The Western Ontario Shoulder Instability Index (WOSI) is a specific self-administered questionnaire measuring the functional impact on patients with chronic glenohumeral instability. In its English version, it is valid, reliable, and sensitive to change. The objective of the present study was to provide a linguistic and cross-cultural adaptation of the original version of the WOSI to French and to assess the metrologic properties of this version in patients with chronic shoulder instability.

The WOSI was translated and adapted both linguistically and culturally to French (WOSI-Fr) according to current guidelines. The metrologic properties of the WOSI-Fr were analyzed in the following groups – unoperated patients with chronic shoulder instability (UOG), operated patients with chronic shoulder instability (OG), patients with instability (TotG=UOG+OG), and control patients (ContG) – through analysis of the construct validity by comparing the WOSI-Fr with the Rowe, Walch-Duplay, QuickDASH, and VAS pain scores, and through analysis of reliability through the reproducibility of internal consistency.

The WOSI-Fr version was established and then accepted by an expert group (n=7). There was a statistically significant correlation between the WOSI and the different pain and function scores for TotG, OG, and UOG (except with the VAS pain score and the QuickDASH for UOG). Reproducibility (n=27) was good: the ICC value for the total score was 0.88 (95% CI, 0.47–0.98), varying from 0.80 to 0.94 according to the four domains of the WOSI-Fr, and from 0.70 to 0.94 for the different items separately. For TotG, Cronbach's alpha was 0.953, the SEM and the MDC were 120.2 (5.7%) and 333 (15.9%), respectively.

The French version of the WOSI (WOSI-Fr) is available, adapted linguistically and culturally, valid, and reliable. We recommend using it in following up patients with shoulder instability.

Prospective, level 2.