Translation and Cross-cultural Adaptation of the "Thumb Disability Exam - TDX" questionnaire into Brazilian Portuguese.

 To perform the translation, cultural adaptation and validation of the Thumb Disability Exam (TDX) questionnaire into Brazilian Portuguese.  The questionnaire was translated, with reverse translation. The translations were evaluated and synthesized by a committee, resulting in the THUMB DISABILITY EXAM - BRASIL (TDX-BR). A total of 31 patients diagnosed with rhizarthrosis were selected and answered the questionnaire. Quality parameters were evaluated, such as internal consistency, reproducibility and ceiling and floor effect.  The questionnaires were translated and adapted according to defined protocols. Internal consistency, through the Cronbach α coefficient for the TDX-BR, was 0.962. The reliability of the questionnaire, through intraclass correlation coefficient (ICC )also proved to be quite high, with κ = 0.953 (0.947-0.959). Agreement, measured using the standard error of measurement, remained with standard values < 5%. There was no ceiling and floor effect.  Through specific methodology, we consider TDX-BR as translated and valid for the Portuguese language of Brazil.