MELBOURNE, Australia - MotoGP World champion Casey Stoner has had successful surgery on his right ankle.His team, Honda, said: "Stoner received surgery to an ankle damaged during a crash while qualifying for the Indianapolis MotoGP 12 days earlier. The procedure was performed in Sydney's North Shore hospital and doctors are pleased with how the operation went.STILL FOURTH"We must now wait through an initial recuperation period. With no complications, or need for Stoner to stay in hospital, he has returned home and Honda will endeavour to share information on his recovery as it is known."Stoner was fourth in the Indianapolis race despite his injuries and is still hoping to return to the track in October, ahead of his home GP on Phillip Island. He intends to retire from racing at the end of the 2012 season.