First-choice goalkeeper Tim Krul was ruled out of the club’s last five games after dislocating his shoulder in Sunday’s 3-0 Tyne-Wear derby defeat to Sunderland.
And Rob Elliot, who replaced Krul early in the second half, hobbled off the field with an ankle injury.
Long-serving Harper – who will leave Newcastle in the summer when his contract expires – made the last of his seven appearances this term in October, keeping a clean sheet in the 1-0 Europa League victory over Club Brugge at St James’s Park.
The 38-year-old – who joined the club 20 years ago – has made 197 appearances for the club in his 15 first-team seasons at Newcastle.
Rob Elliot: “Tim isn’t good, and I’m gutted for him.
“I’m not one of those people that would ever wish an injury on somebody to get my chance.
“He’s a brave lad, so if he had to go to hospital then that tells you it isn’t good. It was a bad day anyway, but losing someone like Tim has made it even worse.”
Source: Newcastle United Mad