"Unfortunately it looks like Matthew Jones has got a broken foot - that is our first impression," admitted Ruddock.
"It looks like it could be a repeat of the stress fracture that he had earlier in the season so that is a blow."
Ruddock admitted losing Jones could create a selection headache in the Europe Challenge Cup and admitted he would now have to look closely at team selection ahead of the London Irish game at Sixways Stadium on Saturday with one eye on the semi-final in France.
"The game in Bourgoin is tough and it is looking even tougher now. I will now need to look if I will have to hold people back before the Bourgoin game and rest them," he added.
"I will have to ask if we can reproduce the same effort from those players, with the amount of tackles we made tonight, before we go to Bourgoin.
"I am short on numbers and players so I need to give that some thought. It is going to be a big ask in France. Willie Walker is cup tied also so our injury bad luck in the backs continues.
"But we want a win to finish the season in style. We have had a good run of late and picked up some scalps.
"We are doing well and want to keep that form up in the league, but we must have one eye on the semi-final. We can't burn ourselves out before we get there."