THIS TRIAL WAS PROSPECTIVELY REGISTERED ON FEBRUARY 27, 2020 IN THE DUTCH TRIAL REGISTRY (www.trialregister.nl), BUT THIS TRIAL REGISTRY WAS TERMINATED. THE DATA ON OUR TRIAL WERE TRANSFERED BY THE DUTCH TRIAL REGISTRY TO WHO'S CLINICAL TRIALS SEARCH PORTAL (REFERENCE NUMBER: NL-OMON54664). WE ALSO REGISTERED THE TRIAL HERE AT CLINICALTRIALS.GOV TO BE ABLE TO ADD MORE DETAILS ON OUR STUDY.

Summary:

OBJECTIVE(S)/RESEARCH QUESTION(S) Does an orthosis combined with exercise therapy results in less pain and less conversion to surgery than an orthosis alone in patients with first carpometacarpal osteoarthritis (CMC-1 OA), at three months and one year after the start of treatment? HYPOTHESIS The investigators hypothesize that the orthosis + exercise therapy group has less pain and conversion to surgery will be lower than the orthosis group.

STUDY DESIGN Randomized controlled multicenter trial STUDY POPULATION(S)/DATASETS Patients with first carpometacarpal osteoarthritis (CMC-1 OA) seeking treatment INTERVENTION Orthosis + exercise therapy USUAL CARE/COMPARISON Orthosis only OUTCOME MEASURES Primary outcomes: pain and conversion to surgery SAMPLE SIZE CALCULATION/DATA ANALYSIS Two groups of 80 participants; analysis based on repeated measures analysis (for pain) and Chi-square tests (for conversion to surgery). The investigators initially planned to perform a survival analysis (log-rank) and logistic regression for conversion to surgery but decided prior to data analysis on using chi-square tests to determine whether there is a between-group difference in the proportion of conversion to surgery. The investigators made this decision due to low inclusion rates, as chi-square tests require smaller sample sizes. The investigators will use a mixed-effect model analysis for pain.

COST-EFFECTIVENESS ANALYSIS (CEA)/ BUDGET IMPACT ANALYSIS (BIA) Economic evaluation will be done from societal & healthcare perspectives, according cost-effectiveness analysis (CEA) guidelines. Medical & non-medical costs and consequences (i.e. productivity loss) will be collected and taken into account. Both CEA and cost-utility analysis will be performed, using conversion to surgery and Quality-adjusted life years (QALYs), respectively TIME SCHEDULE Start preparation: December 2019, inclusion: October 2020- December 2022, final report: December 2023

Inclusion criteria: All participants must meet the following criteria: 1) aged 18 or older; 2) Eaton stage 2-4 first carpometacarpal osteoarthritis (CMC-1 OA) based on radiographics and/or clinical examination; and 3) ability to visit the treatment center for treatment sessions.

Exclusion criteria: A potential participant that meets any of the following criteria will be excluded: 1) secondary first carpometacarpal osteoarthritis (CMC-1 OA) (e.g., due Bennett's fracture); 2) presence of comorbidity that interferes with treatment or outcome (e.g., carpal tunnel syndrome or De Quervain tenosynovitis); 3) surgery in medical history that interferes with treatment or outcome (e.g., trapeziectomy or tendon repair); 4) steroid injection in hand/wrist <6 weeks prior to admission; 5) previous treatment for CMC-1 OA in one of both hands, including orthosis, hand therapy or surgery; or 6) insufficient ability to understand written and spoken Dutch or English language.

We will manage the data following FAIR principles and store the data in DANS