BACKGROUND: The Score Committee of the European Foot and Ankle Society (EFAS) developed, validated, and published the EFAS Score in 11 languages (Dutch, English, German, Finnish, French, Italian, Polish, Portuguese, Persian, Swedish, Turkish). From other languages under validation, the Spanish and Estonian versions completed data acquisition and underwent further validation.

METHODS: The EFAS Score was developed and validated in three stages: 1) item (question) identification (completed during the initial validation study), 2) item reduction and scale exploration (completed during the initial validation study), 3) confirmatory analyses and responsiveness of the Spanish and Estonian versions (completed during the initial validation study in seven other languages). The data were collected pre-operatively and post-operatively at a minimum follow-up of 3 months and mean follow-up of 6 months. Item reduction, scale exploration, confirmatory analyses and responsiveness were executed using classical test theory and item response theory.

RESULTS: The internal consistency of the scale was confirmed in the Spanish and Estonian versions (Cronbach's Alpha>0.8). Responsiveness was good, with moderate to large effect sizes in both languages, and evidence of a statistically significant positive association between the EFAS Score and patient-reported improvement.

CONCLUSIONS: The Spanish and Estonian EFAS Score versions were successfully validated in orthopaedic ankle and foot surgery patients, with a wide variety of foot and ankle pathologies. All score versions are freely available at www.efas.net.