Background: The Western Ontario Shoulder Instability Index (WOSI) score is a tool that helps with self-assessment of the shoulder’s functional status in patients experiencing instability problems.The purpose of this study was the cross-cultural adaptation of WOSI into Arabic and assessment of its psychometric properties in comparison to a gold standard-questionnaire, namely the Arabic Disability of the Arm, Shoulder and Hand (DASH) score. Material & Methods: 100 patients participated in this survey, tested initially and retest after two months. The internal consistency tests were performed using Cronbach's alpha. Besides, Pearson's Correlation and Standard response mean (SRM) were calculated to estimate criterion validity and responsiveness of the Arabic WOSI in comparison to the Arabic DASH. Results: The Arabic WOSI had a Cronbach's alpha score of 0.85 at the baseline and 0.91 at the follow-up time period. All subscales had an internal consistency greater than 0.7, except Sport/Work (0.69 at follow-up). A strong correlation with Arabic DASH score was observed (r = 0.79 at baseline & 0.87 at Follow-up) which suggested good validity. Also, moderately correlated changes of baseline to follow-up in DASH and WOSI indicated moderate responsiveness. No ceiling and floor effects were observed among the responses. Conclusion: Overall, the Arabic version of WOSI proved to be a good and reliable diagnostic tool for patients with shoulder instability.

Introduction: Shoulder pain is a major disorder of the musculoskeletal system. To the best of our knowledge, there is no documentation of an Arabic version of the shoulder disability and pain measurements. Constant Murley Score (CMS) is one of the standard questionnaires for clinical practice and research. The aim of this research centred around the evaluation of the Arabic Constant Murley Score and subsequently assessing the reliability and validity in comparison to disabilities of the arm, shoulder, and hand (DASH). Methods: Hundred and twenty five patients took part in this research. We did the internal consistency tests with Cronbach’s alpha. Intra-correlation coefficient, convergent validity, convergent construct validity, responsiveness, and floor and ceiling effects were also calculated. Results: Principal component analysis showed that the variance was 63.31% with a factor range of 0.42–0.85, which fulfils the uni-dimensionality criterion. Also, the Arabic CMS correlated negatively with the DASH score (−0.82, p < 0.001). The Arabic version of CMS was consistent with Cronbach’s alpha of 0.74. With Inter Class Correlation Coefficient (ICC) = 0.83 it also showed a very good test-retest reliability. Conclusion: Ours is the first translation and cross-cultural adaptation of the CMS into Arabic. Important evidences of validity were tested such as uni-dimensionality, convergent validity, and internal consistency. Results demonstrate an acceptable Cronbach’s alpha of 0.74, ICC = 0.830 indicating excellent reliability and a strong correlation of the Arabic CMS with the DASH score (r = −0.820). Overall, the Arabic version of CMS is a good and reliable diagnostic tool for patients experiencing shoulder pain.