Melbourne and Parramatta will be sweating on the fitness of some of their stars after their thrilling clash last night.
Fellow winger Blake Ferguson is also in doubt for the second week of the finals after leaving the ground in pain late in the game.
“I think Maika is done for the year,” Arthur said after the game.
“They think [It’s an MCL]. Look, it’s a massive blow for the team but we have other blokes that need to step up.
“It’s sad for Maika, he’s work hard and it was his birthday today but it what it is, it’s footy.
“Ferg will have to have scans tomorrow, he might be a chance.”
Melbourne also came out of the game with a fresh injury concern to Cameron Munster.
The five-eighth came off the field with less than 10-minutes in the game with a suspected knee injury.
Munster previously missed matches this year due to an MCL sprain.