Walsh, 27, is likely to miss the rest of the season, according to coach Nathan Brown.
He said: “He’s snapped his fibula, had surgery to put plates and bolts in and will be out for four to five months.
“It’s happened now, it’s done and dusted, so we now have to look and focus on the people we have got to play there.
“Over the course of the season people have stepped in to various positions. Luke has missed a number of games this year that we have done well in and come off the field in a number that we have gone on to win.
“We will pull in, buy in and do a good job.”
One potential replacement in the halves for Walsh is Jon Wilkin. The back rower has his own injury concerns, however.
“Jon Wilkin (shoulder) is an unknown and we’re not sure if he will appear again this season, we will have to see how it goes,” added Brown.