title: Effects of transverse and frontal plane knee laxity on hip and knee neuromechanics during drop landings.
abstract: BACKGROUND
  Varus-valgus (LAX(VV)) and internal-external (LAX(IER)) rotational knee laxity have received attention as potential contributing factors in anterior cruciate ligament injury. This study compared persons with above-and below-average LAX(VV) and LAX(IER) values on hip and knee neuromechanics during drop jump landings.
  
  
  OBJECTIVE
  People with greater LAX(VV) and LAX(IER) values will have greater challenges controlling frontal and transverse plane knee motions, as evidenced by greater joint excursions, joint moments, and muscle activation levels during the landing phase.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Recreationally active participants (52 women and 44 men) between 18 and 30 years old were measured for LAX(VV) and LAX(IER) and for their muscle activation and transverse and frontal plane hip and knee kinetics and kinematics during the initial landing phase of a drop jump. The mean value was obtained for each sex, and those with above-average values on LAX(VV) and LAX(IER) (LAX(HIGH) = 17 women, 16 men) were compared with those with below-average values (LAX(LOW) = 18 women, 17 men).
  
  
  RESULTS
  Women with LAX(HIGH) verus LAX(LOW) were initially positioned in greater hip adduction and knee valgus and also produced more prolonged internal hip adduction and knee varus moments as they moved toward greater hip adduction and internal rotation as the landing progressed. These patterns in LAX(HIGH) women were accompanied by greater prelanding and postlanding muscle activation amplitudes. Men with LAX(HIGH) versus LAX(LOW) also demonstrated greater hip adduction motion and produced greater internal hip internal rotation and knee varus and internal rotation moments.
  
  
  CONCLUSIONS
  Participants with greater LAX(VV) and LAX(IER) landed with greater hip and knee transverse and frontal plane hip and knee motions.
  
  
  CONCLUSIONS
  People (especially, women) with increased frontal and transverse plane knee laxity demonstrate motions associated with noncontact anterior cruciate ligament injury mechanisms.
authors.affiliation: University of North Carolina at Greensboro, Department of Kinesiology, 1408 Walker Avenue, Greensboro, NC 27402, USA. sjshultz@uncg.edu
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Shultz
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Schmitz
mesh_terms: D000293:Adolescent; D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D005260:Female; D025981:Hip Injuries / Q000209:etiology; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007593:Joint Instability / Q000150:complications / Q000503:physiopathology*; D007718:Knee Injuries / Q000209:etiology; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D009068:Movement; D009142:Musculoskeletal Physiological Phenomena; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult