RESUMEN
BACKGROUND: Limitation of mouth opening, widely known as trismus, is a major symptom altering quality of life in individuals presenting from temporomandibular joint disorder or head and neck cancer. A French-language instrument addressing jaw opening limitation following treatment for head and neck cancer (HNC) or temporomandibular joint disorder (TMD) is lacking. OBJECTIVE: The aim of this study was to translate and validate the Gothenburg Trismus Questionnaire-2 (GTQ-2) into French. METHODS: A French translation of the GTQ-2 was performed according to established international guidelines, leading to the French-GTQ-2 (F-GTQ-2). The validation study included 154 participants with trismus (minimum interincisal opening of ≤35 mm) following treatment for TMD or HNC and 149 age-matched participants without trismus. All participants completed the F-GTQ-2 and participants with trismus completed additional health-related quality of life questionnaires to allow for analysis of convergent validity. RESULTS: The F-GTQ-2 demonstrated retained psychometric properties with Cronbach's alpha values above 0.70 for the domains, jaw-related problems, eating limitations, facial pain and somewhat lower for muscular tension (0.60). Mainly moderate correlations were found when comparing the F-GTQ-2 to other instruments, which was in line with the pre-specified hypotheses, indicating satisfactory convergent validity. Discriminant validity was found with statistically significant differences in all domains of the F-GTQ-2 between trismus and non-trismus participants. CONCLUSION: The F-GTQ-2 can be considered a reliable and valid instrument to assess jaw-related difficulties in individuals with trismus due to HNC or TMD.