Foden, who has starred for Sale at full-back this season after starting his senior career as a scrum-half, was hurt during last weekend's International Rugby Board world series event in South Africa.
Foden will undergo surgery on his shoulder on Wednesday - and he may now be sidelined until mid-March.
Given his current form, he would have been an outside bet to make the England squad for this season's RBS 6 Nations Championship.
Foden said: "I am gutted with the diagnosis of the injury and I will have an operation tomorrow to correct the damage.
"I have enjoyed playing regularly this season - and I believe we are on the verge of major success at the club.
"I will be starting my rehabilitation as soon as possible and hope to be back in action as soon as possible."