Last month, Green Bay Packers' wide receiver Jordy Nelson jumped up to grab a ball and landed with his season over. In 2014, against Manchester City, Southampton forward Jay Rodriguez leapt off turf that he wouldn't touch again for another 422 days.
Anterior cruciate ligament injuries suffered by high-profile athletes such as Nelson and Rodriguez, as well as Arsenal's Theo Walcott, have helped the small ligament that connects the shin bone to the thigh bone garner more and more attention in recent years. The Secret Footballer - an anonymous Premier League player who blogs on various issues around the game - described tearing an ACL as "one of the most feared of all football injuries."
For Rodriguez there's light at the end of the tunnel; he made his comeback last month and started his first game for Southampton a few days later, although he's still not yet played a full 90 minutes.
Nelson, however, is staring down the barrel of a long hard slog of surgery, rehabilitation and heartbreak. "It's really draining," New York Jets cornerback Darrelle Revis, who tore his ACL in 2012, said. "It's a dark place because the rehab is pretty tough on a day-to-day basis. Sometimes you might think you're not doing enough for that day, and that's something you have to fight through."
He doesn't stand alone. Revis referred to the 'ACL Club' when responding to questions about Nelson and memberships are being snapped up quickly. As of August 24, there have been 25 ACL injuries in the NFL, and four games into the Premier League season there are seven players absent from action because of ACL injuries. 2013 was a landmark year for the NFL where a record 63 ACL injuries were recorded.
If the average recovery time for an elite athlete to be back on the field is say 10 months - it varies wildly from player to player - that's a total of 20 playing years' lost in the NFL this season alone. That's about as rough an estimate as you're likely to get too; Minnesota Vikings running back Adrian Peterson suffered ACL and MCL tears but was back in nine months, while Newcastle defender Ryan Taylor spent more than two years battling the injury with a relapse in the middle.
Peterson stepped back onto the field against the Jacksonville Jaguars in September 2012. Nine months after he was carted off with his knee in pieces, he managed 84 yards on 17 carries and two touchdowns. Not bad all things considered. By the end of the season he'd ran for 2,097 yards - the second-highest total in the history of the sport.
The 30-year-old is the exception and not the rule. For those able to return to action they may never be the same again. A study in 2014 of American collegiate sports found that athletes who have an ACL reconstruction prior to their Division I college athletic career are almost 20 times more at risk of injury with high-level athletics. Those who have suffered ACL injuries are '14 to 15 times more likely' to have another before they call time on their careers.
Another 2012 study also found that athletes have only a 43 percent chance of getting back to their previous level after suffering an ACL tear. Whichever way you carve it up, an ACL injury can be as bad as it gets for a professional athlete. All the more concerning is that the majority of ACL injuries are non-contact and not the result of a huge bone-crunching tackle. They're caused by a twisting or cutting action that causes a tear; like a serial killer in a slasher flick they're always lurking silently just out of sight, ready to strike when everything seems normal.
Why is it then, that there's a group of experts who believe the vast majority of ACL injuries can not only be avoided - but be predicted too?
Dr. Timothy Hewett, director of biomechanics and sports medicine research at the Mayo Clinic claimed earlier this month that ACL injuries in the NFL could be reduced by anywhere up to 70 percent. How? The solution starts with a surprisingly simple assessment - and it opens up a whole can of worms about how professional sports teams treat their athletes.
"Are Dr.Hewett's findings accurate? Absolutely," says Dr. Trent Nessler when asked by GiveMeSport. "Look at Robert Griffin III at the Combine. The movement you see with his knees not aligned in the broad jump is exactly the type of movement that puts him at risk."
Dr. Nessler, National Director of Sports Medicine and Associate Editor of the International Journal of Athletic Therapy and Training, has spent the last 12 years pushing for answers to the ACL epidemic.
"I have assessed over 2,000 athletes at all levels from professional to high school and you would be amazed at how dysfunctional even some elite athletes are. The cool thing is you can see it. If you can see it, you can fix it," he explains.
