title: In vivo kinematics of the talocrural and subtalar joints during weightbearing ankle rotation in chronic ankle instability.
abstract: BACKGROUND
  Chronic ankle instability (CAI) results in abnormal ankle kinematics, but there exists limited quantitative data characterizing these alterations. This study was undertaken to investigate kinematic alterations of the talocrural and subtalar joints in CAI.
  
  
  METHODS
  A total of 14 male patients with unilateral CAI (mean age = 21.1 ± 2.5 years) were enrolled. Computed tomography and fluoroscopic imaging of both lower extremities during weightbearing passive ankle joint complex (AJC) rotation were obtained. Three-dimensional bone models created from the computed tomography images were matched with the fluoroscopic images to compute the 6 degrees-of-freedom talocrural, subtalar, and AJC kinematics.
  
  
  RESULTS
  In 20° plantarflexion, ankles with CAI demonstrated significantly increased anterior translation of the talocrural joint during AJC internal rotation from 5° to 7° and significantly decreased talocrural internal rotation within an AJC arc of motion from -1° to 5°. CAI joints demonstrated significantly increased internal rotation of the subtalar joint within an AJC arc of motion from -1° to 3°.
  
  
  CONCLUSIONS
  In CAI, altered subtalar internal rotation occurs with increased talocrural anterior translation and reduced talocrural internal rotation during weightbearing ankle internal rotation in plantarflexion. These results suggest that altered subtalar mechanics may contribute to CAI symptoms.
authors: Graduate School of Medical Technology and Health Welfare Sciences, Hiroshima International University, Hiroshima (TK, MS, KG).
authors: Takumi
authors: T
authors: Kobayashi
authors: Masayuki
authors: M
authors: Saka
authors: Eiichi
authors: E
authors: Suzuki
authors: Naohito
authors: N
authors: Yamazaki
authors: Makoto
authors: M
authors: Suzukawa
authors: Atsushi
authors: A
authors: Akaike
authors: Kuniaki
authors: K
authors: Shimizu
authors: Kazuyoshi
authors: K
authors: Gamada
mesh_terms: D000843:Ankle Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001696:Biomechanical Phenomena / Q000502:physiology; D002908:Chronic Disease; D003198:Computer Simulation; D005471:Fluoroscopy; D006801:Humans; D021621:Imaging, Three-Dimensional; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008954:Models, Biological; D012399:Rotation; D013640:Tarsal Joints / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult
keywords: 3D-to-2D registration technique; chronic ankle instability; kinematics; subtalar joint; talocrural joint; weightbearing