title: Knee rotation associated with dynamic knee valgus and toe direction.
abstract: BACKGROUND
  Dynamic knee valgus contributes to injuries of the anterior cruciate ligament (ACL). However, it is unclear how the knee rotates during dynamic knee valgus. Knee rotation significantly affects ACL strain. To understand knee rotation during dynamic knee valgus should help the clinician evaluate dynamic alignment. The purpose of this study was to determine how the knee rotates during dynamic knee valgus and whether the knee rotation is affected by toe direction (foot rotation).
  
  
  METHODS
  Sixteen females performed dynamic knee valgus in three toe directions (neutral, toe-out, and toe-in) while maintaining the knee flexion angle at 30°. The knee rotation angle was evaluated using a 7-camera motion analysis system. Knee rotation was compared between the start position and the dynamic knee valgus position, as well as among the three toe directions, using repeated measures ANOVA models.
  
  
  RESULTS
  The knee significantly rotated externally in the dynamic knee valgus position compared with the start position in two toe directions (neutral and toe-out). A similar tendency was observed with the toe-in condition. Toe direction significantly affected the knee rotation angle. For toe-out and toe-in conditions, external and internal shifts of knee rotation compared with neutral were observed.
  
  
  CONCLUSIONS
  The knee rotates externally during dynamic knee valgus, and the knee rotation is affected by toe direction.
  
  
  CONCLUSIONS
  Because of knee abduction and external rotation, the ACL may impinge on the femoral condyle in the case of dynamic valgus, especially in the toe-out position.
authors.affiliation: Graduate School of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan; Dept. of Rehabilitation, Hokushin Orthopedic Hospital, Sapporo, Hokkaido, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Ishida
authors.affiliation: Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan. Electronic address: yamanaka@hs.hokudai.ac.jp.
authors.forename: Masanori
authors.initials: M
authors.lastname: Yamanaka
authors.affiliation: Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Takeda
authors.affiliation: Dept. of Orthopedic Surgery, Hokushin Orthopedic Hospital, Sapporo, Hokkaido, Japan.
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Aoki
mesh_terms: D000704:Analysis of Variance; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D005528:Foot / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D012399:Rotation; D055815:Young Adult
keywords: Anterior cruciate ligament; Dynamic knee valgus; Knee rotation; Toe direction