Carpal tunnel syndrome coexists with basal joint arthritis in a large percentage of patients. These 2 conditions are often treated surgically through separate incisions. The purpose of this cadaver study is to show the effect of trapeziectomy and transverse carpal ligament release from the scaphoid tubercle on carpal canal pressures. This technique may permit both problems to be addressed through the same Wagner incision. In 4 fresh frozen cadaver limbs pressures in the carpal canal were elevated to 30 mm Hg through a percutaneously placed balloon. Pressures were measured using an 18-gauge sideport needle via a transducer. Trapeziectomy and release of the transverse carpal ligament from the scaphoid were performed in succession through a Wagner incision with canal pressures measured after each step. Carpal canal pressures decreased after trapeziectomy (mean, 7 mm Hg; range, 3–14 mm Hg) but did not return to baseline (0 mm Hg) until complete release of the ligament. Decompression of the carpal tunnel can be performed effectively through a Wagner incision during basal joint arthroplasty. This cadaver model shows reduction in the canal pressures after trapeziectomy and release of the transverse carpal ligament. This single-incision approach is attractive because it may decrease morbidity compared with a 2-incision approach in patients with concomitant carpal tunnel syndrome and basal joint arthritis.