INTRODUCTION Injuries to the metacarpophalangeal joint of the thumb frequently cause complete or partial tears of the collateral ligaments, resulting in marked instability of the involved joint. The ulnar collateral ligament is often torn from its insertion site and reattachment is difficult. The aim of this study was to evaluate the clinical outcome after repair of Grade III ulnar collateral ligament injuries at the metacarpophalangeal joints of the thumb with the with dual threaded metal suture anchors. METHODS 39 acute grade III ulnar collateral ligament injuries (complete ulnar collateral ligament disruptions) were treated by using dual threaded metal suture anchors to reattach the avulsed ligament to bone in its anatomical position. Tendon advancement or graft reinforcement was not used in conjunction with the repair. Final follow-up examination ranged from 4.5 to 13 months. RESULTS A Stener lesion was found in 56.4% patients. X-ray films demonstrated accurate placement of the bone anchor with protraction of the metallic wings within cancellous bone. At the last postoperative follow-up, 92.3% patients had good to excellent results subjectively. All patients exhibited a full return to activities of daily living within 6 weeks and return to their original work or sports activities within 14 weeks. Pain was completely relieved in 84.6% patients. In all joints the postoperative valgus stress angle was within 13 degrees of that of the contralateral digit. Range of motion revealed a 9.7% loss of metacarpophalangeal flexion-extension and a 23.5% loss of interphalangeal motion. Grip strength was 94.1% of the uninjured hand. Pinch strength in apposition averaged 95.8% and in opposition 91.3% of the uninjured hand. DISCUSSION A stable thumb metacarpophalangeal joint was achieved in each case with no recurrent instability at final follow-up. This study supports the use recommend dual threaded metal suture anchors as a simple and effective method of repairing the acute ulnar collateral ligament injury.