Outcome instruments of interest

Shoulder pain intensity during the previous 24 h was assessed on a 100 mm visual analogue scale (VAS) ranging from 0 (no pain) to 100 (extreme pain) (Fig. S1 in the supplementary appendix). Pain at rest and on arm activity were measured separately.

The Constant-Murley score [18] comprises measures of capacity (range of motion and strength) and subjective parameters (pain assessment, work load, and leisure time activities), which yield a score ranging from 0 (worst) to 100 (best). Although the Constant-Murley score is one of the most frequently cited instruments, it does not have convincing evidence for its psychometric properties [20].

The Simple Shoulder Test (SST) [17], consists of 12 questions of shoulder status and function, with yes (1) or no (0) response options. Answers are summed for a score ranging from 0 to 12, with maximum score indicating normal shoulder function. The Simple Shoulder Test has good evidence in support of internal consistency, reliability, structural validity, hypothesis testing, and responsiveness [20].

Participants were asked their subjective satisfaction to treatment outcome relative to baseline at the 6-, 12- and 24-month follow-up visits on a five-point global rating of change (GRC) scale (Table 1).

Global Rating of Change response options^a

^aParticipants were instructed to choose the answer that best represented their current situation. The answer options 1–5 have been translated from Finnish to English