The THumb Osteoarthritis Exercise TriAl

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.