The modified Zancolli arthroplasty for basal thumb arthritis is an alternative to different procedures described for this pathology. As most of the methods, it includes complete trapeziectomy. The main difference is that the interposition is made with capsule (resembling Colonna's method for the hips) and that the base of the metacarpal is stabilized in the correct place by a tendon transfer (performed with an accessory of abductor pollicis longus). The main advantage of this method is the short immobilization time (2 wk) and high percentage (95%) of complete pain-free results and a stable and strong thumb in key pinches.