Season over for Fearns after ACL injury
"That's my season over folks. Rubbish news but I'm a lucky man with lots of support around me," Fearns wrote on Twitter.
The 28-year-old was nominated for French Top 14 Player of the Season last year, before losing out to La Rochelle's New Zealand international loose forward Victor Vito.
Fearns has been in fine form for Lyon, who are shock Top 14 leaders after seven matches.
The former Sale and Bath forward was injured in Saturday's 25-6 win at Agen, after which he had said on Twitter: "The curse of the English 8 got me tonight."
England have a No.8 injury crisis a month out from their November internationals against Argentina, Australia and Samoa.
First choice Billy Vunipola of Saracens is out for months after knee surgery, Nathan Hughes missed Wasps' trip to Sarries on Sunday with a dead leg and Jack Clifford dislocated his shoulder in Harlequins' win over Sale on Friday.
Fearns, who has never played for England, wouldn't be eligible, though, due to the national federation's policy of not selecting overseas-based players.
Fearns left Bath for Lyon in 2015 and although he was set to join Gloucester in the off-season, he finally opted to stay in France.