The quality of evidence is downgraded by study limitations (unclear allocation concealment and lack of blinding) and by inconsistency (unexplained variability in results).
A Cochrane review «Intra‐articular corticosteroid for knee osteoarthritis»1 «Jüni P, Hari R, Rutjes AW et al. Intra-articular corticosteroid for knee osteoarthritis. Cochrane Database Syst Rev 2015;(10):CD005328. . »1 included 27 studies, with a total of 1 767 subjects, comparing intra-articular (IA) corticosteroid against sham or no intervention. IA corticosteroids were more effective in pain reduction than control (SMD -0.40, 95% CI -0.58 to -0.22; statistical heterogeneity I2=68%; 26 studies, n=1 749), which corresponds to a difference in pain scores of 1.0 cm on a 10-cm visual analogue scale between corticosteroids and sham injection and translates into a number needed to treat for an additional beneficial outcome (NNTB) of 8 (95% CI 6 to 13). When stratifying results according to length of follow-up, improvements were observed at 1–2 weeks and 4–6 weeks, but there was no statistically significant differences at 3 and 6 months.
IA corticosteroids appeared to be more effective in function improvement than control (SMD -0.33, 95% CI -0.56 to -0.09; statistical heterogeneity I2=69%; 15 studies, n=1 014), which corresponds to a difference in functions scores of -0.7 units on standardised Western Ontario and McMaster Universities Arthritis Index (WOMAC) disability scale ranging from 0 to 10 and translates into a NNTB of 10 (95% CI 7 to 33). When stratifying results according to length of follow-up, benefits were observed at 1–2 weeks and 4–6 weeks, but there were no statistically significant differences at 3 or 6 months. There was no statistically significant difference in adverse events (RR 0.89, 95% CI 0.64 to 1.23; 2 studies, n=84) or serious adverse events (RR 0.63, 95% CI 0.15 to 2.67; 5 studies, n=331) between corticosteroids and control . There was no difference on quality of life between corticosteroids and control (SMD -0.01, 95% CI -0.30 to 0.28; 2 studies, n=184). There was also no evidence of an effect of corticosteroids on joint space narrowing compared to control interventions (SMD -0.02, 95% CI -0.49 to 0.46; 1 study, n=68).