title: Effect of Laterally Wedged Insoles on the External Knee Adduction Moment across Different Reference Frames.
abstract: OBJECTIVE
  Biomechanical effects of laterally wedged insoles are assessed by reduction in the knee adduction moment. However, the degree of reduction may vary depending on the reference frame with which it is calculated. The purpose of this study was to clarify the effect of reference frame on the reduction in the knee adduction moment by laterally wedged insoles.
  
  
  METHODS
  Twenty-nine healthy participants performed gait trials with a laterally wedged insole and with a flat insole as a control. The knee adduction moment, including the first and second peaks and the angular impulse, were calculated using four different reference frames: the femoral frame, tibial frame, laboratory frame and the Joint Coordinate System.
  
  
  RESULTS
  There were significant effects of reference frame on the knee adduction moment first and second peaks (P < 0.001 for both variables), while the effect was not significant for the angular impulse (P = 0.84). No significant interaction between the gait condition and reference frame was found in either of the knee adduction moment variables (P = 0.99 for all variables), indicating that the effects of laterally wedged insole on the knee adduction moments were similar across the four reference frames. On the other hand, the average percent changes ranged from 9% to 16% for the first peak, from 16% to 18% for the second peak and from 17% to 21% for the angular impulse when using the different reference frames.
  
  
  CONCLUSIONS
  The effects of laterally wedged insole on the reduction in the knee adduction moment were similar across the reference frames. On the other hand, Researchers need to recognize that when the percent change was used as the parameter of the efficacy of laterally wedged insole, the choice of reference frame may influence the interpretation of how laterally wedged insoles affect the knee adduction moment.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Division of Rehabilitation Medicine, Chiba University Hospital, Chuo-ku, Chiba, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Kitamura
authors.affiliation: Division of System Development, Anima Corp, Chofu, Tokyo, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ushikubo
authors.affiliation: Division of Rehabilitation Medicine, Chiba University Hospital, Chuo-ku, Chiba, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Murata
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba, Japan.
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Akagi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Sasho
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D012775:Shoes; D055815:Young Adult