Marcus Mariota returned to the practice field on Wednesday. He said after practice that everything went well.
Mariota: Knee is feeling better. Was able to participate in practice. pic.twitter.com/dQOSqdicq6— Tennessee Titans (@Titans) October 28, 2015
Mariota did say after practice that the key is making sure he has the mobility to be back in there. That is especially true when facing J.J. Watt behind an offensive line that has had trouble in pass protection.
The media on hand did say that Mariota was wearing a knee brace during the open portion of practice. They put a brace on him after the hit happened in the game two weeks ago. I would expect he would wear that brace for the next couple of weeks until he feels like the knee is all the way back to 100%.
Here is a picture from Kuharsky that show the brace: