Surgeons told Newcastle boss Glenn Roeder on Sunday that Shay Given's injuries were similar to those caused by the impact of traffic accidents.
Given, the 30-year-old Republic of Ireland international, will spend several days at a London hospital after undergoing surgery to repair a one-centimetre tear in his bowel following a clash with West Ham striker Marlon Harewood on Sunday.
Roeder, who absolved Harewood of blame, said: 'The surgeon said he has never seen an injury like this happen through football.
'He has seen it happen in car crashes where there has been impact, and I suppose that is what has caused it this time.
'Shay would be the first to admit when he sees the pictures that Marlon Harewood thought he had an opportunity to get to the ball.
'I suppose if it was Shola (Ameobi), we would have expected Shola to try to get to the ball if his team was losing 2-0. Shay being Shay, as brave as he is, was not going to turn away and not go for the ball.
'He went for the ball, both of them were trying to the ball fairly and unfortunately, Shay came off worst.'
Given is expected to be sidelined for around six weeks, but Roeder will not put on time-limit on his recovery.
Roeder said: 'Shay is going to have to spend a few days in hospital. He had an operation in the lower part of his stomach where he had a one-centimetre tear in his lower bowel that had started to leak.
'He needed that to be repaired. He is in great hands - the person who did the operation, I personally know - and he is a great surgeon.
'That has been done and he is feeling a lot more comfortable now than he did half an hour after the game. It is a question now of waiting for Shay to get fit again.
'But this is all about Shay, this is not about us rushing him back or anything like that.
'He will be given all the time he needs and all the help he needs by the club to make a full recovery, which he will do - and in the meantime, we are lucky to have Steve Harper.'