Blackman, who spent last season on loan at Bramall Lane from Chelsea, suffered his injury in Leeds under-23s' 3-0 defeat to Birmingham City earlier this month - and has now returned to his parent club.
It represented the cruellest of timing for the 25-year-old, with head coach Marcelo Bielsa confirming that he would have started in Leeds's recent home game with Bristol City and given the chance to establish himself in goal - if he had not got injured.
Wilder, speaking ahead of the Blades' televised lunch-time appointment with Leeds at Bramall Lane on Saturday afternoon, said: "Our boys have been in contact with him and I have been in contact with Jamal too along with Darren Ward (Blades goalkeeping coach), who worked closely with him.
"He was a great kid to work with and he did fantastically well for us and it is really disappointing for him as he was a popular player in our changing room just as much as he is in their changing room.
"He has got a really good career ahead of him and it is really important, first and foremost, that he gets himself back out on the football pitch and his health is good.
"We wish Jam all the best and I know there has been a lot of contact from our boys."