England and Northampton hooker Steve Thompson has been forced to retire from rugby at the age of 28 because of a serious neck injury.
Thompson last played for England in the 2006 Six Nations
Thompson, who won the World Cup with England in 2003, said he was left with no choice after receiving expert medical opinion.
"If I had taken one more knock, I would have ended up paralysed, or even dead," he told the Mail on Sunday.
He made 195 appearances for Saints and won 47 caps for England.
Thompson's last game for the club was their Heineken Cup group stage 17-8 defeat to Biarritz on 21 January.
"I got tackled, was swung around, and landed head first into the ground," said Thompson.
"I insisted on playing on a for a couple of minutes, thinking I'd regain movement in my arm, but after I collected the ball from a Biarritz penalty kick that hit the post, I booted it down the field and realised I had to go off.
"That was the last action I'd ever see on a rugby field.
I'll miss the adrenalin, the fear, the togetherness and the achievement
Former England hooker Steve Thompson
"I went to see a specialist, Nick Birch, at the Three Shires Hospital in Northampton and he showed me the results of a scan.
"My disc was squashing my spine and he told me I was very lucky to still be walking.
"I felt as if I'd emerged from a serious car accident alive, rather than thinking that something I dearly loved had been taken away from me."
Thompson received a second opinion from specialist Ricky Nelson, who successfully helped England props Jason Leonard and Phil Vickery with neck and back problems, but the original prognosis was confirmed.
"He told me I needed an operation to remove the disc because if I knocked it even during a mundane activity around the house it could kill me," said Thompson.
"I'll miss the game. I'll miss the journeys away with the lads and the adrenalin, the fear, the togetherness and the achievement."
Thompson, who said he would like to move into a coaching role at Saints, becomes the second member of England's World Cup-winning front row to retire prematurely because of injury.
Former Gloucester and Sale prop Trevor Woodman retired at the age of 29 in 2005 with a long-term back injury.
And Vickery - the third member of the starting front row in Sydney - has had to battle against career-threatening back problems before returning as England captain.
Thompson was on the bench for Northampton's Heineken Cup win in 2000, and he won the 2003 Six Nations Grand Slam with England and was selected for the 2005 Lions tour to New Zealand.
He started off as a flanker in Northampton's academy, but former Saints coach Ian McGeechan persuaded him to switch to the front row.
England coach Brian Ashton paid tribute to Thompson's work ethic.
"I remember Steve very well from England's North America tour in 2001," he said.
"He was a rookie hooker then, but two years later he was picking up a World Cup winner's medal, which is tribute to his discipline and hard work.
"I am very sorry to hear that Steve's career has ended like this. I would like to wish him a speedy recovery and the very best wishes for success in the future."
Northampton coach Paul Grayson, a former Saints and England team-mate of Thompson, said the club was devastated by the news.
"It's a big blow for him," said Grayson.
"He achieved so much but injuries are part of the game. I'm really disappointed for him."