31 patients with a diagnosis of grade 1 and 2 thumb carpometacarpal joint osteoarthritis were randomized to wear a custom-made splint, a prefabricated splint, or no splint for 4 weeks in a cross-over study design. Following a 2 week washout period, the intervention was changed and the new splint was worn for another 4 weeks. Results indicated that both splints significantly improved pain and function compared to the control group. Following the first 4-week intervention, there were no significant differences between splints in pain, but the custom-made splint produced significantly better improvements in pain following the second 4-week intervention (i.e. at 10 weeks).