Palmar oblique ligament reconstruction combined with tendon interposition (LRTI) arthroplasty with part of the flexor carpi radialis tendon was developed for advanced osteoarthritis of the thumb basal joint. Twenty-five procedures are reviewed with an average follow-up of 2 years, ranging from 1 to 4 1/2 years. LRTI arthroplasty more consistently improved pinch strength, increased grip strength endurance, and restored thumb web space than did silicone implant arthroplasty. Proximal metacarpal migration averaged only 11% of the initial arthroplasty space versus nearly 50% loss of height with silicone implants. Subluxation averaged only 7% of the width of the thumb metacarpal base relative to the scaphoid versus subluxation of 35% of the base of the implant with silicone arthroplasty. Excellent results were achieved in 23 thumbs or 92% of cases. No deterioration of function or stability has been noted over time, and no revisional procedures have been necessary. On the basis of these encouraging early results, LRTI arthroplasty has become our preferred surgical treatment for advanced basal joint osteoarthritis of the thumb.