Graham Dorrans: Rangers midfielder out for three months after surgery
Rangers midfielder Graham Dorrans will be missing for a further three months following ankle surgery.
Dorrans, 30, last featured on 25 October, coming off during the first half of Rangers' 1-1 draw at home to Kilmarnock.
Meanwhile, striker Kenny Miller's hamstring injury could keep him out of the 30 December meeting with Celtic.
"The end of the year and the game at Celtic may come too soon for [Kenny Miller]," said Murty.
"We may [have to alter transfer plans] as we were expecting Graham to be back. Those conversations are ongoing but this may change the tone of them.
"We initially went down a conservative route on his ankle after medical advice.
"Unfortunately that did not bear fruit and he's now undergone a surgical procedure that will leave us without him for an extended period of time.
"It's a sore one for him as we were really hoping the first course of treatment would work and that hasn't turned out to be the case."
Miller came off on a stretcher early in Rangers' midweek 2-1 win at Hibernian.
"We're hopeful it's not as big [a tear] as it looked, because it looked big," Murty explained.
"But he has quite a big range [of movement] and we're hopeful he's not going to be out for too long."
Meanwhile, Murty has confirmed he has been speaking to former Rangers manager Walter Smith, with Murty's second spell in interim charge expected to last until at least the end of 2017.
The former Scotland defender had six games in charge before Pedro Caixinha was appointed earlier this year and has overseen the first team for the past eight games following Caixinha's sacking, winning six of them.
"I speak to Walter Smith and he was here the other day," Murty added. "It's always an honour and a privilege to speak to someone like that."