Reliability and validity of the Turkish version of the foot function index in patients with calcaneal heel spur


  • Müyesser Okumuş
  • Gülseren Demir
  • Pınar Borman
  • Turgut Kültür
  • Serap Yörübulut


Foot function index, Reliability and validity, Foot diseases


Aim: One of the most extensively used questionnaires in studies and clinical trials is the Foot Function Index (FFI). The aim of our study was to evaluate the reliability and the validity of the FFI in Turkish patients with calcaneal heel spur.

Methods: A cross-sectional study was performed in 20014-2015 in Ankara, Turkey with 146 patients with calcaneal heel spur. Statistical analyses were performed using the SPSS software version 20.0. Intra-class correlation coefficients (ICC) and Cronbach alpha coefficients were used to determine test-retest reliability and internal consistency of FFI. Construct validity was tested by Pearson correlation coefficient approach comparing the correlation of the Visual Analogue Pain Scale (VAS-pain), foot and ankle outcome score (FAOS) and The Short Form-36 (SF-36) questionnaire with FFI.

Results: A hundred and forty six patients (125 women, 21 men) were enrolled in the study. The mean age of the patients were 46,4±10,3 years. The random ICC for the total FFI and three subscales ranged from 0.74 to 0.99. The Cronbach’s alpha coefficient ranged from 0.78 to 0.83. In terms of validity, there was a significant correlation between the Turkish version of FFI, VAS, some of the sub-scales of FAOS and SF-36 scores (p<0.05).

Conclusion: The Turkish version of FFI was valid and reliable to assess the foot disease in patients with heel spur. It can be used for both in clinic and research studies in the assessment of pain, disability and limitation of the function of the foot.


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Okumuş M, Demir G, Borman P, Kültür T, Yörübulut S. Reliability and validity of the Turkish version of the foot function index in patients with calcaneal heel spur. J Surg Med [Internet]. 2018 May 1 [cited 2024 Feb. 28];2(2):118-22. Available from: