title: The upper ankle joint: Curvature morphology of the articulating surfaces and physiological function.
abstract: OBJECTIVE
  The curvature morphology of the articulating surfaces determines the physiological movement pattern. We quantitatively examined the curvature morphology of the tibiotalar articulating surfaces and specified their geometric contact patterns.
  
  
  METHODS
  Geometrically equivalent cartographic nets were marked on the talar and tibial articulating surfaces of true-to-scale moldings of 20 human ankle joints (intervals of 5 mm) to relate corresponding articulating units of the surfaces. The corresponding contours of the net lines were compared, and the incongruity of articulating surfaces could thus be quantified locally.
  
  
  RESULTS
  All tibial sagittal net lines represented circular arcs. Along the sagittal talar net lines, the curvature radii increased medially from anterior to posterior but decreased laterally. Each net line could be approximated by three circular arcs. Examining these three parts of the talar net lines, the anterior sagittal curvature radii increased from medial to lateral, whereas the posterior radii decreased. The tibial and talar transversal net lines were congruent. The articulation surfaces showed a transversal contact line in every dorsal/plantar joint position. The degree of local congruity was solely ascertained by the incongruity of the corresponding sagittal net lines. The maximal degrees of congruity were found laterally for dorsal flexion, laterally/centrally for neutral joint position, and centrally/medially for plantar flexion.
  
  
  CONCLUSIONS
  By the transversal line contact, the contact area is broadened over the articulating surfaces from lateral to medial. In dorsal flexion, compressive loads are mainly transferred by lateral/anterior zones and in plantar flexion by medial/posterior zones of the articulating surfaces. Reconstruction of the transversal contact line is essential.
authors.affiliation: Department of Orthodontics, University of Göttingen, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Nägerl
authors.affiliation: Department of Orthodontics, University of Göttingen, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Hansen
authors.affiliation: Department of Orthodontics, University of Göttingen, Germany.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kubein-Meesenburg
authors.affiliation: Department of Orthodontics, University of Regensburg, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Fanghänel
authors.affiliation: Department of Orthodontics, University of Göttingen, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Dathe
authors.affiliation: Clinical Center Kassel, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Dumont
authors.affiliation: Department of Trauma Surgery, Orthopaedics and Plastic Surgery, University of Göttingen, Germany.
authors.forename: Martin Michael
authors.initials: MM
authors.lastname: Wachowski
mesh_terms: D000369:Aged, 80 and over; D000843:Ankle Joint / Q000033:anatomy & histology* / Q000502:physiology*; D001696:Biomechanical Phenomena; D019245:Compressive Strength; D005260:Female; D006801:Humans; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology*; D016474:Weight-Bearing