Reliability and validity of the Taiwan Chinese version of the foot function index

Shih Huey Wu, Huey Wen Liang, Wen Hsuan Hou

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42 Citations (Scopus)


Background/Purpose: To test the reliability and validity of the Taiwan Chinese version of the Foot Function Index (FFI) among patients with plantar fasciitis and ankle/foot fracture. Methods: Fifty plantar fasciitis patients and 29 ankle/foot fracture patients volunteered for the crosssectional survey and 24 were re-retested later. The response distribution was compared between the two groups. The internal consistency and test-retest reliability were evaluated by using Cronbach's α and intraclass correlation coefficient (ICC). Criterion validity was examined for correlations with the Taiwan version of the Medical Outcomes Study Short Form-36 (SF-36) questionnaire. The influence of covariate (diagnosis, age, gender, employment) on the scores of total FFI and subscales; was explored by multivaria general linear model analysis. Results: Two items in the pain subscale had many answers in the non-applicable category and were removed from analysis. The internal consistency of the 21-item FFI was high (Cronbach's α = 0.94) and the test-retest reliability was satisfactory (ICC = 0.82). The activity limitation subscale had relatively lower Cronbach's α (0.75) and the items in this subscale had a high proportion of floor scores. There was a moderate correlation between the FFI total and subscale scores to the physical component summary scores rather than to the mental component summary scores of the SF-36. Multivariate general linear model analysis showed that the cases of plantar fasciitis had higher pain scores and lower activity limitation scores, although their FFI total scores were comparable. Conclusion: The adapted Taiwan Chinese version of the FFI is reliable and valid and can be applied among traumatic and non-traumatic foot disorders, Nevertheless, its clinical application may be limited by a relatively high proportion of non-applicable answers and significant floor effect in some items.

Original languageEnglish
Pages (from-to)111-122
Number of pages12
JournalJournal of the Formosan Medical Association
Issue number2
Publication statusPublished - Feb 2008
Externally publishedYes


  • Ankle fracture
  • Foot fracture
  • Outcome assessment
  • Plantar fasciitis
  • Questionnaires

ASJC Scopus subject areas

  • General Medicine


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