The Austrian ski federation says a torn collateral ligament was repaired in a hospital in Innsbruck and Schild will be out for three months.
Schild was hurt on Thursday in training at the World Cup slalom in Are, Sweden.
The world championships are scheduled for Feb. 5-17 in Schladming. Schild also missed the world championships in 2009 in Val d'Isere, France, because of injury before winning the world title in 2011 in Garmisch-Partenkirchen, Germany.
A four-time World Cup slalom champion, Schild has won 33 races in the discipline, leaving her one short of matching Vreni Schneider's all-time record.