Cross cultural adaptation and validation of the Greek version of the Western Ontario Rotator Cuff (WORC) index

Purpose We aimed to translate and cross-culturally adapt the Western Ontario Rotator Cuff index into Greek (WORC-GR) and evaluate its reliability and validity in a Greek speaking population with rotator cuff (RC) disorders. Materials and methods Translation and cross-cultural adaptation process followed published guidelines. Content and face validity were assessed by 9 experts and 16 patients with RC pathologies, respectively. Internal structure, reliability, measurement error, and convergent validity (correlation with the Disability of the Arm, Shoulder and Hand - DASH, Shoulder Pain and Disability Index - SPADI, and Short Form-36) of the index were evaluated in 104 participants (44.2% women, mean age +/- SD: 44.9 +/- 15.01 years) with RC related pain. Results The WORC-GR showed excellent item and scale content validity index (0.875-1.00 and 0.975, respectively), internal consistency (Cronbach's alpha range 0.749 - 0.903) and test-retest reliability (intraclass correlation coefficient: 0.942, 95% CI: 0.913-0.961). Factorial validity testing revealed a 4-factor structure explaining 69.7% of the total variance. High positive correlations were found with DASH (r = 0.806) and SPADI (r = 0.852). Conclusions WORC-GR is a reliable and valid instrument to assess symptoms in patients with RC disorders. Further research on the content validity, internal structure, and responsiveness of the tool is required.