title: Differences in torsional joint stiffness of the knee between genders: a human cadaveric study.
abstract: BACKGROUND
  In many sports, female athletes have a higher incidence of anterior cruciate ligament injury than do male athletes. Among many risk factors, the lower rotatory joint stiffness of female knees has been suggested for the increased rate of anterior cruciate ligament injuries.
  
  
  OBJECTIVE
  In response to combined rotatory loads, female knees have significantly lower torsional joint stiffness and higher rotatory joint laxity than do male knees at low flexion angles, despite the fact that no such gender differences would be found in response to an anterior tibial load.
  
  
  METHODS
  Comparative laboratory study.
  
  
  METHODS
  Joint kinematics of 82 human cadaveric knees (38 female, 44 male) in response to (1) combined rotatory loads of 10 N x m valgus and +/- 5 N x m internal tibial torques and (2) a 134-N anterior-posterior tibial load were measured using a robotic/universal force-moment sensor testing system.
  
  
  RESULTS
  In response to combined rotatory loads, female knees had as much as 25% lower torsional joint stiffness (female: 0.79 N x m/deg; 95% confidence interval, 0.67-0.91; male: 1.06 N x m/deg; 95% confidence interval, 0.95-1.17) and up to 35% higher rotatory joint laxity (female: 26.2 degrees; 95% confidence interval, 24.5 degrees-27.9 degrees; male: 20.5 degrees; 95% confidence interval, 18.8 degrees-22.2 degrees) than did male knees (P < .05), whereas there were no gender differences in response to the anterior tibial load (P > .05).
  
  
  CONCLUSIONS
  Female knees had lower torsional joint stiffness and higher rotatory joint laxity than did male knees in response to combined rotatory loads.
  
  
  CONCLUSIONS
  Larger axial rotations of female knees in response to rotatory loads may affect the distribution of forces in soft tissues and the function of muscles that provide knee stability. Control algorithms used during the biomechanical testing of cadaveric knees and computational knee models might need to be gender specific.
authors.affiliation: Department of Orthopedic Surgery, Chang Gung Memorial Hospital, Chia-Yi, Taiwan.
authors.forename: Wei-Hsiu
authors.initials: WH
authors.lastname: Hsu
authors.forename: Jesse A
authors.initials: JA
authors.lastname: Fisk
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Richard E
authors.initials: RE
authors.lastname: Debski
authors.forename: Savio L-Y
authors.initials: SL
authors.lastname: Woo
mesh_terms: D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D005783:Gender Identity; D006801:Humans; D007592:Joint Diseases / Q000503:physiopathology*; D007593:Joint Instability / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012737:Sex Factors