Vunipola had made an outstanding start to the campaign, winning man of the match (for his 27 tackles) against Ireland, then enjoying another stellar first half against France. He left the field shortly after the break and underwent a scan on Monday.
That revealed the ligament damage which will rule him out for as long as 10 weeks. He missed the Autumn Internationals with a calf injury.
Ben Moon or Ellis Genge will step up to replace Vunipola, but his absence is a bitter blow. He joins his Saracens team-mate Maro Itoje, who has a knee injury, on the sidelines.
England, who join up for a three-day camp in London tomorrow, hope to have Itoje back for the end of the campaign but their next game, against Wales on 23 February, is likely to come too soon.
“It is obviously very disappointing to lose Mako at this stage as he is an important player for us but it does provide an opportunity for the team to grow,” said Head Coach Eddie Jones.
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