title: Passive navigation principle for orthopedic interventions with MR fluoroscopy.
abstract: BACKGROUND
  Of late, computer-assisted surgery has become a novel challenge for orthopedic surgeons. However, for orthopedic interventions magnetic resonance (MR) fluoroscopy is in its early stages of development. The authors have developed an innovative passive navigation concept, which is potentially applicable for many magnetic resonance image (MRI)-guided musculoskeletal interventions. With this method, no switching between different planes is required, since the cross-sectional modality of the MRI is used as a new navigation approach.
  
  
  METHODS
  This method was mainly evaluated in retrograde drilling of artificial osteochondral lesions of the talus as an example of difficult navigation in drill placement due to poor visualization with X-ray and complex anatomy. To accomplish this objective, a passive navigation device was constructed and evaluated in nine cadaveric ankle joint specimens. Feasibility and accuracy of navigated drillings were evaluated.
  
  
  RESULTS
  The interactive high-field MR fluoroscopy and the passive aiming device allow precise drilling of osteochondral lesions of the talus, despite the complex anatomy of the ankle. Drillings could be performed with an accuracy of 1.6 mm. The drilling guide was safe and easy to handle.
  
  
  CONCLUSIONS
  The MR-assisted retrograde drilling of osteochondral lesions may enable precise and safe treatment without radiation exposure. This passive navigation technique for MR fluoroscopy is potentially applicable for many orthopedic interventions and may present an alternative to other navigation methods. Especially, the treatment of pediatric and adolescent patients may benefit from the typical MRI properties.
authors.affiliation: Center for Musculoskeletal Surgery, Charité, Universitätsmedizin Berlin, Berlin, Germany. hermann.bail@charite.de
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Bail
authors.forename: Ulf K M
authors.initials: UK
authors.lastname: Teichgräber
authors.forename: Florian
authors.initials: F
authors.lastname: Wichlas
authors.forename: Jens C
authors.initials: JC
authors.lastname: Rump
authors.forename: Thula
authors.initials: T
authors.lastname: Walter
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Seebauer
mesh_terms: D000843:Ankle Joint / Q000601:surgery*; D002358:Cartilage, Articular / Q000601:surgery; D004867:Equipment Design; D005471:Fluoroscopy / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009140:Musculoskeletal Diseases / Q000601:surgery*; D010008:Osteochondritis Dissecans / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000379:methods*