A tiny piece of connective tissue no bigger than an index finger.
It’s the reason why starters choose to sit out most, if not all, of the NFL preseason. It’s the reason Super Bowl-worthy seasons have withered into insignificance. It’s the reason star players have had their careers derailed.
The ACL is public enemy No. 1 for NFL players, coaches and fans alike. The reason why ACL tears are such a big deal is two-fold. For one, recovery is a grueling process. With the contact-heavy nature of football especially, rehabilitation and physical therapy typically last anywhere from 8-12 months, and secondly, even after that process is over, there is no guarantee that the player will ever be the same as they were preinjury.
Adrian Peterson is a prime historical exception of this, as after just eight months of intense rehabilitation from an ACL tear, the running back began a season in which he went on to become the NFL’s Most Valuable Player and fell just eight yards short of the single-season rushing record.
Peterson’s case is, of course, quite the anomaly. While, in many instances, players are able to come back and make an impact, it is rare that they play up to the same level they were at beforehand.
As was the case with Kansas City running back Jamaal Charles, who racked up three straight 1,000-yard seasons and was the focal point of the team’s offense. Five games into the 2015 season, however, Charles tore his right ACL and has never looked the same since. A guy who was once a Pro Bowl lock year after year has amassed just 343 total yards in the three seasons since coming back from the injury.
While collisions and low tackles are often the causes of injury, the vast majority of ACL tears happen in the absence of contact — in fact, more than 70 percent of them occur without a direct blow to the body. Quick cuts, sudden stops and awkward landings are just a few of many possible culprits that spawn hellish tweets that the football gods summon fanbases to.
In fact, ACL injuries are so common in the NFL that over the past six years, there have been an average of more than 20 per season before the season starts alone. So, what can be done to prevent it?
Well, it’s a question that probably doesn’t have a real answer. With strength and agility programs allowing players to hit historically high levels of athleticism, some players are essentially becoming too powerful for their own bodies. While the rest of their muscles grow and become stronger, the ACL stays the same size and has to bear more and more force. All it takes is a little bit too much force going in a slightly unnatural direction for the ligament to tear — in a split second, someone’s career can take a complete 180.
Because of the unavoidable nature of ACL injuries, the premium that is put on quality rehabilitation is eye-popping. Top surgeons, such as Dr. James Andrews (who performed surgeries on both Peterson and Charles), are constantly being called on by elite athletes to provide world-class recovery. But with the knee playing such a vital role in the game of football, getting back to peak performance is anything but a sure bet.
Shailin Singh is the sports editor. Contact him at