title: The importance of Blumensaat's line morphology for accurate femoral ACL footprint evaluation using the quadrant method.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the difference in the center position of the ACL footprint based on grid placement using the quadrant method according to the morphological variations of the Blumensaat's line.
  
  
  METHODS
  Fifty-nine non-paired human cadaver knees were used. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch, and the digital images were evaluated using Image J software. The femoral ACL footprint was periphery outlined and the center position was automatically measured. Following Iriuchishima's classification, the morphology of the Blumensaat's line was classified into straight, small hill, and large hill types. From the images, grid quadrants were placed as: Grid (1) without consideration of hill existence and not including the chondral lesion. Grid (2) without consideration of hill existence and including the chondral lesion. Grid (3) with consideration of hill existence and not including the chondral lesion. Grid (4) with consideration of hill existence and including the chondral lesion.
  
  
  RESULTS
  The straight type consisted of 19 knees, the small hill type 13 knees, and the large hill type 27 knees. Depending on the quadrant grid placement, significant center position difference was observed both in the shallow-deep, and high-low direction. When hill existence was considered, the center position of the ACL was significantly changed to a high position.
  
  
  CONCLUSIONS
  The center position of the ACL footprint exhibited significant differences according to Blumensaat's line morphology. For clinical relevance, when ACL surgery is performed in knees with small or large hill type variations, surgeons should pay close attention to femoral tunnel evaluation and placement, especially when using the quadrant method.
authors.affiliation: Department of Orthopaedic Surgery, Nihon University Hospital, Tokyo, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Yahagi
authors.affiliation: Department of Orthopaedic Surgery, Kamimoku Hot Springs Hospital, Minakami, Japan. sekaiwoseisu@yahoo.co.jp.|Department of Functional Morphology, Nihon University School of Medicine, Tokyo, Japan. sekaiwoseisu@yahoo.co.jp.
authors.forename: Takanori
authors.identifier: http://orcid.org/0000-0001-5789-6520
authors.initials: T
authors.lastname: Iriuchishima
authors.affiliation: Department of Orthopaedic Surgery, Nihon University Hospital, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Horaguchi
authors.affiliation: Department of Orthopaedic Surgery, Nihon University Hospital, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Suruga
authors.affiliation: Department of Orthopaedic Surgery, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tokuhashi
authors.affiliation: Department of Functional Morphology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Aizawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology* / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods; D002102:Cadaver; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007719:Knee Joint / Q000033:anatomy & histology / Q000601:surgery; D008297:Male; D010781:Photography
keywords: Anatomy; Anterior cruciate ligament; Blumensaat’s line; Intercondylar notch; Quadrant method