title: Electromagnetic Real Time Navigation in the Region of the Posterior Pelvic Ring: An Experimental In-Vitro Feasibility Study and Comparison of Image Guided Techniques.
abstract: BACKGROUND
  Electromagnetic tracking is a relatively new technique that allows real time navigation in the absence of radiation. The aim of this study was to prove the feasibility of this technique for the treatment of posterior pelvic ring fractures and to compare the results with established image guided procedures.
  
  
  METHODS
  Tests were performed in pelvic specimens (Sawbones®) with standardized sacral fractures (Type Denis I or II). A gel matrix simulated the operative approach and a cover was used to disable visual control. The electromagnetic setup was performed by using a custom made carbon reference plate and a prototype stainless steel K-wire with an integrated sensor coil. Four different test series were performed: Group OCT: Optical navigation using preoperative CT-scans; group O3D: Optical navigation using intraoperative 3-D-fluoroscopy; group Fluoro: Conventional 2-D-fluoroscopy; group EMT: Electromagnetic navigation combined with a preoperative Dyna-CT. Accuracy of screw placement was analyzed by standardized postoperative CT-scan for each specimen. Operation time and intraoperative radiation exposure for the surgeon was documented. All data was analyzed using SPSS (Version 20, 76 Chicago, IL, USA). Statistical significance was defined as p< 0.05.
  
  
  RESULTS
  160 iliosacral screws were placed (40 per group). EMT resulted in a significantly higher incidence of optimal screw placement (EMT: 36/40) compared to the groups Fluoro (30/40; p< 0.05) and OCT (31/40; p< 0.05). Results between EMT and O3D were comparable (O3D: 37/40; n.s.). Also, the operation time was comparable between groups EMT and O3D (EMT 7.62 min vs. O3D 7.98 min; n.s.), while the surgical time was significantly shorter compared to the Fluoro group (10.69 min; p< 0.001) and the OCT group (13.3 min; p< 0.001).
  
  
  CONCLUSIONS
  Electromagnetic guided iliosacral screw placement is a feasible procedure. In our experimental setup, this method was associated with improved accuracy of screw placement and shorter operation time when compared with the conventional fluoroscopy guided technique and compared to the optical navigation using preoperative CT-scans. Further studies are necessary to rule out drawbacks of this technique regarding ferromagnetic objects.
authors: University of Aachen Medical Center, Department of Orthopedic Trauma, Aachen, Germany.
authors: Miguel
authors: M
authors: Pishnamaz
authors: University of Aachen Medical Center, Department of Diagnostic and Interventional Radiology, Aachen, Germany.|Helmholtz Institute of RWTH Aachen University & Hospital, Institute of Applied Medical Engineering, Aachen, Germany.
authors: Christoph
authors: C
authors: Wilkmann
authors: University of Aachen Medical Center, Department of Diagnostic and Interventional Radiology, Aachen, Germany.
authors: Hong-Sik
authors: HS
authors: Na
authors: University of Aachen Medical Center, Department of Diagnostic and Interventional Radiology, Aachen, Germany.
authors: Jochen
authors: J
authors: Pfeffer
authors: Helmholtz Institute of RWTH Aachen University & Hospital, Chair of Medical Engineering, Aachen, Germany.
authors: Christoph
authors: C
authors: Hänisch
authors: University of Aachen Medical Center, Department of Orthopedic Trauma, Aachen, Germany.
authors: Max
authors: M
authors: Janssen
authors: University of Aachen Medical Center, Department of Diagnostic and Interventional Radiology, Aachen, Germany.
authors: Philipp
authors: P
authors: Bruners
authors: University of Aachen Medical Center, Department of Orthopedic Trauma, Aachen, Germany.
authors: Philipp
authors: P
authors: Kobbe
authors: University of Aachen Medical Center, Department of Orthopedic Trauma, Aachen, Germany.
authors: Frank
authors: F
authors: Hildebrand
authors: Helmholtz Institute of RWTH Aachen University & Hospital, Institute of Applied Medical Engineering, Aachen, Germany.
authors: Thomas
authors: T
authors: Schmitz-Rode
authors: University of Aachen Medical Center, Department of Orthopedic Trauma, Aachen, Germany.
authors: Hans-Christoph
authors: HC
authors: Pape
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry; D001863:Bone Screws; D060733:Electromagnetic Radiation; 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 / Q000473:pathology / Q000601:surgery*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods; D008953:Models, Anatomic; D012447:Sacrum / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods