One or two ultrasonography-guided botulinum toxin A injections in the treatment of refractory lateral epicondylalgia? A retrospective study

Design: Retrospective cohort study evaluating the outcomes and safety of botulinum toxin A injections in refractory lateral epicondylalgia. Participants: Seventy-nine patients (81 elbows) with refractory lateral epicondylalgia (persistent pain despite ≥6 months conservative treatment) treated between August 2022 and December 2023. Interventions: All patients received an initial ultrasound-guided injection of 40 units of botulinum toxin A into the extensor carpi radialis brevis (ECRB). A second injection was offered in case of persistent symptoms, targeting the ECRB, extensor digitorum communis and/or supinator depending on standard provocative tests. Main measures: Clinical outcome was categorised as ‘poor’, ‘temporary’, ‘partial’ or ‘good’ based on self-reported pain evolution. Patients no longer requesting care were classified in the ‘good’ category. Adverse events were systematically recorded. Results: After the first injection, 20% (16/81) had a ‘good’ outcome. Among 51 elbows receiving a second injection, 47% (24/51) reached this category, yielding an overall rate of 49% (40/81). Favourable outcome was not significantly associated with sex, age, or number of muscles injected in univariable analyses. Transient motor weakness occurred in 34% (27/79) of patients; one patient experienced a persistent deficit lasting six months with functional impairment. Conclusions: A second ultrasound-guided botulinum toxin A injection with individually tailored muscle targeting was associated with a favourable outcome in about half of patients insufficiently relieved after the first one. Randomised controlled trials are needed to evaluate the added benefit of a tailored muscle targeting strategy and ultrasound guidance in the management of refractory lateral epicondylalgia.