title: Fibular malalignment in individuals with chronic ankle instability.
abstract: METHODS
  Case series.
  
  
  OBJECTIVE
  To determine whether abnormal fibular alignment is present in individuals with chronic ankle instability (CAI) using 3-D analysis of computed tomography (CT)-based bone models.
  
  
  BACKGROUND
  A positional difference of the distal fibula in individuals with unilateral CAI, when compared to the contralateral side, has been suggested. However, previous studies report no consistent pattern of fibular malalignment in the anteroposterior direction and, to our knowledge, no study has investigated mediolateral malalignment.
  
  
  METHODS
  Seventeen males with unilateral CAI (mean ± SD age, 21.0 ± 2.4 years) and no history of injury in the contralateral side were enrolled. Geometric bone models of the tibia and fibula were created from non-weight-bearing CT images, and anatomical coordinate systems were embedded in the tibia model. Bilateral tibiae were superimposed using a best-fit algorithm that moved the tibia to the position of best congruity, and the amount of side-to-side difference in position of the fibulae was measured. The anteroposterior and mediolateral positional difference of the fibula of the ankle with CAI relative to the contralateral ankle, for the distal 10 cm of the fibula length, was determined using a color-coded map.
  
  
  RESULTS
  The fibula of the ankle with CAI was significantly more lateral (0.57-0.68 mm) than that of the contralateral healthy ankle at all reference points from distal 10 cm to the lateral malleolus. There was no significant difference in anteroposterior position between the healthy ankles and those with CAI.
  
  
  CONCLUSIONS
  This study detected malalignment of the distal fibula in ankles with CAI in a non-weight-bearing position. The fibula of the ankles with CAI had a significantly more lateral position than that of the healthy ankles, which may contribute to recurrent lateral ankle sprain or giving-way episodes.
authors.affiliation: Department of Physical Therapy, Hokkaido Chitose Institute of Rehabilitation Technology, Chitose, Hokkaido, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Eiichi
authors.initials: E
authors.lastname: Suzuki
authors.forename: Naohito
authors.initials: N
authors.lastname: Yamazaki
authors.forename: Makoto
authors.initials: M
authors.lastname: Suzukawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Akaike
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Shimizu
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Gamada
mesh_terms: D016512:Ankle Injuries / Q000209:etiology*; D000843:Ankle Joint / Q000503:physiopathology*; D017760:Bone Malalignment / Q000150:complications* / Q000000981:diagnostic imaging; D005360:Fibula; D006801:Humans; D007593:Joint Instability / Q000209:etiology*; D008297:Male; D011859:Radiography; D012008:Recurrence; D013180:Sprains and Strains / Q000209:etiology*; D055815:Young Adult
keywords: bone model; color-coded map; computed tomography; distal tibiofibular joint; lateral ankle sprain