title: Iliosacral screw insertion using CT-3D-fluoroscopy matching navigation.
abstract: BACKGROUND
  Percutaneous iliosacral screw insertion requires substantial experience and detailed anatomical knowledge to find the proper entry point and trajectory even with the use of a navigation system. Our hypothesis was that three-dimensional (3D) fluoroscopic navigation combined with a preoperative computed tomography (CT)-based plan could enable surgeons to perform safe and reliable iliosacral screw insertion. The purpose of the current study is two-fold: (1) to demonstrate the navigation accuracy for sacral fractures and sacroiliac dislocations on widely displaced cadaveric pelves; and (2) to report the technical and clinical aspects of percutaneous iliosacral screw insertion using the CT-3D-fluoroscopy matching navigation system.
  
  
  METHODS
  We simulated three types of posterior pelvic ring disruptions with vertical displacements of 0, 1, 2 and 3cm using cadaveric pelvic rings. A total of six fiducial markers were fixed to the anterior surface of the sacrum. Target registration error over the sacrum was assessed with the fluoroscopic imaging centre on the second sacral vertebral body. Six patients with pelvic ring fractures underwent percutaneous iliosacral screw placement using the CT-3D-fluoroscopy matching navigation. Three pelvic ring fractures were classified as type B2 and three were classified as type C1 according to the AO-OTA classification. Iliosacral screws for the S1 and S2 vertebra were inserted.
  
  
  RESULTS
  The mean target registration error over the sacrum was 1.2mm (0.5-1.9mm) in the experimental study. Fracture type and amount of vertical displacement did not affect the target registration error. All 12 screws were positioned correctly in the clinical series. There were no postoperative complications including nerve palsy. The mean deviation between the planned and the inserted screw position was 2.5mm at the screw entry point, 1.8mm at the area around the nerve root tunnels and 2.2mm at the tip of the screw.
  
  
  CONCLUSIONS
  The CT-3D-fluoroscopy matching navigation system was accurate and robust regardless of pelvic ring fracture type and fragment displacement. Percutaneous iliosacral screw insertion with the navigation system is clinically feasible.
authors: Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: masaki-tko@umin.ac.jp.
authors: Masaki
authors: M
authors: Takao
authors: Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Takashi
authors: T
authors: Nishii
authors: Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Takashi
authors: T
authors: Sakai
authors: Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Hideki
authors: H
authors: Yoshikawa
authors: Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Nobuhiko
authors: N
authors: Sugano
mesh_terms: D000328:Adult; D001863:Bone Screws; D002102:Cadaver; D002983:Clinical Competence; D005260:Female; D005471:Fluoroscopy / Q000379:methods; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D006801:Humans; D007085:Ilium / Q000000981:diagnostic imaging / Q000293:injuries / Q000473:pathology / Q000601:surgery*; D021621:Imaging, Three-Dimensional; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012447:Sacrum / Q000000981:diagnostic imaging / Q000293:injuries / Q000473:pathology / Q000601:surgery*; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: 3D fluoroscopy; CT-based plan; Iliosacral screw; Navigation