Anderson ended his eight-year association with United by signing a four-year contract at Brazilian Serie A outfit Internacional on Tuesday.
The 26-year-old midfielder arrived at Old Trafford with much fanfare in 2007 and went onto win four Premier League titles as well as the UEFA Champions League.
But Anderson struggled for form and fitness throughout his time in Manchester, featuring in just five league matches last season, while he only made one start under Louis van Gaal this term.
Now back in Brazil for the first time in nine years, Anderson revealed injuries played their part in what was a disappointing end to his United career that had promised so much.
"I played for eight years for Manchester. I would like to thank the club. In my first four years I won everything there, Champions League, Premier League and Clubs World Cup," the former Porto midfielder is quoted as saying by The Guardian.
"I had a knee injury and returned to play again too fast. I played but the knees were not equal and I got myself injured again."
Anderson, who was often criticised about his weight at United, added: "A player will always be criticised. I had injuries in the past, but I have to be quiet right now and answer in the field.
"It will be a pleasure play in a club such as Internacional. I want to be happy as I was in other clubs. I'm coming back to Porto Alegre because Inter went after me. The president gave me attention. I was training [at United] but not playing."
