title: Rotational Dynamics of the Normal Distal Tibiofibular Joint With Weight-Bearing Computed Tomography.
abstract: BACKGROUND
  The normal distal tibiofibular joint is strongly stabilized by the syndesmosis, where previous cadaveric, biomechanical studies demonstrated only minimal widening and posterior translation of the fibula in external rotation of the ankle. However, little is known about normal rotational dynamics of the distal tibiofibular joint in upright weight-bearing conditions. The purpose of this study was to investigate the normal anatomy and rotational dynamics of the distal tibiofibular joint under physiological conditions on weight-bearing cone beam computed tomography (WBCT).
  
  
  METHODS
  In a cross-sectional study of 32 subjects, low-dose WBCT scans of uninjured bilateral ankles were performed. Normal intersubject and intrasubject variation in neutral position and changes in maximal internal and external rotation of the ankle were studied. Sagittal translation of the fibula, anterior and posterior widths of the distal tibiofibular syndesmosis, tibiofibular clear space (TFCS), and rotation of the fibula were measured.
  
  
  RESULTS
  In the neutrally loaded ankle, the fibula was located anteriorly in the tibial incisura in 88% of the subjects. When the ankle was rotated, mean anteroposterior motion was 1.5 mm and mean rotation of the fibula was 3 degrees. There was no significant change in TFCS between internal and external rotation. Large intersubject variation was detected, but intrasubject variation between ankles was less than 1 mm and 1 degree.
  
  
  CONCLUSIONS
  This study provides reference values to evaluate the dynamics of the normal distal tibiofibular joint. The internal control of the contralateral ankle seemed to be a better reference than the population-based normal values.
  
  
  CONCLUSIONS
  The current study provides the reference values to evaluate the rotational dynamics of a normal distal tibiofibular joint.
authors.affiliation: Department of Radiology, Oulu University and University Hospital, Oulu, Finland sannamari.lepojarvi@ppshp.fi.
authors.forename: Sannamari
authors.initials: S
authors.lastname: Lepojärvi
authors.affiliation: Department of Radiology, Oulu University and University Hospital, Oulu, Finland.
authors.forename: Jaakko
authors.initials: J
authors.lastname: Niinimäki
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery, Oulu University Hospital, Oulu, Finland.
authors.forename: Harri
authors.initials: H
authors.lastname: Pakarinen
authors.affiliation: Division of Orthopedic and Trauma Surgery, Department of Surgery, Oulu University Hospital, Oulu, Finland.
authors.forename: Hannu-Ville
authors.initials: HV
authors.lastname: Leskelä
mesh_terms: D016512:Ankle Injuries / Q000503:physiopathology*; D054893:Cone-Beam Computed Tomography; D003430:Cross-Sectional Studies; D005360:Fibula / Q000502:physiology*; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008023:Ligaments, Articular; D012399:Rotation; D013977:Tibia / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016474:Weight-Bearing / Q000502:physiology
keywords: ankle; cone-beam computed tomography; distal tibiofibular joint; syndesmosis; weight-bearing