Long-term effects of intra-articular botulinum toxin A for refractory joint pain

The small study review describes the authors’ 12 month clinical experience with intra-articular injections of Botulinum toxin Type A (BoNT/A) for refractory joint pain. Eleven patients with chronic arthritis (five had osteoarthritis, five had rheumatoid arthritis, and one had psoriatic arthritis) who had failed treatment with oral and/or intra-articular medications and were not surgical candidates were referred for management of moderate to severe refractory joint pain in 15 joints. Two patients were female and nine were male, aged 42-82 years. All patients were on analgesic and/or anti-inflammatory medications and all joints had previous intra-articular steroid or viscosupplement injections with inadequate or unsatisfactory benefit.

The use of BoNT/A to treat joint pain is a non-FDA approved "off label" treatment with potential side effects. Fifteen joints were injected with BoNT/A: three knees, three ankles with 25-50 units and nine shoulders with 50-100 units. Patients were followed for one year or longer. Maximum pain relief was measured by comparing baseline pain on a 0-10 scale to pain at maximum relief. Maximum improvement in function was assessed using paired t-tests for improvement in active flexion and abduction for the shoulder joint, and by the time to perform sit to stand ten times for the lower extremity joints. A clinically and statistically significant improvement was noted after IA-BoNT/A injections. The mean maximum decrease in lower extremity joint pain was 55%, and 36% improvement in the Timed Stands Test was noted at 4 to 10 weeks after injection. There was a 71% reduction in shoulder pain severity. Active range of motion increased 67% in flexion and 42% in abduction. No immediate or delayed adverse effects related to BoNT/A were noted after the injection. Pain relief was variable and ranged from 3 to 12 months. Five joints were re-injected with IA-Bont/A and had a similar decrease in joint pain that lasted 3 to 12 months. This is the first report of the long-term effects of intra-articular BoNT/A injections to treat chronic joint pain and the efficacy of repeated injections. These results suggest that IA-BoNT/A injections are effective and safe for chronic joint pain disorders. Mahowald ML, Singh JA, Dykstra D. Adapted from Neurotox Res. 2006 Apr;9(2-3):179-88.

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