Based on what we know of Adrian Peterson's injury and surgery Thursday, the Vikings shouldn't expect him back this season, according to a prominent orthopedic surgeon who has treated pro athletes in the past.

Dr. Robert Marx, sports medicine surgeon at Hospital for Special Surgery in New York, said based on reports that Peterson has what is known as a "bucket handle" tear of his meniscus, he is likely six months away from a full recovery — meaning Peterson wouldn't play again this season.

To be clear, Marx is not treating Peterson but has performed numerous similar surgeries in the past.

Peterson had surgery Thursday for what was termed a "repair" of his right lateral meniscus. It was deemed a success.

Still, that's a pretty serious injury, surgery and recovery — more so than another more common procedure whereby the meniscus can be trimmed and an athlete can return in 4-6 weeks.

"The meniscus is a C-shaped structure like the handle of a bucket," Marx said. "With a bucket handle tear, basically the meniscus is totally flipped and the whole thing detaches. … Usually what we'll do is repair the meniscus by suturing it. If you suture it the recovery to return to sports is pretty much six months. You can be on the early side, but that's really it.

And that's the only way to fix that specific kind of meniscus tear, Marx said.

"You either suture it or you cut it out," he said. "If you cut it out, you can return to play faster, but that's not good for the long-term health of the knee."

In other words, Peterson might have been able to play this season had he chosen that route, but he would have been "guaranteeing long-term problems," Marx said.

Marx said when he performs this surgery on patients he advises them not to limit the weight they put on their knee for 2-3 weeks and not bend their knee beyond 90 degrees for 4-6 weeks.

So is Peterson really out for the year?

"It's season-ending, I think it's very safe to say," Marx said, though he later couched it a bit by saying it could be possible for Peterson to return very late in the season if he is a fast healer — which Peterson has already proven to be after his ACL tear — and is willing to assume some risk.

But Marx added: "If you're going to go through the trouble of repairing it, it wouldn't make any sense to play at four months. He may be ready. Whether it's a smart idea or not is another story."