Translation, cross-cultural adaptation, and validation of the Italian version of the Oxford Shoulder Instability Score.

Abstract

The Oxford Shoulder Instability Score (OSIS) is self-reported outcome measurement developed to evaluate shoulder instability taking into account also adaptive strategies. Valid, reliable, reproducible, and user-friendly translations of outcome measure instruments are needed to allow comparisons of international study results. The Italian translation and cultural adaptation of the OSIS were completed using a "translation-back translation" method and the final version was administered to a sample of 25 consecutive Italian-speaking patients. The psychometric properties of this adaptation were evaluated in terms of feasibility, reliability, construct validity, and responsiveness. No major differences occurred between the OSIS translations into Italian and back into English, and no content- or linguistic-related difficulties were reported. The Cronbach's alpha for the total OSIS was 0.897. Intraclass correlation coefficient value for inter-rater reliability was 0.805, while for intra-rater reliability was 0.586. Spearman rank correlation coefficient between the OSIS and the Rowe score was 0.548 (p = 0.005) and between OSIS-I and SF-12 was 0.488 (p = 0.013). The Italian version of the OSIS is a reliable, valid, and reproducible outcome measure for clinical evaluation of patients affected by shoulder instability, which remains simple and user-friendly as the original version. Prospective cohort study, Level II. The availability of a validated translation of the OSIS will help surgeon to share their data on shoulder instability diagnostic and treatment in a more reproducible and comparable fashion.