<prompt> Game Keepers thumb is :Ulnar collateral ligament injury of MCP JointRadial collateral ligament injury of MCP jointRadial collateral ligament injury of CMC jointUlnar collateral ligament injury of CMC joint  <response>: Injury to the ulnar collateral ligament of the thumb metacarpophalangeal joint is commonly referred to as gamekeepers thumb or skiers thumb.Injury occurs by fall on hand with forceful radial and palmar adduction of thumb as seen in skiers.It is the most common injury of MCP joint. 