title: Increased knee valgus alignment and moment during single-leg landing after overhead stroke as a potential risk factor of anterior cruciate ligament injury in badminton.
abstract: BACKGROUND
  In badminton, knees opposite to the racket-hand side received anterior cruciate ligament (ACL) injuries during single-leg landing after overhead stroke. Most of them occurred in the backhand-side of the rear court. Comparing lower limb biomechanics during single-leg landing after overhead stroke between the forehand-side and backhand-side court may help explain the different injury rates depending on court position.
  
  
  OBJECTIVE
  The knee kinematics and kinetics during single-leg landing after overhead stroke following back-stepping were different between the forehand-side and backhand-side court.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Hip, knee and ankle joint kinematic and knee kinetic data were collected for 17 right-handed female college badminton players using a 3-dimensional motion analysis system. Subjects performed single-left-legged landing after an overhead stroke following left and right back-stepping. The kinematic and kinetic data of the left lower extremities during landing were measured and compared between left and right back-steps.
  
  
  RESULTS
  Hip flexion and abduction and knee valgus at the initial contact, hip and knee flexion and knee valgus at the maximum knee flexion and the maximum knee valgus moment were significantly larger for the left back-step than the right back-step (p<0.05).
  
  
  CONCLUSIONS
  Significant differences in joint kinematics and kinetics of the lower extremity during single-leg landing after overhead stroke were observed between different back-step directions. Increased knee valgus angle and moment following back-stepping to the backhand-side might be related to the higher incidence of ACL injury during single-leg landing after overhead stroke.
authors.affiliation: Department of Orthopaedic Surgery, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Japan. yukax10@cc.hirosaki-u.ac.jp
authors.forename: Yuka
authors.initials: Y
authors.lastname: Kimura
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Ishibashi
authors.forename: Eiichi
authors.initials: E
authors.lastname: Tsuda
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Shuichi
authors.initials: S
authors.lastname: Sato
mesh_terms: D000843:Ankle Joint / Q000502:physiology; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D011187:Posture / Q000502:physiology*; D015865:Racquet Sports / Q000293:injuries* / Q000502:physiology; D012307:Risk Factors; D012399:Rotation; D055815:Young Adult