Reese Witherspoon\'s publicist says the U.S. actress is wearing a walking cast because she injured her left ankle but the injury is \"nothing serious.\" \"She twisted her ankle and is in a walking cast temporarily. Nothing serious,\" Witherspoon\'s representative told People.com Monday. No details on how she sustained the injury were provided. The actress is best known for her Oscar-winning performance in \"Walk the Line.\" Her other film credits include \"Cruel Intentions,\" \"Election,\" \"Pleasantville,\" \"Legally Blonde,\" \"Rendition\" and \"How Do You Know\".