title: High inter-specimen variability of baseline data for the tibio-talar contact area.
abstract: BACKGROUND
  The tibio-talar contact area has been widely investigated to monitor biomechanical changes due to articular incongruities or an altered loading. This study aims to investigate for the first time in a systematic way the extent of the inter-specimen variability of the tibio-talar contact area, and its repercussions when analyzing data concerning this parameter.
  
  
  METHODS
  Ten specimens were loaded to record the tibio-talar contact characteristics by use of pressure sensitive film. The size of the talar dome area, the size of the (normalized) tibio-talar contact area, the position of the tibio-talar contact area, and the shape of the latter were determined and analyzed. Inter-specimen variability was expressed as the coefficient of variation and was calculated for the datasets of previous studies as well.
  
  
  RESULTS
  The size of the tibio-talar contact area showed a very high inter-specimen variability, as is the case in previous studies. This high variability persisted when a normalized tibio-talar contact area was calculated. The shape of the tibio-talar contact area showed some basic characteristics, but a high variation in details could be observed.
  
  
  CONCLUSIONS
  Every specimen can be considered to have its own "ankle print". By this variability, articular incongruities are expected to have a different effect on local biomechanical characteristics in every single individual. Therefore, every single case has to be evaluated and reported for significant changes. In case of modeling, this also underscores the need to use subject specific models fed by sets of parameters derived from a series of single specimens.
authors.affiliation: Department of Musculoskeletal Sciences, Katholieke Universiteit Leuven, Leuven, Belgium. giovanni.matricali@uzleuven.be
authors.forename: Giovanni A
authors.initials: GA
authors.lastname: Matricali
authors.forename: Ward
authors.initials: W
authors.lastname: Bartels
authors.forename: Luc
authors.initials: L
authors.lastname: Labey
authors.forename: Greta Ph E
authors.initials: GP
authors.lastname: Dereymaeker
authors.forename: Frank P
authors.initials: FP
authors.lastname: Luyten
authors.forename: Jos
authors.initials: J
authors.lastname: Vander Sloten
mesh_terms: D000843:Ankle Joint / Q000033:anatomy & histology*; D015982:Bias; D001696:Biomechanical Phenomena; D006801:Humans; D011312:Pressure; D012016:Reference Values; D013628:Talus / Q000033:anatomy & histology*; D013977:Tibia / Q000033:anatomy & histology*; D014894:Weights and Measures