title: The role of ankle ligaments and articular geometry in stabilizing the ankle.
abstract: BACKGROUND
  Ankle joint stability is a function of multiple factors, but it is unclear to what extent extrinsic factors such as ligaments and intrinsic elements such as geometry of the articular surfaces play a role. The purposes of this study were to determine the contribution of the ligaments and the articular geometry to ankle stability and to determine the effects of ankle position and simulated physiological loading upon ankle stability.
  
  
  METHODS
  Sixteen cadaveric lower extremities were studied in unloaded and with axial load equivalent to body weight. Anterior-posterior, medial-lateral translation and internal-external rotation tests were performed in neutral, dorsiflexion and plantarflexion ankle positions. Intact ankle stability was measured; ankle ligaments were serially sectioned and retested.
  
  
  RESULTS
  For unloaded condition, the lateral ligament accounted for 70% to 80% of anterior stability and the deltoid ligaments for 50% to 80% of posterior stability. Both ligaments contributed 50% to 80% to rotational stability; however, the ligaments did not provide the primary restraints to medial-lateral stability. For loaded ankle condition, articular geometry contributed 100% to translational and 60% to rotational stability. The ankle was less stable in plantarflexion and more stable in dorsiflexion.
  
  
  CONCLUSIONS
  The contribution of extrinsic and intrinsic elements to ankle stability is dependent upon the load and direction of force applied. This study underscores the importance of restoring soft tissues about the ankle to the anatomic condition during reconstruction operations for instability, trauma and arthritis.
authors: Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, South-1, West-16, Chuoku, Sapporo, Hokkaido, 060-8543, Japan.
authors: Kota
authors: K
authors: Watanabe
authors: Harold B
authors: HB
authors: Kitaoka
authors: Lawrence J
authors: LJ
authors: Berglund
authors: Kristin D
authors: KD
authors: Zhao
authors: Kenton R
authors: KR
authors: Kaufman
authors: Kai-Nan
authors: KN
authors: An
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000842:Ankle; D000843:Ankle Joint / Q000033:anatomy & histology* / Q000502:physiology*; D002102:Cadaver; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008023:Ligaments, Articular / Q000033:anatomy & histology* / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009068:Movement / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology