Feuz, second in the World Cup last season, is currently in a stable condition in hospital in Bern.
The 25-year-old, who won four races in the 2011/12 season, became aware of the problem at the opening giant slalom of the season in Soelden where he did not compete.
The situation took a turn for the worse last weekend and Feuz was transported to the Insel Hospital in Bern.
With the help of specialists, Feuz was diagnosed with an infection in the knee and bleeding in the joint.
He has been treated with various therapy and medical measures and efforts are underway to get to the core of the infection.