The Blades, who are battling relegation in the Premier League after promotion last term, have been without Brewster for months.
He is now back, having played for the first time in 11 months at the weekend against West Ham United.
“The last 18 months have been really tough for Rhian," Heckingbottom told reporters.
“We're delighted to have him back and to have him fit and available is great.
“More so, I'm personally delighted for Rhian and to see him on the teamsheet again.
“Would the medical team have wanted him playing 20 minutes? Probably not, because everyone's scared of what could possibly happen.
“But he trained so well for two weeks and was desperate to be involved, so I wanted to reward him that little bit.
“We know we'll have to be patient, we're on the same page, but why can't he contribute? We need to use everything we've got to try and get these points."