"Kieran - not sure at the moment. It is a back injury so we will just have to wait and see how it responds.
"We are at the bare bones of our roster at the moment and we might lose a couple more now," a disappointed McFadden added.
The Warriors coaching staff has been angry at a lack of effort from the side at times during their current seven-game losing skid but McFadden is putting the poor second half showing against the Rabbitohs down to a lack of first choice forwards.
"We are very disappointed," he said. "I thought we started well with plenty of enthusiasm but I think in the end we got a little bit out-classed.
"We lost Jacob Lillyman in the first half and our front rowers and forwards lacked a bit of experience and that is where we got found out in the end.
"It is hard to take at the moment. I think there is a lot of effort out there but we are missing some key personnel in our front row with Ben Matulino, James Gavet and Albert Vete and then we lose Jacob Lillyman - we have lost our experience. Against the two Burgess boys with their size they really started to get some momentum in the middle and we really struggled with that.
"We tried to hang in there but we just couldn't."
There is a chance star halfback Shaun Johnson could return next week having missed the past five games with a knee injury.
The Warriors finish their campaign with games against Manly at Mt Smart Stadium next Sunday and a final round trip to Sydney to face the Wests Tigers at Leichhardt Oval.