Petrucci, has agreed a one-month stay at London Road, whilst Wootton has joined until the end of the season.
"I'm delighted to be back," Wootton told BBC Radio Cambridgeshire. "I know most of the staff and the way they like to play football.
"Last time I was disappointed because maybe I could have played a few more games and I would have liked to show the fans what I can do.
"I've got that chance now and hopefully I'll play a lot more games."
Italian Petrucci moved to Old Trafford from Roma in 2008 but his only first-team appearances so far came on a pre-season tour to South Africa.