SYDNEY - Australian great Andrew Johns risked a "catastrophic" spinal injury by playing on.
The former NSW and Australian captain - regarded as one of the game's greatest players - said the risks in continuing his remarkable 15-year career were too great.
Johns made his decision after aCAT scan on his injured neck and hours of consultation with Knights club doctor Neil Halpin and spinal specialist Professor John Yeo.
Halpin said the scans revealed a previously undetected disc injury which posed serious risk for the Newcastle captain.
"Talking to Neil and the professor, I realised how lucky I am that I haven't had a serious neck injury or a serious accident and be in a wheelchair," Johns said.
Halpin said the injury was not related to the bulging disc in Johns' neck which forced him to miss the last five matches of the 2003 season.
Johns hurt his neck in last Monday's 48-18 loss to Canberra, the game which will now go down as the last of his illustrious career.
He aggravated the injury at Knights training last Thursday in a collision with teammates Daniel Abraham and Adam Woolnough.
"The problem he has is that while his pain at the moment is not a great problem, he's at serious risk of a serious spinal, or catastrophic, spinal injury if he plays on," Halpin said.
"On that basis we've advised him to retire from football forthwith."
Johns admitted he was shaken by his sudden retirement.
"I'm still in shock," he said. "It was really tough telling my family.
"I made an emotional call to my brother Matthew, and it was even tougher talking to the players this afternoon."
He was to have played for the All Golds on their centenary tour of Britain this year.
The All Golds are essentially a Kiwis team, but Johns was eligible to play as the invitation player under the same rules as those of a century ago.
Andrew Johns
* NRL debut for Knights against Gold Coast in 1993.
* Premierships with the Knights in 1997 and 2001.
* Twenty-three State of Origin games for NSW.
* Represented Australia in 21 tests during a 10-year representative career, including the 1995 World Cup and the 2001 Kangaroo tour.
* Three Dally M awards and two Golden Boots as international player of the year.
* Greatest points scorer in NRL history with 2176 points from 249 first grade games with the Knights.
