Purpose To compare the long-term outcomes of trapeziectomy with ligament reconstruction and tendon interposition (LRTI) with trapeziometacarpal arthrodesis for osteoarthritis (OA) of the basal thumb joint. Methods Patients were evaluated for pain, daily functioning, strength, and complications after a mean follow-up of 5.3 years. Generalized estimating equations statistics were used to compare repeated measurements over time in both groups. Results After 5 years, patients who had trapeziectomy with LRTI had significantly better pain reduction and function than the arthrodesis group. Pain and function in the LRTI group continued to improve compared with the results 1 year after surgery, whereas the arthrodesis group did not change. Grip and pinch strength were higher than 1 year after surgery but were not different between groups. In the arthrodesis group, 1 patient was reoperated for nonunion between 1 year and a mean of 5 years after surgery, resulting in a total of 18% nonunion. Another patient underwent reoperation for hardware-related pain. One patient from each group required reoperation because of pain due to scaphotrapeziotrapezoid OA. Conclusions Trapeziectomy with LRTI leads to better pain reduction and functional outcome after between 1 and 5 years compared with trapeziometacarpal arthrodesis in women over 40 years old with OA stages II to III. Type of study/level of evidence Therapeutic IV.