Efficacy of an Intra-articular Injection of Botulinum Toxin A Associated With Splinting 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 epilep…