The Distraction of the Thumb Base study is a randomized controlled trial to assess the effects of joint distraction among patients with carpometacarpal osteoarthritis of the thumb (CMC1 OA). The prevalence of CMC1 OA is high. If patients are not satisfied with non-operative treatment, they can be offered surgical interventions (like excision of one of the carpal bones). The goal of joint distraction is to postpone such an invasive intervention. We place an external distractor device over the affected CMC1 joint to achieve a few millimeters intra-articular distraction. After a period of 6 to 8 weeks, the device will be removed during at an outpatient office visit.

The distraction trial is conducted in the St. Antonius Hospital in the Netherlands. In this study we will assess if we can decrease the duration of distraction from 8 to 6 weeks. Participants will be randomized to 1 of 2 groups:

– Group A will receive 8 weeks of thumb base distraction.

– Group B will receive 6 weeks of thumb base distraction.

All study participants will be followed for five years to assess patient satisfaction, hand health status, physical function, strength and motion of the thumb. We will also ask patients to complete several questions about psychosocial symptoms to test the influence of social and mental health on the outcome of thumb base distraction.