Scans have confirmed Halkett will be sidelined for around three months after damaging medial knee ligaments against St Mirren on Saturday. Souttar has not played since August 4 after injuring an ankle at Aberdeen.
Signing an out-of-contract deputy has been ruled out on the grounds that anyone available would need several weeks to find match fitness. By then, there is a possibility that both Souttar and Peter Haring – who can play in defence – would be back in action.
In the meantime, Christophe Berra is likely to return to the team and partner Michael Smith in the middle of defence. Clevid Dikamona also offers experienced back-up.
“The only people available are out of contract and haven’t played for a while. That means you are probably paying a wage to somebody for a month before he gets up to speed,” Hearts manager Craig Levein told the Evening News.
“In my experience, bringing somebody in at this stage of the season has never been a profitable situation.
“I’m more inclined to stick to our squad and shuffle things around. We hope Peter will be back in the next two or three weeks. He can fill in at centre-back if need be. I’d hope John will be back soon as well.”