The 24-year-old played just one game for the Colts last season before he was ruled out for the year with the problem, but after six months of recovery, he has admitted that he is feeling better than ever.
Allen told the club's official website: "I feel like I'm almost to 110%. It's not just my job to work to train my body where it was. I sat out a year, everyone else is improving. I don't know what percent they're improving, but I guess it's 10%.
"They're getting 10% better than they were the year before. It's my job to work back to where I was before last season, then gain that extra percent so I can stay up with the NFL."
Allen has recorded 46 reception for 541 yards and three touchdowns in his two-year NFL career.