Thumb metacarpophalangeal ulnar and radial collateral ligament injuries occur frequently in the competitive athlete. Collateral ligament integrity is essential to joint stability, pinch strength, and pain-free motion. Acute rupture of the ulnar collateral ligament is due to a sudden radial deviation force on the abducted thumb and is referred to as skier’s thumb. An ulnar-directed force causes injury to the radial collateral ligament. The degree of joint instability on clinical examination allows classification of these injuries and guides management. Surgical repair of acute, complete tears results in good outcomes and allows for return to sporting activity.