First described in 1955 as "gamekeeper's thumb," injuries to the ulnar collateral ligament (UCL) of the thumb metacarpophalangeal joint are common and can cause pain and instability, especially during key pinch and grasp. Although primarily diagnosed on physical examination, stress radiographs, ultrasonography, and magnetic resonance imaging can be used to diagnose UCL injuries and distinguish partial from complete tears. If complete rupture occurs, the adductor aponeurosis can become interposed between the retracted UCL stump and its insertion on the proximal phalanx, known as a "Stener lesion." When instability persists after a trial of nonsurgical management or in the setting of complete rupture, there are various methods of repair or reconstruction. Biomechanically, there are no treatments of repair or reconstruction using native tissues that provide equivalent strength to the preinjured ligament. Recently, suture tape augmentation has been used for the repair or reconstruction with excellent short-term results and earlier return to function, although there is a paucity of literature on longer term outcomes. The various methods of surgical treatment yield excellent outcomes with a low incidence of complications.