On Dec. 24, 2011, Adrian Peterson picked up a dusty, dog-eared book. "How to Recover from a Torn Anterior Cruciate Ligament," the cover read. He flipped through the first few pages, shook his head and set the thing on fire.
The Minnesota Vikings tailback grabbed a pen of grit and sweat and seemingly superhuman healing powers, sat down and re-wrote the book on ACL rehab. In five months, he was working out, shuttling and jumping and bursting. In eight months, he was at full speed.
On Sept. 9, 2012, Peterson launched a 2,097-yard, 12-touchdown assault on the NFL, carrying his Vikings to the playoffs and earning The Associated Press' NFL MVP award.
Now, every NFL player who suffers the same injury picks up the book Peterson wrote. Each one flips to the back, reads the fairy-tale ending and sets off down the same yellow brick road. Unfortunately for non-superhumans, coming back better than ever in eight months is unrealistic—and may be unwise.
Decades ago, ACL injuries were poorly understood, and reconstruction surgeries were poorly executed. As Justin Shaginaw, ATC, and Arthur Bartolozzi, M.D., wrote for Philly.com, the crude surgery and insufficient rehab often ended careers.
In the 1980s and 1990s, the advent of arthroscopic surgery and improved rehab techniques enabled players to return much faster, for better or worse.
A 2002 study in Arthroscopy: The Journal of Arthroscopic and Related Surgery looked at ACL injuries in the NFL from 1994 to 1998. The data came from surveys of every NFL team's trainer. For players with no swelling, typical range of motion and sufficient strength, 90 percent of doctors allowed them back on the field in six months.
Even that wasn't fast enough for Hall of Fame receiver Jerry Rice. He shocked the football-watching world in 1997 when he blew his ACL in Week 1 and got back on the field in Week 15.
Rice's rehab was nowhere near complete, though. In 2012, he told NFL Live the cracked patella he suffered in that game was due to his hasty return, per Michael David Smith of Pro Football Talk:
I feel that I rushed myself back to the football field. And I think that with Adrian Peterson, he’s doing the same thing. Because we are accustomed to being out there with the guys, sweating with the guys, fighting on the football field. And if you’re not able to do that you just don’t feel connected. And that’s the reason why I rushed back. I hope he doesn’t do the same thing.
This was simply too fast. Rice wasn't breaking the mold; he was just breaking the rules. At the time, other athletes thought they could pull off similar turnarounds.
Dr. Christopher Harner, president of the American Orthopedic Society for Sports Medicine, told USA Today's Gary Mihoces this was doomed to fail.
"In the early 2000s, there were a lot of people pushing—without any science—returning in like 2-4 months," Harner said. "Many of these athletes weren't ready. They didn't have the muscle power. They didn't have the balance...their knee would fatigue, and they'd blow the graft out again."
Today's quick, complete returns aren't fueled by patients who ignore doctors' orders, such as Rice, but advances in treatment, surgical techniques and rehab.
Dr. David Chao, a former NFL trainer with 17 years of experience and current columnist for the National Football Post, did a long-running series tracking the ACL rehabs of Denver Broncos linebacker Von Miller and New England Patriots tight end Rob Gronkowski. In that series, he explained exactly how today's treatments facilitate better, faster return to play.
One therapeutic advance has been extended "prehab," range-of-motion rehab before surgery and an extended wait before performing the reconstruction. This lets swelling go down and allows the knee to retain as much of its pre-surgery flexibility as possible.
In the mid-1990s Arthroscopy study, 90 percent of surgeries were done two weeks post-injury, 3 percent were done three weeks after, and 3 percent were done just one week after injury. As Dr. Chao wrote, Miller's surgery came after two-and-a-half weeks of prehab, and Gronkowski's surgery came more than a month post-injury.
"A chronically stiff and swollen knee is among the worst outcomes from ACL surgery and should be avoided at all cost," he wrote. The long pre-surgery waits for Miller and Gronkowski "were meant to speed their recovery and return to play, not delay it."
The surgery itself is largely similar over the past two decades. Over 81 percent of mid-1990s ACL reconstructions used a patellar tendon graft. That's the overwhelmingly preferred choice today, too, per Dr. Harner.
"Putting [the graft] in the right spot, using the athlete's own tissue and returning them cautiously with correct rehab. Those are the three keys," said Harner, who called the athlete's own patellar tendon or hamstring tendon the optimal graft. Synthetic replacements and cadaver tendons have been tried, but Harner thinks "your own tissue is better."
Dr. Chao notes many reconstructions now include an innovation called a "notchplasty," which gives the graft more room to grow and reduces the risk of tearing.
Rehab starts post-surgery. The standard R.I.C.E. treatment (rest, ice, compression and elevation) for soft-tissue injuries is still important, but the rehabbing athlete will utilize a continuous passive motion machine to help regain range of motion, as well as ice machines and anti-inflammatories:
I give my patients four practical goals to reach by the end of week 2. First, we want to get their knee completely straight. Second, we want to perform a straight leg raise. After that we want to progress off crutches and slowly walk normally (heel-toe gait) without a limp. Finally, the last goal is to gently pedal a full revolution on an exercise bike.
If the athlete can hit all four of those goals within two weeks of the operation, Dr. Chao wrote, he's in the 90th-plus percentile of all recoveries and well on his way to a fast turnaround.
