So the story is, as most people know, it was WWE's doctor Dr Maroon that iced him. The lousy thing was, WWE sent him home and used a contract clause to roll over any time he missed. In other words, they sent him home and said "since you're hurt indefinitely, your contract now rolls over indefinitely". ie. he had an eternal contract. Clearly illegal but he'd have had to sue to get out. They eventually smartened up a bit by using him on screen, allowing his contract to continue running down.
Bryan saw his own specialists including, IIRC, the doctor for the Cardinals and was cleared by everyone. He began doing hyperbaric chamber therapy. WWE finally relented and Dr Maroon sent him to see several hand-picked specialists for his last chance to be cleared. They cleared him so Dr Maroon did as well. Thus, he's back.
His contract expires in September.
Assuming he slots in as Shane partner at WM, its a good come back spot for him. I wonder if the WM crowd will hijack the show wanting more of him.
Here's some fantasy booking. Roman beats Brock and then cuts a heel promo, a "How do you like me now", and arrogantly says he will never lose...he'd take on anyone at anytime...if anyone had the balls to come down here right now and face me, I'd put this belt on the line. Cue Bryan's music. He beats Roman and WM ends with 70,000 people doing the Yes chant.