One hundred thirty-nine patients with trapeziometacarpal osteoarthritis were randomized to receive either tendon interposition arthroplasty (n=75 hands) or total joint replacement with a dual mobility prosthesis (n=75 hands). The primary outcome of interest was hand strength. Secondary outcomes included pain (VAS), function (DASH), range of motion (Kapandji and radial abduction), and patient satisfaction. Outcomes were assessed preoperatively and at 1, 3, 6, 12, and 24 months postoperatively. Overall, the results revealed that patients receiving the prosthesis experienced faster and greater improvements in strength, range of motion, and pain relief, with sustained superiority in strength outcomes at 24 months. These findings suggest that dual mobility prosthetic replacement may offer earlier and more sustained functional benefits compared to interposition arthroplasty.