The news has left manager Keith Hill frustrated, but the Dale boss sees it is an opportunity for the club's youngsters to prove themselves in the first team.
"The news on Rory McArdle is particularly bad - he's going to be out for between eight and 12 weeks," he told the Rochdale Observer.
"What was already a thin squad becomes even thinner, but it does provide an opportunity for the likes of Craig Dawson, Marcus Holness and even Chris Brown, from our youth team, to impress.
"It's a massive blow and leaves us with just 16 outfield players. We do not have the finances to replace a player of Rory's calibre and I suppose the only positive to take from this is the fact we have four games in which to experiment and find the right defensive
pairing to start against Port Vale."
McArdle is joined on the sidelines by Ciaran Toner, who is suffering with shin splints and was due to see a specialist on Friday and Holness, who is out with a hamstring injury.