The THumb Osteoarthritis Exercise TriAl (THETA)

The THumb Osteoarthritis Exercise TriAl (THETA); a Multicenter, Randomized Controlled Trial on Exercise Therapy With an Orthosis Compared to an Orthosis Alone in Patients With Thumb Base Osteoarthritis

ZonMw: The Netherlands Organisation for Health Research and Development, Xpert Clinics, Franciscus Gasthuis, IJsselland ziekenhuis, Reinier Haga Orthopedisch Centrum, Elisabeth-TweeSteden Ziekenhuis

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 We 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 irst 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-squared (for conversion to surgery). We initially planned to perform a logistic regression for conversion to surgery but decided prior to data analysis that we will be using Chi-square tests to determine whether there is a between-group difference in the proportion converting to surgery. We will use a repeated measures 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

The orthosis + exercise group receives the same orthosis and instructions as the orthosis group (see next section), supplemented by exercise therapy. This includes weekly 25-30-minute physical therapy sessions with a total of 12 sessions. Sessions include patient education on thumb positioning, functional training and home exercise instructions to improve CMC-1 stability during pinch in extension/abduction, as instability and degeneration occurs in flexion/adduction(17,19,28-31). The first phase (week 0 - week 6) comprises coordination exercises for the thumb intrinsics (except adductor pollicis), extensor pollicis brevis and first dorsal interosseous to support CMC-1 extension/abduction. The second phase (week 6 - month 3) comprises reduced orthosis usage and thenar muscle strengthening exercises(except adductor pollicis).

The orthosis group receives a custom-made thermoplastic orthosis immobilizing the first carpometacarpal joint (CMC-1) in extension/abduction and the metacarpophalangeal joint in flexion. Orthosis usage is 24/7 in the first two weeks, thereafter only during activities with high load until three months. Two appointments take place: one for orthosis fabrication and one for a one-week checkup.

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.