"I don't want to be bitter towards Richmond. I had a few problems with my body last year that I needed surgery on and I played a little bit injured throughout the year," Pattison said.
"I had hip and ankle issues and had some post-season surgery, but now I'm feeling as fit and strong as I ever have and I'm 23 and I think my best footy is ahead of me.
"I'm just looking forward to the opportunity at St Kilda and starting a new chapter."