title: Radiographic positions of femoral ACL, AM and PL centres: accuracy of guidelines based on the lateral quadrant method.
abstract: OBJECTIVE
  Femoral tunnel positioning is an important factor in anatomical ACL reconstructions. To improve accuracy, lateral radiographic support can be used to determine the correct tunnel location, applying the quadrant method. Piefer et al. (Arthroscopy 28:872-881, 2012) combined various outcomes of eight studies applying this method to one guideline. The studies included in that guideline used various insertion margins, imaging techniques and measurement methods to determine the position of the ACL centres. The question we addressed is whether condensing data from various methods into one guideline, results in a more accurate guideline than the results of one study.
  
  
  METHODS
  The accuracy of the Piefer's guideline was determined and compared to a guideline developed by Luites et al. (2000). For both guidelines, we quantified the mean absolute differences in positions of the actual anatomical centres of the ACL, AM and PL measured on the lateral radiographs of twelve femora with the quadrant method and the positions according to the guidelines.
  
  
  RESULTS
  The accuracy of Piefer's guidelines was 2.4 mm (ACL), 2.7 mm (AM) and 4.6 mm (PL), resulting in positions significantly different from the actual anatomical centres. Applying Luites' guidelines for ACL and PL resulted in positions not significantly different from the actual centres. The accuracies were 1.6 mm (ACL) and 2.2 mm (PL and AM), which were significantly different from Piefer for the PL centres, and therefore more accurate.
  
  
  CONCLUSIONS
  Condensing the outcomes of multiple studies using various insertion margins, imaging techniques and measurement methods, results in inaccurate guidelines for femoral ACL tunnel positioning at the lateral view.
  
  
  CONCLUSIONS
  An accurate femoral tunnel positioning for anatomical ACL reconstruction is a key issue. The results of this study demonstrate that averaging of various radiographic guidelines for anatomical femoral ACL tunnel placement in daily practice, can result in inaccurate tunnel positions.
  
  
  METHODS
  Diagnostic study, Level 1.
authors.affiliation: Sint Maartenskliniek Research, P.O. Box 9011, 6500 GM, Nijmegen, The Netherlands. jwhluites@gmail.com.
authors.forename: Joan W H
authors.initials: JWH
authors.lastname: Luites
authors.affiliation: Orthopaedic Research Lab, Radboud University Medical Center, Nijmegen, The Netherlands.|Laboratory for Biomechanical Engineering, University of Twente, Enschede, The Netherlands.
authors.forename: Nico
authors.initials: N
authors.lastname: Verdonschot
mesh_terms: D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging* / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods* / Q000592:standards; D002102:Cadaver; D005269:Femur / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D015203:Reproducibility of Results
keywords: Accuracy; Anterior cruciate ligament reconstruction; Anteromedial and posterolateral bundle femoral centres; Lateral radiographic position; Quadrant method