Exeter boss Rob Baxter says England hooker Luke Cowan-Dickie could be fit in time for the club's European Champions Cup games in December.
"The good news is it doesn't require an operation, but it is a significant injury that will keep him out for the Autumn internationals," Baxter said.
"Hopefully we'll see him back pre-Europe," he told BBC Sport.
Cowan-Dickie was in line to be England's starter having played in all three of the British and Irish Lions tests in South Africa, with inexperienced duo Nic Dolly and Jamie Blamire picked alongside him.
His Lions team-mate Jamie George has been called up as a replacement.
"It's a blow for us obviously, but in reality we're probably only going to miss him for a couple of games out of that period because he would have and should have been away with England," said Baxter.
"It's probably a bigger blow for Luke and England.
"What we've got to do now is help him with his rehab, get him back and firing, and if he plays well through the Christmas period, which includes a lot of the big European games, then obviously he'll put himself right back in the ring seat for getting back with England in the Six Nations."
Baxter added: "He is genuinely disappointed. I think he's worked exceptionally hard and done a lot of good things, both physically, mentally and experience-wise to get where he was.
"To have broke through as England's first choice, go on a Lions tour, almost certainly be in the box seat to carry on with that, I think leadership roles within the England set-up, it's something that he's worked really hard to achieve, and then almost to be taken away as soon as he's got there is tough."