title: Relative strain in the anterior cruciate ligament and medial collateral ligament during simulated jump landing and sidestep cutting tasks: implications for injury risk.
abstract: BACKGROUND
  The medial collateral (MCL) and anterior cruciate ligaments (ACL) are, respectively, the primary and secondary ligamentous restraints against knee abduction, which is a component of the valgus collapse often associated with ACL rupture during athletic tasks. Despite this correlation in function, MCL ruptures occur concomitantly in only 20% to 40% of ACL injuries.
  
  
  OBJECTIVE
  The purpose of this investigation was to determine how athletic tasks load the knee joint in a manner that could lead to ACL failure without concomitant MCL failure. It was hypothesized that (1) the ACL would provide greater overall contribution to intact knee forces than the MCL during simulated motion tasks and (2) the ACL would show greater relative peak strain compared with the MCL during simulated motion tasks.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  A 6-degrees-of-freedom robotic manipulator articulated 18 cadaveric knees through simulations of kinematics recorded from in vivo drop vertical jump and sidestep cutting tasks. Specimens were articulated in the intact-knee and isolated-ligament conditions. After simulation, each ACL and MCL was failed in uniaxial tension along its fiber orientations.
  
  
  RESULTS
  During a drop vertical jump simulation, the ACL experienced greater peak strain than the MCL (6.1% vs 0.4%; P < .01). The isolated ACL expressed greater peak anterior force (4.8% vs 0.3% body weight; P < .01), medial force (1.6% vs 0.4% body weight; P < .01), flexion torque (8.4 vs 0.4 N·m; P < .01), abduction torque (2.6 vs 0.3 N·m; P < .01), and adduction torque (0.5 vs 0.0 N·m; P = .03) than the isolated MCL. During failure testing, ACL specimens preferentially loaded in the anteromedial bundle failed at 637 N, while MCL failure occurred at 776 N.
  
  
  CONCLUSIONS
  During controlled physiologic athletic tasks, the ACL provides greater contributions to knee restraint than the MCL, which is generally unstrained and minimally loaded.
  
  
  CONCLUSIONS
  Current findings support that multiplanar loading during athletic tasks preferentially loads the ACL over the MCL, leaving the ACL more susceptible to injury. An enhanced understanding of joint loading during in vivo tasks may provide insight that enhances the efficacy of injury prevention protocols.
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, Rochester, Minnesota, USA The Sports Health and Performance Institute, The Ohio State University, Columbus, Ohio, USA Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA Division of Sports Medicine Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Nathaniel A
authors.initials: NA
authors.lastname: Bates
authors.affiliation: The Sports Health and Performance Institute, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Nesbitt
authors.affiliation: The Sports Health and Performance Institute, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Jason T
authors.initials: JT
authors.lastname: Shearn
authors.affiliation: The Sports Health and Performance Institute, The Ohio State University, Columbus, Ohio, USA Division of Sports Medicine Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, Ohio, USA Department of Orthopaedic Surgery, College of Medicine, University of Cincinnati, Cincinnati, Ohio, USA The Micheli Center for Sports Injury Prevention, Waltham, Massachusetts, USA.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Myer
authors.affiliation: The Sports Health and Performance Institute, The Ohio State University, Columbus, Ohio, USA Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA Division of Sports Medicine Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, Ohio, USA Department of Orthopaedic Surgery, Mayo Clinic, Rochester, Minnesota, USA Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, Minnesota, USA Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA Departments of Physiology and Cell Biology, Orthopaedics, Family Medicine, and Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA timothy.hewett@osumc.edu.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Hewett
mesh_terms: D016118:Anterior Cruciate Ligament / Q000502:physiology*; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D002102:Cadaver; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000503:physiopathology; D007719:Knee Joint / Q000502:physiology; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000293:injuries / Q000502:physiology*; D008875:Middle Aged; D011897:Random Allocation; D016059:Range of Motion, Articular / Q000502:physiology; D012307:Risk Factors; D012371:Robotics; D012421:Rupture / Q000503:physiopathology; D013177:Sports / Q000502:physiology; D013180:Sprains and Strains / Q000503:physiopathology; D013312:Stress, Physiological / Q000502:physiology; D019415:Torque
keywords: anterior cruciate ligament injury; athletic tasks; cadaveric simulation; knee biomechanics; medial collateral ligament