The 26-year old limped off the field during Sunday’s 36-18 win over the Dragons and was sent for scans on suspected medial damage.
But coach Trent Robinson was confident that the injury was not going to be a long-term issue.
“He’s got the brace on as a precautionary,” Robinson told The Daily Telegraph.
“I don’t think it’s anything too bad. But I don’t know how long it will take to turn it around.
“It’s obviously a concern but I don’t think it’s a long-term concern.”
Keary is expected to miss at least the team’s clash with the Cowboys on Saturday, with Sean O’Sullivan and Ryan Matterson looming as potential replacements.
“I don’t know. I think I’ve been wrong here before on some players and playing the following week,” Robinson said.
“I felt like he knew it was coming on and he adjusted a bit. When an outside back comes off, it’s usually something wrong. Especially a player like Luke I don’t think he’s come off much at all.”
In other injury news, Eels hooker Kaysa Pritchard will miss the rest of the year after after dislocating his shoulder against South Sydney.