A systematic review of randomized controlled trials of lateral epicondylitis interventions, comparing saline solution injections with nonsurgical injection therapies, found 10 articles.1
At one month the difference in pain from baseline recording on the visual analogue scale (0 = no pain and 100 = worst possible pain) was 16; 22 at 3 months, 40 at 6 months and 47 at 12 months. These differences were considered clinically significant.
Many of the studies were not primarily aimed at injecting saline, and there was no reporting of dose and whether or not local anaesthetic was used. This could, however, be an option for clinicians reluctant to inject corticosteroid.
The authors point out that the natural history of improvement between 5 and 24 months.