Åse Klokkeide

1 INTRODUCTION Thumb base osteoarthritis (CMC1-OA) is a common subset of hand OA. The prevalence of symptomatic CMC1-OA is 2% in men and 7% in women, whereas radiographic CMC1-OA is present in 30% of men and 33% of women (Eaton et al., 2022; Haugen et al., 2011). Symptoms and functional consequences of CMC1-OA include pain, stiffness, reduced grip strength and hand function, and impaired activity performance, work ability and quality of life (Kwok et al., 2014).