ThePerfectBeard
Cheesehead
He had 1 injury on each knee and only one required surgery. He played two full seasons after them with no apparent issues. I wouldn't really classify it as "a lot of issues" or at least nothing I have read points to being any more of a concern than most players.
My only concern with TJ is short term. He needs time in the weight room to add 10-20 lbs of muscle. Once that is accomplished, he is going to be a force.
From what I heard it was 2 issues with both knees. He tried to heal without surgery the first time and then required it the second on one knee. Most of it was because he of blocking as a TE, but still. Also, it doesn't matter now.