title: The difference in centre position in the ACL femoral footprint inclusive and exclusive of the fan-like extension fibres.
abstract: OBJECTIVE
  The purpose of this study was to compare the centre position of each anterior cruciate ligament bundle in its femoral footprint in measurements including and excluding the fan-like extension fibres.
  
  
  METHODS
  Fourteen non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ligaments. The ACL was divided into antero-medial (AM) and postero-lateral (PL) bundles according to the difference in tension patterns. The ACL was carefully dissected, and two outlines were made of the periphery of each bundle insertion site: those which included and those which excluded the fan-like extension fibres. An accurate lateral view of the femoral condyle was photographed with a digital camera, and the images were downloaded to a personal computer. The centre position of each bundle, including and excluding the fan-like extension fibres, was measured with ImageJ software (National Institution of Health). Evaluation of the centre position was performed using the modified quadrant method.
  
  
  RESULTS
  The centre of the femoral AM bundle including the fan-like extension was located at 28.8% in a shallow-deep direction and 37.2% in a high-low direction. When the AM bundle was evaluated without the fan-like extension, the centre was significantly different at 34.6% in a shallow-deep direction (p = 0.000) and 36% in a high-low direction. The centre of the PL bundle including the fan-like extension was found at 37.1% in a shallow-deep direction and 73.4% in a high-low direction. When the PL bundle was evaluated without the fan-like extension, the centre was significantly different at 42.7% in a shallow-deep direction (p = 0.000) and 69.3% in a high-low direction (p = 0.000).
  
  
  CONCLUSIONS
  The centre position of the AM and PL bundles in the femoral ACL footprint was significantly different depending on the inclusion or exclusion of the fan-like extension fibres. For the clinical relevance, to reproduce the direct femoral insertion in the anatomical ACL reconstruction, tunnels should be placed relatively shallow and high in the femoral ACL footprint.
authors.affiliation: Department of Orthopaedic Surgery, Kamimoku Hot Springs Hospital, Minakami, Japan. sekaiwoseisu@yahoo.co.jp.
authors.forename: Takanori
authors.initials: T
authors.lastname: Iriuchishima
authors.affiliation: Department of Orthopaedic Surgery, Nihon University Hospital, Tokyo, Japan.
authors.forename: Keinosuke
authors.initials: K
authors.lastname: Ryu
authors.affiliation: Department of Functional Morphology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Aizawa
authors.affiliation: Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburg, PA, USA.
authors.forename: Freddie H
authors.initials: FH
authors.lastname: Fu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology* / Q000601:surgery; D002102:Cadaver; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology* / Q000601:surgery; D008023:Ligaments, Articular / Q000033:anatomy & histology; D008297:Male
keywords: Anatomy; Anterior cruciate ligament; Fan-like extension; Footprint