title: Clinical measures of static foot posture do not agree.
abstract: BACKGROUND
  The aim of this study was to determine the level of agreement between common clinical foot classification measures.
  
  
  METHODS
  Static foot assessment was undertaken using the Foot Posture Index (FPI-6), rearfoot angle (RFA), medial longitudinal arch angle (MLAA) and navicular drop (ND) in 30 participants (29 ± 6 years, 1.72 ± 0.08 m, 75 ± 18 kg). The right foot was measured on two occasions by one rater within the same test environment. Agreement between the test sessions was initially determined for each measure using the Weighted Kappa. Agreement between the measures was determined using Fleiss Kappa.
  
  
  RESULTS
  Foot classification across the two test occasions was almost perfect for MLAA (Kw = .92) and FPI-6 (Kw = .92), moderate for RFA (Kw = .60) and fair for ND (Kw = .40) for comparison within the measures. Overall agreement between the measures for foot classification was moderate (Kf = .58).
  
  
  CONCLUSIONS
  The findings reported in this study highlight discrepancies between the chosen foot classification measures. The FPI-6 was a reliable multi-planar measure whereas navicular drop emerged as an unreliable measure with only fair agreement across test sessions. The use of this measure for foot assessment is discouraged. The lack of strong consensus between measures for foot classification underpins the need for a consensus on appropriate clinical measures of foot structure.
authors.affiliation: Sport and Physical Activity, Edge Hill University, St Helens Road, Lancashire, L39 4QP UK.
authors.forename: Ben
authors.identifier: 0000-0001-8989-4810
authors.initials: B
authors.lastname: Langley
authors.affiliation: Centre of Health and Clinical Research, University of the West of England, Bristol, UK.
authors.forename: Mary
authors.initials: M
authors.lastname: Cramp
authors.affiliation: School of Health Sciences, University of Brighton, Brighton, UK.
authors.forename: Stewart C
authors.initials: SC
authors.lastname: Morrison
mesh_terms: D000328:Adult; D000886:Anthropometry / Q000379:methods*; D005413:Flatfoot / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology; D005528:Foot / Q000033:anatomy & histology* / Q000502:physiology; D006801:Humans; D015588:Observer Variation; D011187:Posture / Q000502:physiology*; D015203:Reproducibility of Results; D000070589:Talipes Cavus / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology; D055815:Young Adult
keywords: Agreement; Foot classification; Morphology; pes cavus; pes planus