Cross-cultural adaptation and validation of the German version of the Western Ontario shoulder instability index

Abstract

The Western Ontario shoulder instability index (WOSI) is a disease-specific quality of life measurement tool with 21 items for patients with shoulder instability. Here, we report on translation and validation of the German version of the WOSI according to international guidelines. A total of 86 patients in three groups were included in this study. In group I, 24 patients underwent surgical stabilization of the shoulder. Preoperatively and at 12 months post-operatively the WOSI, Rowe score, UCLA, Constant score, and the SF-36 were evaluated. In group II, 25 patients were evaluated 2.6 +/- 1.2 years after sustaining a primary traumatic shoulder dislocation. Group III consisted of 37 healthy men and women with normal, healthy shoulders. Evaluation of Pearson's correlation coefficient between WOSI and Rowe score, UCLA, SF-36 and Constant score and for test-retest reliability was made. Moreover, Cronbach's alpha and floor, and ceiling effects were analyzed. Internal consistency was high (Cronbach's alpha 0.92).Test-retest reliability (Pearson correlation coefficient) was excellent (r = 0.92). The construct validity showed a significant correlation between the WOSI and the scores investigated. There were no floor or ceiling effects for the German WOSI score. The German translation of the WOSI is a valid and reliable tool, applicable to outcome studies on patients with shoulder instability.