title: Anterior cruciate ligament: an anatomical exploration in humans and in a selection of animal species.
abstract: OBJECTIVE
  Many anatomical anterior cruciate ligament (ACL) studies have indicated that the human ACL is composed of two functional bundles: the antero-medial (AM) and postero-lateral (PL). The purpose of this study is to compare the ACL anatomy among human and assorted animal species.
  
  
  METHODS
  Twenty fresh-frozen knees specimen were used: five humans, ten porcine, one goat, one Kodiak bear, one African lion, one Diana monkey and one Gazelle antelope. All the specimens were dissected to expose the ACL and to visualize the number of bundles and attachment patterns on the tibia and femur. Following the fibre orientation of the individual bundles, a wire loop was used to bluntly separate the bundles starting from the tibial insertion site to the femoral insertion site. In the human and porcine ACL, each bundle was separated into approximately 2 mm diameter segments and then tracked in order to establish the individual bundle's specific pattern of insertion on the femur and tibia.
  
  
  RESULTS
  It appeared that all human and animal knee specimens had three bundles that made up their ACL. In addition, it was noted that among the various specimens species, all viewed with an anterior view, and at 90° knee flexion, the ACL bony insertion sites had similar attachment patterns.
  
  
  CONCLUSIONS
  In all the specimens, including human, the ACL had three distinct bundles: AM, intermediate (IM) and PL. The bundles were composed of multiple fascicles arranged in a definite order and similar among the different species.
authors.affiliation: Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, 3471 Fifth Avenue, Suite #1011, Pittsburgh, PA, 15213, USA.
authors.forename: Gof
authors.initials: G
authors.lastname: Tantisricharoenkul
authors.forename: Monica
authors.initials: M
authors.lastname: Linde-Rosen
authors.forename: Paulo
authors.initials: P
authors.lastname: Araujo
authors.forename: Jingbin
authors.initials: J
authors.lastname: Zhou
authors.forename: Patrick
authors.initials: P
authors.lastname: Smolinski
authors.forename: Freddie H
authors.initials: FH
authors.lastname: Fu
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology*; D005269:Femur / Q000033:anatomy & histology; D006801:Humans; D007717:Knee / Q000033:anatomy & histology; D008297:Male; D008875:Middle Aged; D013264:Stifle / Q000033:anatomy & histology; D013977:Tibia / Q000033:anatomy & histology