fluoroscopic navigated group each. Procedures providing 3D imaging of the posterior pelvis did not produce any screw misplacement (p>0.05). However, the CT procedure was associated with time-consuming registration and high rates of failed matching procedures.
  
  
  CONCLUSIONS
  Our data show a clear benefit of using C-arm navigation for iliosacral screw placement compared with the CT-based procedure. While both fluoroscopy-based navigation procedures decrease intraoperative radiation exposure times, only 3D fluoroscopic navigation seems to improve the precision compared to non-navigated screw placement.
authors.affiliation: Zentrum für Operative Medizin, Klinik und Poliklinik für Unfall-, Hand- und Wiederherstellungschirurgie, Universitäts-Klinikum Hamburg-Eppendorf, Martinistrasse 42, 20246 Hamburg. briem@uke.uni-hamburg.de
authors.forename: D
authors.initials: D
authors.lastname: Briem
authors.forename: J M
authors.initials: JM
authors.lastname: Rueger
authors.forename: P G C
authors.initials: PG
authors.lastname: Begemann
authors.forename: Z
authors.initials: Z
authors.lastname: Halata
authors.forename: T
authors.initials: T
authors.lastname: Bock
authors.forename: W
authors.initials: W
authors.lastname: Linhart
authors.forename: J
authors.initials: J
authors.lastname: Windolf
mesh_terms: D001863:Bone Screws; D005240:Feasibility Studies; D005471:Fluoroscopy; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D019060:Minimally Invasive Surgical Procedures; D010384:Pelvic Bones / Q000000981:diagnostic imaging / Q000601:surgery*; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D025321:Surgery, Computer-Assisted; D013996:Time and Motion Studies; D014057:Tomography, X-Ray Computed; D014584:User-Computer Interface