title: Clinical evaluation of a new noninvasive ankle arthrometer.
abstract: BACKGROUND
  A nonradiographic arthrometer was developed to objectively quantify anterior talar drawer instability in stable and unstable ankles. Diagnostic validity of this device was previously demonstrated in a cadaver study. The aim of the present study was to validate the ankle arthrometer in an in vivo setting.
  
  
  METHODS
  Twenty-three subjects participated in the study. An orthopedic surgeon first performed a manual anterior talar drawer test to classify the subjects' ankles as stable or unstable. The subjects were then evaluated using the ankle arthrometer, and filled out a validated self-reported questionnaire (German version of the Foot and Ankle Ability Measure [FAAM-G]). Ankle stiffness was calculated from the low linear region (40-60 N) of the load deformation curves obtained from the ankle arthrometer. Reliability testing of these stiffness values was done based on load deformation curves, with 150 and 200 N maximum anterior drawer loads applied in the ankle arthrometer.
  
  
  RESULTS
  Using the manual anterior drawer test, 16 ankles were classified as stable and 7 were classified as unstable. Arthrometer stiffness analysis differentiated stable from unstable ankles (P = 0.00 and P = 0.01, respectively). Test-retest demonstrated an accurate reliability (intraclass correlation coefficient = 0.80). A significant correlation was found between both FAAM-G subscales and the arthrometer stiffness values (r = 0.43 and 0.54; P = 0.04 and 0.01). Discussion Subjects with and without mechanical ankle instability could be differentiated by ankle arthrometer stiffness analysis and the FAAM-G questionnaire results. This nonradiographic device may be relevant for screening athletes at risk for ankle injuries, for clinical follow-up studies, and implementing preventive strategies.
  
  
  CONCLUSIONS
  Validity and reliability of the new ankle arthrometer is demonstrated in a small cohort in an in vivo setting.
authors.affiliation: , , , , .
authors.forename: Tanja
authors.initials: T
authors.lastname: Nauck
authors.forename: Heinz
authors.initials: H
authors.lastname: Lohrer
authors.forename: Albert
authors.initials: A
authors.lastname: Gollhofer
mesh_terms: D000842:Ankle; D000843:Ankle Joint; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis; D015203:Reproducibility of Results; D013639:Tarsal Bones