Club captain John Egan and fellow defender Chris Basham have been sidelined by injuries for the whole of the season, and both of their contracts will expire in the summer.
“This isn’t being negative to the likes of (Chris) Basham and John Egan, who have been outstanding, and I’d love them to be still be part of things moving forward,” Chris Wilder said.
“But we have to make sure John gets back to full fitness and that it is not, yet again, an emotional signing because of what he’s done in the past.
“Everybody knows all these players have got to contribute next year, whether in the Premier League or outside the Premier League.”
Basham has undergone two procedures for a fractured ankle sustained in October, while Egan underwent surgery in December after suffering a severe leg injury in September.
Egan might appear for Wilder’s side before the conclusion of the season, as the Blades boss said: “It’s going to be tight. We’ve had him down to hopefully come back before the end of the season.
“I’m not saying he’s going to be ready in the next month, but you never know, going into the final two or three games, if he makes the speed of recovery that he is at the moment, then you have a general idea where he’ll be at.
“Sometimes things are favourable and if we need him towards the end of the season, he’s certainly somebody we can definitely rely on with his ability and know-how.”
