title: Direct anterior cruciate ligament insertion to the femur assessed by histology and 3-dimensional volume-rendered computed tomography.
abstract: OBJECTIVE
  The purpose of this study was to histologically identify the direct and indirect insertion of the femoral anterior cruciate ligament (ACL) insertion. Furthermore, we quantitatively measured the direct femoral insertion area by use of the 3-dimensional (3D) volume-rendered (VR) computed tomography (CT) model.
  
  
  METHODS
  By use of 8 intact cadaveric knees, the lateral femoral condyle including the ACL attachment was sectioned for histologic examination in 3 oblique-axial planes parallel to the roof of the intercondylar notch and in the sagittal planes. Before sectioning, these knees had been subjected to CT to obtain 3D VR images of the femur. Once the direct insertion of the ACL was identified on each histologic section, the corresponding image was superimposed on the corresponding CT image.
  
  
  RESULTS
  The direct ACL insertion, in which dense collagen fibers were connected to the bone by the fibrocartilaginous layer, was microscopically identified at the region between the posteromedial articular cartilage margin of the lateral femoral condyle and the linear bony ridge 7 to 10 mm anterior to the articular cartilage margin. Meticulous comparison of histologic analysis and the 3D VR CT model showed that the ACL direct insertion coincided with a crescent-shaped hollow just behind the linear bony ridge. The direct insertion measured 17.4 +/- 0.9 mm (mean +/- SD) in length, 8.0 +/- 0.5 mm in width, and 128.3 +/- 10.5 mm(2) in area.
  
  
  CONCLUSIONS
  The direct insertion of the ACL is located in the depression between the resident's ridge and the articular cartilage margin on the lateral femoral condyle. It measured 17.4 +/- 0.9 mm in length, 8.0 +/- 0.5 mm in width, and 128.3 +/- 10.5 mm(2) in area.
  
  
  CONCLUSIONS
  Delineation of the ACL femoral direct insertion by 3D VR CT could be a useful tool for planning of accurate femoral tunnel positioning in anatomic ACL reconstruction.
authors.affiliation: Department of Orthopaedics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan. tiwa1884@yahoo.co.jp
authors.forename: Takehiko
authors.initials: T
authors.lastname: Iwahashi
authors.forename: Konsei
authors.initials: K
authors.lastname: Shino
authors.forename: Ken
authors.initials: K
authors.lastname: Nakata
authors.forename: Hidenori
authors.initials: H
authors.lastname: Otsubo
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Suzuki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Amano
authors.forename: Norimasa
authors.initials: N
authors.lastname: Nakamura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology* / Q000648:ultrastructure; D000886:Anthropometry; D002102:Cadaver; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000648:ultrastructure; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D014057:Tomography, X-Ray Computed