Treatment of chronic radial epicondylitis with botulinum toxin A. A double-blind, placebo-controlled, randomized multicenter study.

BACKGROUND: Radial epicondylitis (tennis elbow) is the most frequent type of myotendinosis. Patients can experience substantial loss of function, especially when this condition becomes chronic. A successful therapy has not yet been established. A preliminary study of injections of botulinum toxin A in patients with chronic epicondylitis has shown promising results.

METHODS: In the present prospective, controlled, double-blinded clinical trial, 130 patients were examined at sixteen study centers. A single injection of botulinum toxin A into the painful origin of the forearm extensor muscles was performed. Follow-up examinations were performed at two, six, twelve, and eighteen weeks. Clinical findings were documented with use of a new clinical pain score and with a visual analogue scale. A global assessment of the result of treatment was also provided by the patient and the attending doctor. Strength of extension of the third finger and the wrist was evaluated with use of the Brunner method, and grip strength (fist closure strength) was measured with a vigorimeter.

RESULTS: The group treated with botulinum toxin A was found to have a significant improvement in the clinical findings, compared with those in the placebo group, as early as the second week after injection (p = 0.003). Subjective general assessment also showed improvement in that group, compared with the placebo group, at six weeks (p = 0.001) and at the time of the final examination (at eighteen weeks) (p = 0.001). There was a consistent increase in fist closure strength in both the group treated with botulinum toxin A and the control group, but there was no significant difference between groups. As was expected as a side effect, extension of the third finger was observed to be significantly weakened at two weeks but this complication had completely resolved at eighteen weeks.

CONCLUSIONS: We concluded that local injection of botulinum toxin A is a beneficial treatment for radial epicondylitis (tennis elbow). The treatment can be performed in an outpatient setting and does not impair the patient's ability to work.