Colts running back Trent Richardson revealed Thursday that he played last season with a chipped collarbone and a separated AC joint, reports ESPN.com. The AC joint is where the collarbone meets the shoulder.

"Toward the end of the season I felt a lot more comfortable, but the other time I was more injured," said Richardson, who had offseason shoulder surgery.

Coach Chuck Pagano said Richardson not only is healthier, but has a much better grasp of the playbook this year.

"He’s a lot more comfortable," Pagano said. "Basically it was survival for him at first, memorization. Now he has a better understanding scheme-wise, why we’re doing things, why we’re calling certain things, how we run plays. He has a better feel for guys he’s playing with, the line, guy in front of him, the fullback. He’s obviously in a much better place."