By returning so quickly from severe knee injuries, Adrian Peterson and Robert Griffin III are making life tougher for NFL defenses.

And another group you might not expect.

Orthopedic surgeons.

Peterson's incredible MVP performance in 2012, coming off tears of his anterior cruciate ligament (ACL) and his medial collateral ligament, has changed the standards of what injured athletes expect from surgery. And it's changed conversations in consulting rooms across the country.

"High school athletes will come in with a torn ACL, and I'll give them the same speech: six to eight months, return to normal level of play is 12 months," says Michael Jablonski, an Orlando-based orthopedic surgeon. "You'd be surprised how many times they say, 'Well, what about Adrian Peterson?' "

Jablonski has operated on athletes at all levels, including in multiple professional sports (not to mention the Orlando ballet), and he trained under Griffin's doctor, James Andrews. He has seen it all, and yet he hasn't seen anything like what Peterson did.

"Adrian Peterson is not a normal person," he says. "His body, it's just different."

Apparently others in his field are just as awed. Jablonski attended a conference of orthopedic surgeons this summer and "Adrian Peterson" came up in what seemed like every other sentence.

"We were all talking about that," he says. "Someone like Adrian Peterson, it puts a standard up there that's almost unrealistic. He was back [training] in four months. It's just not realistic."

That's started what could be termed the "Adrian Peterson Effect," where athletes don't always like to hear that it takes up to a full year to recover from an ACL tear. And now that Griffin is scheduled to start at quarterback for the Redskins next Monday night after his ACL surgery in January, the expectations for others are heightened even more. ACL tears were once career-ending. Yet when Darrelle Revis tore his last season, he was actually relieved to the point of tears when he found out the diagnosis because he knew he'd be back on the field. Revis, too, is likely to play this Sunday for the Bucs, on the very field where he fell to the turf less than a year ago. These are all exceptions to the rule. It just seems like the rule has changed.

"To get back to truly full strength," Jablonski says, "if you talk to anyone who's had ACL surgery, they'll tell you it takes you a full year."

That includes time for feeling stable on the injured leg and being able to cut without stiffness. The last several weeks of recovery can be deceiving, because the pain is gone but the awareness of the healing knee is still there. So a patient can seem 100 percent without feeling 100 percent.

Consider the case of Derrick Rose, the NBA star who was criticized for not returning to play during the Chicago Bulls' playoff run this spring. Rose had ACL surgery on May 12, 2012, so it's completely normal to feel some effects a full year later. Yet Rose became a punch line for his absence.

Recovery is often confused with desire. Peterson has said he wants to make sure no one is outworking him. Griffin has touted his own will (as has Gatorade) and has used it as a major reason for his fast recovery. Clearly, they both worked extraordinarily hard, to their credit, yet the implication is that hard work can overcome science and anatomy. It's a dangerous conclusion to make.

"If you look at studies and what's been done in the past, the human body can only recover so quickly," Jablonski says. "It's hard to tell patients it's a big injury, on average it's six to eight months. That's a hard thing to swallow, especially if you're an 11th grader going into his senior year."

What's lost in this is an incredible advance in science. Even a year is a remarkable time for a recovery from this kind of injury.

"The reason why patients do so much better now is the rehab," Jablonski says. "Back then, they would put people in a cast or a brace and leave them there for four to six weeks. People would not get their range of motion back. It's hard to get back to athletics with a stiff knee.

"Now we start moving the knee the next day. There is no time where we're not moving the knee. Really what's allowed us to be more aggressive is in the rehab."

Yet even rehab has its variances, whether because of a patient's surrounding muscle, unexpected complications, or even genetics.

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