The Effect of Botulinum Toxin Injection into the Common Extensor Tendon in Patients with Chronic Lateral Epicondylitis: A Randomized Trial.

[BACKGROUND] Botulinum toxin (BTX) is widely used for pain control in various musculoskeletal disorders.

[OBJECTIVES] We evaluated the analgesic effect of botulinum toxin type A (BTX-A) in chronic lateral epicondylitis and compared the effect between 10 and 50 IU of BTX-A.

[METHODS] Sixty subjects with chronic lateral epicondylitis were included and underwent a BTX-A injection in the common extensor tendon. The subjects were randomly allocated into two groups: the small-dose group (SD group; 30 subjects, 10 IU) and large-dose group (LD group; 30 subjects, 50 IU). Treatment outcomes were evaluated by measuring the pain level using the numeric rating scale (NRS) and measuring grip strength before and one, two, three, four, five, and six months after treatment.

[RESULTS] Subjects in both groups showed a significant decrease in NRS scores at all evaluation time points after treatment. The reduction in NRS scores was significantly greater in the LD group at one, two, three, and four months after treatment. Six months after treatment, 19 subjects (63.3%) in the SD group and 21 (70%) in the LD group reported successful pain relief (pain relief ≥50%). The rate of successful pain relief was not significantly different between the two groups. Grip strength was more increased in the LD group at one, two, three, four, and six months after treatment.

[CONCLUSIONS] BTX-A injection into the common extensor tendon can be a good treatment option for chronic lateral epicondylitis. The 50-IU BTX-A injection achieved a better outcome than the 10-IU injection.