Number of botulinum toxin injections needed to stop requests for treatment for chronic lateral epicondylar tendinopathy. A 1-year follow-up study.

Background: Epicondylar tendinopathy ("tennis elbow") is a serious issue in manual labourers. Symptoms can persist over months or even more than 1 year, even when treated with trinitrine patches, acupuncture, sclerosis of neovessels, shock-wave therapy, autologous blood injections, platelet-rich plasma or hyaluronic acid. Botulinum toxin (BoNT-A) injections showed promising short-term results, but the long-term beneficial effects are not yet known.

Objective: We aimed to assess the long-term effect, side effects and recurrence rate after BoNT-A injections on chronic lateral epicondylar tendinopathy during 1 year.

Methods: This open study followed a 3-month randomized controlled trial. We included 50 patients followed at day 0 (V0), 90 (V1), 180-270 (V2) and 365 (V3). The main judgment criterion was the number of BoNT-A injections required to achieve pain relief with no further request for treatment by the patient.

Results: After one BoNT-A injection, 22/50 (44%) patients did not ask for further treatment during follow-up because of complete pain relief, and 20/50 (40%) asked for a second BoNT-A injection. For 20 patients with a second injection, 18 (90%) did not ask for further treatment during follow-up. Only 1 patient had a recurrence of pain after an initial pain relief of greater than 75%. Quality of life, and painful and maximal gripping force improved significantly at V1, V2 and V3 as compared with V0, and repercussions on daily and professional activities decreased significantly (P<0.05).

Conclusions: One or 2 BoNT-A injections has favourable results for chronic epicondylar tendinopathy.