Thumb osteoarthritis: botulinum toxin effective against pain

This study was carried out by the team of the musculoskeletal system and spine pathologies rehabilitation and rehabilitation department of the Cochin-Port Royal AP-HP hospital, Inserm and Paris Cité University and coordinated by Professor Christelle Nguyen.

Thumb osteoarthritis: a common pain that is difficult to treat

Hand osteoarthritis is one of the most common diseases of the musculoskeletal system. Women after 45 are the most affected. Beyond the pain, it causes a loss of mobility, aesthetic discomfort and embarrassing limitations on a daily basis.

“Apart from the custom-made rigid rest orthosis, no drug or non-drug treatment has demonstrated its effectiveness with a high level of evidence in the treatment of osteoarthritis of the base of the thumb.“says Inserm. For the acute phases, intra-articular injections of corticosteroids are less effective than in the knee.

Faced with this lack of option, the French researchers wanted to test the effectiveness of an intra-articular injection of a type A botulinum toxin (which in the context of other studies has already demonstrated pain-relieving properties by inhibiting certain pain neurotransmitters).

A comparison between botulinum toxin and saline

To assess the effectiveness of this option, the authors recruited 60 volunteers, aged 65 on average and suffering from osteoarthritis of the thumb, whose average pain was assessed on a standardized scale of 60 points out of 100.

They were divided into two groups of 30 people (80% were women)

• The first received an ultrasound-guided intra-articular injection, in the trapezio-metacarpal joint, of one milliliter of Botox;
• The second, constituting a control group, received an ultrasound-guided intra-articular injection of 1 ml of saline.

Participants in both groups had a custom-made rigid rest orthosis.

A reduction in pain at 3 months

After three months, the researchers found that “the average reduction in pain at the base of the thumb was greater in the experimental group than in the control group: pain decreased by 25.7 points out of 100 in the experimental group compared to 9.7 points out of 100 in the group control, i.e. an absolute difference of 16 points out of 100″.

No adverse effects considered severe were observed.

Results still to be confirmed

For Dr. Laurent Grange, rheumatologist at the Grenoble Alpes University Hospital and member of the Doctissimo expert committee, this conclusion is encouraging. “Botulinum toxin is not yet used routinely, it is not a molecule included in the recommendations. However, it is regularly studied and it seems to give good results. Regarding this study, the group of participants is a bit small… If its large-scale effects can be confirmed, and it does not show any adverse effects, it could be used more widely for pain relief in osteoarthritis“.

The research team now plans to conduct a large-scale, multi-centre study to optimize the Botox® dose and injection schedule.