The 32-year-old could only make eight league starts last season due to his problem that needed an operation.
Young played for 59 minutes for United U-23 side on Monday night, and following the game, he declared himself fit for Jose Mourinho's first team.
"It's great to be back," Young said. "As a player, you want to be back on the pitch and it was good to get minutes under my belt. I'm feeling good, I'm feeling fit. I could've played longer, but I was brought off. I've worked hard since I had the operation done 13 weeks ago so I'm happy to be back out there.
"I've been training with the team for 10 days or so now," Young continued. "So, whenever the manager calls on me, I'm ready to go. For us, it was a bit like a pre-season game, we're obviously trying to get the win, but we wanted to get the fitness levels up too, and we'll just take it from here."