"It was a terrible injury and presented me with a massive challenge, but I have always been positive I could overcome it," he told official Blackburn Rovers website.
"The will has always been there but, in the end, it has not proved realistic.
"I didn't want to be just a footballer.
"I wanted to play at Premier League level twice a week. It's clear now that's not possible, and I have a responsibility to myself, my family and my future."
