Steven Taylor is out for the season after surgery to repair his Achilles, and now full-back Davide Santon has a knee problem.
A replacement for Taylor is a must next month and Newcastle have been linked with Ajax's £10m-rated Jan Vertonghen.
Pardew will also have to face the loss of 13-goal striker Demba Ba and key midfielder Cheick Tioté to the African Cup of Nations and that will blow another hole in the manager's resources for several weeks.
Alan Pardew: "We are having to look at our squad because we are stretched, especially defensively.
"We have made some calls to try to find out who is available, but it's a difficult window.
"You want to try to get a good player in a window when teams don't want to lose their good players, so it's not just difficult for us, it's difficult for every team.
"You locate a player, but then they have got to get a replacement and is another first-team going to let a replacement go? There's a knock-on effect."
"Ba is a great player, and you are going to miss great players. He is going to the African Cup of Nations and he will probably want to win that.
"Knowing Demba and the way he is playing, he probably could. He has been absolutely terrific for us."