Effects of Botulinum Toxin Landmark‐Guided Intra‐articular Injection in Subjects With Knee Osteoarthritis

BACKGROUND: Increasing evidence has suggested that botulinum toxin A (BoNT/A) can inhibit the release of selected neuropeptide transmitters from primary sensory neurons. Thus, intra-articular (IA) injection therapies with BoNT/A may reduce pain in patients with knee osteoarthritis (OA). OBJECTIVE: To investigate the effects of landmark-guided IA injection of BoNT/A on patients with knee OA. DESIGN: A prospective randomized controlled trial. SETTING: A rehabilitation clinic of a private teaching hospital. PATIENTS: A total of 46 patients with symptomatic knee OA (mostly Kellgren-Lawrence grade 2-3). METHODS: The patients were randomly assigned to 1 of the following groups: BoNT/A group (BoNT/A injection; n = 21) or control group (education only; n = 20). The patients in the BoNT/A group received an IA injection of 100 units of BoNT/A into the affected knee. MAIN OUTCOME MEASURES: The short-term (1 week posttreatment) and long-term (6 months posttreatment) effects were evaluated using a pain visual analogue scale (VAS) and questionnaires concerning functional status, including the Lequesne and Western Ontario and McMaster Universities (WOMAC) indexes. RESULTS: The between-group comparison revealed significant differences with regard to the pain VAS score at 1 week (P < .001) and at 6 months (P = .001) posttreatment. Similar findings for the between-group comparison were observed for the WOMAC and Lequesne indexes at 6 months (P < .05) posttreatment. The pain VAS score in the BoNT/A group significantly decreased from 5.05 ± 1.12 (pretreatment) to 2.89 ± 1.04 at 1 week (P < .001) and 3.45 ± 1.70 at 6 months posttreatment (P < .001) but not in the control group (P = .476). CONCLUSIONS: The IA injection of BoNT/A provided pain relief and improved functional abilities in patients with knee OA in both the short- and long-term follow-up. LEVEL OF EVIDENCE: I.