title: Image guidance can support scaphoid K-wire insertion: an experimental study and initial clinical experience.
abstract: OBJECTIVE
  In the treatment of small bone fractures, such as the scaphoid bone, conventional navigation is limited by its dependence on fixed reference arrays. We introduce a new technique based on reference markers in surgical instruments. If visible on a standard fluoroscopic image, static trajectories are overlaid in this image to guide implant insertions. Fixed markers are not required. The purpose of this study was to identify the possible advantages of the new guidance technique.
  
  
  METHODS
  For this study, 20 artificial hand specimens were randomized into two groups and blinded with polyurethane foam: 10 were treated conventionally and 10 were image guided. We used a clip containing radiopaque markers, which was detected by the system's workstation. A static trajectory was displayed consecutively in the fluoroscopic image to serve as an aiming device. Secondly, we included 3 patients with fractures of the scaphoid bone to test the integrability of this novel method in a clinical setting.
  
  
  RESULTS
  In the experimental setup, trajectory guidance reduced the duration of surgery and radiation exposure. Furthermore, it reduced the perforation rate. Accuracy was not improved by the new technique. For clinical cases, the system was integrated into the accommodated surgical workflow and rated as very helpful by users.
  
  
  CONCLUSIONS
  The system helped reduce the misplacement rate and the emission of radiation. The main limitations were that trajectories were not displayed in real time and could only be shown in a single fluoroscopic image. However, the system is simple and can be easily integrated into the surgical workflow.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Ulm University, Albert-Einstein-Allee 23, 89081 Ulm, Germany. hendrik.schoell@uniklinik-ulm.de
authors.forename: Hendrik
authors.initials: H
authors.lastname: Schöll
authors.forename: Martin
authors.initials: M
authors.lastname: Mentzel
authors.forename: Almut
authors.initials: A
authors.lastname: Jones
authors.forename: Joachim
authors.initials: J
authors.lastname: Gülke
authors.forename: Florian
authors.initials: F
authors.lastname: Gebhard
authors.forename: Michael
authors.initials: M
authors.lastname: Kraus
mesh_terms: D000328:Adult; D001864:Bone Wires; D015331:Cohort Studies; D005240:Feasibility Studies; D005260:Female; D005471:Fluoroscopy; D005593:Fracture Fixation, Internal; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011857:Radiographic Image Interpretation, Computer-Assisted; D021361:Scaphoid Bone / Q000293:injuries*; D025321:Surgery, Computer-Assisted; D055815:Young Adult