The retirement of 28-year-old receiver Steve Smith should be a swift reminder that superhuman recoveries like the one made by Minnesota Vikings running back Adrian Peterson remain the exception, not the norm.
His story now sits on the opposite spectrum of Peterson's.
The Vikings star tore his anterior cruciate ligament during a freak injury in December of 2011, but miraculously returned the next season to nearly break the all-time single-season rushing record. Arguably no recovery from knee reconstruction—regardless of sport—has been as fast and effective as Peterson's in 2012.
However, Smith will be the first to vouch that rehabilitation from major injury is far from a cakewalk—no matter how effortless Peterson made it seem this past season.
A former second-round pick of the New York Giants in 2007, Smith caught 65 passes in his first two seasons before erupting for 107 and 1,220 yards during a Pro Bowl year in 2009. Embracing a similar role to the one now occupied by Victor Cruz, Smith appeared destined to be the NFL's next great slot receiver.
By the following December, Smith's promising NFL career came to a crashing halt.
A significant injury to Smith's knee late in the 2010 season required microfracture surgery, a major operation used to repair damaged cartilage in the knee.
According to the University of Maryland Medical Center, doctors must make small holes (or microfractures) in the bone of the knee to help repair the surrounding cartilage. The operation is used to help avoid complete knee replacement.
While the surgery was successful, Smith never recovered as an NFL receiver.
The Philadelphia Eagles eventually signed Smith to a free-agent deal the next summer, but he wasn't the same in terms of burst or athleticism. Like the rest of the "Dream Team" in Philadelphia, Smith failed to make his return to prominence.
The former Pro Bowler caught just 11 passes in nine games with the Eagles in 2011. He was later placed on season-ending injured reserve with a bone bruise on his surgically repaired knee.
In 2012, Smith tallied 14 receptions for only 131 yards in nine games with the St. Louis Rams. He was a healthy scratch in seven different weeks.
The Bucs did give Smith a minimum deal this offseason, with optimism that the still-young receiver could provide something after three years of recovery between now and the microfracture surgery.
But instead of attempting to make another comeback with his fourth team in four years, Smith decided to hang up the cleats at just 28 years old.
Smith now joins a long list of players who saw a significant injury and recovery end their careers in the NFL.
While Peterson's miracle recovery dominated headlines throughout last season—and Robert Griffin III's rehab figures to do the same this coming season—Smith's type of story is rarely discussed.
Avoidance likely stems from the stunning prevalence of this story.
According to Newsday, the American Journal of Sports Medicine published a 2010 study that revealed only 63 percent of NFL players who underwent ACL surgery returned to play another game. The other 37 percent were unable to ever play again.
Dr. James Andrews, who operated on Peterson and Griffin III, told Newsday that 55 percent of the NFL's ACL patients are out of the league in just two years.
Andrews also warned that Peterson's recovery should still be considered the rarest of medical feats:
The last thing I'd want people to be thinking is people are coming back quicker and quicker. The few individuals that you know of who have come back quickly are what I call 'superhuman' athletes . . . There are only a few of those superhuman athletes out there. Their healing potential for some reason is much better than the average patient, but you can't extrapolate their ability to come back from an injury to the average athlete.
As Andrews so eloquently states, Peterson is the rarest type of athlete. Recoveries of his nature are so uncommon that his usage of the word "superhuman" hardly feels overstated. What Peterson accomplished over a calendar year in 2012 is one of the most impressive athletic feats in recent memory.
Smith's failed attempt at a comeback—even three years down the road—reinforces Andrews' message.
As ESPN's Adam Schefter tweeted above, for every Adrian Peterson on the operating table and in the training room, there are 100 like Smith.
Peterson has obviously set a new golden standard for recovery from serious operations and it's certainly possible Griffin III will replicate such a feat when he returns from ACL surgery in 2013.
But more often than not, operations such as a mircofracture surgery and knee reconstruction are career-altering occasions. Smith's retirement Wednesday is a painful reminder of that fact.