Cross-cultural Adaptation and Validation of the European Portuguese Version of the Western Ontario Shoulder Instability Index (WOSI)

Introduction: The Western Ontario Shoulder Instability Index (WOSI) is a self-administered questionnaire specifically used to deter-mine the impact of shoulder instability on quality of life. The aim of this study was to translate the WOSI into European Portuguese and analyze its validity and reliability in a population with shoulder instability. Material and Methods: The WOSI was translated and culturally adapted from its original version into European Portuguese (WOSI-PT). Internal consistency and test-retest analyses were conducted to determine the level of reliability of the scale. WOSI-PT, Quick-DASH, and SF-12 questionnaires were applied to 81 patients with symptomatic shoulder instability to assess validity, and reliability was tested by randomly selecting 50 patients within 72 hours using a test-retest design. Results: The reliability of the WOSI-PT was very high, with Cronbach acute accent s alpha equal to 0.97 and an intraclass correlation coefficient of 0.98. Regarding the construct validity, the correlation between the WOSI-PT and QuickDASH was high and negative (-0.79). The correlations between WOSI-PT and SF-12 were positive, respectively, moderate with physical (0.66) and low with mental (0.34) health. Conclusion: WOSI-PT is a reliable and valid instrument for assessing the functional impact of shoulder joint instability on quality of life.