Weeks four and five focus on strength, using foot-planted exercises such as squats and lunges that don't strain the graft. At week six, Dr. Chao's on-track patients may run short distances in a straight line. "I prefer that a patient jog for 500 yards with normal stride and no limp rather than someone who runs five miles while limping the entire way," he wrote.
After three months, patients still on the fast track may return to on-field drill work. Dr. Chao recommends an ACL brace be worn at this point. Peterson can be seen wearing one in the video above.
It's at this point that athletes seem deceptively close to complete recovery. Rice went out and played in a game (and cracked his patella). In 2008, San Diego Chargers quarterback Philip Rivers participated in minicamp 100 days after surgery. In 2014, soon-to-be Tennessee Titans quarterback Zach Mettenberger threw at his pro day.
Many of the athletes who suffered ACL injuries during the 2014 season are at this point in their recovery right now. Detroit Lions linebacker Stephen Tulloch posted this Instagram video of himself doing on-field drills at four months post-op:
For all the prehab and rehab, though, Tulloch's knee isn't healed. The ligament needs to regrow along the graft, which Dr. Chao describes as a "scaffold." Tissue, blood vessels and nerves need to form. No amount of grit or effort can speed that up.
"The process of turning any tendon graft into a ligament takes a minimum of 18 months," Dr. Chao wrote. Though Peterson was running wild through NFL defenses in 2012, his reconstructed ACL was nowhere near healed. In fact, even as he was bursting through linebackers and racing past safeties, his recovering knee still wasn't performing at pre-injury levels.
A 2015 study in the Journal of Orthopaedic & Sports Physical Therapy tested athletes one year removed from ACL reconstruction against their teammates in NFL combine drills: the broad jump, vertical jump, modified long shuttle, modified pro shuttle, modified agility T-test, timed hop, triple hop, single hop and crossover hop.
Researchers found no difference in performance between healthy and rehabbing athletes in two-legged tasks such as running and jumping but found significant deficits in reconstructed knees in one-legged tests. Despite an apparent return to full performance, the ligament still isn't fully healed—and isn't out of the danger zone for re-injury.
That's exactly what happened to St. Louis Rams quarterback Sam Bradford.
Unfortunately, per Dr. Chao, chances for full-performance recovery drop "significantly" after a repeat ACL rupture. One of the primary reasons: The patellar tendon has already been used as a graft donor, so his surgeon will likely have to use a different tendon or source a cadaver gift.
Even without a re-injury, players such as Gronkowski, with multiple ligament tears and/or cartilage damage, often have an even longer wait between being cleared for full-speed play and truly reaching pre-injury performance.
Gronkowski's Pro Football Focus grades back this up: He had only two positively rated games in the first five weeks of the season but only one negatively graded game the rest of the year. Despite the slow start, he finished the season as PFF's highest-graded tight end.
At 13 months post-surgery and beyond, the ligament's re-growth is well along. Once the "ligamentization" process is complete, per Dr. Chao, the reconstructed ACL is as little as half as likely to rupture as the other knee's healthy ACL!
"Early return has become the industry standard," wrote Dr. Chao. "In a perfect world, an athlete would sit out two seasons before playing, but this is simply not practical."
Peterson's super-fast return has given other athletes false hope that getting back on the field is simply a situation of mind over matter.
"I’m just trying to cut the time in half," Arizona Cardinals defensive lineman Darnell Dockett told the team's official site a little over a week after his late-August ACL reconstruction. "Adrian Peterson did it and came back and led the league in rushing. I just try and look at the whole situation. If there are ways I can cut corners by going four times a day I’ll do that. It doesn’t exactly come easy."
No, it doesn't, especially since Dockett had an MCL tear, too. At the time of this writing, Rotoworld lists Dockett as "questionable for OTAs." OTAs typically occur in late May, which would be nine full months after Dockett's surgery. That would be fast indeed for a multi-ligament rupture but hardly cutting the time in half.
I compiled 27 ACL injuries in 2014 among NFL players with a verifiable return timetable and secure roster spot. The average of their projected post-op return time: just under 10 months. With all the modern innovations in pre-surgery treatment, reconstruction and rehab, most players' knees still aren't strong enough for a safe return to play until at least nine months out.
|Notable ACL return timetables, 2014|
|Name||Surgery Date||Time to Week 1||Likely Return|
|Jared Abbrederis||Aug. 8, 2014 (approx)||13 months||Training camp|
|Branden Albert||Nov. 24, 2014 (approx)||9.5 months||Week 1|
|Kiko Alonso||July 17, 2014||14 months||OTAs|
|Sam Bradford||Sept. 8, 2014||12 months||Training camp|
|Armonty Bryant||Oct. 24, 2014||10.5 months||Minicamp|
|Darnell Dockett||Aug. 26, 2014||12.5 months||Minicamp|
|Carson Palmer||Nov. 18, 2014||9.5 months||Minicamp|
|Lamarr Houston||Nov. 3, 2014||10 months||Week 1|
|Sean Lee||June 12, 2014||16 months||Training camp|
|Stephen Tulloch||Oct. 1, 2014||11 months||Training camp|
|Assembled media reports|
Peterson's still the exception, not the new rule.
Players with clean ACL ruptures, no other torn ligaments, no collateral damage and low positional requirements for reactive cutting can push the timetable; Cardinals quarterback Carson Palmer told ESPN's Ed Werder he'll be ready for May OTAs after his November surgery.
However, unless the 35-year-old wants to risk a Bradford-style re-injury—and the remainder of his career—he'll do the smart thing and sit out until training camp.