Former Olympic gold medal gymnast Shawn Johnson has retired after failing to recover from a knee injury in time to compete at London 2012.
The American, 20, won four Olympic and three World Championship medals in a career where her charisma as much as her talent marked her out as a star.
Johnson earned one gold and three silver medals at the Beijing games.
“It has become obvious that my left knee is not able to sustain the demands of gymnastics any longer,” she said.
“All I can do now is gracefully retire and thank everyone who has believed in me and my journey.
