Study protocol for the PICASSO trial: A randomized placebo-controlled trial to investigate the efficacy and safety of intraarticular steroid injections and an occupational therapy intervention in painful inflammatory carpometacarpal-1 osteoarthritis.

Objective: Our primary objectives are to assess whether intraarticular corticosteroid injections are superior to saline injections with regards to thumb base pain after 4 weeks, and to compare the efficacy of steroid injections, saline injections, and an occupational therapy intervention on thumb base pain after 12 weeks in people with painful inflammatory osteoarthritis (OA) of the first carpometacarpal (CMC-1) joint. Design: In this three-armed, double-blind, randomized multicenter trial, 354 participants with painful inflammatory CMC-1 OA from six Norwegian hospitals are recruited. Participants are randomized 1:1:1 to intraarticular steroid or saline injections in the CMC-1 joint or a multimodal occupational therapy intervention. The primary outcomes are thumb base pain measured on a numeric rating scale (NRS, range: 0-10) after 4 weeks and 12 weeks. Key secondary outcomes include synovitis by Magnetic Resonance Imaging (MRI) after 4 weeks and hand function by the Measure of Activity Performance of the Hand (MAP-Hand) questionnaire after 12 and 24 weeks. Other secondary outcomes are synovitis by clinical examination and ultrasound, measures of pain, function, stiffness, and health-related quality of life, and direct and indirect costs. Adverse events are recorded at each visit. The duration of the randomized controlled trial is 24 weeks, followed by an 80-week open-label observational phase to investigate the long-term efficacy and safety of repeated steroid injections and the occupational therapy intervention. Conclusions: The results from this trial will have important clinical implications and influence future guidelines on OA management of the CMC-1 joint. Clinical trial registration: EU-CT 2023-505254-17-00, NCT06084364.