Yeah, it was due to a back injury. But man, it's hard to see someone you've watched for over a decade have to stop doing what he loves. But, Edge is one of the few who has ever retired on top. He held the World Heavyweight CHampionship, his last run was with Christian (Who he hasn't teamed up with in nearly a decade and he's his best friend), he had a good match at WM and got to leave with that heartfelt speech.
I'll miss him and I hope Christian doesn't leave any time soon or else both E&C will be gone.