The club's caretaker manager, Chris Hughton, announced that the former Manchester City midfielder would be out of action for the foreseeable future today as he prepared for Saturday's Championship match with Bristol City at St James' Park.
"Joey had an exploratory operation yesterday, and the injury could keep him out for a good period of time although we will discover the findings soon and then we will be able to say more," said Hughton.
"It is an injury to his right foot but it is certainly not related to any injury that he has had there before. We are probably looking at a period of months.
"It's a bitter blow because Joey is a quality player and we know that when he is fully fit that he can make a big contribution to what we are doing here.
"But it is also a big blow to the lad himself. Injuries are part and parcel of the game but injuries are a bitter blow for any player that is going to be out for any period of time.
"It has been a difficult time for him here at Newcastle so it is even more so disappointing for him but is part of the game and he will have to do what he has done in the past and that is battled back from injuries.
The injury represents the latest lamentable chapter in Barton's spell on Tyneside which began badly when he was struck down by the curse of the metatarsal shortly after his £5.8 million move from City two years ago.
That was followed by a six-month prison sentence when he was convicted of assault in Liverpool city centre last season and when he did return to action his influence was negligible due to injury as Newcastle slipped out of the Premier League.
Barton, 27, missed out on the last three games of an ill-fated campaign, when he was sent off at Liverpool, following a reckless tackle on Xabi Alonso, that saw fall out with interim manager Alan Shearer before he was suspended by his club.
Barton has missed Newcastle's last three games and Hughton is already without another key player in the shape of Shola Ameobi who has been ruled out for months with a broken foot.
Despite the injury to Barton, Hughton has insisted that he is "not desperate" strengthen his squad.
"Losing Joey is a blow but one of the pluses for us is that we have been able to bring players backs such as Danny Guthrie and Danny Simpson and hopefully Ryan Taylor will be available tomorrow," Hughton said.
"We have to do that because it is a tight squad and we know we will go through periods where we will be really stretched but so far we have been okay. We have options in midfield especially with Geremi coming back in,"
"We are up against a very good passing side in Bristol who certainly will pose a threat up front and we have to be on our guard. We have had to really battle for every results we have had apart from one comfortable win his season. That shows the quality we have in the side.
"It's one that has meant he's missed a few games, it had been concerning him.
"At the time we didn't think it was a big problem and wasn't showing up and has continued to stay."