The necessity of tendon interposition for the maintenance of joint space after basal joint resection arthroplasty with ligament reconstruction has not been established. A prospective, randomized study was performed. In Group I (nine patients), ligament reconstruction was performed to suspend the first metacarpal in addition to placement of a rolled tendon interposition to fill the void created by resection of the trapezium. In Group II (11 patients), ligament reconstruction alone was performed, with use of a Mitek suture anchor. No tendon interposition was performed. This allowed use of a more limited incision and shorter length of tendon graft. Average followup was 23 months. There was no difference between the two groups in range of motion of the thumb, grip strength, lateral pinch strength, the ability to perform activities of daily living, or subjective satisfaction with the procedure. Two- and three-point pinch strength was statistically significantly greater in Group II. Lateral radiographs of the basal joint at followup, at rest and with pinch, showed maintenance of the joint space, and no difference between the two groups. Tendon interposition is not necessary for maintenance of joint space after basal joint resection arthroplasty if ligament reconstruction is performed.