The Dutchman landed awkwardly after punching away an Adam Johnson free-kick and was immediately replaced by Rob Elliot in the second half of the Magpies' humiliating defeat to their bitter rivals on Sunday afternoon.
And Newcastle's afternoon took another turn for the worse when Pardew revealed he would be deprived of Krul's services for the Premier League run-in.
Although they lie 13th in the table, Newcastle are still looking over their shoulders as they are just five points clear of the drop zone with five games of the season remaining.
They were knocked out of the Europa League by Benfica earlier this week and Pardew must rally his troops without his number one goalkeeper.
It is not the first time Krul, who recently returned to action after missing a month due to an ankle injury, has had problems with his shoulder.
The 25-year-old suffered a similar injury when he was on loan at Falkirk in January 2008.