Comparative Effectiveness of Injection Therapies in Lateral Epicondylitis: a Systematic Review and Network Meta-analysis of Randomized Controlled Trials

Background: Injection therapy with glucocorticoids has been used since the 1950s as a treatment strategy for lateral epicondylitis (tennis elbow). Lately, several novel injection therapies have become available.

Purpose: To assess the comparative effectiveness and safety of injection therapies in patients with lateral epicondylitis.

Study Design: Systematic review and meta-analysis.

Methods: Randomized controlled trials comparing different injection therapies for lateral epicondylitis were included provided they contained data for change in pain intensity (primary outcome). Trials were assessed using the Cochrane risk of bias tool. Network (random effects) meta-analysis was applied to combine direct and indirect evidence within and across trial data using the final end point reported in the trials, and results for the arm-based network analyses are reported as standardized mean differences (SMDs).

Results: Seventeen trials (1381 participants; 3 [18%] at low risk of bias) assessing injection with 8 different treatments-glucocorticoid (10 trials), botulinum toxin (4 trials), autologous blood (3 trials), platelet-rich plasma (2 trials), and polidocanol, glycosaminoglycan, prolotherapy, and hyaluronic acid (1 trial each)-were included. Pooled results (SMD [95% confidence interval]) showed that beyond 8 weeks, glucocorticoid injection was no more effective than placebo (-0.04 [-0.45 to 0.35]), but only 1 trial (which did not include a placebo arm) was at low risk of bias. Although botulinum toxin showed marginal benefit (-0.50 [-0.91 to -0.08]), it caused temporary paresis of finger extension, and all trials were at high risk of bias. Both autologous blood (-1.43 [-2.15 to -0.71]) and platelet-rich plasma (-1.13 [-1.77 to -0.49]) were also statistically superior to placebo, but only 1 trial was at low risk of bias. Prolotherapy (-2.71 [-4.60 to -0.82]) and hyaluronic acid (-5.58 [-6.35 to -4.82]) were both more efficacious than placebo, whereas polidocanol (0.39 [-0.42 to 1.20]) and glycosaminoglycan (-0.32 [-1.02 to 0.38]) showed no effect compared with placebo. The criteria for low risk of bias were only met by the prolotherapy and polidocanol trials.

Conclusion: This systematic review and network meta-analysis of randomized controlled trials found a paucity of evidence from unbiased trials on which to base treatment recommendations regarding injection therapies for lateral epicondylitis.