Thornton was hurt late in San Jose’s overtime loss to Winnipeg on Tuesday. General manager Doug Wilson said Wednesday that Thornton will need an MRI to determine whether he will undergo surgery to repair his MCL but will miss several weeks either way.
Thornton tore the ACL and MCL in his left knee late last season. He returned for four playoff games before undergoing off-season surgery.
The 38-year-old Thornton has played all 47 games this season and has 13 goals and 23 assists to rank second on the team in scoring.
Thornton is playing on a one-year, $8 million contract.