Efficacy of an Intra-articular Injection of Botulinum Toxin A Associated With Splinting for Base-of-thumb Osteoarthritis

Base-of-thumb osteoarthritis is a common condition affecting middle-age persons. Base-of-thumb osteoarthritis induces pain and hand-specific limitations in activities. For short and midterm effects, therapeutic options usually include splinting, exercise therapy and intra-articular injections of glucocorticoids or hyaluronic acid. However, evidence of efficacy of intra-articular therapies in base-of-thumb osteoarthritis and international guidelines are inconsistent. Recently, the use of intra-articular botulinum toxin A as a pain killer has raised intense interest. The exact mechanisms of pain modulation by botulinum toxin A in osteoarthritis are unclear. It has been suggested that botulinum toxin A could directly reduce peripheral sensitization and indirectly reduce central sensitization. Indeed, recent studies suggest an inhibitory role of botulinum toxin A on the release of mediators involved in nociception, such as P substance, calcitonin gene-related peptide and glutamate. Open and randomized controlled trials of botulinum toxin A in knee osteoarthritis support short to mid-term positive clinical effects on pain. However, no study has reported results for base-of-thumb osteoarthritis

Inclusion criteria

• Age ≥ 18 years old
• Pain intensity on a self-administered 11-point pain numeric rating scale ≥ 30
• Pain involving the base-of-thumb
• X-ray evidence of base-of-thumb osteoarthritis with at least 2 of the 4 following items involving the trapeziometacarpal joint : osteophytes, joint space narrowing, subchondral bone sclerosis or subchondral cysts
• 1990 American College of Rheumatology classification criteria for hand osteoarthritis adapted to base-of-thumb osteoarthritis
• Medical examination
• Written consent
• Health insurance
• For women of childbearing age, a negative urinary pregnancy test

Exclusion criteria

• History of thumb surgery
• History of inflammatory or crystal-associated rheumatic disease
• Neurological disorders involving the hands other than carpien canal syndrom
• Collagen disorders involving the hands : Dupuytren, Marfan or Ehlers-Danlos diseases
• Osteoarthritis predominating at the scaphotrapezial joint on X-Ray
• Hand or wrist trauma ≤ 2 months
• Hand or wrist intra-articular injections ≤ 2 months
• Contra-indication to botulinum toxin A injection or to splinting
• Cognitive or behavioral disorders making the assessment impossible
• Participant unable to speak, read and write french
• Bilateral BTOA without predominant symptomatic side
• Pregnancy and breast feeding
• Persons referred to in Articles L 1121-5; 6; 8; 9 of the Public Health Code (protected minors or adults, guardianship or trusteeship, etc.)
• Patient with epilepsy