Nineteen RCTs (n=2,120 participants, range 20 to 660) were included in the review. Follow-up ranged from immediately after the last injection to 26 weeks. The mean quality score was 3.3 (range 1 to 5); only one trial used intention-to-treat analysis, six adequately described patient selection and outcome and six used concealed random allocation.
Pain: Hyaluronate injections were statistically significantly more effective than placebo in reducing pain (RR 1.41, 95% CI 1.17 to 1.70; five RCTs and SMD 0.40, 95% CI 0.22 to 0.59; five RCTs). There was no evidence of statistical heterogeneity (I2=33.9% and I2=0%).
Hyaluronate injections versus other hyaluronates showed no statistically significant difference in pain intensity (five RCTs). There was evidence of significant statistical heterogeneity (I2=72.2%). Hyaluronate injections were significantly more effective in reducing pain intensity versus steroid injections (SMD 0.39, 95% CI 0.07 to 0.71, I2=0%; five RCTs).
Shoulder movement (seven RCTs): Hyaluronate injections statistically significantly improved the range of movement compared to placebo (SMD 0.17, 95% CI 0.05 to 0.28). Subgroup analyses showed that hyaluronate injections modestly improved abduction (SMD 0.29, 95% CI 0.12 to 0.46), but did not significantly affect external rotation (data not reported).
Total functional scores: Hyaluronate injections statistically significantly improved total functional scores compared to placebo (SMD 0.36, 95% CI 0.01 to 0.71; four RCTs). There was no evidence of statistical heterogeneity.
There were no statistically significant differences between hyaluronate injections and placebo in the number of adverse events (13 RCTs, I2=0%).
There was no evidence of publication bias.