Parramatta forward Nathan Brown will spend at least the next six weeks on the sidelines with the rehabilitation group after undergoing knee surgery this week.

Brown had his lateral meniscus removed after suffering the injury in a training mishap while the squad was put through a wrestling drill.

The setback is on the opposite leg to the injury that meant he missed Parramatta’s finish to the 2018 Telstra Premiership.

"I was just wrestling and it come up sore, I didn't think anything of it but it just kept getting worse," Brown said.

"I had a clean-out, about six to eight weeks. You can run in a couple of weeks, I'll probably just miss all the hard sessions before Christmas.

"I've been good lately, my last surgery was when I was 22. I thought it would've been my last one but hopefully it's this one."

Brown joined half the Eels squad at the Royal Children's Hospital in Westmead on Tuesday to take time out of their pre-season training schedule and spread some cheer to infants and their families before Christmas.

Eels bring Christmas cheer

The other half of the squad went to the Ronald McDonald House on Tuesday evening including playmaker Corey Norman, who is one of several high-profile Parramatta players coming off contract next season.

Brown wouldn't be drawn into questions about whether Norman could be moved on by the club in the off-season but said he had been impressed with his attitude despite questions around his short-term future.

More than half the Eels squad will be free agents at the end of 2019 with Brown an exception after agreeing to a two-year extension on the back of a strong individual year.

"He's a freak of a talent and if that's where Parramatta board are going to go then that's it, we can't really control what happens," Brown said.

"Obviously it would be disappointing but a lot of people are off contract and that means a lot of movement will be happening, that's just the way it is.

"It's a business these days, especially with everything that's been happening. Everyone knows they're off contract.

"If you come into our camp you wouldn't think so many players said they weren't wanted or plenty of movement is going on. Everyone's positive and the energy is good."