If you’ve been impressed by Adrian Peterson’s comeback from major knee surgery, you’re not alone. The surgeon who performed the operation on the Vikings’ star running back can’t believe it, either.

NFL.com reporter Jeff Darlington has the story of Peterson’s long road back from his Christmas Eve injury, in which he tore the anterior cruciate and medial collateral ligaments in his left knee. And it begins with the words of James Andrews, the world-renowned surgeon who operated on him.

“I can’t believe it,” Andrews told Peterson’s parents, according to the article. “For this guy to have played as much football as he’s played his whole life, and not to have hardly any wear and tear, it’s incredible. I’ve never seen a football player, especially one who runs and cuts as much as he does, with a knee in that condition. It’s like a newborn baby.”

Fast forward 11 months, and Peterson is a leading candidate for the NFL’s Most Valuable Player and Comeback Player of the Year awards. He has rushed for a league-leading 1,128 yards and seven touchdowns in leading the Vikings to a surprising 6-4 record.

Darlington’s article takes an in-depth look at Peterson’s comeback, along with the return of Kansas City’s Jamaal Charles, who tore his ACL early in the 2011 season. He’s ninth in the league with 734 yards.

Follow Kevin Cusick at twitter.com/theloopnow.