Stuart McCall will consider short-term defensive reinforcements to replace the crocked Mark Bower.
Centre half Bower went under the knife at the Yorkshire Clinic in Cottingley today after tearing cartilage in his right knee.
He will be out for at least a month to six weeks - and possibly longer if it is decided to repair the damaged area rather than take it out.
Craig Bentham underwent the same procedure when he injured his knee in pre-season 18 months ago and was not involved again until the following November.
Bower has played only one game in two months since Matt Clarke seized his chance in the heart of the defence alongside David Wetherall.
He was out briefly through illness and then a slight injury picked up during a reserve game. But with the long-serving defender now expected to be sidelined for a lengthy spell, McCall finds himself short of experienced back-up.
And the City boss may be forced to take action before the January transfer window shuts.
McCall said: "We thought there was something sinister when Mark did it during the warm-up at Accrington. It's not often your knee will lock for no reason like that.
"It is a disappointment and we'll decide over the next 48 hours what to do next. We're always looking to bring people in but that might be an area of the team where we will have to look now.
"We've got Simon Ainge as cover but we're thin on the ground for defensive players with Tom Harban going back."
Bower suffered the injury on New Year's Day when his right knee locked as he passed the ball.
The problem appeared to ease over the next 48 hours. But the test results from an MRI scan confirmed there was a small tear which needed to be operated on.
Physio Steve Redmond said: "It was a routine passing exercise on the pitch but Mark felt this sudden pain in the knee.
"He may have had a little wear and tear there before and this has just triggered it off. Unfortunately it's one of those things that happens to sportsmen.
"But he's in good hands with (consultant orthopaedic surgeon) Steve Bollen and we'll assess the situation once everything has settled down from the operation."
- City's postponed home game against Rotherham has been re-arranged for Tuesday, February 26.
- Start or join a debate on this issue in our online forum - Click here
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article