title: Codominance of the individual posterior cruciate ligament bundles. An analysis of bundle lengths and orientation.
abstract: BACKGROUND
  It is unclear how each bundle of the posterior cruciate ligament contributes to posterior knee stability.
  
  
  OBJECTIVE
  Changes in bundle orientation and length occur such that neither bundle dominates in restraining posterior tibial motion throughout knee flexion and extension.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Six fresh-frozen cadaveric knees were studied in a joint-testing rig with individual quadriceps and hamstring muscle loading. Kinematic data for the tibia and femur were obtained at knee flexion angles from 0 degrees to 120 degrees. The joint was then disarticulated, and the insertions of the two bundles on the tibia and femur were digitized.
  
  
  RESULTS
  Length of the anterolateral bundle increased with increasing knee flexion angle from 10 degrees to 120 degrees. Length of the posteromedial bundle decreased with increasing knee flexion angle from 0 degrees to 45 degrees and increased slightly from 60 degrees to 120 degrees. Length of the anteromedial bundle was significantly less than that of the posteromedial at 0 degrees, 10 degrees, and 20 degrees of knee flexion. The anterolateral bundle was significantly more horizontal at flexion angles of 0 degrees, 10 degrees, 20 degrees, 30 degrees, and 45 degrees (P < 0.05). The posteromedial bundle was more horizontal at 120 degrees.
  
  
  CONCLUSIONS
  Changes in orientation take place such that neither bundle dominates in restraining posterior tibial motion throughout knee flexion and extension.
  
  
  CONCLUSIONS
  Double-bundle reconstructions achieve more physiologic knee function.
authors.affiliation: Center for Shoulder, Elbow, and Sports Medicine, Department of Orthopaedic Surgery and Orthopaedic Research Laboratory, Columbia University, New York, New York 10032, USA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Ahmad
authors.forename: Zohara A
authors.initials: ZA
authors.lastname: Cohen
authors.forename: William N
authors.initials: WN
authors.lastname: Levine
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Gardner
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Ateshian
authors.forename: Van C
authors.initials: VC
authors.lastname: Mow
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D005269:Femur / Q000502:physiology*; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000502:physiology; D016119:Posterior Cruciate Ligament / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D012016:Reference Values; D013314:Stress, Mechanical; D013977:Tibia / Q000502:physiology*