title: Accuracy of femoral tunnel placement in medial patellofemoral ligament reconstruction: the effect of a nearly true-lateral fluoroscopic view.
abstract: BACKGROUND
  Reconstruction of the medial patellofemoral ligament (MPFL) is an established operative procedure for patients with recurrent episodes of lateral patellar instability. However, recent articles have reported remarkable complication rates, with nonanatomic femoral tunnel positioning in up to 64% of patients.
  
  
  OBJECTIVE
  To evaluate the sensitivity of femoral tunnel placement using lateral fluoroscopic guidance to minor degrees of deviation from the true-lateral view using established radiographic landmarks.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Six human cadaveric femora were used for this study. A 6-mm radiopaque eyelet was used to mark the native femoral insertion of the MPFL according to previously described radiographic landmarks. Radiographic landmarks were also applied with the femur positioned in 2.5° and 5° of internal and external rotation, respectively, and with the femur in 2.5° and 5° of hip abduction and adduction, respectively. The distance between the center of the 6-mm eyelet to the center of the native femoral MPFL insertion, as established in the true-lateral view, was measured and determined as the degree of shift in each position.
  
  
  RESULTS
  Hip adduction, abduction, and internal and external rotations of 2.5° resulted in a shift from the native femoral MPFL insertion point to a more distal (adduction), proximal (abduction), anterior (internal rotation), and posterior location (external rotation) of 2.7 ± 0.7, 2.0 ± 0.7, 2.7 ± 1.1, and 3.0 ± 1.3 mm, respectively (all P < .05). Malpositioning increased to a distance of 5.0 ± 0.7 mm distally, 3.6 ± 1.0 mm proximally, 5.2 ± 0.8 mm anteriorly, and 6.2 ± 0.6 mm posteriorly to the native insertion point when the attachment was marked with 5° of divergence from the true-lateral view (all P < .05).
  
  
  CONCLUSIONS
  The results of this study indicate the high sensitivity of femoral tunnel placement using lateral fluoroscopic guidance to minor degrees of deviation from the true-lateral view.
  
  
  CONCLUSIONS
  The study highlights the importance of an exact lateral view when fluoroscopic guidance is used for femoral tunnel positioning in the daily practice of MPFL reconstruction, and a possible explanation for the high incidence of nonanatomic tunnel placement is suggested.
authors.affiliation: Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medical Center, Göttingen, Germany ARCUS Sportsclinic, Pforzheim, Germany balcarek@sportklinik.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Balcarek
authors.affiliation: Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medical Center, Göttingen, Germany.
authors.forename: Tim Alexander
authors.initials: TA
authors.lastname: Walde
mesh_terms: D000328:Adult; D000368:Aged; D002102:Cadaver; D016022:Case-Control Studies; D005269:Femur / Q000601:surgery; D005471:Fluoroscopy / Q000379:methods / Q000592:standards; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D008023:Ligaments, Articular / Q000601:surgery*; D008297:Male; D017847:Patellar Ligament / Q000601:surgery; D057071:Patellofemoral Joint / Q000601:surgery*; D015641:Radiography, Interventional / Q000379:methods / Q000592:standards; D012008:Recurrence
keywords: fluoroscopy; medial patellofemoral ligament; patellar instability; tunnel placement