"I'm a huge advocate for individual movement assessments as a part of pre-season physicals. Every athlete moves a little differently and it is poor movement that puts even elite athletes at risk. We developed a sequence of movements that allow us to determine where the problem is and how we address it. This is simply based on the last 15 years of science. Until now, you needed a PhD level person to do it. What we developed and are using in our work leverages technologies to make it more readily available, reliable and effective."
The process of analysis amongst experts can start with simply watching an athlete jump, recording the process and watching it back. Dr. Hewett's methods include watching athletes jump from a milk crate and, while that's overly reductive and isn't the panacea to ending ACL injuries, it's startling just how much can be done with relatively little effort.
"In our study, we found that by assessing the athlete, creating correctives based on their movement and implementing with our protocol, that we had a 58.2 percent reduction of all lower kinetic chain injuries from the foot to the spine. Honestly pretty simple but amazing results," Dr. Nessler says.
"For one Division I College soccer team, this equated to a $200,000 savings in two years. Just one team. We had a 60 percent reduction in the number of days out injured and had a huge impact on sprint speed/vertical jump over time. Decreased injury rates, decreased cost and improved performance."
The most recent series of the NFL's Hard Knocks programme shed plenty of light on life behind the scenes with the Houston Texans. Aside from the slick production values and loose mouth of coach Bill O'Brien one thing is apparent; these men work like dogs. Montage follows montage of linemen in the weight room, JJ Watt tossing tyres and running back Arian Foster dripping with sweat as he prepares for a new season that he is destined to miss the start of with a groin injury.
Deeply engrained in the collective psyche of most sports teams is the need to work hard and push to the limit. At face value at least it seems effort is prioritised over intelligence when it comes to training.
"Absolutely not," says Dr. Nessler when asked if teams do enough to protect their athletes. "The science is crystal clear on what we should be looking at, and yet only 5-10 percent actually do."
15 of the 32 NFL teams use wearable technology and 15 of 20 Premier League clubs use STATSports technology to track movements and log data from training sessions. Although, it's one thing having access to the data and another thing altogether interpreting it. "It's like providing the painter with paint," concedes Gary McCoy, the sports performance director for Catapult who provide the tracking technology for NFL teams. "It's up to the artists what they render."
It seems as though European football clubs are a little further ahead of the curve than their US counterparts as it stands. Swansea, for example, have emerged at the forefront of sports science in the Premier League, while Stoke's head of sport science, Damian Roden, told GiveMeSport that they deploy "video as part of a screening process to look at movement patterns and identify those at risk."
He added: "The difficulty is that every player is different and responds differently to training and games."
The data seems to back that up too. Data from injury experts Physio Room shows that ACL injuries in the Premier League remain fairly constant over the last 10 years and, while the NFL say the numbers are starting to fall, they still affect a higher proportion of players in the league than they do across the pond, even when you factor in the bigger rosters and extra teams. Of course it's a more physical sport but 23 of the 25 ACL injuries in the NFL this year were 'non-contact'.
"There's nothing sinister going on," explains Dr. Nessler. "I think it is simply a lack of understanding of the science and how to apply that in a sequential way to determine the root cause for the problem. You need to push to the limit and push hard but don’t do it if you are simply training bad movement. There is a balance but the first step in that is being aware of what the movements are in the first place."
There's progress being made in the NFL. Chip Kelly's Philadelphia Eagles rely heavily on sports science data to fill in the gaps. In one pre-season session DeMarco Murray, recently acquired from the Dallas Cowboys for whom the running back carried the ball 436 times - the seventh-highest figure in NFL history - sat out because the data showed he was dehydrated. The Eagles lead the way in seeking proactive prevention, and others will surely follow.
Other factors, such as fatigue and the rush to get back to action too soon before rehabilitation is complete, figure as major contributors, while more studies are starting to show a history of concussion is an issue too.
But, as Dr. Nessler spells out, this is really an open and shut case. Whatever's behind the rise of the ACL, be it the increased physicality of modern sports or rule changes, there's plenty more that can be done to help out those on the front line. "ACL injuries are non-contact in orientation and you can reduce those by 70 percent simply be identifying those at risk and training them properly once identified." It really is as simple as that.
One size doesn't fit all when it comes to training and the fact that so many careers are damaged, and so many months are lost in hospitals and rehabilitation facilities for no good reason should be a warning for all teams, no matter what sport.