title: ACL forces and knee kinematics produced by axial tibial compression during a passive flexion-extension cycle.
abstract: Application of axial tibial force to the knee at a fixed flexion angle has been shown to generate ACL force. However, direct measurements of ACL force under an applied axial tibial force have not been reported during a passive flexion-extension cycle. We hypothesized that ACL forces and knee kinematics during knee extension would be significantly different than those during knee flexion, and that ACL removal would significantly increase all kinematic measurements. A 500 N axial tibial force was applied to intact knees during knee flexion-extension between 0° and 50°. Contact force on the sloping lateral tibial plateau produced a coupled internal + valgus rotation of the tibia, anterior tibial displacement, and elevated ACL forces. ACL forces during knee extension were significantly greater than those during knee flexion between 5° and 50°. During knee extension, ACL removal significantly increased anterior tibial displacement between 0° and 50°, valgus rotation between 5° and 50°, and internal tibial rotation between 5° and 15°. With the ACL removed, kinematic measurements during knee extension were significantly greater than those during knee flexion between 5° and 45°. The direction of knee flexion-extension movement is an important variable in determining ACL forces and knee kinematics produced by axial tibial force.
authors.affiliation: Biomechanics Research Section, Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, 1000 Veteran Ave Room 21-67, Los Angeles, California.
authors.forename: Keith L
authors.initials: KL
authors.lastname: Markolf
authors.forename: Steven R
authors.initials: SR
authors.lastname: Jackson
authors.forename: Brock
authors.initials: B
authors.lastname: Foster
authors.forename: David R
authors.initials: DR
authors.lastname: McAllister
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000502:physiology; D002102:Cadaver; D019245:Compressive Strength / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008875:Middle Aged; D008954:Models, Biological; D009068:Movement / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D013977:Tibia / Q000502:physiology*; D019415:Torque; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult
keywords: ACL; biomechanics; joint load; kinematics; knee