Thirty-six consecutive patients with 37 complete tears of the ulnar collateral ligament of the thumb metacarpophalangeal (MP) joint were treated with primary repair using a miniature intraosseous suture anchor. Thirty patients were evaluated by clinical examination or by questionnaire at an average of 11 months after repair. Loss of interphalangeal joint motion averaged 15 degrees on the involved side versus the other side, while loss of MP joint motion averaged 10 degrees. There was no significant difference on stress testing measurements between repaired and nonrepaired thumbs. There were no instances of nerve injury, infection, device failure, or reoperation. The authors concluded that this is a safe and effective method for repair of complete tears of the ulnar collateral ligament of the thumb MP joint.