Foster, 24, has been sidelined with cruciate knee ligament damage since his two-season loan spell with Watford.
Manager Sir Alex Ferguson has praised Foster's attitude during a difficult period in his career.
"You need a lot of determination and sacrifice during a time like this, " said the United boss.
"Most of the work has been done by himself. You have to get down to it. You need to work hard and not take days off.
"Ben has listened to advice from specialists. At his age it is not a problem. If he was in his 30s it would be different altogether.
"We may have had to rush him back a bit. But he is young and they are doing the right thing with him."