title: Varying femoral tunnels between the anatomical footprint and isometric positions: effect on kinematics of the anterior cruciate ligament-reconstructed knee.
abstract: BACKGROUND
  Knee kinematics and in situ forces resulting from anterior cruciate ligament reconstructions with 2 femoral tunnel positions were evaluated.
  
  
  OBJECTIVE
  A graft placed inside the anatomical footprint of the anterior cruciate ligament will restore knee function better than a graft placed at a position for best graft isometry.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Ten cadaveric knees were tested in response to a 134-N anterior load and a combined 10-N.m valgus and 5-N.m internal rotation load. A robotic universal force-moment sensor testing system was used to apply loads, and resulting kinematics were recorded. An active surgical robot system was used for positioning tunnels in 2 locations in the femoral notch: inside the anatomical footprint of the anterior cruciate ligament and a position for best graft isometry. The same quadrupled hamstring tendon graft was used for both tunnel positions. The 2 loading conditions were applied.
  
  
  RESULTS
  At 30 degrees of knee flexion, anterior tibial translation in response to the anterior load for the intact knee was 9.8 +/- 3.1 mm. Both femoral tunnel positions resulted in significantly higher anterior tibial translation (position 1: 13.8 +/- 4.6 mm; position 2: 16.6 +/- 3.7 mm; P < .05). There was a significant difference between the 2 tunnel positions. At the same flexion angle, the anterior tibial translation in response to the combined load for the intact knee was 7.7 +/- 4.0 mm. Both femoral tunnel positions resulted in significantly higher anterior tibial translation (position 1: 10.4 +/- 5.5 mm; position 2: 12.0 +/- 5.2 mm; P < .05), with a significant difference between the tunnel positions.
  
  
  CONCLUSIONS
  Neither femoral tunnel position restores normal kinematics of the intact knee. A femoral tunnel position inside the anatomical footprint of the anterior cruciate ligament results in knee kinematics closer to the intact knee than does a tunnel position located for best graft isometry.
  
  
  CONCLUSIONS
  Anatomical femoral tunnel position is important in reproducing function of the anterior cruciate ligament.
authors.affiliation: Department of Orthopaedic Surgery, University of Pittsburgh, 3471 Fifth Avenue, Pittsburgh, PA 15213, USA.
authors.forename: Volker
authors.initials: V
authors.lastname: Musahl
authors.forename: Anton
authors.initials: A
authors.lastname: Plakseychuk
authors.forename: Andrew
authors.initials: A
authors.lastname: VanScyoc
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Sasaki
authors.forename: Richard E
authors.initials: RE
authors.lastname: Debski
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: McMahon
authors.forename: Freddie H
authors.initials: FH
authors.lastname: Fu
mesh_terms: D000328:Adult; D000368:Aged; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001696:Biomechanical Phenomena; D002102:Cadaver; D005269:Femur / Q000601:surgery*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007719:Knee Joint / Q000502:physiology / Q000503:physiopathology* / Q000601:surgery*; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods*; D011187:Posture; D016059:Range of Motion, Articular; D012016:Reference Values; D016474:Weight-Bearing / Q000502:physiology