Only 4 randomized controlled clinical trials have been published to date to assess the short-term effectiveness of intra-articular Botulinum Toxin injection on pain, function and quality of life in patients suffering from chronic knee pain related or not to knee osteoarthritis and also in the context of ankle osteoarthritis. The analgesic properties and the reported safety make intra-articular Botulinum toxin a strong candidate in the treatment of symptomatic manifestations of osteoarthritis disease and more particularly in certain locations such as the trapezo-metacarpal joint. Investigators hypothesize that injection of intra-articular Botulinum toxin into the trapezo-metacarpal joint will be of benefit in reducing pain and improving function in patients with rhizarthrosis. Investigators will begin a monocentric randomized controlled trial comparing intra-articular injections of Botulinum toxin and placebo.

Inclusion Criteria:

• Patient >18 years old
• Patient with rhizarthrosis objectified by interrogation, radiography with at least 2 of the following criteria: osteophyte, joint space narrowing, subchondral sclerosis or geode
• Patient who has had an X-ray of the wrist (face, profile and Kapandji incidence) to estimate the severity of the rhizarthrosis.
• Patient with signed informed consent.
• Visual analog scale (VAS) of pain > 4
• Failure of well-conducted drug treatments with level 1 and 2 analgesics, anti-inflammatory drugs and orthotic devices
• Patients must have stopped all corticosteroid or non-steroidal anti-inflammatory drugs therapy within the last 48 hours.
• Patient affiliated with a Social Security plan
• Patient who can understand the study instructions
• Patient on effective contraception for more than one month according to the marketing authorization (Pill, intrauterine device, vaginal ring, contraceptive skin patch, hormonal subcutaneous implant)
• Infertile patients in connection with surgery (tubal ligation, oophorectomy, adnexectomy, hysterectomy)

Exclusion Criteria:

• History of surgery of the thumb column
• Patient who has received an intra-articular trapezoidal metacarpal injection of corticoids, botulinum toxin or hyaluronic acid or other product within the last 6 months.
• Patient who has received a Botulinum toxin injection at any site within the last 3 months
• Myasthenia or Lambert-Eaton disease, neuromuscular dysfunction, hypersensitivity to incobotulinumtoxin A, severe respiratory disorder or severe swallowing disorder
• Patients with hypersensitivity to botulinum toxin or to any of the excipients (human albumin sucrose)
• Patient with an infection or inflammation at the injection site concerned
• Pregnant or breastfeeding women (a urine pregnancy test will be performed)
• Patients with chronic inflammatory joint disease or microcrystalline pathology
• Current participation or less than 30 days of participation in a clinical drug trial
• Any medical or psychiatric condition that could prevent the proper understanding and conduct of the treatment and study (adult under guardianship)
• Patient who wishes to discontinue contraception during the study
• Patients at high risk of bleeding complications from the intra-articular injection (hemophilia, anticoagulant treatment, etc.)