Saints said that the 25-year-old will require up to four weeks of rehabilitation.
"I'm sure George will be diligent in his rehab and we all wish him a swift recovery," Northampton Technical Coaching Consultant Alan Gaffney said on the club's website (www.northamptonsaints.co.uk).
North, who has 69 caps for Wales, is the latest to join a lengthy injury list for Warren Gatland's side, with the likes of Taulupe Faletau, Sam Warburton, Jonathan Davies and Dan Lydiate also sidelined.
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Wales kick off their Six Nations campaign against Scotland on Feb. 3 in Cardiff.
(Reporting by Aditi Prakash in Bengaluru; Editing by Christian Radnedge)
