The 26-year-old damaged his knee ligaments in the 2-2 draw with Wigan on Saturday and had to limp off after just 17 minutes.
Barton got the injury in a challenge with Lee Cattermole.
He said: “I am not blaming Lee Cattermole in any way for this injury. It was a 50-50 ball and we both went for it, and these things happen.
“Obviously, it’s disappointing and frustrating, and my sole intention is to knuckle down and bounce back and get fit again to help the Newcastle United cause.”
