Non-inferiority of saline versus corticosteroid injections for trapeziometacarpal osteoarthritis: a protocol for a pilot and feasibility randomised controlled trial.

introductionTrapeziometacarpal osteoarthritis (TMO) is among the most prevalent forms of upper extremity osteoarthritis. It is frequently associated with significant levels of pain and disability, particularly among ageing women. The typical care pathway for TMO relies on non-surgical approaches for up to 2 years, before surgery is considered. One of the most common non-surgical approaches is an intra-articular cortisone injection. However, these are not universally recommended due to their safety profile and unclear efficacy compared with saline injections. Recent evidence suggests that saline might be non-inferior to cortisone, but this remains to be clarified. This pilot trial aims to assess the feasibility of a trial examining the non-inferiority of saline compared with cortisone injections for TMO. METHODS AND ANALYSIS: This trial will recruit 40 adults with a diagnosis of TMO and a prescription for a cortisone injection from the Centre hospitalier de l'Université de Montréal (CHUM), Canada. Participants will be randomised to receive either an intra-articular injection of 0.9% sodium chloride (experimental arm, n=20) or triamcinolone acetonide (standard of care, n=20) under fluoroscopic guidance at the Radiology Department or under ultrasound guidance at the Physiatry Clinic. Opaque syringes will be used to blind participants and physicians. Feasibility outcomes, collected at all time points, will include recruitment rates, follow-up completion rates and blinding indices. Preliminary efficacy outcomes, collected at baseline and at 1 day, 1 month, 3 months and 6 months post-injection, will include pain intensity (0-10 scales), hand function (QuickDASH 11-items), cumulative analgesic consumption scores, concurrent interventions, adverse events and number of participants receiving a second injection or an arthroplasty. Descriptive statistics will be used to present feasibility outcomes. Preliminary data on the effectiveness of saline and cortisone injections will inform the design of a large-scale study for formal hypothesis testing. ETHICS AND DISSEMINATION: The trial was approved by the CHUM Human Research Ethics Board (2025-11815). The research output will be presented at conferences and published in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: NCT06401317.