What is a torn meniscus? And what does it mean for Vikings’ J.J. McCarthy?

The Vikings’ J.J. McCarthy tore the meniscus in his right knee during the team’s 24-23 preseason victory Saturday over the Raiders. But what exactly is a torn meniscus and what does it mean for the rookie quarterback?

A tear in the meniscus — the rubbery cartilage that acts as a cushion in between the shin and thigh bones — is a common knee injury, according to MayoClinic.org. That’s particularly true for those who, like football players, twist or rotate their knees with their full weight on it.

The Vikings have already determined that McCarthy will need surgery for the tear in his right knee, coach Kevin O’Connell said Tuesday.

If the tear is small enough that McCarthy would require just a trim to the damaged cartilage, he could return in several weeks. Players often opt for a full meniscus repair, though, since the surgery typically yields better long-term results. The return from a full meniscus repair can take three to six months — most or all of McCarthy’s rookie season.

Dr. Ryan Fader, a specialist in orthopedic surgery and sports medicine with Allina Health Orthopedics — and a local sports fan — said he was “literally stitching a meniscus back together” when he heard the news about McCarthy. Not a lot can be known until surgery occurs, Fader said, but he elaborated on the possible options for McCarthy.

“The trimming type of scenario, that can be better for getting someone back quicker but it can also set you up for problems in the future because you’re missing some of that cushion, and that can cause some wearing and tearing of the cartilage,” Fader said. “Or if it’s a repair, it’s a little bit of a longer recovery process and longer return to get back in the sport but it can have some pretty major upside in the long term as far as protecting the knee and giving him a nice, healthy knee for the long run.”

McCarthy’s youth will help, he said, in both healing potential and a likely lack of other underlying issues such as arthritis or other cartilage problems in the knee.

“The big thing for fans to know is that I think he’ll come out of this OK,” Fader said. “The timeline is up in the air right now, but I do think he’ll come out of this OK. I don’t picture this being a career-ending injury for him.”

There’s a definite chance he could be back this season, Fader said.

“I wish him a speedy recovery and as a Vikings fan I’ll keep my hopes strong, knowing that he’s getting good care and the right thing will be done,” Fader said.

Vikings staff writer Ben Goessling contributed to this story.