Olympic champion Shawn Johnson injures knee

DES MOINES, Iowa -- Olympic gold medalist Shawn Johnson injured her knee while skiing in Colorado on a family vacation and will be out of competition for about six months.

Her father, Doug Johnson, told The Des Moines Register that the injury happened last month.

Johnson's agent, Sheryl Shade, said the 18-year-old gymnast had arthroscopic surgery on Tuesday and has already started physical therapy. She will be in a leg brace for about six weeks.

Shade characterized the injury to Johnson's ACL as minor. She said Johnson wanted all of her options available to continue in gymnastics, so the decision was made to have surgery.

Johnson won gold on the beam at the Beijing Olympics. She returned to the gym in December and is considering a run at the 2012 Olympics in London.