Clinical efficacy of botulinum toxin in lateral elbow tendinopathy: A systematic review and meta-analysis of randomized controlled trials

Background: Botulinum toxin injections for lateral elbow tendinopathy have been used as an alternative therapeutic option. However, few studies have quantitatively summarized the effect of botulinum toxin as well as its clinical significance. We aimed to evaluate the clinical efficacy (based on pain and grip strength) and adverse events of botulinum toxin on lateral elbow tendinopathy. Patients and methods: The MEDLINE, EMBASE, Web of Science, and Scopus databases were searched until March 2023 for randomized controlled trials reporting the effects of botulinum toxin injections on lateral elbow tendinopathy. A random-or fixed-effects model (depending of inter-study variability) and generic inverse variance method were used to pool quantitative data from outcomes. The risk of bias was assessed with the Cochrane Risk of Bias 2.0 tool. Results: A total of 8 clinical trials recruiting 438 subjects were included for meta-analysis. Pooled analysis revealed that botulinum toxin significantly reduced pain (mean difference [MD] -0.95, 95% CI [-1.63, -0.26], p = 0.007) but it was not clinically relevant. No significant effect was detected for grip strength (MD-0.62 kg, 95% CI [-2.25, 1.02], p = 0.46) or in the risk for adverse events (odds ratio [OR] 0.41, 95% CI [0.05, 3.56], p = 0.42) between botulinum toxin injection and control interventions. Discussion: The use of botulinum toxin reached greater pain relief than control interventions and normal saline after a period of 12 to 24 weeks. However, changes in pain relief did not reach clinical significance. The studies that had the greatest reduction in pain used higher doses of botulinum toxin (60 U). Additionally, differences in grip strength and adverse events did not reach statistical or clinical importance. A subanalysis indicated that botulinum toxin outperformed corticosteroid injections in terms of improving grip strength. Botulinum toxin only causes local and minimal side effects such as irritation, ecchymosis, and paralysis. Level of evidence: I. (c) 2023 Elsevier Masson SAS. All rights reserved.