title: Anatomic double-bundle anterior cruciate ligament reconstruction, using CT-based navigation and fiducial markers.
abstract: OBJECTIVE
  Accurate placement of separate anteromedial and posterolateral bundle bone tunnels is crucial for anatomic, double-bundle anterior cruciate ligament (ACL) reconstruction. However, identifying the anatomic footprint at which to make the tibial and femoral bone tunnels is not a straightforward procedure. To overcome this problem, we used a CT-based navigation technique with a registration procedure based on fiducial markers (FMs).
  
  
  METHODS
  Preoperatively, 10 FM points were placed on skin around knee joint and scanned with CT. Imaging data of the knee were recorded on the computer system for preoperative registration and surgical planning. Intraoperatively, with a reference frame fixed to the distal medial aspect of femur and tibia, paired-point matching registration was performed with the use of points marked on skin through FM center holes. During tibial tunnel guide wire placement, tibial aiming guide with tracking device fed back the position of tip and direction of the guide wire on the three-dimensional (3D) tibia bone surface image and multiple image planes in real time. For the femoral side, the navigation pointer was placed at the footprint center with visual guidance of 3D image of lateral wall sagittal view on navigation monitor and marked with navigation awl.
  
  
  RESULTS
  The average registration accuracy of 22 consecutive patients was 0.7 ± 0.2 mm and 0.6 ± 0.2 mm for femoral and tibial bone, respectively. Most of the bone tunnel positions evaluated with 3D-CT image were confirmed to be accurately placed in reference to the preoperative plan. There was no damage to femoral condyle cartilage and no other complication.
  
  
  CONCLUSIONS
  This new CT-based computer navigation system opens the possibility for surgeons to plan bone tunnel positioning preoperatively and control it during technically demanding anatomic double-bundle ACL reconstruction.
authors.affiliation: Department of Orthopedic Surgery, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Tensho
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kodaira
authors.forename: Gaku
authors.initials: G
authors.lastname: Yasuda
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yoshimura
authors.forename: Nobuyo
authors.initials: N
authors.lastname: Narita
authors.forename: Susumu
authors.initials: S
authors.lastname: Morioka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kato
authors.forename: Naoto
authors.initials: N
authors.lastname: Saito
mesh_terms: D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging / Q000601:surgery*; D001182:Arthroscopy / Q000379:methods; D015331:Cohort Studies; D005260:Female; D057918:Fiducial Markers / Q000706:statistics & numerical data; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D011300:Preoperative Care / Q000379:methods; D015641:Radiography, Interventional / Q000379:methods*; D019651:Plastic Surgery Procedures / Q000379:methods; D053441:Suture Anchors; D014057:Tomography, X-Ray Computed / Q000379:methods