Wilder, in a letter shared on social media, wrote to Mick Chambers, who he said was undergoing chemotherapy treatment.
He said Mr Chambers had been 'dealt such a bad deal’ and said he hoped the chemotherapy hadn't been ‘too gruelling’.
Wilder said: “Your last session was apparently on September 1 and we played Chelsea the day before and came away with a point, in what was a superb second half display from the lads, so I hope the news of that gave you a bit of a boost.
“Hopefully everything will begin to settle down for you and your wife now. On behalf of everyone at Sheffield United, may I wish you a speedy recovery and wish you and your family the very best for the future.
“Keep supporting the Blades from afar and take the very best of care.”