title: Cortical Bony Thickening of the Lateral Intercondylar Wall: The Functional Attachment of the Anterior Cruciate Ligament.
abstract: The anatomy of the anterior cruciate ligament (ACL) has become the subject of much debate. There has been extensive study into attachment points of the native ligament, especially regarding the femoral attachment. Some of these studies have suggested that fibers in the ACL are of differing functional importance. Fibers with higher functional importance would be expected to exert larger mechanical stress on the bone. According to Wolff's law, cortical thickening would be expected in these areas.
  
  
  
  To examine cortical thickening in the region of the ACL footprint (ie, the functional footprint of the ACL).
  
  
  
  Descriptive laboratory study.
  
  
  
  Using micro-computed tomography with resolutions ranging from 71 to 91 μm, the cortical thickness of the lateral wall of the intercondylar notch in 17 cadaveric knees was examined, along with surface topography. After image processing, the relationship between the cortical thickening and surface topology was visually compared.
  
  
  
  A pattern of cortical thickening consistent with the functional footprint of the ACL was found. On average, this area was 3 times thicker than the surrounding bone and significantly thicker than the remaining lateral wall ( P < .0001). This thickening was roughly elliptical in shape (with a mean centroid at 23.5 h:31 t on a Bernard and Hertel grid) and had areas higher on the wall where greater thickness was present. The relationship to previously reported osseous landmarks was variable, although the patterns were broadly consistent with those reported in previous studies describing direct and indirect fibers of the ACL.
  
  
  
  The findings of this study are consistent with those of recent studies describing fibers in the ACL of differing functional importance. The area in which the thickening was found has been defined and is likely to represent the functional footprint of the ACL.
  
  
  
  This information is of value to surgeons when determining the optimal place to position the femoral attachment site of the reconstructed ACL.
authors.affiliation: University of Warwick, Coventry, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Norman
authors.affiliation: University Hospital Coventry and Warwickshire NHS Trust, Coventry, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Metcalfe
authors.affiliation: University Hospital Coventry and Warwickshire NHS Trust, Coventry, UK.
authors.forename: Timothy
authors.initials: T
authors.lastname: Barlow
authors.affiliation: University of Warwick, Coventry, UK.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Hutchinson
authors.affiliation: University Hospital Coventry and Warwickshire NHS Trust, Coventry, UK.
authors.forename: Peter J M
authors.initials: PJ
authors.lastname: Thompson
authors.affiliation: University Hospital Coventry and Warwickshire NHS Trust, Coventry, UK.
authors.forename: Timothy J W
authors.initials: TJ
authors.lastname: Spalding
authors.affiliation: University of Warwick, Coventry, UK.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Williams
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D002102:Cadaver; D000071538:Cortical Bone / Q000502:physiology*; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D055114:X-Ray Microtomography
keywords: ACL anatomy; anterior cruciate ligament; attachment site; micro-CT measurement