Purpose To compare the results for treatment of basal thumb osteoarthritis with and without the use of a bone tunnel at the base of the first metacarpal. Methods Women aged 40 years or older with stage IV osteoarthritis were randomized to 1 of 2 treatments. Patients were evaluated preoperatively and postoperatively at 3 and 12 months by assessing pain, outcome function measures, range of motion, strength, time to return to work or activities, satisfaction with the results, and complication rate. Results A total of 79 patients were enrolled in this study. Three months after surgery, Patient-Rated Wrist and Hand Evaluation pain and total scores were significantly improved in the bone tunnel group compared with the tunnel-free group. At 12 months, however, we found no significant differences for all outcome scores between groups. In addition, we observed no significant differences between groups in strength, duration to return to work or activities, patient satisfaction, and complication rates. Conclusions After the bone tunnel technique, patients have better function and less pain 3 months after surgery than do those in the non–bone tunnel group, which indicates faster recovery. However, 12 months after surgery, the functional outcome was similar. Because of faster recovery, we prefer the bone tunnel technique in the treatment of stage IV osteoarthritis. Type of study/level of evidence Therapeutic I.