Study purpose is to compare the outcome after proximal row carpectomy (PRC) vs four-corner fusion (FCA) for SLAC/SNAC II-III type osteoarthritis (OA) in a double-blinded randomized controlled study setting. Patients with radiologically and clinically confirmed OA are randomized (1:1 computer generated sequence with random block size) to two parallel groups and will undergo either PRC or FCA. The study will be patient and assessor blinded. Baseline data is collected preoperatively and is followed by a follow-up visits at 2 and 6 weeks, 3, 6, 12 months, and 5, 10 years after the intervention. Unveiling of the allocation is at 12 months post-intervention.