efficacy of two ultrasound-guided intra-articular injections of botox® combined with custom-made rigid splinting in painful base-of-thumb osteoarthritis.

Conditions: Base-of-thumb Osteoarthritis; Osteoarthritis

Summary: the main objective of this study will be to compare the effects of 2 intra-articular injections of onabotulinumtoxina with those of 1 intra-articular injection of onabotulinumtoxina and 1 of normal saline and those of 2 intra-articular injections of normal saline on base-of-thumb pain at 6 months after the first injection.

the base of the thumb is a frequent location of osteoarthritis. base-of-thumb osteoarthritis affects middle-aged and older individuals and results in base-of-thumb pain and limitations in hand-specific activities. for the medium and long term, evidence suggests that splinting could reduce pain and improve hand function. for the short term, a combination of conservative treatments is recommended, with small-to-moderate treatment effect. however, use of intra-articular treatments (e.g., glucocorticoids and hyaluronan) for the short and medium term is currently debated. use of intra-articular botulinum toxin a injection as a pain modulator in joint diseases has recently raised interest. botulinum toxin a is a neurotoxin produced by clostridium botulinum that inhibits acetylcholine release into the synaptic cleft in cholinergic nerve terminals. additionally, treatment with botulinum toxin a showed intrinsic antinociceptive effects in various animal models of joint diseases. in a pilot single-centred randomized controlled trial of 60 participants with painful base-of-thumb osteoarthritis, the investigators compared the effects of a single intra-articular injection of onabotulinumtoxina (botox® ) with those of a single intra-articular injection of normal saline on base-of-thumb pain, and found a significant reduction in pain. several perspectives raised from this pilot study. like in the treatment of spasticity, repeated courses of intra-articular injections onabotulinumtoxina may be necessary to obtain sustained analgesic effects over time. a replication of these findings in a multicentred setting, analysis of cost-effectiveness and description of safety at longer term are also needed before the official recommendation of this treatment. in rhibot ii, the investigators hypothesize that 2 ultrasound-guided intra-articular injections of onabotulinumtoxina, as an add-on therapy to custom-made rigid splinting, could reduce base-of-thumb pain at 6 months after the first injection.

Eligibility criteria:
inclusion criteria: * • individuals aged at least 18 years; * pain intensity of at least 30 on a self-administered 11-point pain numeric rating scale (0: no pain to 100: maximal pain); * pain involving the base of the thumb; * x-ray evidence of trapezometacarpial osteoarthritis with at least two of the following items involving the trapezometacarpial joint: osteophytes, joint space narrowing, subchondral bone sclerosis, or subchondral cysts; * 1990 acr classification criteria for hand osteoarthritis adapted to trapezometacarpial osteoarthritis. * patient able to give written informed consent prior to participation in the study * affiliation with a mode of social security (profit or being entitled). * negative pregnancy test in women of childbearing potential exclusion criteria: * • secondary osteoarthritis; * history of thumb surgery, inflammatory or crystal-associated rheumatic disease, or epilepsy; * uncontrolled dysphagia, pneumonia, cardiovascular diseases, or clinical or subclinical signs of neuromuscular transmission disorders; * contra-indication to onabotulinumtoxina; * neurological disorders involving the hands other than carpal tunnel syndrome; * collagen disorders involving the hands; * osteoarthritis predominating at the scaphotrapezial joint on x-ray; * bilateral trapezometacarpial osteoarthritis without a predominant painful side; * hand or wrist trauma for up to 2 months; * intra-articular treatments for up to 2 months; * use of im, iv or oral corticosteroids for up to 2 months. * protected adults (including individual under guardianship by court order) * pregnant women and lactation; lack of contraception for women of childbearing potential * patient participating in another investigational therapeutic study * patient unable to speak and read french

Keywords: base-of-thumb osteoarthritis