The 23-year-old, who has recently moved to lock from a back-row role, was forced off during the Sharks' 42-26 defeat to Harlequins in the Aviva Premiership on Friday and scans have now revealed the injury is more severe than first feared.
"Josh will be out for three months. It's a blow as he had been playing really well and had adapted brilliantly to playing in the second row," Sale's director of rugby Steve Diamond said.
Beaumont has been included in Eddie Jones' England squad on a number of occasions over the last two years, although he is yet to win a senior cap, but Diamond is convinced the youngster can return fitter and stronger from his latest injury setback.
"He's had a few injury setbacks but he's only 23 and he's still a young lad," Diamond added. He's getting all the support he needs and I'm sure that he will come back bigger and stronger."
Sale themselves have had to deal with a number of injury issues over the opening weeks of the season, as centers Johnny Leota and Will Addison have also been ruled out for a sustained period of time, and Diamond admits the club are actively seeking replacements in the transfer market.
"The message has gone out to agents that whether it is a short-term deal for three months or a long-term agreement for three years we are actively in the market for players in those two positions," Diamond added.