The 27-year-old Australian centre has not played since suffering a heart attack in the aftermath of Bradford's Magic Weekend defeat by Leeds at Manchester's Etihad Stadium on May 27.
He has been involved in modified training while waiting for the results of tests and was told by a London specialist this week that he can now start full training and resume playing in early March.
"I didn't know what to expect really and I was in shock when the specialist gave me the news," Purtell said. "It didn't really sink in until I was on the train coming home but I am obviously delighted.
"I felt myself that I'd be okay because I have been doing some training and felt good, but I am not a medical person so it was pretty awesome to get that news from such an eminent specialist.
"I had the mentality of 'hope for the best, prepare for the worst', so it was tremendous to have such a positive outcome. I am just looking forward now to getting back into full-time training and playing games with my mates. That's what I want to do most of all.
"Last year was a tough one for the Bulls but the boys all bonded together and stuck by me and the club has been absolutely tremendous throughout."
Purtell, formerly with Canberra and Penrith, is 12 months into a three-year contract with the Bulls. He was told in early September that his heart had repaired itself well and he reported back for pre-season training before being given squad number two for the 2013 campaign.
Bradford coach Francis Cummins said: "It's great for us because we have got one of our star players back, but for Adrian it's an amazing piece of news because we weren't even sure whether he would be able to live a normal life, let alone play again.
"It's a very tight group here and Adrian is a big part of that so the whole squad are absolutely delighted for him."
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