The prevalence of digital osteoarthritis varies according to whether a radiological or clinical definition is adopted.

Interventions: Thumb orthoses to be worn at night and usual care vs usual care. Outcome measures: Pain at 1 month assessed on visual analog scale is the main outcome measure. Disability at 6 months (Cochin Hand Function Scale) and deformation at 1 year are the main secondary outcome measures.

The prevalence of digital osteoarthritis varies according to whether a radiological or clinical definition is adopted. Radiologically defined osteoarthritis of the hand has been estimated to represent 38% of women and 24.5% of men over 66 years of age but higher prevalence of 60-70% has also been reported. Of patients with radiological signs, 20 to 40% become symptomatic. For patients over 55 years of age, the distal interphalangeal joints are the most prevalent site of osteoarthritis (20%) determined radiologically and clinically, followed by the base of the thumb (8%) and proximal interphalangeal joints (5%). This prevalence increases with age, and the incidence peaks in perimenopausal women. Osteoarthritis in the base of the thumb (BTOA) concerns the trapeziometacarpal joint, with a possible secondary location at the trapezotrapezoidial and scaphotrapezial joints. BTOA induces a closure of the first web, which in turn causes an alteration of the thumb-index pinch and therefore a limitation in hand function. Pain induced by the compression of the thumb column during pinching could also lead to functional disability. Effect of a simple intervention such as wearing rest thumb orthoses on pain and disability is unknown.

Inclusion Criteria:

• Pain at the base of the thumb 30 mm on VAS
• Patient aged 45 and < 75 years old
• At least 2 of the 5 items on the trapeziometacarpal joint radiograph osteophytes
• joint space narrowing
• subchondral bone sclerosis
• subchondral cysts
• At least 1 of the 2 clinical items trapeziometacarpal joint enlargement closure of the first web

Exclusion Criteria:

• Post traumatic osteoarthritis
• Cristal arthropathy
• Inflammatory arthritis
• Neurologic disorder involving upper limb
• Psychiatric disorder needing treatment adaptation in the last 3 months
• Hand or wrist trauma within the last 2 months
• Previous hand surgery
• Unable to speak or write French
• Pregnancy
• Collagen diseases (Dupuytren, Marfan, Ehlers Danlos syndromes)
• Hand or wrist infiltration within 2 months
• Skin disease interfering with the wearing of the orthoses
• Having already worn a BTOA orthoses
• Having bilateral BTOA without predominant symptomatic side